replace relay in boss amp possible?

My cousin has a BOSS amp that doesn't work properly. I'm trying to get it working as well as fixing up the rest of his truck for graduation as a surprise. I do not have the amp in front of me but it is an older 2 channel BOSS amp similar to their current Chaos line. The issue is the amp will not turn off via the turn-on lead. I have tested the turn on lead from the head unit and see a perceptible drop in voltage and, even when the lead is completely disconnected from the amp, it still stays on. My question is does the amp use a regular bosch type relay or is the turn-on a function of some type of built-in circuit that is not easily serviceable? If I can't replace the internal relay, could I just wire the turn-on lead into a relay for the power source and accomplish the same result?

Can you take a high resolution extremely close up photo of the circuit board in the areas of the remote terminal and the transformer.

Sorry, I don't have physical access to the amp anymore. But, if as you say, the turn-on circuit is PCB based I will forgo any internal repairs. I'll only have a few hours to work with it once I get the truck so I'll just plan on building an external turn-on circuit. Thanks

One more question regarding this. I do remember the amp in question draws 60amps. If I use the 75amp relay below, using the ground circuit from the amp and triggering with the turn-on lead from the HU, would this work properly? Would I need some kind of additional resistor or anything? TYCO relay

Do not use the ground circuit - you may burnout signal wires if +12V is still applied. It should be on the hot side (+12V). (Unless you can totally float the system - eg, break chassis to ground and input grounds etc.)

Thanks for the info. I surely don't want to create more problems. I'd replace the amp but it works fine otherwise. Anyway, I plan on using a TYCO V23232-D0001-X001 75amp relay unless anyone tells me if there will be a problem. This is a small part of a big project including new paint, headlights, speakers, alarm and more for his birthday & graduation.

Hmmm - seems expensive. I've been using (eg) 150A SPDT (AUD$15) or its 60A equivalent to connect aux batteries. But that 150A rating is for resistive loads - I don't know what inductive rating applies.... (Batteries are not inductive; fans are.) But the 60A is listed as a "Horn Relay" - hence implying inductive. (Horns are coils like fans are.) The 150A is listed as an "Automotive Relay" for big loads like audio... (a ha!??) Ah I hate stuff like this.... Suck it and see? Save a few buck? Or is screw better than 9mm (3/8"?) spades anyhow? (~6mm = 1/4" is the norm.) - I'd suggest screw - especially since I have found TWO (yellow) 9mm variants - and one one fit!) And will a cap across the contacts negate inductive effects (like the 0.22uF cap across ignition points)? Nah - it's 05:10... sleepy bye-bye time. Bi bi. (Not that I am.)    PS - 75A etc relay seems fine. Relay should be rated at least to the amp's on-board/internal fusing, but also be equal to or greater than the upstream (battery end) fuse supplying it.    Yes - fusing won't rupture/fuse at (eg) 110% rating, but relay contacts have similar rating behavior.   Many (like the FRC I linked to) seem to handle well above their rating - I know someone that's been running their 30A relay at over 40A - typically 45A - for a few years... PPS - you wouldn't happen to adopt cousins would you? I might be interested...

PPS - after a reasonable sleep.... Stick to the TYCO you suggested - or others you think suitable. Its screw terminals and easier mounting (flanges) can be a BIG advantage! (Be wary of plastic flange brittleness - secure well and don't force connections - though that is more a problem typical single-flange plastic Bosch/Hella type relays when fitting/removing tight spade connectors. Yes - I learnt!) And as much as I like quick-connect spades etc, screws can be easier than the slower find, buy, fit or crimp the spade connector! (Just use gold-plated wire.... LOL!) I actually like that Bosch/Tyco. IMO it's excellent for a "solid mount" application - whether in or on an amp (chassis), or body panel.

Thanks again for the feedback. That TYCO relay might be overkill but since it's someone else's system, I would rather go a little overboard. And yes, the screw terminals were very attractive to me. I haven't done much anything car audio related in too many years and never did relays back then anyway. Funny thing is, last time I looked at his system, the amp ground wire was just placed into a hole in the floorpan. No bolt, no ring, just stuck into a hole. He couldn't figure out why it was shutting off and sparking every time he hit a bump in the road. I think just correcting the poor wiring job will be a big (safety) improvement over what he has now. Under rated wire, over rated fuses, poor grounds and all. Thanks again....you'll probably see me over on the relay board as I have a few other future projects in my head.

Ouch! Having no connection is worse than an undersized connection. At least a rigid undersized connection will burn/fuse out. But a loose connection is an intermittent connection is a heat and fire hazard. VERY dangerous. And the fuse/protection will NOT prevent it. The TYCO overkill? Nah - it is extra margin or safety. Or longer life through less strain (maybe). And it allows future expansion (extra output FETs and bigger speakers... LOL). That is simply good engineering... the cost penalty being insignificant in relation to benefits like ease of supply, quality, installation, piece of mind.... Good stuff! And what a great present! (What's gonna be the catch... how to wrap it?) Best wishes.