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  1. quadmatrix82

    Marantz 2500 transistor matching?

    Hi Marantz 2500 experts, I’m working through my 2500 had a few pitfalls along the way but making progress, wondering do the below transistors need to be matched pairs? Finding it hard to find matched pairs these days Qm03 - 2sd610 Qm04 - 2sb630 I have mje15032/33 but about 50hfe apart? Would...
  2. quadmatrix82

    DAC recommendation for vintage system

    Hi all, I decided I want to upgrade my digital set up I am currently using a blue sound node 2i with various 70s vintage amps mainly sansui or Marantz and Imf Rspm Iv speakers. Can anyone recommend a dac for a set up of this elk that would match well, I plan to use the bluesound node 2i as the...
  3. quadmatrix82

    Sansui BA-2000 bias adjustment

    Hi Sansui experts i installed new trim pots on my Sansui ba-2000 and now needs to be dialled in, the service manual procedure for the bias seems overly complex, I read some other threads going through the procedure and wondered - can the bias be measured across one emitter .33ohm resistor...
  4. quadmatrix82

    Marantz 250M - odd resistor values in circuit

    Hi all, so I have been doing some preventative maintenance on my Marantz 250M which seems to work well however I have noticed the left channel has many resistors that test low in circuit compared with the right channel - when tested out of circuit all these resistors measure fine. what could be...
  5. quadmatrix82

    Sony TA-1630 pilot light replacement

    Hi Sony experts, just refurbed a Sony TA-1630 which is sounding lovely but noticed it has no power light in the switch, the service manual doesn’t list any specification - does anyone know what the original spec was? All it says is NL401 thanks!
  6. quadmatrix82

    Marantz 2500 scope help

    Hi Marantz 2500 experts, hoping to get some guidance on repairing a Marantz 2500 scope, there’s no centre dot and whilst works otherwise the scope display is pretty faint, I tried adjusting the the rear adjustments but not much difference. AM and FM okay great very strong signal on all stations...
  7. quadmatrix82

    Luxman L-100 woes

    Hi all hoping to get some help on my Luxman L-100, it’s started blowing the main fuse and the w04 rectifier keeps shorting on the power supply board d901 outputs all test good as do the drivers, the amp is recapped excluding the main filter caps, confirming able to get ~57.5v +/- when testing...
  8. quadmatrix82

    Luxman l-100 power supply help

    Hi Luxman experts, today the rectifier on my Luxman l-100 blew d901, W04 on power supply board pb647, it took out the main fuse too, the rest of the board seems fine I recapped the unit a few years ago and changed the zeners. is this a good substitute ...
  9. quadmatrix82

    Sansui C-2101 input selection help

    Hi Sansui experts, I am restoring a Sansui C-2101 preamp for a friend, it works great in cd input phono and line in, the other inputs don’t seem to work - no output when used. I tried replacing one relay for the tuner input to see if the relay was at fault - replaced with G5v-2-dc24 omicron...
  10. quadmatrix82

    Sansui AU-6600 repair - F-2092a board mod?

    Hi Sansui experts, I’m restoring a Sansui AU-6600 and noticed the power supply eq board F-2092a has this damage on the trace side - do you think this is a factory change to the board or someone has done this in an attempt to mod or repair previously?
  11. quadmatrix82

    Marantz 2500 - Repair woes

    Hi Marantz 2500 experts, I’ve made some good progress restoring my Marantz 2500 - certainly the biggest restoration I’ve done to date… I’m up to the soft start circuit and noticed someone has wired 4 x 100 ohm resistors together, my model is a multivoltage unit and I read that ‘European models’...
  12. quadmatrix82

    Marantz 2500 Filter capacitor options

    Hi all Marantz 2500 experts, I have been trawling the Marantz 2500 posts here to see what options people have done to replace the filter capacitors it seems some restuff the originals or replace with 4 larger capacitors -I'm inclined to replicate what xraytony and others have done with 4...
  13. quadmatrix82

    Marantz 170dc additional capacitors?

    Hi all - was trawling online looking at various Marantz 170dc restorations looking to see how some people replaced the dual capacitor - ended up using the catrafter method which worked well with clamps - however I did come across many 170dc photos that show additional capacitors fitted that look...
  14. quadmatrix82

    Sansui b-2101 adjustments

    Hi sansui experts, I’m noticing a lot of errors in the sansui b-2101 manual, can anyone confirm the correct test points for bias adjustment especially the GND points? I read another thread stating the b-2102 was incorrect I suspect this is similar given the boards are not laid out the same from...
  15. quadmatrix82

    Sansui AU-X911dg restoration

    Hi Sansui enthusiasts, I was lucky enough to recently acquire a Sansui AU-X911DG...I've never owned one of these more recent Sansui's, from the initial reading here I saw lots of positive comments but no restoration threads so thought I'd share mine...upon a quick look inside its mostly original...
  16. quadmatrix82

    Luxman L-100 help

    Hi all I have been restoring a Luxman L-100 which wasn’t working after a recap and replacing zeners I have it up and running on one channel only, I’ve narrowed it down to a preamp fault the output modules work well on both channels when connected directly. Testing all the transistors appear ok...
  17. quadmatrix82

    Luxman L-100 repair

    Hi Luxman experts, I’m currently refurbishing a L-100 and noticed on pb-638 q312 tested as shorted in circuit I removed the transistor - 2sc945 and tests well with my transistor tester and meter, why would this happen? The board is recapped I have left original tantalums in place for now the...
  18. quadmatrix82

    Luxman l-100 adjustment help

    Hi all wondering does anyone know the correct procedure to set the Luxman l-100 power supply voltage? I couldn’t find anything in the service manual or here on AK? Thanks for your help!
  19. quadmatrix82

    Denon Pma-777 diode sub

    Hi everyone I just got a denon pma-777 and noticed an odd diode in it according to service manual hz11b-1 for d313-316 one is faulty it looks two diodes connected together does anyone know a substitute? I couldn’t find much online my guess it’s a 11v zener? Thanks!
  20. quadmatrix82

    Marantz 125 no output

    Hi tuner experts I’m working on a Marantz 125 tuner which has no output I suspect a power supply issue there is no output for AM and FM bands and the tuner meters does not move. I got zero voltage at test point j404 h407 I test approx 14v on emitter and base points H403 I test 41v emitter...
  21. quadmatrix82

    Sansui au-555a flying saucer transistor replacement

    Hi all I’m restoring a Sansui au-555a and wondering if bd-139 and bd-140 are suitable replacements for cdc8002/90002 transistors? Given ksc2690 and ksa1220 are getting hard to find now I have a lot of the bd transistors on hand which I’d prefer to use given they are still readily available any...
  22. quadmatrix82

    Thermistor substitution - Marantz 4070

    Hi all does anyone know a new substitute for thermistor td-a135 fitted to a Marantz 4070 location h719? Thankyou!
  23. quadmatrix82

    Marantz 4070 transistor substitute

    Hi all, currently repairing a Marantz 4070 can I use a 2sa970BL transistor in place of 2sa641 for h701-704? I’ve seen other posts that recommend bc556bta but looking at specs and what I have on hand I think the 2sa970 would suffice but I’m no expert, thanks!
  24. quadmatrix82

    Marantz 125 tuner capacitor orientation

    Hello tuner experts I opened up my Marantz 125 tuner today to clean and change lamps and noticed two capacitors orientated the wrong way to the board - it works well and I recapped it many years ago I’m sure I checked the original cap polarity at the time but hoping someone can confirm if the...
  25. quadmatrix82

    Kenwood KR-10000mk2 repair

    Hi Kenwood gurus im repairing a Kenwood KR-10000mk2 so far all recapped replaced zener diodes on the power amp board and differential transistors however I’m getting a slightly weaker left channel intermittently based on vu meter read and pops from speaker bias and offset were ok prior to...
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