Just picked up a Sony TA-E77ESD preamp, and left channel not working?

[TEKWRX]

Hey everybody, I've wanted to get into the vintage 2 channel game for a long time to see what I've been missing (I've always used modern AV receivers) and I found a Sony TA-E77ESD for a decent price at a pawn shop yesterday. I'm a huge Sony fan and love ES gear, so I was excited. Unfortunately it has an issue with the left channel. In normal operation, the volume of the left channel is less than half of the right channel. I've done some troubleshooting to rule out my interconnects, speakers, and power amp being the problem. I also have used DeOxit the best I could on both the volume and balance pots.The low/off left channel problem is there through headphones and all other inputs (including coaxial digital) as well so that leads me to believe it is a problem with the preamp.

Does anybody know of anything obvious I can look for? I downloaded the service manual, but while I can use a soldering iron for basic stuff, I am not an engineer, LOL. I really like this unit so I'd love to get it working, but I do have 7 days to return it for a refund. I can't put any more money into it, so taking it have serviced is not an option.

Help!

 

[TEKWRX]

I just took off the front panel to try and do a better job with the Deoxit. I tested after, and I still have the problem but I notice if I set the balance knob all the way to left channel, I don't hear anything until the vol knob is turned up about a quarter of the way, but the output is MUCH lower than the right at the same position of the knob. Another weird thing is as I turn the knob all the way to down to 0 (or ∞ as the panel says), I do hear the left speaker suddenly come on, but the sound is very thin and tinny, but it's not off. So with the volume pot all the way to the off position the right speaker makes no sound and the left is still playing for some reason. If I move the balance knob will in this "off" state, the music gets quieter as I move to the right channel but it never goes all the way off.

Sorry if that doesn't make sense, maybe I should upload a video showing the issue?

 

[TEKWRX]

Another bit of troubleshooting... I hooked up my turntable and did a quick needledrop and both channels are the same volume going into my recorder through the REC outputs. Now I'm even more bummed, because it sounds pretty good from what I can hear. I really hope I can get it 100% working

I also looked all over to see if there were any bad solder joints, but I'm still not sure where to look specifically

 

[captouch]

Do you have the Source Direct button pressed? I'm wondering if you bypassing the tone controls will help.

The fact that you can get the REC out working well is promising. Are you comfortable with trying to probe for a signal on the PCB?

 

[TEKWRX]

Do you have the Source Direct button pressed? I'm wondering if you bypassing the tone controls will help.

The fact that you can get the REC out working well is promising. Are you comfortable with trying to probe for a signal on the PCB?

The problem is there with or without Source Direct pressed. At first I thought the left channel was completely out because I was using Source Direct and when that is engaged the balance control doesn't work. It was when I turned it off that I realized the left channel was just extremely low output, not missing.

I have a basic DMM and could try and probe for a signal, but like I said I'm not really sure how to go about that.

 

[ryuuoh]

What's with that wire draped over the transformer?
Have you pulled the actuator off of the remote switches and directly applied cleaner? The service manual details how to remove the actuator.

 

[captouch]

You might start by opening it up and seeing if it's clear on the PCB where the signal goes into and out of the volume pot.

Knowing where to probe is a good first step.

Also, does the left channel come back if you go into Mono mode with the Mode Select button?

Download the service manual here:
http://www.hifiengine.com/hfe_downloads/index.php?sony/sony_ta-e77es_esd_service.pdf

You'll need to create a free account, but I think there's schematics there. It crashes my iPad (pbb due to file size), so I can't verify.

I used to have this unit and it's too bad I still don't to help to guide you through some of this, and I don't remember how packed and visible the PCB(s) was/were, but if you can trace the signal from input to output visually, it should be possible to find the bad component and perhaps fix it. Could also be a bad cap in the Left channel signal path, which would probably be easy to fix.

 

[TEKWRX]

What's with that wire draped over the transformer?
Have you pulled the actuator off of the remote switches and directly applied cleaner? The service manual details how to remove the actuator.

I'm not sure what that wire is, but it looks like it was taped to the transformer at the factory. I haven't removed the actuator to clean directly yet as I don't have the right size hex key to remove the volume knob. I'll if I can get the right one at the store tomorrow

 

[TEKWRX]

You might start by opening it up and seeing if it's clear on the PCB where the signal goes into and out of the volume pot.

Knowing where to probe is a good first step.

Also, does the left channel come back if you go into Mono mode with the Mode Select button?

Download the service manual here:
http://www.hifiengine.com/hfe_downloads/index.php?sony/sony_ta-e77es_esd_service.pdf

You'll need to create a free account, but I think there's schematics there. It crashes my iPad (pbb due to file size), so I can't verify.

I used to have this unit and it's too bad I still don't to help to guide you through some of this, and I don't remember how packed and visible the PCB(s) was/were, but if you can trace the signal from input to output visually, it should be possible to find the bad component and perhaps fix it. Could also be a bad cap in the Left channel signal path, which would probably be easy to fix.

Thanks @captouch. The Mono button doesn't have any affect. I did download the service manual this morning, but like I said I'm not so great at deciphering schematics I'll try and find the signal path. How would I use my DMM to find where the problem is? I'm not even sure what settings to use on the meter.

 

[ryuuoh]

You just pop the remote actuator off, no need to remove the knob.

 

[TEKWRX]

You just pop the remote actuator off, no need to remove the knob.

This morning I removed the screws from the PCB that the volume pot is attached to hoping to remove it and clean it good, but it would come off with the knob attached. Maybe I'm not sure which part is the actuator? Here is a picture of the assembly:

 

[ryuuoh]

In your original post, the photo shows two slide switches mounted on the PCB, actuated by metal ribbons. Also, looking at pics of your unit on the net, that wire over the transformer is not original.

 

[TEKWRX]

In your original post, the photo shows two slide switches mounted on the PCB, actuated by metal ribbons. Also, looking at pics of your unit on the net, that wire over the transformer is not original.

Oh, now I know what actuators you mean. Those for for the MM/MC selection, and the REC OUT selection. Would they have something to do with the issue? Remember, the REC OUT seems to work with both channels full output.

As far as that wire across the transformer, I'm not sure why is routed over that way, but I followed it and it looks like it goes to the headphone socket.

EDIT: I just checked on google, and I found another on a German forum with the wire held down with the same black tape http://www.hifi-forum.de/bild/image_621917.html So I would assume that's normal.

 

[ryuuoh]

Probably not connected with your issue then. It wouldn't hurt to clean them though. That taped wire looks rather funky for such an expensive piece of gear, lol.

 

[TEKWRX]

Probably not connected with your issue then. It wouldn't hurt to clean them though. That taped wire looks rather funky for such an expensive piece of gear, lol.

Yeah I agree. I guess Sony had a reason for taping it like that

I hope I figure this issue out. I have the unit on my computer desk for troubleshooting, and I adjusted the balance knob to favor the left channel to get the volume pretty even, and this preamp sounds pretty great. I just have average speakers on my desk setup (Sony SS-HA3) and the music sounds much better with this in the chain. Hope I don't have to return it and can put it in my main rig

 

[captouch]

As a fallback, and it may not be what you want to hear, but perhaps you can consider using a passive volume control (like Schiit Sys) on the Rec out if you can't fix the unit.

 

[northpaw]

Your description of the left channel coming on at particular times, albeit thin and tinny, is suggestive of a poor contact, either in a switch, solder joint, or relay. The SM indicates several relays are present. I'd look that info over to see if any might control the left and/or right channel signal (e.g., it could be a problem in a double-pole relay, with only the left channel side in trouble). If there are, I'd locate them physically on the board and try tapping them gently while the unit plays, to see if you can find any sensitivity in your left channel sound to taping directly on the relay. Corrosion on the relay contacts can produce this kind of problem, which is fixed by dissambling the relay and cleaning it if possible, or just replacing it (usually a better solution).

 

[TEKWRX]

As a fallback, and it may not be what you want to hear, but perhaps you can consider using a passive volume control (like Schiit Sys) on the Rec out if you can't fix the unit.

That's not ideal, but something to think about. I wanted to integrate my new 2 channel system with my HDMI A/V receiver anyway, so I play around with using REC out and see how everything sounds. Would I'd still be getting the sound quality benefit of using this preamp if my A/V receiver is downstream and doing the volume control?

 

[TEKWRX]

Your description of the left channel coming on at particular times, albeit thin and tinny, is suggestive of a poor contact, either in a switch, solder joint, or relay. The SM indicates several relays are present. I'd look that info over to see if any might control the left and/or right channel signal (e.g., it could be a problem in a double-pole relay, with only the left channel side in trouble). If there are, I'd locate them physically on the board and try tapping them gently while the unit plays, to see if you can find any sensitivity in your left channel sound to taping directly on the relay. Corrosion on the relay contacts can produce this kind of problem, which is fixed by dissambling the relay and cleaning it if possible, or just replacing it (usually a better solution).

That's interesting. I'm not seeing any obvious relays, but I'm sure they're in there (hear them clicking when powering up). Just not sure where they are. It looks like the digital boards are shielded underneath the mainboard for sound quality? I only have the top cover off right now, but there are screws and a large panel on the bottom. Maybe the relays are there? I looked at the service manual again, but not having much luck

 

[Binkman]

Not being cynical? if the option to return instead of a headache is open, I'd return it. imo.