Need Some Railsounds Help Please

If memory serves, there should be three connections to the volume potentiometer. Broken wire, perhaps?

You're correct Rudy, at least for all the wiring diagrams I find, as well as my personal experience.  Don't recall any Lionel volume pot with just two connections.

Rail sounds and GRJ: Your memories are good gentlemen; I just re-checked the installation and there are indeed three wires coming off the pot. They are green/yellow/blue wires that pass through a multi-pin mini connector. The three wires traced down to the MB where they are soldered on the upper side where the pot MAY have been mounted in other applications since there is a hole in the center of the solder site.

Yep, there's a spot for the pot on many motherboards.  Other motherboards route those to a connector.

You didn't mention the speaker, that's an obvious place to check.  Try a different 8 ohm speaker...

I have a spare ERR sourced speaker I can try tomorrow  John. The Fatboy speaker that was original equipment checked out at 8 ohms; hopefully the ERR one is as well, other wise I'll have to start digging in another engine.

The ERR speakers are 8 ohms.  From your description, the speaker is a prime suspect.  If the speaker didn't measure around 8 ohms, it probably wouldn't work at all.  What frequently happens is the cone warps and the coil drags on the magnet, that makes the audio muddy and weak. 

The other suspect is, of course, the RS power supply board, I'd try swapping that as well.  If you have another TMCC locomotive, that should be an easy test.  The RS power supplies are generic all the way through RS5.

Still worth considering the pot as a possible culprit. Is there any change to the sound when you rotate it?

No argument there Rudy, just putting out the other candidates.

Rudy & John:  I just found the time to slave in the ERR speaker (unsoldered the Fatboy and jumped the ERR speaker wires to the originals from the MB connector. This did not improve the situation-still low volume on the ERR speaker as well.

I did R&R the amplifier board again, and it still did not result in any improvement. Turning the volume pot does nothing to the volume-remains extremely low, but clear.

I am including two pictures of the MB setup with a question about a third board-I suspect it is a "mini" R2LC to fire the electro-coupler and power the lights?

Do you think the pot may be the item causing the low volume situation at this point (as changing the amplifier board and speaker has not improved it....)?

That is the AD20 board, it receives the serial data from the IR wireless drawbar.  It has nothing to do with the audio volume.

Did you try changing the RS power supply?

Try turning the volume pot to the center of it's travel.  Then, short between one end lug and the middle lug with a jumper.  If the sound is totally gone, move the outside connection to the other lug of the pot.  If that doesn't increase the volume, I don't think it's the pot.

One of those tests should result in no audio, the other in full audio.

Good advice.

Rudy & John: The frustration continues....

I jumped the center post of the pot to each individual outside post one at a time and saw no change in perceived volume while on either post.

I then broke down all the wire nut connections and re-did them. I also removed all three plug-ins from the MB along with the remaining mini connectors. I removed the MB from the chassis for an up close inspection of both sides. I saw nothing visually suspicious, so re-assembled and re-tested again. At his point, the original issue remains.

I'm going to step away tonight and look for a different (#3) audio amplifier board tomorrow just to try another one ( that being the original + the one replacement I have tried). I also exercised the RailSounds/SignalSounds switch several times with no change in operation.

Did you swap out the power supply board?  How about putting the original boards into a different engine one at a time and seeing if you can isolate the issue.

Debugging is just isolating the possibilities until only one remains.  Let's start eliminating components.

Or the wires from the pot are not properly connected all the way through to their destination--this would include the wire nuts, the mother board connectors, circuit board traces, etc.. It don't make sense that the pot at full vs. off makes no difference to the output volume.

As John suggests, moving the railsounds board to another locomotive would be an interesting experiment.

John & Rudy: After getting the lawn mowed, I sat down for another troubleshooting session. I have a Lionel 38080 USRA switcher of similar vintage and electrical components, so that became my testing mule. This is what transpired so far....

Tested my 38080 tender behind the 38080 loco for proper operation and everything worked as designed.

I then placed the 38053 Mountain tender behind the 38080 USRA loco; the volume was still very low.

I the took the 38053 Mountain amplifier board and installed it in the 38080 USRA tender. The sounds were full volume. I the put the 38080 amplifier board into the 38053 Mountain tender which resulted in continued low volume operation. From this I deduce the amplifier board is not the issue.

Next, I took the Railsounds board from the 38053 Mountain and installed it in the 38080 USRA tender-the sounds were normal volume. I then took the Railsounds board from the 38080 USRA and installed it into the 38053 Mountain tender-I still had low volume. From this I deduce the RS board is not the issue.

The next T/S step involved hooking the volume pot from the 38080 USRA into the 38053 tender-this resulted in continued low volume. I then hooked the 38053 pot into the 38080 tender and got normal volume. From this I deduce the 38053 volume pot is not the offending culprit.

I hooked all the original 38080 components back into the 38080 tender and all operates well. The 38053 tender still has the low volume issue. At this point I will make continuity checks on the three wires from the 38053 pot down to the MB connections. The three wires only go through one mini-connector.

It's time to look under the motherboard in that tender to see what going on under there.  Clearly, something in the environment is causing it.   Let's recap.

• It's not the speaker.
• It's not either of the RailSounds boards.
• It's not the volume pot or it's wiring.

What's left is the motherboard and associated wiring. 

Even though I don't know how it would affect the volume, have you swapped the AD-20 board to the other tender to see if that has an effect?

Agree, I am suspicious of the motherboard given everything else you have swapped. Just a minor point to clarify--the audio amplifier is part of the main railsounds board; the second board is the power supply. Your tests are all valid, just wanted to note that everything related to the audio signal is on the main railsounds board, except for the pot and loudspeaker connections which pass through the connector from railsounds board to the motherboard en route to their respective destinations.

Testing the power supply was just to see if it's really putting out the proper power for the RS audio board, but I think we've run out of options.  Since it's not the speaker, volume pot, or the RS boards, something must have happened on the way to those components.

Rudy, can you think of any way the AD-20 could be doing this?  I don't think so, but maybe there's something odd afoot?

John & Rudy: I did not swap the AD-20 board so far. I did ohm-out the wiring direct between the solder joints on the back of the volume pot to the solder joints on top of the MB-all three showed continuity.

I also removed the MB one more time for another look under magnification and didn't find any "smoking gun" I could pin-point as a suspect area. All the black covering looked pristine without any bubbled areas.

At this point, I also have to suspect something not visually apparent with the MB since, as we've said, the obvious components have checked OK. I just hate to lose this RS unit as the Crewtalk is loco-specific + it has a killer freight whistle recording as well. I may have to check to see if Lionel might have a new MB if your have no further ideas.....?

(I will check to see if my 28079 "Texas" has the same MB set-up........)

Lionel still seems to have the motherboard for $20.  Hard to imagine if you don't see any sign of damage that it suddenly went bad.  Did you examine the solder joints on the connectors and board sockets to see if there's a bad solder joint?

If for some reason you can't get one from Lionel, I have one in my parts box.  However, I'm not convinced this is the actual issue.

MOTHERBOARD / RS / MOHAWK / TETHERED POT

John: I still need to check solder joints; the ones from the pot to the MB looked shiny and tight on the back side. I may re-melt them to see if that helps any.

Funny thing about solder joints-I had an electronics tech "re-furbish" my Fisher 800T stereo receiver last year and "re-furbishment" basically was removing solder from all original connections and re-soldering them after 45 years.....

I need to put this project away until tomorrow, so I'll keep you posted on any progress.

You did some testing in conventional?  Re seat sound chips?

With low volume, I can't imagine how conventional operation is going to change that.  This is not like MTH PS/2 or PS/3, the volume control is always active.

Here's another one Guns..... Reset the code.

Gregg: The first step I took prior to opening up the tender was a loco re-set; per the manual it was code "74". It did not cure the issue.

And to your other question, both sound chips were pulled and re-seated with no improvement noted.

Have you transplanted all the boards from another locomotive to this one to see if the volume issue exists with different boards?

Gentlemen: Success at last!

I tried the boards from my 28079  "Texas" in the Mohawk tender and volume was low. I then stripped the MB of all plug-ins and connectors. I checked all the mini connector pins and they all were snug in their pins.

At this point I broke out the soldering pencil and re-did the three pot connections to the MB (on both sides). I also unsoldered one black wire on the bottom of the AD20 board that seems to run up to the Railsounds/SignalSounds switch.

I then re-installed everything and it finally is back to normal volume level (which in this case is LOUD). Thanks to you John & Rudy & Gregg. Feels good to have my baby fixed....

Great !I would never have found that in a million years ... But glad you did.    

You knew it had to be somewhere, we had kinda' narrowed it down to the motherboard.  Glad you got it going, back to chuffing and puffing!