Hello everyone, I have a Sony TA-F630ESD amp. The problem I'm having is that there is a crackling/distortion and low volume on right channel - but only in first 5-10 minutes after turning it on!
That time is reduce if I turn up the volume a bit, and the crackling goes completely away. If I turn the volume down again and wait, the crackling slowly comes back (so I'm guessing it's heat related?).
I'm guessing the problem is quite simple (bad solder, bad transistor etc.) but if someone could tell me at which section of the amp I should look, it would help a lot.
Also, it's not source related - it's the same if I use analog or digital input.
That time is reduce if I turn up the volume a bit, and the crackling goes completely away. If I turn the volume down again and wait, the crackling slowly comes back (so I'm guessing it's heat related?).
I'm guessing the problem is quite simple (bad solder, bad transistor etc.) but if someone could tell me at which section of the amp I should look, it would help a lot.
Also, it's not source related - it's the same if I use analog or digital input.
Will check, however the crackling does not change with turning the volume knob so I guess the contacts are ok.
I'll check the solder on it before trying contact cleaner.
Ok so I checked the soldering around the heatsink area, I did notice one of the pins on a 2SA985A pnp transistor had what to me looked like a bad solder.
I resoldered but had problems with solder making contact with the traces.
Decided to give it a go - to me it sounded that the crackling went away much faster than before, but not sure so I will try a few more times, just need to let everything cool back down and then I will see.
I also resoldered all other transistors just as a safe measure.
EDIT: Got the wrong part, it's 2SC3423 transistor, and based on the diagram it's for bias.
I resoldered but had problems with solder making contact with the traces.
Decided to give it a go - to me it sounded that the crackling went away much faster than before, but not sure so I will try a few more times, just need to let everything cool back down and then I will see.
I also resoldered all other transistors just as a safe measure.
EDIT: Got the wrong part, it's 2SC3423 transistor, and based on the diagram it's for bias.
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I'm only seeing one stk3102-III, same in the wiring diagram, or did I miss it somewhere.
I can report that after the first soldering try, the crackling goes away faster than before (I'll keep testing further).
I'll have to revisit that solder on 2SC3423, maybe unsolder it completely and check the trace since the solder doesn't want to make contact with part of it - at least I hope that will be the fix. I don't have as much knowledge as to what exactly does that transistor do and if it could cause the issues I'm having, anyone has any experience?
Just a quick update, took off the front panel today and cleaned the volume pot with contact cleaner, but the issue still remains.
I decided to get a freeze spray and try those transistors, I was thinking of using it on that soldered pin but I'm a little afraid of condensation that it might produce - maybe best if I just try to resolder one more time.
I decided to get a freeze spray and try those transistors, I was thinking of using it on that soldered pin but I'm a little afraid of condensation that it might produce - maybe best if I just try to resolder one more time.
stk3102-III it is a dual, misread the schematic
audiolabga have 1 STK3122III in stock, this is the slightly higher voltage version, should dropin...
STK3122III
Also have a look at diyaudio fake-stk3152-stk3102
audiolabga have 1 STK3122III in stock, this is the slightly higher voltage version, should dropin...
STK3122III
Also have a look at diyaudio fake-stk3152-stk3102
Apply the "Enzo whack"[tm] : ball up your fist tight and hit the top of the cabinet *hard*.
Does crackling improve/worsen?
Does crackling accompany the physical "thump"?
It´s a broad test but helps confirm/discard there is a mechanical problem.
In my book, dirty connectors and cracked solder counts as such.
IF you find there is, then tapping all and every parts, pushing PCB here and there to flex a little, using a chopstick or plastic ballpoint BIC type pen can help you find where it is.
Does crackling improve/worsen?
Does crackling accompany the physical "thump"?
It´s a broad test but helps confirm/discard there is a mechanical problem.
In my book, dirty connectors and cracked solder counts as such.
IF you find there is, then tapping all and every parts, pushing PCB here and there to flex a little, using a chopstick or plastic ballpoint BIC type pen can help you find where it is.
Enzo whack produced nothing sadly. I'll be off for a week, so I won't be able to investigate further, when I'm back I'll try freeze spray on transistors.
Especially on 2SC945 - I found several reports of those failing. One is used as a ripple filter on the selector board and the other is on the EQ board (B+ channel).
Thank you everyone for suggestions and help, hopefully cooling components will produce some results when I get back.
Ok, so just a little update. Got the freeze spray, tried the transistors but did not get any results.
Then I tried it on the STK3102-III, it did produce some crackling - but not always. Sometimes I didn't get distorted sound but static/static crackling even with volume turned all the way down - in the left channel as well! Would this confirm it's the STK failing/bad?
Is the quoted STK3122-III the correct replacement part?
I tried several other components but it did not produce any results, I also cleaned the volume pot for the third time now but it didn't help.
I'm using headphones - that would mean the relays are bypassed if I'm not mistaken?
I guess I'll just try and replace the STK - it's the only component that produced static/crackling when cooled down.
Apart from the fact that that Sanyo's STK series modules do eventually fail, this seems to be heat related as you found you can reduce the time it takes for the crackling to fade after you've done a bit of soldering.
The bad joints will be due to corrosion products and the accumulated grime of many years which prevents the flow of new solder, particularly if you are trying to add modern lead-free solder to older 60/40 alloy. Melt and brush it off with a suede brush or similar or wick it up with one of the solder-braid products you can buy for the purpose and start again, using some extra flux this time.
Edit: just checked; RY301 which is the speaker relay, is located before the headphone socket. The speakers have additional selection switching too.
The bad joints will be due to corrosion products and the accumulated grime of many years which prevents the flow of new solder, particularly if you are trying to add modern lead-free solder to older 60/40 alloy. Melt and brush it off with a suede brush or similar or wick it up with one of the solder-braid products you can buy for the purpose and start again, using some extra flux this time.
Edit: just checked; RY301 which is the speaker relay, is located before the headphone socket. The speakers have additional selection switching too.
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I'm not really sure that soldering helped, and I also tried cooling down the solders I did and there was no change at all. The issue comes back even with the amp powered for several hours so it's not running cold anymore.
I will however check one more time and maybe clean it completely like you said, just to rule out a bad solder.
Yesterday I did a more extensive test, the amp was on the whole day, when played at normal listening volume the sound was clear.
When I lowered the volume the crackling in the right channel came back (in 10 to 20 minutes it depends) at stayed there until I either increase the volume or just blip it to a higher level (if I lower the volume all the way down there is no crackling so I guess it's component related and not a bad contact?).
So based on that, the problem is somewhere after the volume pot (the volume pot itself is good).
I will check the relay you mentioned to rule it out, after that I'll probably just order the STK and try blind.
I really appreciate all the suggestions here from everyone, keep them coming.
It sure seems like a heat issue to me - You turn it up, the amp warms up with more dissipation and the crackling dies - it sounds better. You turn it back down, the crackling returns after some time, right? Sure, it takes quite a while for temperatures inside the amp to change much once the whole system has warmed up but it still has a noticeable effect, going by your description. I wouldn't expect turning the volume down for only a short period would have much effect either. None of this takes much away from the fact that it's probably the module that causes the noise though.
Just be warned , the likelihood of a getting genuine STK replacement modules is zero, that of getting a decent refurbished one is dependent on the shop doing the refurb/replacements and the chance of getting a piece of junk is very good to excellent
Just be warned , the likelihood of a getting genuine STK replacement modules is zero, that of getting a decent refurbished one is dependent on the shop doing the refurb/replacements and the chance of getting a piece of junk is very good to excellent
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