Author Topic: Zenith SFF2535R low left channel  (Read 793 times)


  • Newbie
  • *
  • Posts: 9
    • View Profile
Zenith SFF2535R low left channel
« on: June 28, 2017, 07:16:57 PM »
Hi All

I'm new to vintage stereo repair although not vintage stereos except they weren't vintage when I was using them. :) Recently my wife bought me beautiful vintage stereo and I have been working to bring it back to it's original sound quality. I have read many forums and threads in preparation for this project. At this point, I've got if fully operational but with a few issues.

I began with replacing all the electrolytic capacitors, cleaned all the switches and pots and replaced the channel AF amp tubes and the left and right output tubes.

I get good volume from the right channel although a little distorted at the high end and low volume with a lot of distortion on the left channel.

Another more minor issue is that I don't get any sound from the mid-range or tweeters on either channel. I replaced the caps on them with the specified non-polarized replacement. I have bypassed the caps to make sure the speakers are good and have even tried driving them from a different amp source.

I was a technician for a short time 40 years ago but my profession took off in another direction. Now that I'm retired I back to where I started. Only trouble is, I don't know where to start trouble shooting this. I have the SAMs for the system and can still read the schematic. I just don't know what to look for or where. Any help would be appreciated.


TC Chris

  • Hero Member
  • *****
  • Posts: 1901
    • View Profile
Re: Zenith SFF2535R low left channel
« Reply #1 on: June 28, 2017, 08:10:12 PM »
So your high and mid freq. speakers work when the caps are bypassed or on other sources?  If not, they have been fried. If they do work, and if you've replaced the crossover caps, then it's either (1) the amp is not putting out any higher frequencies, or (2) there's some wiring issue.

Small speakers can be fried by under-powered amps driven into clipping.  The usual problem is not enough power instead of too much.

As to the channel issues, have you checked the voltages around the tube pins?  If you don't have a schematic, L should equal R for the same pin on each tube.

Chris Campbell