I have a 3V board set that has an issue that isn't covered by the standard component replacement guide. The board has audio, the motor runs properly in forward and reverse, and the smoke unit work properly. I'm missing all the lights except the to sets of marker outputs in conventional or DCS mode. Does anyone know what component would control that combo, hard to believe all the FET's are bad for the lights, there must be something common.
Replies sorted oldest to newest
John,
I assume that you've already tried a Factory Reset, correct?
What is the sound file in the board and have you tried a different one?
Probe the 12-pin connector at pin 2 (usually purple) which is the rectified track voltage common to the incandescents. You can use pin 10 (usually blue) as the circuit-ground. I assume your markers are LEDs which don't use pin 2 as the power common so that's why they still work.
Of course this assumes the lights are properly configured and enabled via the soundset to Barry's point.
I have not tried a different sound board, that was going to be a test. However, the front and rear headlights should be active on most any sound file.
I just went back and loaded a Premier GG-1 sound file that should have most of the lights.
I did try a factory reset, that didn't do anything.
I'm running this board on the PS/2 test set, so I know it's not the "engine", as other boards test normally on the test set. I've also swapped the power supply board, so I know it's on the processor board.
I noticed that the couplers also don't work. The only stuff working are the two markers, motor control, the smoke (both fan and heater), and the sound. All the incandescent lights and the couplers are dead.
Stan is say you may have a burned trace to the PV pin on the 12 pin. The repair is to jump PV from the smoke 4 pin to the 2 pin. This is most likely since you still have smoke. G
Since couplers also use pin-2 of the 12-pin as their common (on all harnesses I've seen), it's almost a certainty that the problem is as G says. You can confirm by ohming-out pin-2 of the 12-pin with pin-1 of the 4-pin (smoke) - I'm guessing it's open.
I've seen the printed-circuit traces burn out before the corresponding FET pops so it stands to reason that the PV trace might also do so (GGG has probably seen it all so he might comment). It does make you wonder though why this occurred possibly suggesting a wiring problem (shorts) in the harness/coupler/lights of the engine the board came from.
Sure enough, no connection there. One little jumper and then there were lights and couplers! 
I didn't get the burned trace inference, but it makes perfect sense now.
Thanks guys, that was easy. Board fixed. I'm guessing the bare wires on the couplers are the issue that started the ball rolling.
The purpose of the black wire under the processor brings PV from the rectifier directly to the Smoke heat PV pin. Makes sense since smoke is a heavy draw and the pins are far from the source. Probably no room for a wide trace like that.
The trace for the 12 pin PV runs between the back of the 12 pin and the front of the 4 and 8 pin connectors. Found it on a bad short where the white plastic connectors were slightly melted and black.
Those FET do short before the blow, but most likely the PV wire was pinched to chassis ground, the skies the limit on current since the FET is no longer in the circuit. G
Good thread guys. Thanks for posting the solution!
Dave
That is it Stan, I love it when the trace runs under the white silk screen, makes tracing them so much more fun!
Your welcome Dave. G
No FET's died in the short, at least they all appear to function. Thanks again guys, I wouldn't have suspected a bad trace, now I know to look for that in these situations.
I bookmarked this page for future reverence. Thanks for posting.
Access to this requires an OGR Forum Supporting Membership
