I want bought one of these TA 4550s after winning my VFeT lottery and loving the way it sounded.
There some problems with this unit that Im looking at. I have not looked inside yet to figure out a few things but this is at the bench checking a few things out prior to purchase. ($390)
1 Initially on a cold start up there’s no audio at all. And then a 15 seconds or so you can get some output.
2 The left channel only has a time interval popping sound like a discharge capacitor after about five minutes or so the popping stops and the audio is normal. (I don’t think it’s in the power supply side because it’s only one channel and because the interval is a few seconds between each pop I believe it’s after a resistor somewhere maybe in the preamp section because I don’t believe it’s volume sensitive)
3 The speaker selector will not play audio through the A+B and B Position it will play on the A only.
Any initial thoughts, the amp is in working order but definitely has a few gremlins and there.
There some problems with this unit that Im looking at. I have not looked inside yet to figure out a few things but this is at the bench checking a few things out prior to purchase. ($390)
1 Initially on a cold start up there’s no audio at all. And then a 15 seconds or so you can get some output.
2 The left channel only has a time interval popping sound like a discharge capacitor after about five minutes or so the popping stops and the audio is normal. (I don’t think it’s in the power supply side because it’s only one channel and because the interval is a few seconds between each pop I believe it’s after a resistor somewhere maybe in the preamp section because I don’t believe it’s volume sensitive)
3 The speaker selector will not play audio through the A+B and B Position it will play on the A only.
Any initial thoughts, the amp is in working order but definitely has a few gremlins and there.
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Any Audio troubleshooting starts with Voltage checks - download the service manual check Voltage points and check.
second step is to check output offset and bias
then you are certain that things are working fine
second step is to check output offset and bias
then you are certain that things are working fine
I bought one recently, it's a Japanese 100Vac model, fully working set.
The first thing I do was to change out all the old electrolytic caps, perform the "death diodes" mods and change the trafo to suit my main supply 230Vac.
There is a bulletin on swapping some resistors and rebiasing to a lower 45mV instead of the original 75mV from factory.
The output relay used to kick in some 5~8 seconds, now it activates in 2 seconds flat, and music starts playing, I think this got to do with the new bias being more balance and the spk circuit sense output stability faster.
Personally, i do not like the speaker switch function at all, very tempted to just remove the power supply and the power amp module to a seperate chassis and just used it as a Vfet power amp.
@volpar,
Sorry, I didn't have a mouser bom, as I got mine from a local electronic shop.
Please take note that there are different models for TA4650, they use different values of the capacitors, double-check from the service manual.
You may want to do the "death diodes" mods first and rebias those Vfets properly.
Sorry, I didn't have a mouser bom, as I got mine from a local electronic shop.
Please take note that there are different models for TA4650, they use different values of the capacitors, double-check from the service manual.
You may want to do the "death diodes" mods first and rebias those Vfets properly.
Good luck, I would call it a lemon
https://auctions.c.yimg.jp/images.a...abf9ac15/i-img1200x900-1566822553r8dhy782.jpg
https://auctions.c.yimg.jp/images.a...abf9ac15/i-img1200x900-1566822553r8dhy782.jpg
Will the amp work with these installed generic chips as intended or is it just the principle that is no longer of a V-Fet. I kind of need to know so that I know how to do my negotiations with this retail store that I purchased it at.
Have a read, this guy replaced the Vfets with Mosfets....
Restoration of a Sony TA-4650
Not sure if you want to go this path, it's no longer a Vfets TA4650!
Good luck!
Restoration of a Sony TA-4650
Not sure if you want to go this path, it's no longer a Vfets TA4650!
Good luck!
Let's see. If you like it then it's fine.
To the question of yours: Properly done it will operate.
But it will not sound as V-Fet, period. Good one costs around $500 where I live which is not that cheap.
P.S. If you replace original small block in Chevy with Volvo bi-turbo of 86 cu in of displacement will it still be a Chevrolet per say?
To the question of yours: Properly done it will operate.
But it will not sound as V-Fet, period. Good one costs around $500 where I live which is not that cheap.
P.S. If you replace original small block in Chevy with Volvo bi-turbo of 86 cu in of displacement will it still be a Chevrolet per say?
If your retail store has a return policy, it's better to get your money back and look for a better set next time.
This also happened to me, the amp section is replaced with a amp kit with quasi output. Glad, I had found another junk 4650 with complete board with heatsink excluding vfets, now restored with original Vfets.
I am working (fighting) this till the end. Not saying much just yet. But what I need is some estimates for repair or estimate that said it can not be fixed at all.
Odds are that the estimates will say it cannot be properly repaired, since the correct
replacement parts are not available.
replacement parts are not available.