Garage orphans

[TC Chris]

Long-timers here will know that all orphan electronics are welcome at my place. Most of them are curbside finds but a few are donations from people who know my proclivities. Today I had to hang the local sailboat's mooring float up in the garage, on the hook where it spends the winter. That meant moving accumulated cool stuff out of the way so I could step up onto the table under the hook. I found 4 of my orphans and decided to try the three that had never been tested.

--Pioneer RX-1180, looks like tuner, amp, and dual cassette deck, but it's all one box at the lowest end of the Pioneer range. Plugged in the headhones and it works!

--J.C. Penney Model 1755, one of those old AM/FM/8-track devices with a low-end BSR (is that redundant?) changer on top. The changer is frozen solid but the radio works just fine! I the changer cartridge works too.

--Truetone model GPE-6040A-08, AM/FM/ cassette/BSR on top. BSR frozen. Crackles in the headphones from the volume control but no audio.

--And then there's the real winner, a Kenwood KS-707P, a little receiver with a Miracord changer on top (needs a headshell). This was a donation. It had a "heartbeat" in the audio on all inputs. Thump-thump-thump. Must be a power supply issue but when I tackled it 30 years ago I could not figure it out.

Chris Campbell

[Firedome]

That's called "motorboating" iirc... kinda ironic for a sailor.

[TC Chris]

That's called "motorboating" iirc... kinda ironic for a sailor.

I always think of motorboating as putt-putt-putt. This is slower. Thump-thump. Equally ironic for a guy with heart issues. Must be some sort of charge-discharge phenomenon. The schematic made my eyes glaze over.

And when I looked online, it appears that the changer is P-E and not Miracord.

Chris Campbell

[electra225]

I'm assuming it's solid state. Those things are loaded with electrolytic capacitors, many in places tube equipment would never have them. My money is on an electrolytic cap that has committed suicide over the years. Does it "thump" on both channels, or just one? Shango troubleshoots those things like you would tube equipment, only they have small voltages, usually 12 volts is all you see past the power transformer. Saving orphans from an undesirable fate is a good thing. I have as much fun with the "junk" as I do the more valuable stuff. All those would make good projects to share on the forum. We might even start an "Orphans" board just for orphans brought back from the curb.

[TC Chris]

Yeah, it's solid state, and it thumps in both channels and on all inputs, so it's gotta be power supply. I think the best plan would be to replace all the P.S. caps and hope that makes it go away. It doesn't hum, it just thumps.

Chris Campbell

[electra225]

A squeal is a high-frequency oscillation. A putt-putt is a medium-frequency oscillation, and a thump is a very low frequency oscillation. The power supply would be the first area of suspicion, IMHO, but I would not rule out something in the audio that is feeding back into another stage. Perhaps something as simple as a dirty function switch.

I have a Zenith 5D-611 that has a 12K7 IF amplifier tube. IT has a grid cap on it. If you place the wire on the grid cap all the way, the thing hums like a toothless barber. If you just lay the wire barely on the grid cap, the thing plays like a Magnavox. I hate Zenith for this reason, for their obscure, head-scratching faults no other manufacturer has. "The Obscure Faults And SMD Go In Before The Name Goes On". Maybe if you can fix your thump, I can fix this hum.....

[hermitcrab]

Long-timers here will know that all orphan electronics are welcome at my place. Most of them are curbside finds but a few are donations from people who know my proclivities.

I am in the same boat, my family knows if they find something , they can bring it to me , doesn't matter the condition , I did a cleanout of my basement and found stuff I had forgot I had ... it is kinda cool to find a long lost treasure, but lately my mindset has been , why did I keep this?... locally I could fill my basement with consoles for almost nothing... free to 20 bucks ... but no room , there is a nice fisher diplomat locally they started at 100 now it is make a offer... same with most around here , but most are not that desirable in the first place...