Phono system problems

[Planar_head]

I'm having an unusual problem. If anyone could point me in the right direction, that would be greatly appreciated.

I bought a used Technics SL-1200 MK2, with broken output wires. I replaced the wires with new single conductor shielded cable similar to the original wire. I was unable to test my soldering job then, but I recently purchased a phono preamp used and when I tried it, very little sound came out and at listening volume, the hum and noise from the preamp was very loud. Also, the channel imbalance was toward the left; with the left channel almost completely gone.

So, there are a few possible causes for this problem.

My cartridge could be bad. I got this cartridge from the same guy whom I bought the turntable from; it's a Ortofon Concorde.

The tonearm could be bad. Maybe the wires could have corroded or something.

My soldering job could be bad. I hope that I'm not that incompetent.

The preamp could be bad. It's a Audio Technica AT-PEQ3, lightly used.

Any help would be appreciated.

 

[Uncle Erik]

Sounds like it may be a grounding issue. Is the turntable grounded to the phonostage?

Do you have a DMM? Even a $5 one would let you check for problems.

 

[Planar_head]

The turntable is grounded to the preamp, but it appears the ground connection is not as strong as it could be.

With everything hooked up proper, the only sound I'm getting is from the left, and in order to hear anything I need to turn up my headphone amp to maximum to hear the signal. Of course, at that volume the noise from the preamp and the turntable are very high.

I do not have a DMM, I will try to get one though.

 

[Planar_head]

Well, it appears I did something right; my left channel is working perfectly. I was messing with the tonearm cables and I noticed one was broken; I stripped it and resoldered it. The left channel works perfectly now, the right channel still silent. I'll keep poking at it and update this thread.

 

[samsquanch]

Got any pictures of your solder joints?

 

[Planar_head]

Sorry, when I crack it open today, I'll take a picture. If it ends up working, then the picture will be simply academic, but if it still doesn't work hopefully it'll help figure out what's wrong.

 

[Planar_head]

Alright, here's some large pics of my admittedly poor handiwork, at internet-destroying sizes.

 

[samsquanch]

it looks like you may have a cold joint on the Right + connection, it also appears that the wire is not making contact with the pad.  Try heating the joint again, adding a small amount of solder, just enough to reflux, hold the cable so that the wire makes contact with the pad, and hold it there until the joint cools.
 
If that doesn't fix your problem, I would try doing a resistance test between the contacts on the end of the tone arm to the rca connectors.

 

[Planar_head]

Does this picture confirm your suspicions?

 

[samsquanch]

yes, your solder joints should be smooth and shiny, otherwise they'll cause trouble.  It's an easy enough fix though, heat and a touch of flux....

 

[Planar_head]

Okay, I fixed that. I measured the resistance between the corresponding points and they measure zero ohms, as expected. So, there isn't any resistance problems there. I measured between L+ and L- and R+ and R-, shows no problems there. Resoldered a wire that broke off in the right channel, maybe that was the issue. Cross your fingers, hopefully this works.

 

[Planar_head]

Still nothing on the right channel. Should I be looking at an alignment issue, or a cartridge issue?

 

[samsquanch]

probably the cart.  if the channel is dead silent then it's not the alignment.  Last hope with that would be to hit the cart contacts with some deoxit, but if you don't have any laying around, you might want to look into a new cartridge.
 
Do you also have a picture of the tone arm wire you soldered?

 

[samsquanch]

Also, have you checked both channels of your pre?  maybe the right channel is out?

 

[Planar_head]

I switched the left and right from the turntable on the preamp, and the sound switches to the right channel, so it's not the preamp.

The tonearm wire I soldered is visible in the first image I posted; its the green one. It's not in focus, but I made sure the joint wasn't cold. That wire is super-thin stuff which breaks at the slightest provocation, just like that blue wire in the first picture.

In any case, if it's the cartridge... Guess that means I need to get another and hope that it works.

EDIT: Well god damn, pulling the needle off and blowing out those contact worked perfectly. Woot! Thanks samsquanch!