Hotbox Reefer Sound Board Troubleshooting

@DaveJfr0 posted:

found that the sound board is causing the short with no other harnesses

If the answer is that this board should directly touch both leads to the rails for AC input, then how do I go about troubleshooting it further?  I've looked at all of the diode pads and the only one that is populated and connected to input power is D3. (D1 and/or D2 are as well, but D2 as you can see has a 0-ohm R across the pads.)

If I was a betting person, you killed the processor on that sound board. Since it is socketed your can just lift it out (the chip with HBX). If the board is no longer shorted when you unplug that processor, then effectively we know what is wrong but there is no fix- other than replacing the whole board. They don't sell just the chip that I have seen and it need programmed specifically with the sounds.

That is a trainsounds board. So if the chip was good, you in theory can buy a different board and swap chips, but my experience has been the chip is what dies and then shorts the board. Again, my experience is that I have seen a few dead ones of these cross my bench.

https://www.lionelsupport.com/TRAINSOUNDS-HOT-BOX

Hi Vernon,

Thanks for a quick reply. I just un-socketed the chip, reconnected the board back to track power, and still get an immediate short.  So hopefully that is good news.  I take it by your reply that this board should indeed be accepting of AC power directly into its input leads? no other rectifier circuit required?

Since we know what board type, here is an expanded wiring diagram https://ogrforum.ogaugerr.com/...51#79142442638386751

And yes, nothing special, these went straight as labeled to center rail and outside rail.

@Vernon Barry posted:

@DaveJfr0 posted:

If I was a betting person, you killed the processor on that sound board. Since it is socketed your can just lift it out (the chip with HBX). If the board is no longer shorted when you unplug that processor, then effectively we know what is wrong but there is no fix- other than replacing the whole board. They don't sell just the chip that I have seen and it need programmed specifically with the sounds.

Apparently, that ain't happening.

You can try putting that chip into another trainsounds board or try to find another hotbox one?

Note there are multiple pages to look through.

https://www.lionelsupport.com/...keywords=trainsounds

Thank you for helping confirm the inputs and that I didn't make a mistake.

Hmmm...I might shelve this long enough to see if I can find another HB at York.  If I come up empty there, then maybe I'll take a stab at another TS board that supports the hall effect sensor (which may very well be all of them since the diagram you linked me to shows the speaker, hall, and pot all being supported). SMK is handled entirely by its own board + on/off SW.

I'm guessing the TS PCB's have been available long enough that no one has ever spent the time to diagnose these at the component level.  I wouldn't mind trying to do component replacement, but not really sure what to look at and the time for my amateur skills to RE the board would make the $40 replacement board a bargain.

Beyond component-level troubleshooting, do you have any advice for helping protect the processor once I get this working again?  My guess is its really sensitive to transients and that a TVS across the power leads (1.5KE20CA) would help against that.

David

My thoughts and none of these are good. Trainsounds boards are a hybrid of through hole and large surface mount tech. Given the ever changing trend, the current state of electronic supplies- especially anything older, I think there is poor ROI on a repair attempt. Maybe you get lucky, maybe I'm wrong. I've tried recapping a failed one, I tried replacing various parts, in the end, just grabbed another board and moved on. Maybe someone else can help you further on a board repair, but my luck and this board, I just gave up.

For that matter, GRJ, develops custom MP3 boards for just such sound cars as another route.