Sony TA-F6B PSU repair

[djacco]

Lol, almost a year

If the PSU is making a high pitched noise then it may be locked and running at a harmonic or just running at the wrong frequency. Very difficult to suggest much really... I think the first thing would be to look at the secondary outputs on a scope and try and gauge what is happening by looking at the frequency and what the overall waveshape looks like.

Thanks for the reply but regrettably I have to say I have no scope...

 

[Mooly]

A scope is pretty much essential for this kind of thing, it tells you so much. Not that its going to be an easy fix... but you need to gather all the information you can about what's going on.

 

[djacco]

I know someone who does have a scope maybe he van help. I will alsof check R622 because of what I read in other posts.

 

[Mooly]

OK (I suspect this will be a tough one to crack though)

 

[djacco]

Is it possible to use another powersupply?

 

[Mooly]

For the whole amplifier you mean ? Yes absolutely. A conventional linear type (tranny + bridge + caps) would give much cleaner rails and 100% reliability. The only problem is size/weight. You would need (at a guess) a 250va rated or higher transformer and typically 6800uf or higher reservoir caps to make a decent supply that would cover any normal domestic use the amp may receive.

 

[djacco]

I thought of just replacing the metal box part...

 

[Mooly]

With what ? another one from another similar amp do you mean ? I'm not sure you would find a good one that easily tbh.

 

[djacco]

With a ring transformer (pardon my english)

 

[Mooly]

Yep, either one of those or a conventional EI frame (square type) which in may ways are better but have become less fashionable.

Internal space to fit one could be a problem though.

 

[djacco]

Have to find one that fits in the metal box
In what wat wat are the old fashioned ones are better

 

[Mooly]

The older ones can be much quieter mechanically. Toroidal (round ones) can buzz a little (not all of them, and it depends a lot on how pure the mains is)

Your probably looking at around 120mm diameter and around 55mm deep for a toroidal. Would that fit in the space where the can lives.

 

[djacco]

Thanks for the info, I will measure the space tonight.

 

[djacco]

the box is 12,5cm high by 7cm wide by 16cm tall

 

[Mooly]

OK, well next you would need to look at what is available in your area and remember you also need to be able to fit two reservoir caps (at least 6800uf/63 volt) and a bridge rectifier.

It is all the mechanical details of fitting it all in that is the challenge... only you know what will be do-able or not with regard to that.

 

[djacco]

I thougt the metal box was the transformer because it looks like the reservoir caps are on the side outside the metal box. If so can't I leave the old caps in and just change the transformer?

 

[Mooly]

No no no The metal box isn't a transformer in that sense, its a high frequency switching supply full of electronics. The transformer in the box is tiny and light because it operates at around 25kHz rather than 50/60hz. The caps you mention are all far to small with regard to 50/60Hz ripple current rating that a conventional supply needs.

 

[djacco]

I think I need a schematic for this since I'm no technical engeneer.

 

[Mooly]

For the power supply using a conventional tranny or the Sony amp ? or both ?

The amp manual is available from "hifiengine"

HiFi Engine - Owners and Service Manuals

The conventional PSU is just a the standard tranny plus bridge rectifier + caps

 

[djacco]

I have the schematics for the amp but never build a powersupply myself.