JVC JR-S 501 sound problem.

[Brealytrent]

I'm not 100% sure. I just kind of let him work his magic But from looking at the pictures, it looks like it goes from the one trace to the uppermost pin of the top capacitor there, C550

 

[ELzekio]

Once again thanks to all that helped me get this beautiful piece running again. Just finished putting the finishing touches on recapping the amp board, sea board, and DC power board. Sounds beautiful. Like I said before I also just got the JVC jr s 400 which is pictured right next to it. The seller said it had no sound output, but turns out all it needed was Pre amp to amp jumpers and a bit of TLC.

Now all I need is a turntable and a friend can sell me a good one for $200

 

[ELzekio]

so about a week ago I seen a JVC JR-S 401 pop up on eBay. Seller said it turned on and tuned stations but no sound.

I decided to take the risk on it as he was only asking 60 plus 30 shipping. I got him to accept 50. It came in today and when I pulled it out of the box I was shocked to see how clean and nice this unit looked hardly a scratch anywhere on the unit. Beautiful cosmetics! It even has the original styrofoam on the am antenna!



Opened it up to diagnose the problem and Lone Behold, it had the same issue as my 501 and the other poster on this thread. A corroded lead at the bottom of the SEA board blocking the pre amp signal from the main amp board. Just had to install a couple jumpers and she booted up and purred like a kitten



Unit must not have gotten that much use considering the excellent interior and exterrior condition. Absolute steal at $80.

One thing I'm wondering is how common is this issue if that makes three receivers that I know of that this happened to (2 of mine and the poster above) I have a friend that collects JVC stereo equipment and has had over 20 JVC units from the 201 to the 501 and he says he never seen the problem before. I also wonder what could be causing it. I don't think there is any glue that becomes corrosive on the board. My only guess is the capacitors leak but judging from the way the leads are corroded and the still good condition of the caps, I have a hard time believing that is the issue.

 

[GD70]

Looks mint! You stole that receiver!

 

[cbrown094]

I have a good fluke multi meter so I will check this when I get the chance this weekend.

I have your model also and my power meters aren't working at all. Any idea what other JR-S__1 power meters might be interchangeable? You've gone way deeper into your unit than I have by far. Thanks!

 

[6taafondo]

Yeah, looks great! And what's not to like about finding the issue is the same on all of them

 

[Hak Foo]

I have your model also and my power meters aren't working at all. Any idea what other JR-S__1 power meters might be interchangeable? You've gone way deeper into your unit than I have by far. Thanks!

The 201 uses a different physical meter assembly, only one gauge per window, I am not sure if the meter assembly is larger in the 401 and 501 than the 301. I looked at some photos, and the 401/501 use a different lighting assembly (two bulbs per box, versus one on the 301).

Best case: they may use similar physical meters with different resistors to scale them differently. Looking at the 301's serivce manual, there's an 8200 ohm resistor in parallel with the power meter; I'd be unsurprised to see a different vakue in other models, to give appropriate scales. However, that still wouldn't change the fact the difficult-to-replace labeling plate is wrong for the model, and it may not physically fit (see previous comment)

For a quick sanity test though, turn off the speaker outputs, switch to a known-playing source, and slide the volume to 10. The combination of modern, efficient speakers and small rooms mean I have to deliberately force the dials much higher than my normal listening levels on my S301 to see more than the slightest twitch; on the beefier units, it's likely even worse.

 

[ELzekio]

What i do to test if the power meters are functioning properly is put my multi meter on diode test and hook the leads up to the black and white wire joints on the recievers VU meter. If done correctly the VU meter on the receiver will shoot all the way to the right and then come back to normal when you take the multimeter leads off of the joints.

Not sure if it is the safest thing to do but it works.

I beleive the s 401 and 501 meters are the same size but not interchangeable because of the way the meters are scaled differently for the differemt wattages.

Is that your only problem? Do you get sound out of your receiever?

 

[stunz]

I CAN NOT BELIEVE IT!!!

I finally got this puppy running!

All I had to do was install a jumper to connect the ICs to the signal which is just like you said.
View attachment 724295

I always had a suspicion that I had an open circuit somewhere because when I unexpectedly won that JVC jr s 400 It would act exactly like the jr s 501. It would just give faint output when maxed out and that was because there was an open circuit (no jumpers from pre amp to amp)

One thing that really makes me wonder is when I got this 501 and opened it up, there was very little evidence of it being opened up and messed with. So it shocks me that somehow a jumper could have just dissapered from those two connection spots.

Hi,
Do you have any other photos of this TAC-488B board and components?
Specifically I am looking for the value of capacitor C521, which is shown on the PCB layout but not in the schematic or parts list in the service manual.