Just picked up a Sony TA-E77ESD preamp, and left channel not working?
TEKWRX
Active Member
Well I guess I spoke too soon 
It appears the problem isn't so bad when the volume knob is turned up past halfway so that's why I thought it was working better. The channel imbalance is really bad when the knob is below 1/4 volume. I guess I will have to take it apart again and see about testing the relays. In the meantime I have adjusted the gain on my power amps so the volume on L-R speakers is more or less even. Not ideal, but I like this unit so at least I can enjoy some music until I figure out what the problem is
It appears the problem isn't so bad when the volume knob is turned up past halfway so that's why I thought it was working better. The channel imbalance is really bad when the knob is below 1/4 volume. I guess I will have to take it apart again and see about testing the relays. In the meantime I have adjusted the gain on my power amps so the volume on L-R speakers is more or less even. Not ideal, but I like this unit so at least I can enjoy some music until I figure out what the problem is 
northpaw
Super Member
hmm... it would help if you could provide more specific info on what you are hearing/not hearing. Is it only low output/no output and no noise in between? Or is there static, crackly, etc. sounds (particularly as it goes into or out of the no output condition), and the volume on the L channel varies somewhat? If it is noisy and variable, it is most likely a poor/dirty contact on a pot (vol or bal) or a switch or relay contact that actually carries the signal. I know you worked to clean the vol and bal pots, but if the problem is tightly tied to the vol position, and it is noisy at times, my main suspicion would be that pot.
If it is only low/no output on the L channel with no middle ground and things are reasonably quiet, I think it points to a relay, specifically the -20dB relay. It could be a sticky contact in that relay, although because that would most likely have some noise asociated with it, it makes me suspicious that the power to that relay might be the culprit.
To check that relay, first I'd try to check if the problem is that the L channel is a constant 20dB down when output is low. A simple test would be, using headphones to maximize your hearing sensitivity, engage the -20dB muting switch and play some content while slowly raising and lowering the vol through the positions you know the problem comes and goes. Overall volume will be low because of the muting, but with headphones hopefully you will be able to hear something while the vol is in the lower ranges. If the R channel is suffering from having the -20dB muting at low vol regardless of the switch position, then engaging the switch should "even up" the channel outputs. So with the switch engaged, if you get balanced output while you raise and lower the volume through the problem area, the relay on that muting circuit is almost certainly the culprit.
But as I said above, the relay itself might be ok, but the power to the relay is the problem. That issue could be a problem on the voltage provided by the power supply, or a problem with the muting switch (since this switch is not in the signal path itself, poor/dirty contacts would not necessarily produce noise). This can be checked by looking for voltages on the relay pins, but you might be able to get a sense if this is the issue by playing with muting switch a bit. While playing music both above and below the key volume levels, try putting some variable pressure on the muting switch while in both the depressed and free positions -- not enough to fully engage or release the switch -- to see if you can get the relay to misbehave. If you find that the L channel output is sensitive to that, try cleaning that switch again.
Ultimately, if it is the muting relay circuit and you are having trouble fixing/replacing either the relay or the switch, the relay can probably be simply removed from the circuit. Obviously this would disable the muting function (I doubt most of us find a muting switch all that useful).
If it is only low/no output on the L channel with no middle ground and things are reasonably quiet, I think it points to a relay, specifically the -20dB relay. It could be a sticky contact in that relay, although because that would most likely have some noise asociated with it, it makes me suspicious that the power to that relay might be the culprit.
To check that relay, first I'd try to check if the problem is that the L channel is a constant 20dB down when output is low. A simple test would be, using headphones to maximize your hearing sensitivity, engage the -20dB muting switch and play some content while slowly raising and lowering the vol through the positions you know the problem comes and goes. Overall volume will be low because of the muting, but with headphones hopefully you will be able to hear something while the vol is in the lower ranges. If the R channel is suffering from having the -20dB muting at low vol regardless of the switch position, then engaging the switch should "even up" the channel outputs. So with the switch engaged, if you get balanced output while you raise and lower the volume through the problem area, the relay on that muting circuit is almost certainly the culprit.
But as I said above, the relay itself might be ok, but the power to the relay is the problem. That issue could be a problem on the voltage provided by the power supply, or a problem with the muting switch (since this switch is not in the signal path itself, poor/dirty contacts would not necessarily produce noise). This can be checked by looking for voltages on the relay pins, but you might be able to get a sense if this is the issue by playing with muting switch a bit. While playing music both above and below the key volume levels, try putting some variable pressure on the muting switch while in both the depressed and free positions -- not enough to fully engage or release the switch -- to see if you can get the relay to misbehave. If you find that the L channel output is sensitive to that, try cleaning that switch again.
Ultimately, if it is the muting relay circuit and you are having trouble fixing/replacing either the relay or the switch, the relay can probably be simply removed from the circuit. Obviously this would disable the muting function (I doubt most of us find a muting switch all that useful).
I had a similar Sony unit and it was the volume control. Verify by checking resistance on each side as you turn the volume (you need two meters for this).
Same symptoms (I think, I read thru quickly) - one channel with reduced output as compared to the "good" channel. Difference in output wasn't consistent, but varied as volume was adjusted.
hard to find a replacement, I had to settle for like a 100k vs. the 120K that was originally in there. But it works find now. Mine is a 444ES IIRC. Maybe I can find the thread..
Here it is... maybe it will help...
http://www.audiokarma.org/forums/in...h-alps-volume-237-175-11.690796/#post-9228794
Same symptoms (I think, I read thru quickly) - one channel with reduced output as compared to the "good" channel. Difference in output wasn't consistent, but varied as volume was adjusted.
hard to find a replacement, I had to settle for like a 100k vs. the 120K that was originally in there. But it works find now. Mine is a 444ES IIRC. Maybe I can find the thread..
Here it is... maybe it will help...
http://www.audiokarma.org/forums/in...h-alps-volume-237-175-11.690796/#post-9228794
TEKWRX
Active Member
Thanks for your thoughts guys. I have uploaded a quick video clip showing what the output is doing, maybe that will help (sorry for the shaky-ness, just did it with my phone). I'm thinking more and more that it must be a problem with the ALPS pot. Again, the low output only affects both sets of pre-outs on the back as well has the headphone output. The TAPE REC outputs are not affected. That strongly points to the ALPS pot because the volume know has no affect on the REC out during normal operation, correct?
Here is the video:
@northpaw, I don't hear any crackle, noise, or other distortion. It's just very low output until you get to about half volume on the dial, and even then it is still quieter than the right channel. I put on headphones and played with the muting switch like you suggested but I could't get any change in behavior or any noise introduced.
@Dingman, thanks for the thread link where you were having a similar issue. So the new ALPS pot fixed the issue for you? Was it hard to replace? I know how to use a soldering iron, but I'm very much a novice (I've done stuff like replace the RCA cables on turntables, installed MOD chips in game consoles so I think I should be able to handle it). I'm nervous about damaging the board it's attched to and then really being screwed unless I find a doner unit, but these don't come up for sale that often I think. I'm sure I won't be able to find the exact Sony part used, but a quick look on eBay shows this one. At first glance it looks similar to what's in my preamp: http://www.ebay.com/itm/ALPS-RK2711...080756?hash=item21167b0134:g:9HcAAOSwi0RX0R6w
I have the service manual, but am having a hard time finding the original part number. The exploded parts view only show the ALPS pot attached to the board assembly called 1-623-836-11 PC BOARD, MASTER VR. But if I look at the ALPS part itself in my unit I see a sticker with part #237-851-11 and it does say it's 120k
What do all you guys think my next course of action is? I'd like to know for sure if the eBay part will fix my issue (or at least 90% sure, LOL. Money is real tight at the moment so I can go wasting any)
Also, as I said before I am able to adjust the gain on my TA-N220 power amps so that the volume is more or less even at the volume I listen at. I have 1 amp for each speaker. I'm not hurting anything by running it this way am I? Probably not, but just want to double check
Here is the video:
@northpaw, I don't hear any crackle, noise, or other distortion. It's just very low output until you get to about half volume on the dial, and even then it is still quieter than the right channel. I put on headphones and played with the muting switch like you suggested but I could't get any change in behavior or any noise introduced.
@Dingman, thanks for the thread link where you were having a similar issue. So the new ALPS pot fixed the issue for you? Was it hard to replace? I know how to use a soldering iron, but I'm very much a novice (I've done stuff like replace the RCA cables on turntables, installed MOD chips in game consoles so I think I should be able to handle it). I'm nervous about damaging the board it's attched to and then really being screwed unless I find a doner unit, but these don't come up for sale that often I think. I'm sure I won't be able to find the exact Sony part used, but a quick look on eBay shows this one. At first glance it looks similar to what's in my preamp: http://www.ebay.com/itm/ALPS-RK2711...080756?hash=item21167b0134:g:9HcAAOSwi0RX0R6w
I have the service manual, but am having a hard time finding the original part number. The exploded parts view only show the ALPS pot attached to the board assembly called 1-623-836-11 PC BOARD, MASTER VR. But if I look at the ALPS part itself in my unit I see a sticker with part #237-851-11 and it does say it's 120k
What do all you guys think my next course of action is? I'd like to know for sure if the eBay part will fix my issue (or at least 90% sure, LOL. Money is real tight at the moment so I can go wasting any)
Also, as I said before I am able to adjust the gain on my TA-N220 power amps so that the volume is more or less even at the volume I listen at. I have 1 amp for each speaker. I'm not hurting anything by running it this way am I? Probably not, but just want to double check
northpaw
Super Member
Your observations rule out the -20dB muting circuit as the problem. There certainly is something going on with the vol pot, given that you get pass through on the L channel at min volume. You mentioned this early on, but was uncertain what to make of it then, but it is not right.
Dingman is your source for info and experience on the vol pot. I do have a Sony TA-F444 ES II integrated, but my vol pot has had no issues, and is quite different (10K, and non-motorized). I'd guess that the soldering should be rather straightforward, just taking care to keep heating and the duration of heating of components (and the board) to a minimum. You will find desoldering braid or a solder sucker to be very helpful with that, and they are cheap.
Someone with much more experience than me would have to comment on any harmful consequences of running with the amps compensating for the volume difference. My concerns are that you are probably not getting the best sound running that way (the freq response through a compromised pot probably isn't linear and therefore colors the sound, and the overall noise levels in the L channel in both the pre and your amp are probably raised relative to what it would otherwise be).
Dingman is your source for info and experience on the vol pot. I do have a Sony TA-F444 ES II integrated, but my vol pot has had no issues, and is quite different (10K, and non-motorized). I'd guess that the soldering should be rather straightforward, just taking care to keep heating and the duration of heating of components (and the board) to a minimum. You will find desoldering braid or a solder sucker to be very helpful with that, and they are cheap.
Someone with much more experience than me would have to comment on any harmful consequences of running with the amps compensating for the volume difference. My concerns are that you are probably not getting the best sound running that way (the freq response through a compromised pot probably isn't linear and therefore colors the sound, and the overall noise levels in the L channel in both the pre and your amp are probably raised relative to what it would otherwise be).
TEKWRX
Active Member
Is there anyway to disassemble the ALPS pot to give it a better cleaning and to see if something is broken/misaligned? Earlier I removed the Master VR board with the ALPS attached, and sprayed Deoxit Gold into both holes on the side of the blue plastic then worked the knob back and forth a bunch of times. I guess I did it right. Still hoping for an easy fix, lol
TEKWRX
Active Member
Doing a little research on the ALPS, it looks like only a 3-pin version of the motorized one I need is available 
I guess I can live with having SOURCE DIRECT on permanently, but I'd rather not. I'd like the unit to function properly. I wonder if there is a way to buy the 4-pin version that worked for @Dingman and the 3-pin motorized version and switch out the actual blue Potentiometer so I end up with a motorized 4-pin version? Probably not, that would be too easy... LOL
I guess I can live with having SOURCE DIRECT on permanently, but I'd rather not. I'd like the unit to function properly. I wonder if there is a way to buy the 4-pin version that worked for @Dingman and the 3-pin motorized version and switch out the actual blue Potentiometer so I end up with a motorized 4-pin version? Probably not, that would be too easy... LOL
You can try to disassemble and repair but the replacements are only $12. They come on a slow boat from China tho.
I did the same with De0X - didn't help, my volume had an actual mechanical wiper\trace issue.
Yes, that's the route I'd go. I'm certain you can swap the motorized part onto the new volume control.Doing a little research on the ALPS, it looks like only a 3-pin version of the motorized one I need is available
The 4pin should work, if your unit doesn't use the 4th set of pins, just clip them off.
Come to think of it, I bought 2 of those volume pots - I don't need the second one, you can have it.
TEKWRX
Active Member
Thanks, I hope you're right and I can just transplant the motor to the 4-pin version. That's awesome if you have an extra you don't need anymore. PM sent
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
I have a TA ES77ESD and a Sony 80 ES power amp...I have just had both serviced after similar problems...$270. CDN...Contacts are silver and corrode over time 20 years...cleaned and lubed with silicone..some cold solder joints and so on...Now I am trying to remember what cables join the amp and preamp together!!