TMCC PA1 Lost Sound

@Richard Whipkey posted:

Merry Christmas To All,

I need some advice.  I have a Lionel TMCC PA1 set with Odyssey.  Up until yesterday the units (lashed up) have worked well.  Yesterday the unit with the Railsounds picked a switch and derailed.  After that, all of the sounds ceased and when I addressed the lash up there was just a crackling noise.  I reprogrammed the unit to restore the features and the sound returned.  I reset the lash up and, for just a brief period, all was well again.  However, shortly the sound ceased again.  I then first turned the Railsounds switch off and seperately addressed the unit that contained the sounds.  The horn was loud and clear.  I turned on the Railsounds switch and addressed the unit again.  All sounds (horn, crewtalk, RPMs, etc.) were very faint, but all could be accessed, but as I said, barely heard.  Raising the sound by my Cab1 controller made no difference and the Pot is turned up high.  I'm no electrical genius.  What should be my next step?

I had this happen once and it turned out it fried the soundboard. Once that happened, it’s upgrade time unless you can find a used one. The other thing I did after this was I put TVS’s in every locomotive now I don’t worry about derailment as much.

Richard,

From your description these appear to be the either the NYC or ATSF PA's.  I have the NYC versions, both PA (6-18953, Powered but no RailSounds) and PB (6-18966, Non-Powered yet does have RailSounds).  These are from the year 2000.

The PA unit was made without sound in order to be relatively low-cost way of getting into command control (TMCC).  The PB was sold separately as a thrifty way to add the RailSounds at a later date.  I can see how you would MU (lash-up) the two of them to create a train and operate that way.  But since the 'B' Unit has no motor or drive system, and the 'A' unit no sounds, you can also simply set the ID's on both to be identical and skip the lashup.  They cannot fight each other, with either motion or sounds, because of the way that these are split up between the two units.

@ThatGuy may be correct about a sound failure, but there isn't just one soundboard, there are 4 individual boards that make up the sound system.

Before you consider upgrading, I've previously seen the symptoms you describe with your 'B' unit.  The first thing to do, if you're a little bit handy with such things, is to remove the shell on the PB, then unplug and reseat each of the PC boards (see Nos. 14, 15, and 16 in the diagram below) that are presently plugged into the motherboard (see No. 13 in the diagram).  Do this one at a time to make sure that you get each of them back in the same location they came out of.

This uninstall/reinstall action will clean the contacts on the connectors between them.  Frequently this is sufficient to restore proper operation.

How does a short circuit make the contacts dirty?  It doesn't.  They get that way over the years prior, but a short-circuit can easily expose the problem once it exists.

While you're inside check for any obvious short circuit damage, like melted wires or charred components or burned copper traces on the PC boards.  If you find something simple you may be able to replace a wire or change out a bad board instead of investing in a big upgrade.

Also, be careful putting the boards back in because it's too easy to get them misaligned on the mating connector, side-to-side by one pin, as you reinstall them.  (If they're not correctly aligned you'll probably see smoke and a large repair bill.)

Try it.

Mike

@Mellow Hudson Mike posted:

Richard,

From your description these appear to be the either the NYC or ATSF PA's.  I have the NYC versions, both PA (6-18953, Powered but no RailSounds) and PB (6-18966, Non-Powered yet does have RailSounds).  These are from the year 2000.

The PA unit was made without sound in order to be relatively low-cost way of getting into command control (TMCC).  The PB was sold separately as a thrifty way to add the RailSounds at a later date.  I can see how you would MU (lash-up) the two of them to create a train and operate that way.  But since the 'B' Unit has no motor or drive system, and the 'A' unit no sounds, you can also simply set the ID's on both to be identical and skip the lashup.  They cannot fight each other, with either motion or sounds, because of the way that these are split up between the two units.

@ThatGuy may be correct about a sound failure, but there isn't just one soundboard, there are 4 individual boards that make up the sound system.

Before you consider upgrading, I've previously seen the symptoms you describe with your 'B' unit.  The first thing to do, if you're a little bit handy with such things, is to remove the shell on the PB, then unplug and reseat each of the PC boards (see Nos. 14, 15, and 16 in the diagram below) that are presently plugged into the motherboard (see No. 13 in the diagram).  Do this one at a time to make sure that you get each of them back in the same location they came out of.

This uninstall/reinstall action will clean the contacts on the connectors between them.  Frequently this is sufficient to restore proper operation.

How does a short circuit make the contacts dirty?  It doesn't.  They get that way over the years prior, but a short-circuit can easily expose the problem once it exists.

While you're inside check for any obvious short circuit damage, like melted wires or charred components or burned copper traces on the PC boards.  If you find something simple you may be able to replace a wire or change out a bad board instead of investing in a big upgrade.

Also, be careful putting the boards back in because it's too easy to get them misaligned on the mating connector, side-to-side by one pin, as you reinstall them.  (If they're not correctly aligned you'll probably see smoke and a large repair bill.)

Try it.

Mike

Sorry about that I forgot my own mantra, simple stuff first……well done.

it’s not Apollo, we are not building the lunar lem we are not going to the moon it’s a toy train

@Mellow Hudson Mike posted:

Before you consider upgrading, I've previously seen the symptoms you describe with your 'B' unit.  The first thing to do, if you're a little bit handy with such things, is to remove the shell on the PB, then unplug and reseat each of the PC boards (see Nos. 14, 15, and 16 in the diagram below) that are presently plugged into the motherboard (see No. 13 in the diagram).  Do this one at a time to make sure that you get each of them back in the same location they came out of.

This uninstall/reinstall action will clean the contacts on the connectors between them.  Frequently this is sufficient to restore proper operation.

More often, the act of extracting and reseating the two chips on the audio board will fix sound issues, I see that being the problem at about a 10:1 ratio to the actual connector contacts.

If you're reseating the PLCC chips, do make SURE you use a proper PLCC Extraction Tool and don't try prying them out with a screwdriver or similar tool!

Mike, Gunrunner John, and ThatGuy

Thank you all very much.  Reseating the PC Boards fixed everything.  My PA is working perfectly.  Again, OGR Forum members come to my rescue!

Rick