pg octane 900.5 repair

If the amp was properly fused, there should have not been any damage.  If you have an Ohm meter and a digital camera,  And can answer some questions, I am sure we can figure out what the problem is.

If polarity was reversed, it would have blown all of the fuses. 

Do not remove the clamps from the heat sink unless we determine it is necessary.  The cleanliness of the bond of the transistors to the heat sink is important.  The less time it spends apart the better off we are.

If it blows the fuse without the remote terminal connected, the problem lies in the power supply area.  If it only blows the fuse when remote power is applied, the problem lies in the output devices.   Look for the large diode to the left of the picture.  There may or may not be one. 

With your meter set to the diode test function, it should be the only setting with a symbol.  It is the symbol for a diode. 

Remove all fuses from the amp, There are 3 legs on each of the power supply transistors.  Place and hold one meter lead to the center leg of the first transistor, now touch the other lead to another leg of the same transistor.  Write down that reading.  Now move the last lead to the other leg ot the transistor.  Write down that reading.  Move to the next transistor.  Repeat.  On either the set of 4 or the set of 6 there will be one or more of them that read very near 0.00  This is the problem set of transistors.  Once you figure out the shorted set, remove the clamp from that set of transistors so we can get the number off of the top of the transistor.   If you can not read the numbers, place your finger in some of the white heat sink grease and rub it onto the top of the transistor.  Wipe most of it off and you will be able to read the number.

We need to cut the legs off of the top left transistor and both of the TIP 36 transistors.   Cut the legs off as close as you can to the case of the transistor.  After cutting each leg, move it a bit towards the center of the board to make sure it is not making contact with the transistor.  REPLACE ALL of the clamps that you removed, Place a 10 amp fuse in the slot that has been blowing.  And if you have (2) 5 amp fuses, place them in the other 2 slots.   Place the amp back in the vehicle and connect power ground and remote.  It may or may not blow the 10 amp fuse, if it does not blow the fuse,

Set your meter to the DC Volts selection.  I need to know the DC voltage from the outside legs of the 4 power supply transistors.  2 on top of pic and 2 on bottom of pic.  These are the only 4 parts that we are concerned about at this time.

Check the transistors directly across from the TIP36Cs.  They should be TIP35Cs.  Also check these from the left leg to the right leg.  Also recheck the one remaining transistor at the top left of the pic, and the 2 at the bottom left of the picture.

Also there is a resistor connected to the left leg of each of the power supply transistors.  The transistors in the top row of the pic are positioned correctly.  The bottom row are positioned opposite.  The resistor will be connected to the left leg of the top row and the right leg of the bottom row.  Using the meter now set to the Ohms selection, what is the reading of the 4 transistors we are checking now?  Is the resistor that was connected to the top left discolored or burnt?

The A1266s  I am assuming that one is connected to the resistors in top of pic and the other is connected to resistors in the bottom of the pic.  With your meter I need ot make sure both of these give the same readings as the other one.  Check all possible combinations of leg and lead positions. 

Also check the 35s from left leg to right leg. 

We are going to have to replace all 4 of the power supply transistors, so cut the bottom 2 out also.  But cut them as close to the case as possible.  Bend the legs so that they are perpendicular to the board.  Do not cut these near the board.  This will make it much easier to remove the legs when it comes time.  After you cut these 2 out, reinstall all clamps and another 10 amp fuse,  (it will not blow this time)  Power it up and set your meter to DC volts.  One lead on left leg and one lead on right leg.   It should be near 5 Volts on each of the transistors.  I am thinking that one pair is going to be lower or higher than that.  Also there should be a chip with about 16 pins on it.  I need to know the number,  it will be XX494 or XX594 or XX352X.  One of the other legs of the 1266s will go to that chip.

I can not find anything on their website.  If you could call them or go by there and see if they carry the TIP36s and an IRF-Z44.  Preferably the International Rectifier brand.  If they try to sell you an NTE cross reference, you would be better off ordering the originals from DigiKey.com  or Mouser.com

Thinking back, there is still possibly something shorted, that is why the fuse kept blowing when the power supply transistors were still in the amp.  When we removed them and verified that there was around 5 volts on the gate of the transistor, this leads me to believe that there is still a problem with the audio section.  While you are ordering, go ahead and get a couple TIP35s also. 

If you have verified that there is 5 volts on the left leg of each of the power supply transistor pads, and you have the resistors or the light bulb to limit the current, we are ready to start installing the parts.  Do not turn the amp on without mounting it back into the heat sink.  And you must install the resistors or the light bulb in series with the power wire.

When soldering the parts back in, the left leg of the power supply transistors are very critical that you get a good solder connection.  It is really essential that all of the solder connections are good.  But if there is a bad connection on the left leg of the power supply transistor will cause that transistor to turn on full throttle, and that will not be good  at all.

Using your ohm meter, (if you have not done this yet)  we need to check the resistors connected directly to the left leg of the power supply transistors.  They should all be the same value.  If one is not in tolerance it needs to be replaced.

We need to put a single 5 amp fuse in the fuses for each supply.  I think I remember that there are 2 separate sets of fuses.  One for the 4 channel section and another set for the Sub channel.  If this is the case, one 5 amp fuse in each of the 2 banks of fuses, for a total of 2 fuses.

When you do turn it on, you need to leave it on for only 5 seconds then turn it off.   When you turn it off, touch the resistor briefly to see if it is hot or warm.  If not warm, try it for 10 or 15 seconds and repeat.  While it is on for these brief periods, check the left leg of each power supply transistor, if any of them are different than the pack, stop and post your findings.

Do not even attempt this using a gun type soldering iron.  If you have to purchase an iron, at least look into a Weller branded iron.  A WP-35 shuld work well for you.
https://www.amazon.com/Weller-Watts-Professional-Soldering-3-wire/dp/B000WT6LOI
It may be easier to cut the legs off of the parts and remove them one leg at a time.  Cut them as close as you can to the case of the transistors.

All of those numbers look in order, it could be the dead battery that is making me think that there is too much chrrent draw.  DO NOT CHARGE THE BATTERY YET.  It will be safer to test the amp if the battery is not hot.  If you still have the single 5 amp fuse per supply, remove the 2 ohm resistor and briefly turn the amp on.  If the fuse blows, have another 5 amp fuse ready and try it only one more time.  The capacitors trying to charge on the initial turn on may blow the fuse, if you quickly change the fuse and it blows again, we have a problem.    If that happens, you need to find and remove the rectifier diodes for the supply that is blowing the fuses.  There are 2 rectifiers on each supply.  They are located next to the power supply transistors.  There are 2 different numbers.   They must go back into the same location from which they were removed from.  Mark them with a silver sharpie or a paint pen, or take a picture so you will know which location they came from.  Removing these will tell us if the problem is in the amplifier section or in the power supply section.  After removing them, once again a single 5 amp fuse in that supply.  Try it only once this time, there are no capacitors to charge up.  Removing the rectifiers, essentially removed them from the circuit.

Sorry, the rectifier diodes are in the same case as the Z44s.  They are probably the next items in the row.  They will have either a picture of 2 diodes on each one.  One set of pictures will be pointing inward, and the other diodes will be pointing outward.  They may have the following letters all followed by some numbers.  FEN and FEP   or MUR.   The devices numbered 78XX and 79XX are not the diodes.  Do not remove them.  The 3 places that they may be located are labeled by the ? mark in the new red square on the picture.

Read the second paragraph before you take the amp apart to check for bridged solder joints on the bottom of the board.

We seem to still have a problem at the output transistors.  Check and make sure you do not have a bridged solder joint on one of the outputs you replaced.  Check the top and the bottom of the board.  Also check to see that you did put them back in the right spot.  In order to check this, the middle leg of one of the rectifier diodes will show a dead short between the middle or the right leg of the outputs.  The CA diode will be connected to one and the CC will be connected to the other.  You may have to pull the clamps off of the 4 channel part and verify which output is connected to which diode.  They will be the same on the part of the amp we are working on. 

Before you do anything else,  run the amp for a few minutes to see if the heat sink is heating up on the supply you worked on.  Make sure you mount it back into the sink.  If there is a problem with the drivers, the 44s will heat up on that side before they heat up on the other side.  After you leave it on for a bit and determine that it is not heating up, check for shorted solder joints on the outputs.  Also check the resistance of the rectangular concrete looking resistors near the outputs.  Now set your meter to the diode test function and check for shorted driver transistors near the outputs you changed.  Check all possible combinations of those legs.  If you get any readings below .300, check the same transistor on one of the other channels of the amp.

After you test for heat with the diodes still removed, at least remove the 36s, they may be leaking, Since you have them I would replace them.  They are rated at the same current as the 35s, they went through the same abuse as the 35s, they may have survived but could be weak. 

We are getting close.  But just to be safe, power it back up and leave it on for about 5 minutes.  You need to monitor the heat sink the entire time to see if it is getting warm.  No Speaker wires and no RCA jacks.  After 5 mnutes you should begin to feel it warming slightly.  If it is getting hot you may want to stop.  If it is only getting a few degrees above ambient, connect speaker wires and RCA cables and try playing it.  With the 5 amp fuses, it will only play at a very low volume, turn it up until you can barely hear any audio.  Walk areound the vehicle listening carefully to each speaker.  If they all sound free of distortion,  gradually turn the volume up until you blow the fuses.  If all sounded good until the fuse blew, Cross your fingers and insert the proper size fuses.  Play it again and see what happens.