Model Train Forum banner

1 - 20 of 31 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter #1
I have a Lionel Postwar Celebration Virginian FM Trainmaster. It has TMCC and Railsounds. I picked this up about 6 weeks ago. Everything was working find, then exactly 31 days after purchase (30 day return policy), the sounds stopped working completely. All of the TMCC functions work correctly, but no RS. I do get what sounds like a low level "pulsing" sound out of the speaker, but that's it. I did check the resistance on the speaker, and I got a reading (about 16 ohms, I think). I pulled and replaced all three boards (sound, control and power boards), and reseated most of the connectors. I even pulled out the sound module from the unit and put it in another TMCC/RS locomotive I have, and the sound worked. I then tried that unit's sound board in the Trainmaster, and same result as with the original board. So, it does not seem to be a bad sound board. Any other tests I can do to narrow this down? Any idea what may be at fault?

Thanks!
 

·
Registered
Joined
·
20 Posts
Discussion Starter #5
Yeah, while I had things open this morning (but after posting the question), I tried connecting the speaker from the Trainmaster to the other unit's speaker connector. The sound from the other unit came out just fine through the Trainmaster speaker, so I'm pretty sure the speaker is ok. I then connected the speaker from the other unit to the speaker jack on the Trainmaster, and same result - just some low level sound. It actually sounds like the idle pulse that you normally get, just really low and distorted, so it would make sense if this were a RS power supply issue. Will post when I have a chance to swap those boards.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #7
OK swapped the power boards, and no difference. I also tried putting the Radio board from another engine in, but still no difference in the sound. That only leaves the 'mother board' where all the other boards plug in. Maybe I've got a bad solder joint, or bad connection somewhere. Suggestions....
 

·
Registered
Joined
·
20 Posts
Discussion Starter #9
OK, I've already moved the volume control a lot, just in case there was a bad spot on the potentiometer. Should I be looking for some kind of bad connection there?
 

·
Admin
Joined
·
43,697 Posts
Time to break out the meter. Although it's possible the motherboard is bad, that's way down the list of things I'd be looking for. Obviously, you need to carefully examine all the wiring. You can also jumper out the pot to eliminate it as the issue. Turn it to midrange, and then jumper out each end terminal to the middle terminal. One will kill the volume totally, the other should put it to full volume.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #11
OK, will check that pot. I agree about checking all of the wiring. I suspect this is just a loose connection somewhere. Unfortunately, there is a lot of wiring. Just wondering if one of the connections is more likely to cause this problem than another? If not, I'll have to check them one by one.

It's possible there's a cracked solder joint somewhere, though I agree, it's probably not likely. When I've done trouble shooting on other electronics (70s stereos) I've always had a schematic to go from.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #12
Another thing I noticed, not sure if this helps, when powering on the engine the sound from the speaker is louder at low voltage, then gets softer and constant by the time I get the transformer up to about 10 volts. Again, don't know if this is significant, just more information.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #13
Tried jumpering the volume pot, but that didn't seem to do anything on either side. I have some Caig Deoxit D5 on hand from my stereo work. When we have scratchy switches or pots, Deoxit is the first thing that's tried. The pot looks fairy sealed, but thought I'd try spraying some in there anyway, as well as cleaning both switches on either side. After doing that and working the pot and switches, I did get sound back intermittently. So, maybe the problem is the volume pot? I can reflow the solder around all three connections to see if I've got a bad joint there, but otherwise, might need replacing? I really could not find any other connections that affected the sound when I moved them around.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #15
Yes, one is Run/Program the other is SS/RS. I had wondered about the RS/SS switch also, but previously putting the switch in either position made no difference. I'll have a look at that switch again later today. Those are "open" switches, so easy to get Deoxit in there to clean.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #16
Well, looks like the problem is a dirty RS/SS switch. I did another Deoxit spray on both switches and worked them a lot. Got the sounds back, but if I move the switch at all, the sound would go out. Then, if I moved it back and forth a bunch of times and left it in RS, the sound came back. It's all working right now. Not sure if I need to change that switch or if the cleaning will clear things up?

On another note, I also pulled all of the connectors off the mother board and then reconnected them in case there was a bad connection. After I did that the engine didn't move at all when powered up! Tried pushing down the power connector to the reversing unit on the mother board, and that solved it. It's amazing how touchy all of these connections are.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #18
Older units get oxidation on the contacts, I use Deoxit-D5 for contacts when I have to clean them up.
Yes, it's the same in old stereos. First step is to Deoxit all pots and switches. The vast majority of my collection is postwar Lionel where we don't have those issues. Glad this was not a more expensive fix. Thanks so much for your help John!
 

·
Registered
Joined
·
20 Posts
Discussion Starter #20
Thanks for the link and the manual. Looks like you have to order a whole new mother board if you want new switches. Might consider that if this problem persists. It would be an easy swap.
 
1 - 20 of 31 Posts
Top