170DC amp w/3250B preamp issues

[angelaudio]

Hello fellow AK’ers!

So I am currently running the above setup with a pioneer pl-61 TT as the source and Dahlquist DQ-10’s as my speakers but I’m having some issues with the amp.

At first I had some scratchy pots on my pre which I took care of easily with some deoxit.

But then I noticed that my left channel VU meter is showing weaker signal. The right channel meter swings like crazy while the left channel is much more tame, usually 5-10 watts less than the right. I tried turning the left gain up and although it does help the volume, I feel that I should not have to do that. Mind you, I’ve played MONO albums just to make sure it’s not just the stereo playback to no avail.

What could be causing this issue? Any help would be greatly appreciated.

Thanks in advance!

 

[wlhd1610]

Swap the RCA cables on back of amp.
Is right meter weaker now or not?
If so it's the preamp.

Does the volume sound the same level both channels?
If so it could be just the meter calibration.

It wouldn't hurt to swap speaker cables left to right just in case the left speaker is loading down the left amp module more than the right speaker does to the right amp module.

Bob

 

[quadmatrix82]

The pre amp does suffer from dirty switches on this model which can cause channel drop out and the problems your cause the only way to really clean them good Is by removing the front panel and removing the board where they are to get in and clean them thoroughly particularly the push button switches

 

[angelaudio]

Swap the RCA cables on back of amp.
Is right meter weaker now or not?
If so it's the preamp.

Does the volume sound the same level both channels?
If so it could be just the meter calibration.

It wouldn't hurt to swap speaker cables left to right just in case the left speaker is loading down the left amp module more than the right speaker does to the right amp module.

Bob

Switched rca cable from preamp (right to left and left to right) but nothing changed. The volume does sound a bit lower on the left channel, even when playing mono records.

I’ll try switching speaker cables next

 

[angelaudio]

The pre amp does suffer from dirty switches on this model which can cause channel drop out and the problems your cause the only way to really clean them good Is by removing the front panel and removing the board where they are to get in and clean them thoroughly particularly the push button switches

I’ll have to try that. I had only gotten to the pots and the sliders but it hadn’t occured to me that the push buttons might be to blame. Will update after cleaning. Quick question while you’re here...how long should I wait to turn the pre back on after hitting it with deoxit d5?

 

[quadmatrix82]

A few minutes is ok I like to use a q tip with deoxit to help clean the contacts be gentle

 

[vintageadict]

old thread but curious if you ever got this resolved? I had the same issue and it came from the balance slider. Once everything was cleaned that solved the problem. All the switches have a tendency to get dirty and be problematic as mentioned above.