General Electric RP-2060A

[William]

Some advice, please. I have a GE RP-2060A that I have been working on. The Sam’s is in the downloads, under changers, and is on page 3 all the way to the bottom of that page. This is one of General Electrics Trimline units.

First off, the filter capacitor was one of those junk paper ones and it was bulging at each end and fat in the middle, so I did not fire this unit up until I changed that out. Remembering Electra 225’s comments about a Trimline he had worked on, I followed his advice and increased the values of each of the three parts to this filter capacitor. With that done I fired it up to see what I had. The unit did play but definitely needs work.

Next, I checked all the resistors and only found one out of tolerance. The rest were surprisingly all very close to rated values. I changed the resistor that was bad and then began voltage tests. Again, I was surprised to find things very close to the recommended voltages found in the Sam’s schematic. I cleaned the tube sockets and checked the tubes. No shorts, no emissions, and the only tube that was on the weak side was the 12AX7. I also cleaned all the controls twice. Time for another sound test and it actually sounds good, good bass and treble and plenty of volume, but the volume control needs another cleaning, and I have a buzz. No hum, just a buzz, and the buzz will go away if I put my finger on any metal part on the chassis. Also, the buzz will get louder if I hover my hand over the 12AX7 tube or touch the volume control which is kind of odd as the shaft of the volume control is plastic. Again, hand hovering, if I touch the chassis the buzz is gone. The buzz does not interfere with performance while a record is playing, but it is kind of annoying between tracks and can be faintly heard during soft passages.

Thinking this is a ground problem, I used my meter to trace all circuits in the PC boards especially the ones that pertain to grounding and all check good. I swapped out the 12AX7 with no change, the buzz was still there. I pulled the output tubes one at a time, buzz still there. I tested the tubes again leaving them in the tube tester for a long time to see if getting good and hot made a difference with results. NOPE! I did clean the volume control again, but I still have the buzz. At this point I am stumped and was hoping maybe one of you might have a suggestion on where to look next. I suppose it is possible that it is just the nature of the beast, but I am thinking GE would not sell something like this.

Sorry I do not have photos to share, I still can’t load photos to the forum for some reason. My guess, my camera is too old to be accepted to the newer forum updates.

Thanks in advance,
Bill

[stbasil]

You didn't mention flipping the AC power plug, assuming it's non polarized. That might have an effect.

[Hi-Fi-Mogul]

If reversing polarity does not fix the problem,
I would re-flow the solder points around the
Volume control wiring.

On a couple of my record players, this did fix the problem
you state.

[TC Chris]

Also, there's usually a cap to ground from the power line. The current standard is to use "safety caps. Somebody had posted a link to a good article on safety cap use a couple weeks ago. Maybe look in the "getting started" section. I just looked at the copy I printed. It' from the "Just Radios" site.

Long ago, (I mean nearly 60 years ago), my Bogen DB-115 amp started buzzing. It had a ceramic cap to ground. When I lifted it, the buzz stopped. I haven't used that amp in years, but a rebuilding would start with safety caps installed.

Chris Campbell

[Hi-Fi-Mogul]

Also, there's usually a cap to ground from the power line. The current standard is to use "safety caps.
Chris Campbell

I don't see that type of cap in the schematic.
Maybe because there is a power transformer.

[TC Chris]

My Bogen amp is a transformer-powered device and it had the cap to ground. Here's the article:

https://www.justradios.com/safetytips.html

The focus is on the interference-suppression work of these caps. You may have noise coming in on your power lines. It's common now.

Chris Campbell

[William]

Thanks, guys, and will check each suggestion out and let you know what if any thing I find.

Bill

[William]

I had some time yesterday so I tried the suggestions you offered with no results. I did not see the "safety cap", Chris. It is better when the steel shield is installed. It covers the PC board that the controls attach too and goes around all 4 tubes. With the cover in place it reduces the amount of buzz but it is still there while holding your hand over the volume control and 12AX7 tube. Also when you touch the volume control knob. Whether I hover, or touch the knob, when I touch the chassis the buzz is gone.

Bill

[TC Chris]

Might be worth trying a safety cap to see if it filters out AC-line crud.

Chris Campbell

[William]

Thanks, Chris, and if my next few ideas don't pan out that is exactly what I intend to do.

Bill

[electra225]

Are you using a Variac and/or an isolation transformer with this stereo? If you are, disconnect it, connect directly to the wall. If you aren't using a Variac and/or an isolation transformer, connect the stereo to one. See if either connection helps the buzz. The schematic doesn't show the metal shield. Ground it and see if that helps.

[William]

Yes, using the Variac and it is on my agenda today to just plug it into a wall socket. I have noticed something else, I have distorted bass in the RH channel. The LH seems clean but weak bass.

Bill

[electra225]

I wouldn't get too excited about weak bass response from one channel if you are running a Pfanstiel needle. Tonearm weight is critical on the Custom Tonearm. Wimpy bass is not a feature of that little stereo. Rattling speakers can be, though ...

[William]

Variac was not the issue, buzz still there with a direct plug into a wall outlet. The bass in the RH channel sounds like that channel/speaker is being overdriven. I also unplugged the audio cables to the changer to see if the changer might be the cause, nope, and then I remembered that I hotwired this GE/VM changer to the Magnavox Imperial while I was working on the Collaro changer. It played great with the Imperial, so cartridge and tone arm wiring are good. I did replace the needle but it is a Walco that I picked up from Mike. This GE Trimline still had the original needle with the GE emblem on the flip over tab.

Bill

[William]

It is time for an update on the GE Trimline. The buss is still there but much better, I finally came to the conclusion that some buzz is just part of the beast. What I did was just continue to find little things that helped just a little. Clean the tube sockets and pins again, flow some solder in a few grounding places and triple clean all of the controls again which seemed to make the biggest difference. At this point it is going back into the cabinet. I still need to get new crossover caps, these are dead so once they arrive I will have tweeters but for now it plays, and it sounds good for a portable record player and better than most portables I have heard. It actually has bass, something my Motorola SH12N lacks, like none! One of these days I am going to post the schematic to see if anyone can tell me why this powerful Motorola has no bass.

Thank you for you advice and help, I do appreciate it.

Bill

[Hi-Fi-Mogul]

Glad the buzz is reduced Bill.

Your reminder of thorough and repeat cleanings,
and re-flow of ground points are things to remember to do
as part of these restorations.

I myself do not adhere to this advice consistently.

[William]

Join the club, Mr. Mogul, I forget about going the extra mile too and then I pay for my senior moments.

Bill

[electra225]

Would that be like my refusal to adequately clean the little tripper thingy on VM changers, put it back into the cabinet, then wonder why it doesn't work right? Something like that?........

The little GE Trimline series is pretty simple and basic, yet can be a challenge to service and to get them to work right. There is considerable criticism of the PCB chassis, not without merit. Not only does it use a pretty cheaply-constructed chassis, but the tubes are hung upside down, allowing the chassis to absorb the heat. They use a metal shield over the chassis, but I'm not sure how much good it does, either helping the heat from the tubes or for use as shielding. Getting the chassis out and back in is a horror show. Then cleaning the controls is a challenge after you get the chassis out. But, in their defense, they work much better than their modest livery would dictate....

[William]

I believe you are correct, it's the extra 5% that makes a difference.

To the point of the GE Trimline, the shield that goes over the chassis and surrounds the tubes does make a difference with shielding. It probably cut my buzz in half when it is installed.

Bill

[electra225]

Good to hear there is a benefit to it.