Is it a dodgy decoder ?

Hi all.
Make sure you're sitting comfortably cos it's a saga. I've asked the question on NRM, but seem to have everyone baffled.
A friend of mine bought a Bachmann 350 Desiro with an ESU 21 pin chip in it. The interior lights were always on so I thought that was normal.

He then bought a Loksound V4 sound decoder (21 pin) and I put it in for him because he couldn't get the body off to fit the speaker which was a large bass reflex job. I removed the body, took out the seat moulding and cut out some seat backs out to fit the speaker. I soldered the wires on to the appropriate pads on the decoder. This is where the original wires were for a small round speaker, but one fell off anyway, so I went to the same pads.
Reassembled it and no running lights. The sound worked ok, but as I say, no lights except for the interior in the driving car (the one with the motor).

I took it apart and checked the wiring and had a look at the pcb. This is when I found that a wire had come off it's solder point on one of the coupling bars. I managed to solder it back on… not easy, reassembled it and no interior lights. I reset the decoder and now instead of the horns working on F2 and F3 I find nothing on F2 and door opening and closing on F3. I've been looking at it today, checking diodes and rectifiers on the pcb and continuity on anything I could find and still nothing.

It drives normally and except for F2 and F3 the sounds seem normal.

Any help for me with this one ?

Ps: I wonder if the wire I re soldered to the coupling bar could have shorted before I found it. They're really close in there.

This may not help in your case, but I have a Bachmann class 105 DMU and the design of the PCB has mistakes built in at the factory.  The PCB printed wiring is wrong, the factory bodged it by soldering a jumper wire across the board, breaking a track, painting out the pin no. on the decoder socket and requiring the 8 pin decoder to be inserted the opposite way round to the original intention.  It doesn't inspire confidence in the designers.

The interior lights should be switchable, but are permanently on as yours were, but the bodging makes the the head and tail lights work properly. If there is a similar design error on yours that may explain some of your problems.

Thanks Brian.

Unfortunately I can't see any faults with the board such as you describe. I've got the board out now, but think there must be a fault with the decoder too. I have noticed that the boards motor supply tabs are marked with Pos' and Neg' back to front.

I found the pin outs on the web earlier, so will have another check tomorrow.

'salright Sol. :thumbs


 
On Edit - PeterM- I have deleted those few posts of no consequence now.  and tomorrow will delete this one as well.
Sol