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RE-8420 issues

PiMaxC

PiMaxC

New Member
My grandfather gave me his old quadraphonic 8 track player and I recently took it to work to power a set of Kenwood 3 way floorstanders I found in an abandoned area of the building. When I hooked everything up it worked but sounded very quiet, then all of a sudden the right channel gets really loud and the left goes out completely. I do a little troubleshooting and realize that the front left channel is dead and the rear right channel too. So I adjust my wiring so I'm using the front right and rear left channel. This works, but I'd like to get it back to it's former glory as this was not a cheap receiver when it was bought and I love the retro charm of the light up sliding tuner.

I have already opened it up and prayed down all the pots and sliders etc with contact cleaner and worked them to loosen up any ancient dirt or corrosion. and I'm thinking I might need to re-cap it. I started looking for service manuals online but aside from the usual suspects who charge ~$20 for a pdf and a few listings on ebay for physical copies I've had no luck.

Anyone out there either have a service manual they can share with me, or know what might be causing this issue and what I can do to repair it aside from replacing all of the caps, that's my plan B as I'm going to need to open it up and make a list of all the caps I'll have to order.
 
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PiMaxC,

You posted a Panasonic 8-track receiver in the Pioneer Forum. You may get a better result if you post in a more general forum. I had one of those Panasonic receivers. They are pretty cool. Good luck getting it going.

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Another AK usage note is that posting the same topic in multiple forums is literally against the rules.
 
Are you using only internal (i.e. 8 track and tuner) signal sources? Maybe try plugging something into each of the AUX input channels and see if you get the same results.
 
I used the aux to determine this with the radio not for if the one rear input is working correctly or not but both front inputs do
 
First I checked the radio to find only one front channel was working, then confirmed with the aux that it didn’t work from both sources.

then I hooked the aux up to the rear channels and tested them and found one of those channels was out.
I did not have a quadraphonic source to test with to test if the rear channel was completely out or if it was just the input that was dead from the aux.
 
Gotcha. The way a good tech would diagnose this would be to run an audio signal into each nonworking input, then trace the signal path using an oscilloscope, until the signal is lost. That point is probably where the problem lies. While it's possible that the receiver needs a recapping, I wouldn't recommend this "shotgun" approach as a first step, since it may be that the caps are not what's causing the issue.

However, there is a relatively easy way to test the output transistors using just a multimeter, which might be a good first step for you if you don't have access to a 'scope. That's assuming that your receiver uses transistors and not an integrated STK type device. Check out this video.

 
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