Printer Friendly Forum Posts - Blown JBL PX300.4 Amplifier?

Ok, so I have a JBL px300.4 amplifier (125 wattrs x4 rms), and I went to get a car wash the other day and my trunk must have leaked, and my amplifier stopped working, as soon as I realized it I immediately turned everything off. I took my amplifier apart and here is what I found to be the problem:

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So I was wondering - rather than buying a new amplifier, couldnt I just simply solder on replacement parts? I'm not sure what those are, but I think they're tiny capacitors...am I right? Where could I find replacment parts?

In case its not clear on the picture, the blue (capacitor?) that is blown up and hanging on by a thread says "(M)P", "85 DEGREESCELIUS", "U5E" (maybe micro 5E), and "16V"

Any help would be appreciated.
Thank you

What are the numbers on the other side of the cap. See the caps behind that one that say 16V 22micro F those are the numbers we need. When replacing them, it is very important that you notice the polarity of the cap. The board appears to have a + on the positive location. The cap will have the negative marked.

Do not set the amp on carpet. There are MOSFET transistors in the amp. They are static sensitive, I have only heard of static taking one out. But they say it is possible.

Its hard to tell because the plastic surrounding the cap melted, I believe it says 16V 10uf, but it might be 18uf. Im leaning more towards 10, because I grabbed a magnifying glass and took a look and I dont seem to see any sign of a horizontal line in the middle of the 0 to indicate an 8.

hey i am an idiot yo said mosfet what is that and what does it mean? and what about sub box carpet? or does it have to be pos charged?

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Blazerspl
6 rockford 12s
5500 watt pa amp
12.0 cubic enclosure
BIG 3

MOSFET - Metal Oxide Semiconductor Field Effect Transistor.

They are static sensitive when not referenced to a ground, such as the chassis or heat sink of the amplifier. While mounted in the chassis, they are (relatively) immune to static, but while out of the chassis, as this board is, a TINY static pop - one so small you can't even feel it - can damage them beyond use.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

wow its amazing i wonder how often that sorta thing happens?

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Blazerspl
6 rockford 12s
5500 watt pa amp
12.0 cubic enclosure
BIG 3

When Rockford built the Power 650 in the mid 1980s, it was then interpreted by a bunch of fella's from Lake Charles, La. to stand for Made Of Something (Don't Remember what word goes here) Extra Terrestrial. But Haem's translation was right on the money.

I have tried to take one out with no luck. However I do know of one that was taken out by static. It must happen occasionally, the manufacturers take all kinds of precautions when shipping them.

Ok, so I went to the local shop to buy some capacitors. It couldn't find the exact same capacitors, so I bought some that were rated at 16v, and 10 uf, but rather than 85 degrees C they're 105 degree celcius - i didn't think that would make a huge difference. I soldered them in and bolted everything back up. I now have a new problem!

The protecion light doesnt come on anymore, but as soon as I turn on the radio and the amplifier powers up I hear a humming noise coming from the amplifier. I looked at it, and the protection light is off, the power light is on, and the I-E/OPT light is flashing. After about 5-7 seconds the fuses blow (2x30amp) and the humming stops.

I turned everything off, replaced the fuses, turned the car on, without the HU in, and then rechecked the fuses - they were fine. So they blow pretty much when the amp powers up.

Any thoughts?

Chances are it has shorted output transistors. If you have a meter and are willing to do a little footwork, I can help you get it repaired.

I have 2 multimeters of the same brand and model. 1 is just newer.

After you talking about the mosfets before, I was doing some research on them, and apparently your meter has to diode test with more than 3.3 volts. I set one meter on diode testing, and set the other to read DCV, and it read 2.76 V. Did the reverse and the other read 2.91 V. Are my meters ok, or do I need one that does 3.3 volts?

Either way I'm willing to try. I want to learn more than anything. I appreciate your help. I read in another thread that you run your amps in 1 ohm sometimes, even if they arent' stable and then you just fix them if they blow - so I'm assuming you're the man for the job.

Thanks a lot!

I have no idea about the 3.3V thing you are talking about. I am not familiar with that particular amp. Can you take a picture of the circuit board. One photo of the top of the circuit board will be fine. No need to remove any clamps yet.

I remember that thread, I think I was telling him not to do it. He wasn't hearing that. SO I tried to scare him into not doing it.

OK well what i was reading about the 3.3 v was not specific to my amp - it was just mosfets in general. Maybe inaccurate info. Anyways the thing is completle removed from the casing because like I said I have already replaced those 2 capacitors. Pics will be up in a few minutes.

Here are the pictures:

1.Superior view of the circuit board

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2.Superior view of the circuit board zoomed (1/2) (The capacitors I changed are the 2 brown ones that are right at the top left of this picture- may be difficult to see the brown)

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3.Superior view of the circuit board zoomed (2/2)

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4.Inferior view of the circuit board

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*subscribing to the thread*

Bottom photo. The 8 larger devices are the output transistors. With your meter set to the diode test function, touch one meter lead to the large area of metal on the back of the transistor, the other meter lead first on the left leg, notice the reading on the meter. Then move that lead to the right leg. Notice the reading. Check all 8 of the transistors, One or two of them will give you a very low reading compared to the others. Let me know what you find out. Do not power the amp up without mounting the board back into the heat sink. You must put all screws back in. All screws that hold transistors down. Cover screws ok to leave out.

If you find the devices that are shorted, give me the numbers on the front of the device.

Which end do I consider left? Because I have 4 on each end of the board 4 are "right way up" and 4 are upside down. Do I consider left with the "body" above the three legs, or do I consider left with the "body" below the 3 legs when looking at it. Thanks

For what we are doing now, it does not matter. One or two of the transistors will read very near .000 on either left right or both. If you do not find any reading close to a short, check for bad solder joints on the small transistors between the output transistors.

Ok, so essentially just to brifely go over my meter. When I set it to diode testing - is I hold the probes in the air it reads 1 on the display - so 1= no connection. On the diagam "*" means that it gave me a reading slowly kept increasing and after 1900ish it went to 1.

posted_image

With the meter on diode test, hold the leads together, what number is displayed on the meter?

When they arent touching it reads:

------------
| 1 |
------------

When the leads are touching it reads:

-----------
| 001|
-----------

Note the difference in alignment (left vs right). When I get a reading it is alligned to the right, similar to when the leads are touching.

The outputs appear to be fine. See the 4 devices with no exposed metal on the back? These are the rectifier diodes, One lead on middle leg, other lead to left then right leg. Notice reading on both.

just to clarify - the 1 and the "*" on my last diagram were 1s and not 001s, as in similar to no connection, not leads touching. I cant check the other ones right now, because I am not a home now. But I will get to it asap and get back to you. I appreciate all the help!

Here are the results from the next part - seems pretty consistent to me.

posted_image

Those appear to be ok too. When you took the amp apart, did you remove any rubber pads that went between the transistors and the heat sink?

Between the transistors/circuit board and the casing it was bolted to, there is this long sort of film like material that has a rubbery feel to it: here are some pictures.

Here is just a quick "blow-up" view of the entire amp:

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Here is the rubber I hope you were referring to:

posted_image

Actually, I just noticed all that "burnt" looking stuff on the last picture right..........................here ^^^^^ looking at the picture now. Relevant?
It is possible that when I put everything back together to test it that maybe one of the transistors didnt have the rubber thing between it, because when I pulled it out it was folded on itself near the end.

If it was folded and one or more of the transistors were touching the heat sink, that is definitely your problem. The hot spots on the bottom of the board are nothing to worry about. But since you have the board out of the heat sink, it might be a good idea to add a little solder to the joints. Chances are on the other side of the board, there are 2 high power resistors. These are to drop the voltage for the preamp power supply. It is normal for them to run a little hot.

Ya you're right - there are resistors on the other end. So you're saying - I should try putting everything back together again, paying close attention to the rubber strip and try again? Looks like Im heading to good old canadian tire for some more fuses. I only have mini ones left, this take ATO ones.

Just to be safe, purchase a few 5 amp fuses too. If you put the 5s in it and it still has a problem, the power supply should be very well protected. If it powers up with the 5s, and does not blow them, all is fine and you can place the larger fuses in the amp. Do not play it with the 5s, unless you have no other use for them. It will not play loud with 5 amp fuses. They are just to make sure there are no problems at power up.

Ok, so I bolted it all back together - left the fuses out and hooked up the 12+ and ground, no RCAs, no speaker, no Remote signal from the HU.
The second I put in the fuse (I used 10a - didnt have any 5a lying around) I got a spark a bad smell and some smoke. I immediately took it out disconnected the power and took it all back apart. Here is whats up:

1) A Capacitor blew up again - another 16v 10uf one - I have the end that blew off, but I cant find where it came from on the circuit board

posted_image

2) Out of the 3 separate devices in the back (the output transitors, the rectifier diodes, and the ones we didnt test - they look like rectifier dioder but have a metal backing. Well the one we didnt test one fried big time.

posted_image

3) The protection LED is broken ( I noticed this before applying the power) I must have done it when manipulating it. Any ideas what spec I would need on another LED to replace it?

posted_image

So, I figured you would want me to redo pretty much everything that has been done so here it is:

posted_image

Oh, wow - I dont know what happened there. I resized them smaller. Guess I screwed up - stupid tap and click on laptops. Sorry - could a moderator fix those for me please? Thanks

That is a power supply transistor. It probably got damaged when the tape was folded and the transistors were touching the heat sink. I have no idea why the capacitors are exploding. Chances are that all of the power supply transistors have been damaged. You will have to pull the exploded transistor out of the board and check the remaining ones just as we did the others. The Metal back of the transistor is connected to the middle leg of the transistor.

IMPORTANT When removing the transistors, it will be less harmful on the circuit board if you add as much solder as the joint will hold, then heat all 3 joints at once, lay your iron across the 3 joints. Now with a pair of pliers gently remove the transistor from the board. You are using the pliers only so you do not burn your fingers. Do not manhandle the transistor with the pliers. After you remove the part, now you can use a solder sucker or desoldering braid to clean the hole out.

What is the part number of the burnt transistor? IRF-Z44, IRF 3205, or MTP50N06? Or something else?

No I'm 100% sure it got damaged this time - it wasn't like that before, or at least got damaged to this extent. Anyways - I have a precision soldering iron that is essentially the size of a pencil - works well for soldering on stuff like this. But I feel like if I am going to completly remove this power transistor I might have to apply the heat to them for a long long time - would it be better to use my larger hotter soldering iron - which would reduce the amount of time I have to hold the iron on the board.

Also - this rubber thing - what is it really? I want to replace it with fresh stuff - is it just an insulator? One of the strips has an extra set of holes in it from the screws that secure the board to the heatsink. The rubber strip must have moved a little when I put it all back together and me not knowing what the stuff was must not have realize it. So the extra set of holes worries me - maybe the rectifier diodes, power supply transistors and/or output transistors are making contact with the heat sink through these extra holes.

The LED - I'm sure I can replace it with any old LED. I'll get on it asap.

The Part number of the power transistor is... I cant find it. Maybe its written on the transistor itself. I'll try to remove it and get back to you.

Actually now that I look at it - the power transistor that fried was on the good side of the board with the intact insulator/rubber strip. Relevant? Or could it have equally have happened on either side due to another transistor touching the heatsink on the other side?

If the outputs were touching the heat sink, it could have damaged it. It is an insulator. I have no idea where you can get a replacement. It is called a Sil-Pad Silicone pad. I use Kapton tape to replace them. You have to remove the adhesive from the kapton tape. You probably should use the larger iron. Or you could cut the legs off of the transistor and remove the legs one at a time with the small iron. Once again the key to saving the board is adding solder to the legs so they retain heat and will easily pull out of the board.

I got it out no problem. However - getting all the solder out of the holes seems impossible. I used the braid to essentially remove all the solder I added - but I can't get it all out of the hole. No biggie for now.

The part number for the transistor is found where? Right on the transistor? It says:

"Fancy italicized "F"" 1G29
FQP
50N08

Kapton Tape? Never heard of it - just googled it. Can it be bought locally? I wont necessariyl completly remove the Sil-pad, but patch it up for sure.

Im having trouble getting readings for the rest of these transistors now. I cant get anything consistent - I just dont understand how they work.

I started with the row opposite the fried one, and I essentially got readings of 1471/460 on all 4. Then I went to the 3 on the same side as the fried one - and I was getting pretty much */1. So I went back to the bottom row and I was getting */1 or 1/1. Is there a more precise method to testing these thing that wont get me frustrated? I essentially positive probe on back plate, and then negative to the left, then to the right. Just isnt working well.

That is a Fairchild part. It is an N channel mosfet transistor rated at 50 amps and 80 volts. I have never seen a 50N08, are you sure it is not an 06? If you can not find Kapton tape without buying an entire roll of it, I can mail you a piece. You need to check the rest of the power supply transistors to see if they are shorted. Even if they are not shorted, I would recommend you change all 6 of them. They all went through the same abuse. They may have been weakened by the strain. There are several other things you will need to check before replacing them. It will be easier to check with the power supply transistors out of the board.

If you are going to use the Kapton tape, you need to replace the entire length of the sil-pad with the kapton tape. There is a thickness difference that will possibly keep some transistors from being held tightly to the heat sink if you just patch the bad spots.

F1G29
FQP
50N06.

It was difficult to read - and it wasnt clear. I was scared to scrape the crud off it thinking I would scrape the letters off - but I made it much easier to read. Its definately 06 like you said.

I just ordered a 20mm wide roll of kapton tape for $5.33 here: https://www.dealextreme.com/details.dx/sku.5442 - free shipping too.

As far as the kapton tape - I didnt mean I was going to just patch the holes. I meant I would add a strip along both end pretty much identical to the Sil-pad just over it. Do you think it would be better to just completly remove the Sil-pad? Btw - thx for the offer for the tape - you've already done much much more than expected.

So now that the fried transistor is out - what do you recomend I do next? Remove all the power output transistors?

When you say you recommend changing all 6 of them - do you mean all 8 of them? Cuz if thats what you recommend thats what I'm doing. You really know your stuff; who am I to disagree.

I thought there were 3 and 3. After taking another look, there are 2 separate power supplies on that amp. Pull the one out and check the 3 associated with it. Check them just as we did the outputs. Check the other 4 also.

Ok, so I pulled all 8. The only one that seems like it has a short was the one that fried. There is full continuity on all 3 legs with one probe on the backing plate. The other 7, with one probe on the backing plate the left and right legs read 1 - as in no connection (not 001), and the middle reads 001.

But like you said if I'm going to replace them all - is it really even relevant?

Oh ya - also when shopping for new ones do I need to look at voltage and amperage ratings or are all 50N06 the same?

It has 2 separate supplies. You could have gotten away with only the 4 on the side with the bad one. You need to check the value of the resistor that was directly connected to the leg of the transistor that blew up. There is only one resistor near that transistor. There is one resistor per power supply transistor. DO NOT remove the resistors. Make sure the one near the blown up transistor is reading the same value as the others. If there is solder bridged from one joint to another, you need to clean them up. We need to connect the amp again and I need a DC voltage reading on the resistors that you just checked. It should be around 5 Volts. If the one that exploded and the one next to it read lower than the other 2 by it, you have a damaged driver transistor. DO NOT remove the resistors or the driver transistor. You only need power ground and remote connected to perform these tests. You do not have to mount the amp to the heat sink. Just make sure none of the components touch the metal of the car.

50N06 = 50 amp N channel 60 volts

Ok, well Its 2:47 am - so I'm going to go to bed for the night. Will try in the morning. Have a few questions though. Considering all the mosfets are out - can I still do the test you said?

Also I'm not sure exactly what you are looking for - you mention we need to check the resistance of the amp and then mention voltage. Do you want to measure the voltage drop after the resistor? or do you want Ohms or...what? Essentially do you want me to check the resistance, or the DCV?
In that case of DVC, would I just set my multimeter to DVC and put a probe on each end of the resistor?

Thank you so much for your help!

Have a good night!

you need to check the resistance of the resistor. Compare it to the resistance of the other 7. Then in order to check the driver transistors, I need you to connect power ground and remote to the amp (with the transistors out of the circuit) Black meter lead on the ground terminal of the amp, red meter lead to either end of the resistor, meter set to DC voltage. Check the voltage on all 8 resistors, either end of the resistor. Should be very near 5 volts. If the exploded one and the one next to it are reading less than the other 6, you may have a bad driver transistor. Post what you find here and do not remove any more parts. Do not remove the resistors to check them.

I did not see any thickness specs on your Kapton tape. The adhesive hampers it's ability to transfer heat. You really need to remove the adhesive from the tape before inserting on the heat sink. Acetone works great, in a metal parts bowl or pie pan, pour a small amount of acetone into pan, set a few inches of the tape into the acetone, let it sit for a minute or so. Acetone is extremely flammable. Remove it from the acetone and rub the adhesive off with your finger. You will be able to tell when that section is clean. Do the same to another few inches until the entire piece is free of adhesive.

Cut the tape a few inches longer than you need it. You can wrap it around the heat sink and using scotch tape, tape it to the outside of the heat sink to hold it in place.

Ok so I went to the electronic store to get a desoldering pump because I ran out of wick. While I was there I decided to check to see if they had the 50N06 transistors and he said they do not have them but they have IRFZ44N - which he said were the equivalents. Are these ok?

Those will work. The only thing we need to check the value of the resistors. If they are below 47 ohms you may want to change them.

working on it.... im trying to clean those holes where the transistors were so they arent bridged.

I looked at your picture, they appear to be 47 ohm resistors. The Z44s should work just fine in those locations.

Ok, so I have all the holes cleaned up - took some time. Anyways - one of the pads on the bottom of the board lifted. It was the middle pad, of where the fried transistor used to be. I don't think its a huge deal because the pad on the top side is still sitting where it needs to be. And I checked on an intact slot, and the bottom and top pads of left, middle, and right are continous with each other. I still have the pads though - when we got to the point of putting in the Z44s, should i stick the pad back in there and solder over it?

Ok, so I'm going to go check the resistors in 5 minutes - I have 1 quick question. You mentioned I need to connect the remote wire - does that mean when I test you want me to have the HU on, playing something? Also - 5amp fuse ok, or should I put 30amp fuses in now?

Throw the pad away. The connection is actually on the top of the board. You want to solder that one from the top of board anyway.

Radio needs to be on for remote power only. No need to turn the volume up. 5 amp fuse is fine.

Well good news is..nothing blew up. Bad news is...I can't get a reading. I replaced the protection LED - so I cans see when it is in protection. So when I turn the HU on, the amp goes into protection and the LED comes on - 3 seconds later that LED goes off, and the "power" led comes on...thats when I can get my readings at the resistors - except 2 seconds later the power LED turns off and the protection one comes on - a nice little cycle like that. So I tried to get readings at the resistors between cycles, but as the power comes on the voltage starts at 0 and climbs - its at 2.3~2.4 when the amp goes back into protection. Im not sure if this is what you expected to happen - and those are the reading you want, or if we are getting cut off early.

The amp can not come on. It has no power supply. Are the 2 resistors near the exploded transistor acting exactly as the other 6 resistors? The LEDs in that amp may work off of remote power.

It is not going to be a real big deal if you can not get the readings. Do you have an old sealed beam headlight laying around? We can use it for a current limiting resistor when attempting to power the amp up. If there is a problem, we can find out without burning anything up.

Ok, well I just looked at them - and I noticed that all of them osscilated between 0 and roughly 2.5 V. However, one of them remained at a constant 12.2 V - exactly what my distribution leading the the amp read - so theres obviously no power regulating going on there. The one right next to it osccilated between 0 and roughly 3.5-4 V. So I figured aha! there it is...but when I brought it back inside I realized this is not the resistors next to the blown transistor - it is the ones on the opposite side - the side which initially had the folded Sil-pad. So it didn't add up - so I figured maybe I screwed up it was dark outside - I'll retest again tomorrow morning.

As far as an old sealed beam headlight goes I do not have one - but I have my laptop power supply which is 19V at 3.2 amps - could we just use this as a power supply instead? I know the voltage is a little high - but the amperage is almost zilch.

No do not use your laptop supply.

Do not worry - I wont do anything without you first saying that is what must be done.

Ok so I re-tested everything this morning in the light and it appears I did not screw up - here are the results of the DCV test:

posted_image

-A few notes to keep in mind. The blown transistor was the one on the bottom right.
-I measured the voltage at both ends of the resistors because I got diffrent results depending on the end I used - so I figured that could be useful.
-Another perhaps useful tidbit of information is that in each row of 4 transistors/resitors, there are 2 resistors not associated with any of the transistors. I decided to measure them for the hell of it...the 2 on the bottom measured normally (ie. fluctuated from 0-1.8 or so). The 2 on the top read 0.0V at all times.....

I need to know if the resistor that was connected to the exploded transistor is connected to the top left power supply transistor. Not the ends connected to the transistor, but the ends of the resistors nearest the center of the board. I think you have a defective driver transistor. If those resistors read near 0 Ohms when checking as described above, follow the trace on the bottom of the board, it goes through a feed through and ends up on top of the board. It should go directly to a small transistor. It may go to a second transistor also. I need the number of both. 2SC and a 2SA numbers possibly. DO NOT remove them I just need the number.

Will check when I get home - but like I said the 2 resistors that read 0 are not ones directly connected to transistors...they are the ones u see inbetween the transistors. Also - the exploded transistor is on the bottom of the board in that picture, and the zero reading resistors are on top. Anyways - I will check and get back to you.

Thanks for all the help btw - it is much appreciated.

Here is the layout of the traces:

Once again - the blown transistor is the bottom right most one. (On the red line with yellow junctions)

You have yellow and purple dots on all 4 corners of the 2 pairs of transistors. What are the part numbers on those transistors?

Ok, wel they arent on all 4 corners of the transistors...the transistors only have 2 poles - there are resistors right next to them to. Its weird...they're wired in parallel. Anyways the numbers written on the side is:

K-632
A1266
GR

The transistors have 3 legs. That one you gave numbers on is a 2SA1266. There should be 2 of those and (2) 2SC****. I looked again at your picture. You have 4 yellow dots surronding 2 transistors. 4 Dots around each. And you have 4 violet dots around 2 more transistors. I am sure that 2 are the 2SA1266 you mentioned earlier. There should be (2) 2SC****. I think that the 2SA1266 is bad, but I need to know if there is a 2SC there also. The 2SA connected to the resistor that was connected to the exploded transistor will need to be removed from the board. If you notice at the bottom of the board, all 3 of the legs of that transistor are bent over to hold the transistor in the board while it was being sent down the line to get soldered. These bends need to be taken out of the legs in order to remove them without damaging the board. One leg will be bent one direction and the other 2 are bent in the opposite direction. I add solder and use a small flat blade jewelers screwdriver to straighten the leg out. With the screwdriver under the end of the leg, heat the joint and gently lift up intil the leg is straight. Repeat for the other 2 legs. Now if you have a pair of Hemostats, they will help here. Clamp them onto the transistor at the top of the board, flip the board over and heat up the 3 joints all at one time. The transistor should easily fall out of the board. I will post a link to a page that will show you how to check a transistor.

Ya your right...I missed the 3rd leg in the middle.

Ok just so we are clear - the transistors we are talking about are roughly in the middle of the board, and look pretty much like half circles from a top view rigt?

The blue line, passes through 2 of them, and they are both surrounded by 4 purple dots each.
The red line passes through 2 of them, just to the right of the blue ones, and they too are both surrounded by 4 yellow dots each.
Right?

All 4 of them have the samething written on them which is:

K-632
A1266
GR

--- EDIT ---

So when you say the transistor connected to the resistor of the exploded transistor has to be removed, do you mean the TWO of them that are in the red line?

https://www.bcae1.com/ampfail.htm was the page I was looking for, but I just noticed that there are instructions for checking NPN transistors but not for checking PNP transistors. He is e-mailing me a link to a chart for you to fill out. I will get that to you in an hour or so.

I need to know if there are 2 of the 2SA transistors? Are there also 2 of the 2SC transistors? I need to make sure that both types are present, before you go removing anything.

All four are 2SA, and none are 2SC. I can start randomly looking for 2SC if you want. Im sure they might be there SOMEWHERE.

The Chip west of the transistors, what is the number on it? TL594. SG3525 ??

Ok I must not be understanding you correctly. I appologize in advance. I'm not quite sure why you quoted yourself - clearly because there is something in there that SHOULD be clearing something up. But it is not... and for that I appologize. I hope these pictures clarify something.

posted_image

The chipset, which can be seen in the first picture had I not put writing over it, says:

58HJ1VK
TL494CN

---EDIT---

OMG the resizing of images is seriously bugged! As a result I give up on reducing their width below 640. Is there a way I can use Html code, rather than the buttons at the top of the bar?

In the top picture, I can see the 2SC3198, but I can not see where it is. Are you saying that every transistor with the red lines pointing to them are all 2Sa1266s? Where are the 2SC3198s?

I have never seen this before, but there may be (2) 2SA1266s per bank of FETs, Are the legs of the 1266s connected to another of the 1266s?

In the top picture the arrows indicate what letters they connect to. The second picture was just showing that the arrows point to all the same sort of transistor which has the model # in clear view on one. So yes I guess there are 2 different ? (one had K546 and BL, and the other has K632 and GR) 3198s. Here is a clear picture:

posted_image

So, as you can see in the picture, the transistors that I orginally drew traces over have their center leg attached to each other. So the traces I drew actually cross then.

The other random 2 A1266s, are connected by their left legs. The bottom one has a trace that goes up to a cap, then a resistor. From the resistor a trace on the bottom of the board goes to the top A1266, and it also branches out more to the left...Hope thats clear.

I'm not quite sure what you mean by FETs and stuff like that. I do consider myself to be a smart guy, and I'm more than capable of doing whatever you tell me to do, and I learn quick also, but I have no training in electronics other than basic CEGEP physics...so like reading circuits, calculating resistance, capcitance etc.

FET = short for MOSFET = IRF-Z44 or 50N06 Do not remove any of these yet. Did you get the Z44s yet. If so I really recommend you purchasing 4 of These from Radio Shack. Wire the 4 in parallel, for a 2 ohm outcome. We will have to put the 44s in and mount the amp back in the heat sink, wire the resistors in series with the power wire and turn it on first for about 10 seconds. Let me know when you have the 44s and the resistors.

Here is the Link to check the transistors But remember we have decided not to do that at this point. Do not remove any of the transistors. You will have to click on the link at top of this page that says click here for bipolar transistors. If we were checking them. You may need to pull them out later, but for now, let's not.

i am an idiot wrote:

FET = short for MOSFET = IRF-Z44 or 50N06 Do not remove any of these yet.

I already removed all 8 of the 50N06s remember?

i am an idiot wrote:

Did you get the Z44s yet. If so I really recommend you purchasing 4 of These from Radio Shack

I bought 8 new Z44s the other day, they're ready to go. As far as the resistors go, do you think they will have them if I just walk into radio shack?

i am an idiot wrote:

Wire the 4 in parallel, for a 2 ohm outcome. We will have to put the 44s in and mount the amp back in the heat sink, wire the resistors in series with the power wire and turn it on first for about 10 seconds.

Ok, you said parallel and series - just want to make sure we're clear here. You want me to wire the resistors in parallel to reduce overall resistance and wire than in series right? Are we getting these in lieu of a sealed beam? Like this:

posted_image

So I=V/R or 12/2 =6 amps. Why is it that we want 6amps, why wouldnt we just want to use 1 resistor, and do 12/8=1.5 amps?

i am an idiot wrote:

Let me know when you have the 44s and the resistors.

Will do.

So lets make a checklist:

1)Install Z44s, exactly in place of the 50N06s
2)Buy 4 of thoses resistors
3)Do you want me to remove that transistor that you explained how to do before, or should I leave it in for now? Im assuming leave it in.

Yes leave the other transistors in the board. Diagram is exactly right. Yes you should be able to walk in and purchase. I do not know if they will have 4 but they should have some. You may have to hit a couple stores.

Alright, well 2morrow I probabbly wont get to that because I have 2 exams, one from 2-5pm, and another from 7-10pm. Prior to that I'll be cramming. But I'll put the Z44s in tomorrow after the exams, and thursday I'll start the hunt. Thanks again!

Ok, well the Z44s are sitting happily in their new home on the circuit board. I'm having trouble finding the resistors though - apparently Canada doesnt have radioshacks anymore - they're now called The Source, and its rather difficult to find those resistors.

I understand that I need to reduce the amperage going to the amp using resistors - but what is an acceptable range for the Watts and total ohms. This way I can hopefully have a little more luck finding some. I found a few 20 W resistors, but the lowest resistance was 200 ohms - and wiring 100 in parallel isnt exactly practical. If within the next 2-3 days I cant find anything I'll order the ones from radioshack - if they deliver to canada. After all - I'm still waiting for the Kapton tape to arrive before I can even put everything back into the heatsink.

If there is a problem with the drivers in the power supply, a 2 ohm resistor will limit the current to no more than around 7 amps. This will keep you from damaging anything if there is a problem. Without an oscilloscope, I highly recommend using some sort of current limiting device. You can buy an old sealed beam headlight and use it instead. The light will serve a second purpose too. If there is a problem the light will light up. If all is well, it will be very dim if lit at all.
Wait on the Kapton tape.

Kapton tape came in, I put it in some nail polish remover to remove the sticky side. But it on the heat sink and bolted the amp back up. However, I ran into a tiny problem. Radioshack doesnt exist in Canada anymore - I knew they changed it to "The Source by Circuit City", but I thought it was just a name change because every RadioShack became that - but apparently they aren't the same....and RadioShack.com doesn't deliver to Canada...sooo....

https://www.canadiantire.ca/AST/browse/4/Auto/AutoHeadlights/SealedBeam/PRDOVR~0203678P/GE%2BSealed%2BBeam%2BHeadlight%252C%2BH5006.jsp

will this work?

This will work better and it is cheaper. This is a dual element bulb, you need to parallel the 2 elements. It is a 3 pin connector on the back of the bulb. You will have to use your meter to determine the common connection and connect that to the battery wire. Then connect both of the other pins to the amp's power wire.

https://www.canadiantire.ca/AST/browse/4/Auto/AutoHeadlights/SealedBeam/PRD~0203676P/GE%2BHalogen%2BHeadlight%252C%2BH6054.jsp

Place a single 10 amp fuse in the amplifier. Do not secure the remote wire to the amp, you will need to be able to quickly remove it. Touch the remote wire to the remote terminal for a couple seconds at first. Notice the brightness of the headlamp. If it is a class D amplifier, it is normal for the light to flicker a bit before it turns on dimly but steady.

Ok, so I just bought the sealed beam - I had a $5 off coupon as well - scored it for like $7 w/ tax. I have not opened it from the box yet - but what will we be looking for when we do this? Just to see if the light comes on?

Just to see if the light comes on brightly or just barely lights up. We are hoping for not bright. We also need to check some voltages when you get it on. You need to ground your black meter lead and touch the red lead to the Left leg of each power supply transistor. Notice the DC voltage. If all of the driver transistors are OK, they should all read the same. Do not leave the amp on long enough to test all 8 transistors. Check 2 notice reading, remove remote wire and write down what you find. Power it up again and check the other 2 on that side, remove remote and write those down. Allow the amp to rest for a minute, and repeat steps for the other 4 transistors.

Awesome sounds good - except one tiny problem. The headlight I got was an H6054 style sealed beam. It has 3 pins in the back and they all have full continuity w/ each other. Am I missing something here?

Nevermind - I figured it out by using a 6V battery on it.

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Ummm...new problem. I grabbed everything getting ready to bring it out to my car and well - I realized I can not get to all the Z44s while it is bolted into the heatsink...

However, you know that link you gave me to test transistors? I did that on my Z44s before I soldered them to the board to make sure they were good before I installed them to the board. They all were then. So should I still connect it up and check the brightness of the light? Or should I take it all apart and solder wires to every left leg leading out of the heatsink - that way I can test them when its in the heat sink?