I am no expert on electronics just have a basic understanding and am a new member to this forum I have been referred to this site by someone who specialises in vintage radio. Here's my problem:
I have a wonderful sounding Luxman SQ202 amp (vintage approx 1972) which
hums thru rt channel only even when volume on zero. Lft side is ok. It stops when RH speaker wire disconnected (obviously) - does not transfer to other channel etc
Trouble is it really gets bad after abt 30mins. Someone said it could be
the current smoothing capacitors can anyone help? I do have original manual and wiring digram (can scan and email). It has a gorgeous sound and is very powerful (80W RMS)
so would like to keep it going. It weighs a ton so reluctant to post
I live in the NEast near Newcastle. Is there anyone who can advise/help?
I have a wonderful sounding Luxman SQ202 amp (vintage approx 1972) which
hums thru rt channel only even when volume on zero. Lft side is ok. It stops when RH speaker wire disconnected (obviously) - does not transfer to other channel etc
Trouble is it really gets bad after abt 30mins. Someone said it could be
the current smoothing capacitors can anyone help? I do have original manual and wiring digram (can scan and email). It has a gorgeous sound and is very powerful (80W RMS)
so would like to keep it going. It weighs a ton so reluctant to post
I live in the NEast near Newcastle. Is there anyone who can advise/help?
Luxman SQ-202
Well no one has replied yet i have not got my schematics yet!!!!!!!
I have run the working channel in the sq-202 it sounded flat and lifeless in its original condition. I replaced the electro caps in the working power amp(with low leakage types the same values) and it really sparkled. The blown power modulel really neat construction
died because of a leaking electro cap so replacement will be mandatory
worth the effort i think. I will replace the 1/4 watt carbon resistors in the power amps for 1/2 watt metal types the values do drift with age
the higher power dissipation of the 1/2 watts won't hurt iam going to replace the ceramic caps with modern polyproplene or polyester caps.
i will post another message when i get the schematics!!!!!
Well no one has replied yet i have not got my schematics yet!!!!!!!
I have run the working channel in the sq-202 it sounded flat and lifeless in its original condition. I replaced the electro caps in the working power amp(with low leakage types the same values) and it really sparkled. The blown power modulel really neat construction
died because of a leaking electro cap so replacement will be mandatory
worth the effort i think. I will replace the 1/4 watt carbon resistors in the power amps for 1/2 watt metal types the values do drift with age
the higher power dissipation of the 1/2 watts won't hurt iam going to replace the ceramic caps with modern polyproplene or polyester caps.
i will post another message when i get the schematics!!!!!
Attachments
Hi Fantasia,
We were waiting for you to get your diagrams.
Low value ceramics should get mica types as a replacement. The larger values can be replaced with film or foil types.
I'd be careful with the resistors. Most of those should be carbon film types. I find metal oxides do wonders (as long as the original was out of tolerance). Metal film types may be inductive depending on the manufacturer. So watch that. The input stages will show the largest reduction in noise if there is any due to resistor types.
-Chris
We were waiting for you to get your diagrams.
Low value ceramics should get mica types as a replacement. The larger values can be replaced with film or foil types.
I'd be careful with the resistors. Most of those should be carbon film types. I find metal oxides do wonders (as long as the original was out of tolerance). Metal film types may be inductive depending on the manufacturer. So watch that. The input stages will show the largest reduction in noise if there is any due to resistor types.
-Chris
Luxman SQ-202
WELL hi fi friends and other LUXMAN SQ-202 addicts
Just joking!!!!!!!!! mine with just one working channel sounds very nice i
NOW HAVE THE SCHEMATICS AND A SERVICE MANUAL
here is the reall good part for GWJ ??? they even have PCB board track layouts full size so you could actually cut your own board if you had a missing one neat hey!!!!!!!
THE specs are what Norman said actually 70watt rms into 8 ohms
*80 watts into 4 ohms distortion <0.04% being a Luxman it probably measures better than that!!!!!
THE phono board as it is seperate could be replaced with a modern
read quieter design but it has a single supply rail.
IF one was quite GAH GAH ( Mad enough) it might be possible to
design a new phono pcb with the same transistor a NPN type
but just paralelling them to reduce the noise!!!!!!!!( instead of 3 per channel 6 or 9 !!!!!) it would keep they sound much the same
or replacing the tantalum caps which are small in value (it is like the
SQ-505 ,507 lots of tantalum and it is DC coupled) with polyester or better polyprolene.
Having looked at prices of NEW integrated amps from quality manufacturers this is well worth it in money terms not to mention fun and the sound is worth it
your in LUXMAN adiction
FANTASIA
WELL hi fi friends and other LUXMAN SQ-202 addicts
Just joking!!!!!!!!! mine with just one working channel sounds very nice i
NOW HAVE THE SCHEMATICS AND A SERVICE MANUAL
here is the reall good part for GWJ ??? they even have PCB board track layouts full size so you could actually cut your own board if you had a missing one neat hey!!!!!!!
THE specs are what Norman said actually 70watt rms into 8 ohms
*80 watts into 4 ohms distortion <0.04% being a Luxman it probably measures better than that!!!!!
THE phono board as it is seperate could be replaced with a modern
read quieter design but it has a single supply rail.
IF one was quite GAH GAH ( Mad enough) it might be possible to
design a new phono pcb with the same transistor a NPN type
but just paralelling them to reduce the noise!!!!!!!!( instead of 3 per channel 6 or 9 !!!!!) it would keep they sound much the same
or replacing the tantalum caps which are small in value (it is like the
SQ-505 ,507 lots of tantalum and it is DC coupled) with polyester or better polyprolene.
Having looked at prices of NEW integrated amps from quality manufacturers this is well worth it in money terms not to mention fun and the sound is worth it
your in LUXMAN adiction
FANTASIA
Luxman SQ-202 schematics
Well here are the Luxman SQ-202 schematics which will help all out there.
I haven't start much at the moment the blown power amp was caused by leaked electolytic. I found that when i removed the caps on the blown board the power transistors were fried as were quite a lot of 1/4watt carbon resistors going for 1/2 watt will be better.
PS anatec what do you think of replacing the phono board with a modern design????? or designing a descreet board with paralelling
of the same transistor??????
Best Whishes
Fantasia
PSS. i cant upload the files just too big!!!!!!!!! email me,
i will at least put them on the Yahoo Luxman Group
Well here are the Luxman SQ-202 schematics which will help all out there.
I haven't start much at the moment the blown power amp was caused by leaked electolytic. I found that when i removed the caps on the blown board the power transistors were fried as were quite a lot of 1/4watt carbon resistors going for 1/2 watt will be better.
PS anatec what do you think of replacing the phono board with a modern design????? or designing a descreet board with paralelling
of the same transistor??????
Best Whishes
Fantasia
PSS. i cant upload the files just too big!!!!!!!!! email me,
i will at least put them on the Yahoo Luxman Group
Hi Fantasia,
Your mail button is not activated. If you use mine, I will reply. Thank you!
As for your phono stage, I can't comment until I see yours. Some of the best phono designs came out in the late 70's / early 80's. Of course there have been some excellent designs since then. My favorite one is in the Marantz 3650 / SC-9. It runs off of + / - 32 VDC.
If you want the button to appear, ask and I'll help you with that.
-Chris
Your mail button is not activated. If you use mine, I will reply. Thank you!
As for your phono stage, I can't comment until I see yours. Some of the best phono designs came out in the late 70's / early 80's. Of course there have been some excellent designs since then. My favorite one is in the Marantz 3650 / SC-9. It runs off of + / - 32 VDC.
If you want the button to appear, ask and I'll help you with that.
-Chris
LUXMAN 202 SCHEMATIC
Hi Fantasia,
I would appreciate a copy of the main output PCB for the 202. Both PCBs including the heatsinks are missing from my amp so I intend making the boards. I was sent a schematic from Norman a year or two ago but the copy is not good enough to make new boards.
Regards, Greg
Canberra 02 62901469
Hi Fantasia,
I would appreciate a copy of the main output PCB for the 202. Both PCBs including the heatsinks are missing from my amp so I intend making the boards. I was sent a schematic from Norman a year or two ago but the copy is not good enough to make new boards.
Regards, Greg
Canberra 02 62901469
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