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Old 29th March 2011, 09:33 PM   #11
Javin5 is offline Javin5  Switzerland
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Hi meisteris

If the transformer is damaged, which I doubt, I recommend to buy a replacement from the HK Service Center. If they don't stock them any more and you would really need a replacement, here are some hints:

The AC voltage on the scondary is 29.5 - 0 - 29.5 Volt.
The transformer has an additional secondary winding, not sure about the AC-voltage, maybe for some control circuits?
The resulting DC-voltage at idle is +- 38.4 Volt at the filter caps after the rectifier bridge.

Not sure why you would recap, the original caps are of good quality.

Maybe you should try to obtain a service manual before doing any further experiments.
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Old 29th March 2011, 10:05 PM   #12
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I have taken out the transistors, and tested them with multimeter, i am really confident, that those are OK, so it's most likely Transformer at fault.
Quote:
Not sure why you would recap, the original caps are of good quality.
They sure were good quality, but in my case one of two elna caps, were leeking fluids through the top (probably due to age or something, i do not know, so i decided to replace both, as i could not find same elna's, used mundorfs instead.
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Old 29th March 2011, 10:18 PM   #13
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Quote:
Originally Posted by meisteris View Post
Now I am confused one person says it's OK, and you say it may not be OK.

Well, i too think that i should see some more Ohms. Plus there is also a werid thing, that if i connect it back to board, then i get short circuits everywhere. Even if i take ground from a metal case of the amp, and with other tester lead check all the places where i know is a +, i get same .000 output. And then when i remove the transformer out, then on the board all goes back to normal.
Sounds like the power supply diodes are shorted.
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Old 29th March 2011, 10:44 PM   #14
labjr is online now labjr  United States
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Quote:
Originally Posted by meisteris View Post

They sure were good quality, but in my case one of two elna caps, were leeking fluids through the top (probably due to age or something, i do not know, so i decided to replace both, as i could not find same elna's, used mundorfs instead.
Mundorf capacitors? In that?

It's rare that a transformer would fail. That's what the fuse is for.
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Old 30th March 2011, 05:24 AM   #15
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Quote:
Originally Posted by labjr View Post
It's rare that a transformer would fail. That's what the fuse is for.
As far as I know, fuses are put to protect your house from fire, not to protect your electronic equipment. At least that is written in many service manuals

Quote:
Sounds like the power supply diodes are shorted.
Erm, I'll have to check on that more closely, but at the moment i see only some diodes before the transformer, and after the transformer (on the main board), there is no diodes at all (lots of small transistors thou). And i have disconnected transformer unit, from DC side, connected AC wires again, and same thing happens. Disconnect the unit completely, then everything is back to normal on the main board. Check the unit disconnected, it shows .000 everywhere. So the more I check, the more I believe, that the transformer is dead.

One question thou, it seems, that i could fairly easily obtain toroidal transformer something similar to this one: Antek - AN-2230

Would this work?
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Old 30th March 2011, 05:31 AM   #16
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Quote:
Originally Posted by Javin5 View Post
Hi meisteris
The AC voltage on the scondary is 29.5 - 0 - 29.5 Volt.
The transformer has an additional secondary winding, not sure about the AC-voltage, maybe for some control circuits?
The resulting DC-voltage at idle is +- 38.4 Volt at the filter caps after the rectifier bridge.

Maybe you should try to obtain a service manual before doing any further experiments.
Thank you very much Javin5, this is the kind of info, that i am after And yes, i am searching for a service manual actively (damn those manual resellers), but without much luck yet. As I do not have it yet, i promisse to be carefull and experimment as little as possible on it. At the moment, gathering information is more important than experiments
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Old 30th March 2011, 05:53 AM   #17
GoranB is offline GoranB  Poland
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Quote:
Originally Posted by simon7000 View Post
Sounds like the power supply diodes are shorted.
As Simon7000 said, it could be a damaged power supply diodes. Replace them and try to run just power supply, if all is fine, and you are sure that power trans. are ok, connect the power supply to amp. Be sure you have fusses between PS and amp.
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Old 30th March 2011, 06:19 AM   #18
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ok, there is not a lot of them, 4 to be precise, on the little power supply board. I can take them out in the evening, once I am back from work. I'll test them and replace if necesarry, then we will see. Also i think I'll do some photos, as they often say more, than a tousand words could
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Old 30th March 2011, 06:42 AM   #19
GoranB is offline GoranB  Poland
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Photos could help, use macro so we can read the components values
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Old 30th March 2011, 12:16 PM   #20
labjr is online now labjr  United States
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Just disconnect the transformer secondary form the rest of the amplifier and plug it in to see if it has power.
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