SOLVED-Help sound issues Atlas GP-35(Southern)#1108-2

Ron pull your boards and reseat them and make sure they are plugged in good as well. 

If reseating the boards doesn't help, one thing that happens with those boards is oxidation of the contacts on the two PLCC chips.  With a chip puller, I remove them and reseat them.  That has fixed a number of boards with those exact symptoms.

Don't try to remove the PLCC chips without the correct tool!  You'll almost certainly break the socket and then you're kinda' screwed.

Hey John and Cheesie,

For the most part have tried what you both suggested.  But if I recall correctly only pull and reseated the sound board.  Have had the suggestion to pull and seat the power board.

As a little more history, I first decided to sell this engine about 3-years ago after getting a MTH SD45.  In fact had six engines and two cabooses to sell on forum.  So after taking pictures (the very first time engine out of box) I placed each engine on dynamic test stand to make sure all engines function. 

If I recall correctly when I powered up this Atlas GP-35 for the first time it did come up with prime mover idle sounds.  But when pressing the horn button the horn started to blast and then the sounds went south.  As stated above all other TMCC function respond.

Was just hoping someone had run into same issues and had an answer.  As you know removing and replacing the body on an Atlas is NO fun.  This is especially true when one dose not intend to keep. 

Wish knew if any of the parts from this GP-35 would be compatible to my Atlas GP-7/9 for spares in case.  If so would part those parts out before trashing the GP-35.

Thanks again for you responses.

Ron

I have two early issue SD35's and have replaced the speaker on one.  Not uncommon on my Atlas SW9's to replace speakers. SW's, the speaker comes on at full and then you have to ramp it back.  IMO, that eventually damages the speaker.

".......erratic, sporadic, and garbled with a slight background hum............" could be a speaker problem. 

Early issue GP and SD 35's had a different mother board, usually noted by vertical positioning of the modular boards.  There were also some slight changes with R2LC control boards before 08 models that effects the marker lights if replaced with an 08 or newer board.   

The C07 and earlier R2LC have reversed polarity of the lighting outputs.  If you replace them with a C08, you have to swap the leads to the markers to get them to light.

Why are you trashing the GP-35?  Would you like to trash it my way?

FWIW, your symptoms sound exactly like the issues I usually consider reseating the two sound chips for.

Well John, since I am committed to part it out I popped the top.  Boy those handrails are a bear to get out of the cab without marring the body.

Here is pics.

I pulled the three boards.  The pulled the two chips twice and reseated.  I reseated the boards twice also.

NO real joy!  When powered back up there was a prime mover sound albeit erratic.  Got even more so when horn and/or bell button pressed.

Kind of wish I still lived about 50-miles south of here where I belonged to three "ranges."  I set this thing up down range and "blast."

Do see a bad solder joint on the sound switch and a horrible solder joint on the "run/program" switch.  Will touch these up late and see if any change.

Ron

If you like, you can send me the three boards and I'll test them and let you know what I find.  That will eliminate the boards.

You can also swap the boards for another TMCC locomotive of similar vintage, they are plug-compatible. 

Well touching the solder joints on the sound switch made no change.  On the other hand touching the joints on the "run/program" switch gave me the capability to assign a different eng ID number.  So some good came out of that.

I pulled and reseated the boards and chips three more times, no joy.

John, thanks for the offer but I have all but given up on this.  As stated some time earlier since I have replace with a MTH and a Lionel era appropriate engines it no longer hold any intrinsic.  What I hate is only Atlas got the 'Imitation Aluminum" band correct.

And oh, sure wish Atlas made it easy to disconnect the headlights so the body could be set aside!!!!!!!!!!!!!

Ron

If you're tossing it, toss it in my direction and I'll get it running!

Hey, did you check the speaker?  It could be a bad connection at the speaker, or it could be cracked.  Try to connect a different speaker before you give up.

An update of sort with another piece of the puzzle.

I recently completed "Junior" a much smaller and easy to deploy dynamic-test-stand than Senior designed and built back in 06.

To test the JR. I powered with an Atlas 80 and placed the GP-35 on it.

When powering up at lower voltages had a sort of metronome beat of distorted sound.  As voltage increased a clear sound of the prime mover appeared.  Increasing the voltage the prime mover sound reved up.  But only to a point of reaching probably around 18-volts.  Unfortunately since my mindset was on test JR. did not have the presents of mind to clip on a multimeter.  Also noted pressing the "horn" button only increased the speed.  Pressing the "bell" button did the opposite  slowing the down.

Dose this ring any kind of bells?

Ron

Ron,

Try turning the POT (the manual volume control).  I have a weaver engine that has a bad pot and if the contacts are not clean, I will get lots of static, even when running in Command Mode.  If that fixes it, you might want to get contact cleaner to ensure it has a good connection.

Problem identified!  It is in fact the sound board.

Another board would have cost me $45.00.  Not worth it to me!

So I my look into making the unit into a dummy.  Or next time I show price it at $150.00 with info for fix.  Then again maybe I will just bast it to kingdom come.

Ron

If it was a PRR, I'd consider buying it.