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  1. strandtentje

    Amplifier recommended for IMF super compact

    I've the SuperCompact 1's, and if my experience of those are anything to go by: I've run those on a Sansui AU-217-II for a while, and then a NAIM NAP 90 for a longer while; the midrange performance (both staging and clarity-wise) was second to none in the NAIM-setup. But a Sansui of that series...
  2. strandtentje

    MC250 crackle 1-2s after power-off

    Thank you, this sounds like a great place to do some measurements that I had not considered yet; I've only validated the bias at the emitter resistors, but it should be interesting to see what I might measure beween Q14/Q18/Q22 and Q16/Q20/Q24. I've put the MC250 to one side for a few days to...
  3. strandtentje

    Yamaha A1000 - negative part of waveform clips and oscillation on positive half of waveform

    So the fault only occurs faintly when no load is applied, if I understand correctly. Could you check what happens when you apply a 1KOhm load? And a 100 Ohm load? I've had such an issue in the past; turned out the drivers were only outputting into the... output. There was something up with the...
  4. strandtentje

    MC250 crackle 1-2s after power-off

    Yeah, those parts are on my replace on sight list, ha. Been seeing an awful lot of crackling 70's Japanese gear. There's a selection of docs on Hi-Fi Engine, and Googling can fill in the gaps. I put together a complete PDF for this model for my own sanity but I'm not sure what the legality...
  5. strandtentje

    MC250 crackle 1-2s after power-off

    Okay, the issue followed swapping Q11 and Q12, again. It turned into a pronounced series of pulses on shutdown, in the left channel, instead of the right, undeniably suggesting that the fault at least has something to do with Q11 and Q12, but maybe not the devices themselves. Realised these...
  6. strandtentje

    MC250 crackle 1-2s after power-off

    Following your suggestion: The problem does not occur at the base of the voltage amplifier Q12, but it does at the collector. It seems to get triggered by the input stage giving some DC during shutdown, causing some sort of hysteresis. The voltage amplifier itself is ruled out; the problem...
  7. strandtentje

    MC250 crackle 1-2s after power-off

    Thanks for the recommendations. All supply lines measure to be in working order, stable and largely unstrained. For the purpose of debugging, I detached the white/gray signal lines that hook up the input stage to the output circuits, and hooked up the inputs of the power stages to ground...
  8. strandtentje

    MC250 crackle 1-2s after power-off

    Thank you, it's good to have this confirmed. I'm inclined to think my problem is likely in some semiconductor on its way out, but as to which one- I'm at a loss. Q15 thru Q18 have been replaced to match too and I don't believe the diodes are known to fail.
  9. strandtentje

    MA-5100 Serial Numbers Starting With AA

    I had a look at the schematic and what C21 and C22 should connect to in there, and I'm pretty confident this PCB layout is a bit of a misprint. + of C20 should be connected to R32/34/36, not R38/Q12. Good eye for detail though, never noticed that when getting my MA5100 ready. As to what the...
  10. strandtentje

    MC250 crackle 1-2s after power-off

    Hi, A dear friend who's managed to accumulate more Hi-Fi gear than I did (astonishingly) - he recently uncovered an MC250 from his attic, which he bought for a good price a few years back and briefly played with. We figured we best open it up to check out how it's doing before plugging her in...
  11. strandtentje

    STK3102 driver, replace with TO-220's...could it be done?

    Check ye inbox! I'm hoping to bring a Marantz PM-80 back to life, will report back with results if shipping PCBs turns out viable.
  12. strandtentje

    Onkyo Integra A-8017 2SK246 blown in pre-amp PSU

    I meant a picture of the bottom panel, but if 12mv seems to be the right value, go with that and don't adjust using my cowboyesque method. Multi-turn trimpots are a sound investment for bias setting, I heard.
  13. strandtentje

    Onkyo Integra A-8017 2SK246 blown in pre-amp PSU

    Remove the bottom panel, take a picture and I'll circle them. But I'll also pressingly tell you that what you'll be doing is risky and that if misconduct on your part or otherwise makes causes damage to you and your kit, that's your risk. If in doubt, don't do it yourself, and/or don't do it...
  14. strandtentje

    Onkyo Integra A-8017 2SK246 blown in pre-amp PSU

    Replacing ref voltage JFETs (Q903, 904) brought the signal supply back. The working JFET was replaced as well for good measure. I suspect the 246 went thermonuclear after excessive stress caused by owner abuse. Both output pairs were replaced with slightly beefier parts, even though only one of...
  15. strandtentje

    Best speaker score under $100

    €12,50 ($15) for two heavy closed cabinets with 15" Orion, Philips midrange (replaced due to foam rot), Realistic Dome Tweeter. Oddly, also came with Motorola Piezo tweeters placed a good 13in away from the dome, tweeter configuration is symmetrical between speakers. Odds were small that would...
  16. strandtentje

    Denon PMA 757 advice and opinions

    I have acquired a Denon PMA 757 by means of exchanging it with a fellow audio nut for my Musical Fidelity David. We both seemed very pleased with the deal. The David seems to sit in a slightly higher price category, but the Denon unit (picture attached) was looking a lot better than the David...
  17. strandtentje

    Count To 2018 BEFORE 2018

    1008 bruins is that one heckin' handsome sansui pairing in your profile picture, or can i not tell sansuis apart?
  18. strandtentje

    Onkyo Integra A-8017 2SK246 blown in pre-amp PSU

    Oh my word, that looks gorgeous so far. Do you've a thread about the project? How will you be replacing the markings on the faceplate? Normally I'm a bit skeptical about altering the looks of vintage equipment, but in the right hands it can end very well. I picked up my service manual at hifi...
  19. strandtentje

    Weak right channel on MC2255....erghhhh

    MC2255 is using autoformers like its predecessors, right? As far as I'm aware these pass DC just fine, perhaps with a little bit of resistance, but they pass it.
  20. strandtentje

    Weak right channel on MC2255....erghhhh

    Has it recently been in service? Are you able to check for DC on the outputs? Power guard lights might indicate clipping, DC or otherwise damaging conditions for the speaker. Something is probably working really hard right now in that amp to make sure no transformers or speakers are getting...
  21. strandtentje

    Onkyo Integra A-8017 2SK246 blown in pre-amp PSU

    On the bench I have an A-8017 which is displaying a severe refusal to chooch. I hope to find some help here figuring out what happened, and increasing the chooch-factor¹. This post might read a little easier with the service manual in hand. The following symptoms I observe: - 6,3A Fuse on...
  22. strandtentje

    Replacing The STV-3H and -4H Diodes

    About 30 hours in, the perfboard solution continues to hold up well. It's not as pretty as epoxylug can be, but at this point I think I can recommend it. 3xUF4007 seems to be suitable as well. I'll be trying the epoxylug next time I need a replacement, getting perfboards down to this size...
  23. strandtentje

    Replacing The STV-3H and -4H Diodes

    Thanks! That's it, yeah. I want to give it a good week of playing at moderate levels before I can recommend it definitively. Adding detailed crop of hack later, along with definitive verdict. I'm still a bit worried about mechanical stress on the diode legs that might occur with temperature...
  24. strandtentje

    Hi from the Netherlands

    Ooooh what a lovely dog! Great name too! I'm familiar with Rotterdam, though I don't live as near anymore. I'm still there every other weekend to sip coffee and pet cats. There's a little shop selling old crap on every corner in Rotterdam, I lost count of the great deals- I believe the most...
  25. strandtentje

    Keeping secrets... Great under the radar gear.

    Occasionally, 'Multitech' branded CD players pop up in Western Europe. Usually sporting unironically colorful frontplates, they're easily rejected for looking toylike- A mistake I made once, wihch brings me to the following: My partner has two now, they both sport the same drawer as the NAD...
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