Hello,
I have a problem with my amp, which I liked, and I have attempted to disassemble and recap, rewire it, which went rather well, but I have failed to notice, that those thermal isolation's beneath the transistors were missing... So, once I have tried to turn it on, it just refused to do it. When i opened it to see whats wrong, then i saw, that one fuse is blown. And after some poking with multimeter, i have diagnosed that my transformer is gone (short circuit all ower it). Once i have removed it, i poked with multimeter some more, and decided, that all the components on the main board are (or at least should be) OK.
Maybe I could find something similar for replacement. But I do not know any technical specifications of it. I do not even know how much voltage and current it should produce. I have spent hours searching for service manual, or schematics for this amp, but all the links seems dead, so I am desperate and asking for help here.
If someone has a service manual for this amp, please could you share? If not, then any advices about finding the technical data I need, are very welcome.
If that helps, i see couple numbers on the transformer itself:
5584-T4402
IK 4L2 TK
But at least I was't lucky to find anything useful with these numbers.
Thank you very much in advance, if you need any more information, I will do my best to provide it.
I have a problem with my amp, which I liked, and I have attempted to disassemble and recap, rewire it, which went rather well, but I have failed to notice, that those thermal isolation's beneath the transistors were missing... So, once I have tried to turn it on, it just refused to do it. When i opened it to see whats wrong, then i saw, that one fuse is blown. And after some poking with multimeter, i have diagnosed that my transformer is gone (short circuit all ower it). Once i have removed it, i poked with multimeter some more, and decided, that all the components on the main board are (or at least should be) OK.
Maybe I could find something similar for replacement. But I do not know any technical specifications of it. I do not even know how much voltage and current it should produce. I have spent hours searching for service manual, or schematics for this amp, but all the links seems dead, so I am desperate and asking for help here.
If someone has a service manual for this amp, please could you share? If not, then any advices about finding the technical data I need, are very welcome.
If that helps, i see couple numbers on the transformer itself:
5584-T4402
IK 4L2 TK
But at least I was't lucky to find anything useful with these numbers.
Thank you very much in advance, if you need any more information, I will do my best to provide it.
Are you sure your trafo is dead? If you are meassuring the secundar it will show short circuit and thats the way should be. In fact there is some resistance but very low. Long time ago i was repairing the HK610 and i remember that trafo was 25-0-25 about 200W, for HK620 the voltage on secundar should be little higher but i cant tell precisly.
I still believe your trafo is good.
I still believe your trafo is good.
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Hmm, now you got me wondering, well in the output side, between V-Gnd-V connections, i have chort circuit multimeter shows .000 . Next to those trhee connections, i have two separate for somethigin, again .000 between them. On the input side, where 220V is connected, i've also have .000 between the wires. If that does not mean anything bad, then i would be interesdted in how this transformer should be tested 
I also tried to smell it, and it has no bad smell, visually it seems fine.
I also tried to smell it, and it has no bad smell, visually it seems fine.
it is written 250V 1.6A on the blown fuse. I needed to replace some leaked capacitors, thats why. And i did not liked the original thin wires, so as it did not seemed too hard, and the unit was taken apart allready, i just took the oportunity to replace them with slightly thicker and better quality ones. Thas all. I have some skill with soldering, but in electronic stuff i am more like a beginner.
Hmm, now you got me wondering, well in the output side, between V-Gnd-V connections, i have chort circuit multimeter shows .000 . Next to those trhee connections, i have two separate for somethigin, again .000 between them. On the input side, where 220V is connected, i've also have .000 between the wires. If that does not mean anything bad, then i would be interesdted in how this transformer should be tested
Just using test leads should give you a higher reading than .000 ohms! Put it back in and connect the primary but insulate the secondary. Turn it on through a light bulb box.
I agree, that seeking for professional help is probably fastest way to get that amp working again. But, I would like to take this opportunity to learn something from this. Electronics, is interesting world for me
Plus if damage is that serious (repairs would cost a lot), then I'll just find another amp for me. But until then, lets learn Ok, if transformer not dead, that means I should check transistors. There two little ones at the sides of board. There are total four of bigger ones and on weird looking in the middle. I am assuming that those should be taken out in order to test them, right? If they turns out OK, what next I should check?
I kindly thank for your (and everyone else s) time on these questions of mine
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.
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.
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.
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.
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.
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
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?
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
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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