Hi folks,
So not to be too lenghty about this , I got this amplifier from an electronics recycling facility.at first the idea was to salvage the transformers because i'm in searh for some but then I kinda started to lok at it and decided to see maybe it still lives.
the case is in bad condition, the upper cover is missing, front glass broken etc.now the inside the output transistors were blown , also the driver transistors too, some old resistors had changed values and some were dead (open circuit) Now I've went over to check the parts and internals swapped the dead resistors with new ones, checked for shorts and so on.
I want to insert new transistors to give it a try, the original ones are hard to find so I have some replacements at hand I want to ask what you think will they be good?
So the outputs, originals are 2sc2581 and 2sa1106 pairs, I have in mind say toshibas 2sc1943 and sa5200, or the on semi mj21193/94 or something along these lines.
then for the drivers the originals are tc2238 and ta968, now I have at hand some mje15032/33 , as for the idle bias transistor the original is c1815, i have some bc546.
Oh and also any info on this amp would me appreciated like maybe someone has worked on it , repaired etc, also I managed to find only one schematic of it, and its happens to be only the left channel and it's incomplete as the wires that go away to PSU and other blocks can't be seen, only the bare channel circuit.well to repair the channel this one helped and some creative thinking and imagination.So yeah maybe someone has the full schematic.
oh and since it seems the inner parts were different from earlier years to later the code on my channel is " NAMA1195"
just in case I added the schematic that I have so that you could see how much i have.
So not to be too lenghty about this , I got this amplifier from an electronics recycling facility.at first the idea was to salvage the transformers because i'm in searh for some but then I kinda started to lok at it and decided to see maybe it still lives.
the case is in bad condition, the upper cover is missing, front glass broken etc.now the inside the output transistors were blown , also the driver transistors too, some old resistors had changed values and some were dead (open circuit) Now I've went over to check the parts and internals swapped the dead resistors with new ones, checked for shorts and so on.
I want to insert new transistors to give it a try, the original ones are hard to find so I have some replacements at hand I want to ask what you think will they be good?
So the outputs, originals are 2sc2581 and 2sa1106 pairs, I have in mind say toshibas 2sc1943 and sa5200, or the on semi mj21193/94 or something along these lines.
then for the drivers the originals are tc2238 and ta968, now I have at hand some mje15032/33 , as for the idle bias transistor the original is c1815, i have some bc546.
Oh and also any info on this amp would me appreciated like maybe someone has worked on it , repaired etc, also I managed to find only one schematic of it, and its happens to be only the left channel and it's incomplete as the wires that go away to PSU and other blocks can't be seen, only the bare channel circuit.well to repair the channel this one helped and some creative thinking and imagination.So yeah maybe someone has the full schematic.
oh and since it seems the inner parts were different from earlier years to later the code on my channel is " NAMA1195"
just in case I added the schematic that I have so that you could see how much i have.
Attachments
mj21193/94 are too slow, mje15032/33 could perhaps be adequate.
2SA1943 and 2SC5200 (or 2SA1216/2SC2922 if available) should be good, see if you can find 2SA1837/2SC4793 for the drivers.
BC546 is adequate only for the VBEM Q413.
That said an interesting design with a two stages VFA driving a two stages CFA, the whole thing being of course a....VFA..
2SA1943 and 2SC5200 (or 2SA1216/2SC2922 if available) should be good, see if you can find 2SA1837/2SC4793 for the drivers.
BC546 is adequate only for the VBEM Q413.
That said an interesting design with a two stages VFA driving a two stages CFA, the whole thing being of course a....VFA..
yes I was thinking using the bc546 for the q413 actually.
Ok, so I think I can get the drivers you suggested in my local store , that's good.I also hope that can can still get the 2sc1943/5200 pairs even though I'm not sure are they in production anymore ?
Anyway even if their not , I have some in an unfinished amplifier sitting at my basement , I guess I will borrow 😀
speaking from a purely electronics viewpoint ,would the mje15032/33 drivers be any different from the ones you suggested?I mean in a way they would perform in the circuit?
Also I'm not sure what has happened to the amplifier , because almoust all of the output and all of the driver transistors were blown , also mains fuses on the incomming line were also blown , I mean these amplifiers have some protection for the output atleast it seems so from inspecting the case seeing relays or maybe they are for soft DC start I'm not sure as I haven't got the full schematic of this.
Anyway the transformers are fine, measured them , only the output was hurt, also some resistors along the output were totally open circuit, interesting physically they had no burn marks on them one of them just had a slight discoloration of the indicating bands , but measuring them showed open circuit.
in terms of transistors everything before the drivers except the q413 is fine.hopefully there will not be any sudden surprises when powering this up,
sadly i dont have the full schematic maybe i can power it up without the outputs and drivers to measure some voltages that way I could avoid damage to the output transistors in case if something else unforeseen is wrong.
Ok, so I think I can get the drivers you suggested in my local store , that's good.I also hope that can can still get the 2sc1943/5200 pairs even though I'm not sure are they in production anymore ?
Anyway even if their not , I have some in an unfinished amplifier sitting at my basement , I guess I will borrow 😀
speaking from a purely electronics viewpoint ,would the mje15032/33 drivers be any different from the ones you suggested?I mean in a way they would perform in the circuit?
Also I'm not sure what has happened to the amplifier , because almoust all of the output and all of the driver transistors were blown , also mains fuses on the incomming line were also blown , I mean these amplifiers have some protection for the output atleast it seems so from inspecting the case seeing relays or maybe they are for soft DC start I'm not sure as I haven't got the full schematic of this.
Anyway the transformers are fine, measured them , only the output was hurt, also some resistors along the output were totally open circuit, interesting physically they had no burn marks on them one of them just had a slight discoloration of the indicating bands , but measuring them showed open circuit.
in terms of transistors everything before the drivers except the q413 is fine.hopefully there will not be any sudden surprises when powering this up,
sadly i dont have the full schematic maybe i can power it up without the outputs and drivers to measure some voltages that way I could avoid damage to the output transistors in case if something else unforeseen is wrong.
The original drivers are 100MHz, the 2SA1837/2SC4793 are 70MHz IIRC while the MJEs are 30MHz, the design apparently mandate fast devices.
The full schematic can be found here :
ONKYO M-5060R SM Service Manual free download, schematics, eeprom, repair info for electronics
The full schematic can be found here :
ONKYO M-5060R SM Service Manual free download, schematics, eeprom, repair info for electronics
could you please be so kind and do me a favour , I can't download the file because I know this page I found it yesterday but couldn't download, maybe you could download it and upload it here on this thread so I could download it from here ?
The file is too big to be attached, guess that you didnt find the button..
Preview the doc and then the text below :
Will be changed to :
With the link activated on this word.
Preview the doc and then the text below :
Will be changed to :
With the link activated on this word.
thanks I got it , oh by the way , in the schematic of the amplifier , there is a double diode thermo regulator in series with the bias transistor base ,
the part of the diode is labelled D404, the transistor in question is q413, my question is how should it measure when measured with an multimeter turned on the semiconductor measuring range.?
when i measure it no matter whether with semiconductor rage or with ohms range I get nothing , open circuit.
the part of the diode is labelled D404, the transistor in question is q413, my question is how should it measure when measured with an multimeter turned on the semiconductor measuring range.?
when i measure it no matter whether with semiconductor rage or with ohms range I get nothing , open circuit.
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