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I have a PS2 3v processor board with some issues that have me stumped.  

Symptoms are:

The sounds decreases in volume about 2 seconds after it starts up.  

The motor will not change directions but the headlights do



Things I have changed:

Relay K1

Audio Amp U5 (board originally had no sound)

U4 (board was originally non responsive)

Q19 (was burnt)



Any help would be greatly appreciated!

Last edited by David Minarik
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Considering the damage you had be careful with the test a new power board may smoke Q-19 again.

There is a Fet that controls relay.  I never have changed  a relay on a 3V board.

BUT the critical issue is the volume.  While battery charging and such is done on the PS board, the processor directly controls those chips.  If the processor took a hit you can't fix it.  Are you testing with DCS or conventional, will it play shutdown sounds when power shut off.  G

Alan, Jon and George,

Thank you for your input!  Here is more info:

  • Alan, The reset did nothing.
  • Jon, The Power board seems to be OK.  I tried a new power board and got the same results.  I also tried this power board with another processor board and it worked fine.
  • George, The relay does not click when powered up. Do you happen to know what FET it is that controls the relay?  Do you know what processor chip that might be?  I can try to pull one off of a donor board with hot air.
  • I am testing on a PS2 Test Fixture and it does power down ok when shut down.


It seems I might have gone too far down the rabbit hole on this one.

I am sorry, you said Q-19 smoke and I was thinking Q-23 on PS.  So sounds like battery circuit is fine?  Again, conventional shut down works, not DCS shut down.  Only way to ensure battery circuit works. 

Q-10 is the relay fet same part as light fets.  I have a half volume board on the bench.  Relay, and half volume can be loss of trace internally, damaged processor.  Don't remember which one by number just sight.  I traced the battery signal to it along time ago.  Your talking the large processor chip with 4 sides of legs.  Good luck on that one.

Can't fix them all, but I love your effort:-)  G

@Alan Mancus posted:

by the time you heat the processor chip to remove a old good chip you will have destroyed the process ic and then the chip is shot anyway!

A hot air tool is what many rework shops use to remove and replace the large chips.  If you have a full setup, you have a set of nozzles that direct the hot air right to the leads and not on the chip body.

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Well I have given up on this board.  I replaced Q10 with no luck reviving the relay.  

i was able to remove the MTH chip pretty easily with very little heat.  I used some low temp solder and a single tip on a hot air torch.   It came right off.

I would imagine that most of you are using a microscope.  I finally got one and was able to repair about a dozen boards in the last two weeks.   I wish I had one years ago.   What a game changer!

Something else I wish I had years ago are the replacement pads/trace sheets.  Another game changer.

Thanks to all of you who offered help it was as very appreciated!

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