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MCS 3249 Phono Output Only One Channel

cyto said:
BP means bipolar and the schematic symbol indicates bipolar also. I wonder if those are from the factory or were replaced by someone.

When you pulled those capacitors do you remember if the pcb had the cap polarity marked? Those caps in your hand are polarized.

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I messed up on post #38. I did not replace those. The only caps I changed were the canister style. Sorry
 
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golfnut said:
I messed up on post #38. I did not replace those. The only caps I changed were the canister style. Sorry
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I don’t know what you mean by canister style.

The capacitors in the C519 and 520 positions in your pic are polarized but should be bipolar.
 
I need to see better pics of those orange electrolytic capacitors, they may be bipolar. In your hand post #39. Post pics so I can see all sides.
 
cyto said:
BP means bipolar and the schematic symbol indicates bipolar also. I wonder if those are from the factory or were replaced by someone.

When you pulled those capacitors do you remember if the pcb had the cap polarity marked? Those caps in your hand are polarized.

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Ok.
cyto said:
This is from your pic, C519 is in the center, C520 is out of frame. Did you change them?
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I did change those. Those were one of these (see pic below). I thought that the rectangles on the sides represented negative. I will do a test on my ESR to see if they are ok and can reinstall.
 
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golfnut said:
Stupid question probably, but how would the right channel be working?
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The inputs and/or outputs of opamps are often polarized, NPN or PNP and if so need the appropriate capacitors. A polarized capacitor will often work if it is put in the right direction.
What is very strange is that C519 was polarized and C520 was bipolar. Are you certain those are the caps from those positions?
 
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C501/502 at the inputs are also 2.2uF but are polarized. So the input caps are polarized and the output caps are bipolar. Maybe you mixed them up. If you look at the caps you pulled from the board you should have four 2.2uF 50V caps, 2 polarized and 2 bipolar.
 
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cyto said:
C501/502 at the inputs are also 2.2uF but are polarized. So the input caps are polarized and the output caps are bipolar. Maybe you mixed them up. If you look at the caps you pulled from the board you should have four 2.2uF 50V caps, 2 polarized and 2 bipolar.
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I removed my polarized e-cap at C519 and reinstalled the old BP there. They both measured 2700nf but it should be 2.2uf so some difference. I do not have any BP's on hand.
After reinstalling the BP, I took measurements on the opamp while the turntable was playing a record.
pins 2 both measured at .004VAC
pin 6 on the right fluctuated at .2-.3VAC
pin 6 on the left measured .004VAC
So, yes still no sound out of left channel.

I have to leave right now for awhile but wanted to share this first. I'll get the measurements you asked for on the volume IC's 601/602. I think I'll have access underneath for those.

I do have another opamp as I ordered two. If it makes sense sometime, I could put that one in.
 
You really don’t have the proper troubleshooting equipment. Maybe you should try flipping the left and right opamps. If the problem moves to the other channel the problem is the opamp, if it stays in the left channel the problem is something else.
 
cyto said:
You really don’t have the proper troubleshooting equipment. Maybe you should try flipping the left and right opamps. If the problem moves to the other channel the problem is the opamp, if it stays in the left channel the problem is something else.
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Thanks for the try. I did remove the good side right original opamp and put it in the left channel with no change. I then put the original left opamp in the right channel and it works fine. So, it appears that the opamps were good. I guess I'll resort to an external eq for the turntable unless you or someone else can advise something else to try.
 
I ended up getting more 2.2uf NP capacitors and replaced the one I had already replaced. It is now working properly. Thanks again for all the help.
 
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