Hi.
A sad story.
On my last trip out of town I picked up an HK PM665. It was fantastic.
I brought home and plugged it in. It blew fuses.
I figured out afterward that the amp was designed for 110 and not 220. No, I hadn't checked, I had assumed.
Fortunately the amp had two transformers and PSUs. Connected the trafos in series, and it was up and running.
Or so I thought.
The right channel is feeding about 15VDC into the speakers. The output devices seem fine, it's just blowing up my woofers. the left channel is delivering pristine audio.
I need to do a circuit trace, and I'm looking desperately for a schematic of the power amp section. The construction is similar to a truck, so pulling parts is not easy at all.
Anybody with any experience of this amp please do post.
Sang.
A sad story.
On my last trip out of town I picked up an HK PM665. It was fantastic.
I brought home and plugged it in. It blew fuses.
I figured out afterward that the amp was designed for 110 and not 220. No, I hadn't checked, I had assumed.
Fortunately the amp had two transformers and PSUs. Connected the trafos in series, and it was up and running.
Or so I thought.
The right channel is feeding about 15VDC into the speakers. The output devices seem fine, it's just blowing up my woofers. the left channel is delivering pristine audio.
I need to do a circuit trace, and I'm looking desperately for a schematic of the power amp section. The construction is similar to a truck, so pulling parts is not easy at all.
Anybody with any experience of this amp please do post.
Sang.
PSU
If the both transformers are supplying the both channels separatly,you cant wire the primaries in series.
The channel with higher output will cause his transformer to draw more current, resulting in a lower impedance in his primary winding.
This means that the other transformer has a higher voltage at his input causing overvoltage in the secondary.Almost sure the result will be smoking parts.
You can go two ways:
1.)Get a stepdown transformer 220 > 110 Volts, this can be a type that is not mains isolated (economy - type)
2.) You can wire the primaries in series and both secondaries in parallel,the easiest way will be connecting +Vb of the left channel with +Vb of the right channel and -Vb left with -Vb right, this automatically balances out the differences between the transformers.
The drawback will be that the channels are not separated any longer.
If the both transformers are supplying the both channels separatly,you cant wire the primaries in series.
The channel with higher output will cause his transformer to draw more current, resulting in a lower impedance in his primary winding.
This means that the other transformer has a higher voltage at his input causing overvoltage in the secondary.Almost sure the result will be smoking parts.
You can go two ways:
1.)Get a stepdown transformer 220 > 110 Volts, this can be a type that is not mains isolated (economy - type)
2.) You can wire the primaries in series and both secondaries in parallel,the easiest way will be connecting +Vb of the left channel with +Vb of the right channel and -Vb left with -Vb right, this automatically balances out the differences between the transformers.
The drawback will be that the channels are not separated any longer.
You could use a fairly smallauto transformer with a single 220v winding that has a centre tap. Put your two power trannies in series, (*HATE* that word "trafos") with the junction of the two primaries to the CT of of the auto tranny. The load on the autotranny is only the *difference* of the other two trannies at any given moment.
Circlotron said:
Circlotron
Did not understand.
Are the two ends of the auto*TRANNY*
connected to the mains too? along with the two ends of the two 110 V trannies?In which case it is one 220 V tranny connected in parallel with 2 110 V trannies (assume it is like two 220VCT primaries?) across the mains, with the two 'center taps' together?
Thanks
Sang
Off-topic, sorry.
What's wrong with the word "trafos" ? When I read trannies I think of grannies !
German/Dutch speakers will abbreviate the word transformer ( in German/Dutch: transformator ) to "trafo". Because of English/American influence people think this sounds to "hard" and today they soften it to the word "travo". This is wrong because a "travo" means a transvestite which is really something else I've been told.
Unfortunately a lot of words are changed because they have to be soft like in English. That is supposed to sound better so we adapt ( well, not all of us ). I don't understand why we have to change our language because of an other language !?!?! We even eat a "slice" of pizza nowadays instead of a "stuk". You can probably imagine what a monster our language is becoming through the years. Some kind of mixture that is very difficult to teach to children. All this because English is THE worldlanguage so we are taught. No wonder nationalistic parties are winning the elections the last years.
First I thought the French were very stubborn with their language. On the French national radio they practically only play French music ( I think it is even forbidden to play less than 70 % French music). Names of companies have to be French. I remember that they didn't even like the name Alcatel because it wasn't French enough. Now I've learned they are right. They will speak French after a hundred years from now, we will speak English for sure.
So let's accept both words: trafo and tranny.
Same goes for capacitor and condenser. Although a condenser is a part of a refrigerator the Japanese prefer to call capacitors condensers. I can live with that.
What's wrong with the word "trafos" ? When I read trannies I think of grannies !
German/Dutch speakers will abbreviate the word transformer ( in German/Dutch: transformator ) to "trafo". Because of English/American influence people think this sounds to "hard" and today they soften it to the word "travo". This is wrong because a "travo" means a transvestite which is really something else I've been told.
Unfortunately a lot of words are changed because they have to be soft like in English. That is supposed to sound better so we adapt ( well, not all of us ). I don't understand why we have to change our language because of an other language !?!?! We even eat a "slice" of pizza nowadays instead of a "stuk". You can probably imagine what a monster our language is becoming through the years. Some kind of mixture that is very difficult to teach to children. All this because English is THE worldlanguage so we are taught. No wonder nationalistic parties are winning the elections the last years.
First I thought the French were very stubborn with their language. On the French national radio they practically only play French music ( I think it is even forbidden to play less than 70 % French music). Names of companies have to be French. I remember that they didn't even like the name Alcatel because it wasn't French enough. Now I've learned they are right. They will speak French after a hundred years from now, we will speak English for sure.
So let's accept both words: trafo and tranny.
Same goes for capacitor and condenser. Although a condenser is a part of a refrigerator the Japanese prefer to call capacitors condensers. I can live with that.
Re: Off-topic, sorry.
"Same goes for capacitor and condenser. Although a condenser is a part of a refrigerator the Japanese prefer to call capacitors condensers. I can live with that."
Condensor is an old "steam-age" word. Car engines are full of 19th century engineering words like manifold, flywheel, rich, lean, advance, retard, dynamo, radiator, battery, crank etc. A real time capsule of old words.
Yeah, that's really strange, especially when you consider it isn't really a slice but a sector!jean-paul said:
"Same goes for capacitor and condenser. Although a condenser is a part of a refrigerator the Japanese prefer to call capacitors condensers. I can live with that."
Condensor is an old "steam-age" word. Car engines are full of 19th century engineering words like manifold, flywheel, rich, lean, advance, retard, dynamo, radiator, battery, crank etc. A real time capsule of old words.
LOL !
Really ? So they even adapted the wrong word !?!? Ha ha !
Those companies are American and they offer : a slice of real American pizza ! I like that one too, it's like the Italians invented the hamburger.
BTW I learnt the word "generator" for "dynamo" as the latter wasn't supposed to be an English word !?! The German word "Lichtmaschine" ( lightmachine ) is fantastic and simply accurate at the same time.
The Japanese say "condenser", not "condensor". But I like the phrase about the time capsule. Those words remind one of the early age of technics and have a certain "mystique" ( might not be an English word ) around them.
Sorry for threadjacking, please back to the subject ( if necessary ).
Really ? So they even adapted the wrong word !?!? Ha ha !
Those companies are American and they offer : a slice of real American pizza ! I like that one too, it's like the Italians invented the hamburger.
BTW I learnt the word "generator" for "dynamo" as the latter wasn't supposed to be an English word !?! The German word "Lichtmaschine" ( lightmachine ) is fantastic and simply accurate at the same time.
The Japanese say "condenser", not "condensor". But I like the phrase about the time capsule. Those words remind one of the early age of technics and have a certain "mystique" ( might not be an English word ) around them.
Sorry for threadjacking, please back to the subject ( if necessary ).
Thanks Jean
No, the transformers have 110V primaries. No doubt about that. and no voltage selector, either.
The power transistors seem OK. The amp was switched off before the load connection cut in. As I said, there is sound but also a lot of DC. It took out two speakers before I figured it could be DC...
I desperately need a schematic.
No, the transformers have 110V primaries. No doubt about that. and no voltage selector, either.
The power transistors seem OK. The amp was switched off before the load connection cut in. As I said, there is sound but also a lot of DC. It took out two speakers before I figured it could be DC...
I desperately need a schematic.
Searched for you too but I found nothing. Is there a representative of HK in India ? Order the schematic there since it won't be very expensive and you need it.
You can repair it if you are experienced without a schematic otherwise there is a big chance the amp will become worse. It is easy to make small errors while repairing and replacing parts.
Remember that if the power transistors are defective you will have to replace them in both channels. Yes, the good channel needs new transistors too because you will definately hear difference between channels if you don't.
You can repair it if you are experienced without a schematic otherwise there is a big chance the amp will become worse. It is easy to make small errors while repairing and replacing parts.
Remember that if the power transistors are defective you will have to replace them in both channels. Yes, the good channel needs new transistors too because you will definately hear difference between channels if you don't.
The power transistors are fine. No additional heat, sound OK when series-connected with capacitor ( to protect woofer from DC).
No resolution of DC at output, though.
Still hoping for a schematic. No, there are no HK reps in India. I have written to HK from their website. Awaiting a reply.
Anyone? Anyone at all?
No resolution of DC at output, though.
Still hoping for a schematic. No, there are no HK reps in India. I have written to HK from their website. Awaiting a reply.
Anyone? Anyone at all?
Manuals for sale. Service Manuals.
PARTS BOX - Service manuals for sale
http://www.partsbox.net/
Parts from, and for, experimenters, tinkers, hobbyists and prototypers.
To purchase, send email to cnc@partsbox.net
Service manuals for sale.
Including schematics
---------
Kenwood Service Manuals
Harmon Kardon Service Manuals
JVC Service Manuals
NAD Service Manuals
Pioneer Service Manuals
/gromanswe
PARTS BOX - Service manuals for sale
http://www.partsbox.net/
Parts from, and for, experimenters, tinkers, hobbyists and prototypers.
To purchase, send email to cnc@partsbox.net
Service manuals for sale.
Including schematics
---------
Kenwood Service Manuals
Harmon Kardon Service Manuals
JVC Service Manuals
NAD Service Manuals
Pioneer Service Manuals
/gromanswe
HK prob
I also a know a guy in Calcutta who could be of help. His name in Ramesh Dave and his repairshop (if you can call it that) is located in a dilapidated building just across 3 Mangoe Lane. I can't remember the numebr of the buidling, but its a 4 or 5 stories builing and declared unfir by the Municipal Corporation. Ramesh Dave heleped me with my Pioneer Class A a few years ago. But off-course this is a very "non diy" approach .
Good luck
You can pay in Forex. Thats not a problem. Much easier if you do it with a Credit Card. Otherwise you have the hassel of asking for a Proforma and taking it to your forex dealer (usually a bank authorised to do that). I do it all the time.sangram said:
I also a know a guy in Calcutta who could be of help. His name in Ramesh Dave and his repairshop (if you can call it that) is located in a dilapidated building just across 3 Mangoe Lane. I can't remember the numebr of the buidling, but its a 4 or 5 stories builing and declared unfir by the Municipal Corporation. Ramesh Dave heleped me with my Pioneer Class A a few years ago. But off-course this is a very "non diy" approach .
Good luck
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