J C Penney Stereo

[RWV]

My brother has an old JCP Stereo System he bot in the mid to late 80’s. Model 683-2242.

Speakers got ruined in a flooded basement so I am building new speaker cabinets for him. Have one done. Hooking old and new speakers up w RCA port allows solid sound out of both speakers for AM/FM, CD, and cassette. HOWEVER turntable sound output to the speakers is practically zero (can faintly hear the song) at full volume. I am looking for any guidance on what to check to figure out why the turntable sound will not come through as it should. I have very little experience in electronics and wiring, I’m just a dumb ol’ woodworker. 😉Any thoughts appreciated!!

 

[RWV]

 

[DAPUNISHER]

Man does that system take me back.

I don't know much about audio; does the wood you chose, and the way you are building the cabinet, help with sound quality?

 

[RWV]

Man does that system take me back.

I don't know much about audio; does the wood you chose, and the way you are building the cabinet, help with sound quality?

I’m not quite done yet but it shud. Using red oak and walnut and partially lining the inside with a sound proofing foam to minimize vibration in the wood. Sounds good even without that and without full enclosure completed.

 

[DAPUNISHER]

Looking forward to the project finished pics

 

[balloonshark]

Man did I love window shopping for these as a kid.

I don't know much about this stuff so I'm posting what I would try. Did the turntable work before it got to you?

It's hard to see in the pic but is the stylus on the turntable arm? I see what looks like a white colored one laying to the right of the turntable. It could also be a spare. Maybe try swapping them to troubleshoot.

I would mess around with the buttons and sliders on the component above the EQ. The phono button may not be working correctly. Click another button and then click the phono button again. I can't quite see all the button labels to the right. I think I see a loudness and hi-filter you could try as well as the volume slider. It looks like it has two speaker outputs. Have you tried both?

Would something like this have a phono pre-amp? If so it could be suspect but repairing is way beyond my knowledge.

Those are the things I would try to troubleshoot. I've never messed with the electronics inside so someone else would have to help.

 

[RWV]

Man did I love window shopping for these as a kid.

I don't know much about this stuff so I'm posting what I would try. Did the turntable work before it got to you?

It's hard to see in the pic but is the stylus on the turntable arm? I see what looks like a white colored one laying to the right of the turntable. It could also be a spare. Maybe try swapping them to troubleshoot.

I would mess around with the buttons and sliders on the component above the EQ. The phono button may not be working correctly. Click another button and then click the phono button again. I can't quite see all the button labels to the right. I think I see a loudness and hi-filter you could try as well as the volume slider. It looks like it has two speaker outputs. Have you tried both?

Would something like this have a phono pre-amp? If so it could be suspect but repairing is way beyond my knowledge.

Those are the things I would try to troubleshoot. I've never messed with the electronics inside so someone else would have to help.

Thanks Shark. I have swapped needles and they all work the same. Have tried all buttons on off multiple times in as many configs as I can think of. It must have a preamp as it’s a direct plug for the RCA jacks. There are two sets of those and have tried them both with the same results, and they did work on phono before travel to my shop. It’s possible something was jostled loose.

Thanks for the ideas, will keep chasing it as I finish the build on the speakers. Guess I can always buy a new turntable and pre amp as a last resort.

Thanks again!

 

[mindless1]

This is probably going to need either schematics or a pretty in-depth analysis of discrete component architecture unless it just uses chipamp /opamp ICs, and then still the experience to trace the audio signal with a multimeter set to it's lowest AC voltage range and/or ensure (DC) power delivery to each stage.

If something might be jostled loose, observe all solder joints, though sometimes very old electrolytic capacitors (or not so old but nearly dead anyway) can go bad from vibration disturbances, ie - moving it. For best sound, many of the capacitors may need replaced anyway, at least the electrolytics. I doubt something that age has any SMD ceramic caps but if it does, or anything SMD really, then also examine the PCB and solder joints (and ceramic caps themselves) for cracks.

I'm leaving out a few things of course, like whether any internal connectors might've come loose, or wiring falling apart, frayed off at stress points or insulation gone and shorting out., even dead insect remains... Storage conditions mean a lot for equipment that old.

 

[RWV]

This is probably going to need either schematics or a pretty in-depth analysis of discrete component architecture unless it just uses chipamp /opamp ICs, and then still the experience to trace the audio signal with a multimeter set to it's lowest AC voltage range and/or ensure (DC) power delivery to each stage.

If something might be jostled loose, observe all solder joints, though sometimes very old electrolytic capacitors (or not so old but nearly dead anyway) can go bad from vibration disturbances, ie - moving it. For best sound, many of the capacitors may need replaced anyway, at least the electrolytics. I doubt something that age has any SMD ceramic caps but if it does, or anything SMD really, then also examine the PCB and solder joints (and ceramic caps themselves) for cracks.

I'm leaving out a few things of course, like whether any internal connectors might've come loose, or wiring falling apart, frayed off at stress points or insulation gone and shorting out., even dead insect remains... Storage conditions mean a lot for equipment that old.

Thanks for this response. I have checked the things I can, which really means just looking for loose/frayed wires. It’s a jumble inside (to me). See new pic.

Thinking maybe my best option might be to remove the old and buy a new turntable, plug it into the auxiliary IN ports and try that.

 

[mindless1]

Thanks for this response. I have checked the things I can, which really means just looking for loose/frayed wires. It’s a jumble inside (to me). See new pic.

Thinking maybe my best option might be to remove the old and buy a new turntable, plug it into the auxiliary IN ports and try that.

I no longer use records so I don't have product suggestions for you, but do remember that any turntable that does not specifically state that has a built in phono preamp, will need that added between it and standard aux inputs which expect a higher AC voltage.

A basic opamp circuit could provide that gain stage on the cheap, probably could find a bare preamp module somewhere like Aliexpress for a couple dollars then just need to add a DC linear regulated (not SMPS) power supply (very important for low level signal amplification).

That PSU could be as simple as just tapping into the existing DC power circuit in that JCP AIO and adding on an LM7812 regulator or equivalent, or split rail center tapped with an LM7912 for the negative rail if you want to avoid a DC-blocking output coupling capacitor between such a DIY preamp and the AIO's aux input... except the AIO may already have DC blocking caps on it's aux inputs, making that redundant.

Clearly this stereo AIO has some value to you or else you wouldn't bother, but it could take a lot of work to keep it all working, not just replacing capacitors but cleaning/refurbishing the potentiometers (including the EQ linear slider type), and cassette deck lubrication and new belts.

Considering the rat's nest of wiring pictured inside and the amount of labor to even access those areas to refurbish it... you must really like listening to records. 🙂 In that case, a good turntable added is going to sound better than what was in that AIO anyway.

 

[RWV]

Well I thank you so much for putting this much effort into my issue. Much of what you said may as well have been in Greek, for what I can understand. Understand the need for a preamp before the AUX components. Super helpful, will try to find a turntable with the preamp built in. Also understand the ongoing needs. In the end at least will have the speakers and can use those with most things.

Thanks again Mindless for taking the time!!!