Lost left channel on old Realistic amp

[Rygiz]

Hi All,

I picked up a Realistic “System 601” a few months ago, which has an AMP (SA-601), tuner (TM-601), tape deck (SCT-601) and a turntable (LAB-601). While it worked great for a while, over the last two weeks the left speaker has been cutting in and out. Additionally, the system has the option for choosing “A” or “A+B” speakers, this button has never worked since I owned it, only the “A” option works. This was a non-issue up until now, and I am not sure if this could be a realted issue.

While I usually enjoy trying to figure this stuff out on my own, I don't have the time these days to devote a lot of time to it, nor have I found someone local to work on the unit. So, I'm looking for tips to at least streamline my troubleshooting, and perhaps general best practices for fixing it. I have very little experience with stereo equipment.

So far what I have observed:
-The right speaker output has shown no problem.
-The fuses have been checked, even swapped to see if it makes a difference.
-I have tried the speakers on both outputs, the speakers are fine.
-When I have just the left speaker plugged in, there tends to be a crackle sound, and I do notice sound from the speaker when the volume is turned up rather high, this is also where I hear the crackle. This crackle does not appear when I have both speakers in, change balance to left only, and turn up the volume.
-To my mind, it appears as though there is only a portion of the power required to power the speaker being sent out the left output. Could a component have aged, or become damaged (see below) over time?
-I've tried a good ol'e whack to the unit to see if there was a loose connection that could be jarred, no luck.

I can can scan the electrical schematics, take pictures, etc. what ever would be helpful to troubleshoot this issue.

I did not turn the unit off for about 2 months prior to this problem occurring. My room has been warmer as of late, since I've turned the heat on for winter (25C or so). While I have left amps on for long periods of time before, I am not certain if I have left an amp this old on (I could be wrong, my father had a very old one) for so long, nor have they ever been stacked like this (amp on top). It never got what I had considered very warm, my desktop runs hotter.

Thanks for any help,

Ryg

Update: When I was sliding it back into position after cracking it open to look for something blatantly obvious (I saw nothing), I had the unit on and suddenly the left channel kicked in, then out again. I rattled the wire around some, but couldn't recover except for some quick moments. I then changed the source audio via the control pannel, and the left channel returned again. I cycled between the phono and tuner several times, and the left channel returned strong. Though, it eventually did cut out again.

 

[Guest]

I'd continue to play with the input selector switch and perhaps the tape monitor and volume control -- try some switch cleaner.

Beyond that I'm afraid that older Realistic gear comes under the heading of veteran but not vintage. It was built down to a price and usually sold for more than it was worth (as there was no competitive brands sold within Radio Shack branches).

Personally I'd replace it with a similar age model from one of the big Japanese brands -- many were almost unbreakable and sound surprisingly good.

 

[Rygiz]

Thanks for the reply. The sound came back, and I was unable to get it to break again to track down the problem. Shucks! :O

I'll definitely take a look at getting some switch cleaner.

 

[soundguruman]

"switch cleaner" is not control cleaner. It may damage the controls.
You need to use lubricated control cleaner, like deoxit 100. Spraying the wrong type of cleaner into a control can destroy it.
Also, clean the contacts on the headphone jack.

Contact cleaner and switch cleaner is NOT suitable for cleaning volume controls! Get your application straight!
Incorrect type of cleaner will strip the lubrication out of a volume control and render your control FUBAR. Contact cleaner MELTS plastic! Using the wrong type of cleaner can DESTROY your controls.
Use ONLY lubricated control cleaner, which is specifically designed to clean rotating mechanical parts. THIS IS NOT CONTACT CLEANER!!!
The correct type of cleaner is sprayed into the control in small amounts, ONE spray. Spray this into both sections (left and right) of the control.
Next, rotate the control back and fourth several times, to distribute the cleaner across the entire surface. Allow the control to dry, and wipe off excess cleaner.

An example of REAL control cleaner is DEOXIT or PRO GOLD, sold by CAIG chemical company. This is not cheap, but it will not harm your expensive equipment.

DO NOT rely on a sales person to recommend the correct type of cleaner, verify it YOURSELF, using the recommendations posted on the cleaner manufacturer's website.
You have been warned.

 

[Guest]

"DO NOT rely on a sales person to recommend the correct type of cleaner, verify it YOURSELF, using the recommendations posted on the cleaner manufacturer's website.
You have been warned."

That's the problem -- try finding anything other than switch cleaner at the average electronics parts store.

 

[soundguruman]

Sales person is un-educated. That's why they will sell you anything. Ignorance is bliss.