amplifier

  1. Racingh11

    Soundcraftsmen PM860 / PCR800 power-amp restoration

    I bought this amp in rough shape as a project to match my other PM860 beater amp. I should have taken before pictures. The inside was coated in heavy dust that was also oily. And all of the black sheet metal parts had the paint pealing off. I opted to fully disassemble the amp. Ultrasonic...
  2. Bob123456

    Pioneer SA-8800 - high voltage readings

    Hello, newbie here hoping for some advice. I was recently given an SA-8800 in not-great-condition to refurb and sell on behalf of an elderly relative. I've got a little experience with electrical repairs and I guess I've had some luck in the past, but I have limited equipment (and space) to work...
  3. JamesWest...

    Nikko TRM-1200 Amplifier (1970) Repair Questions

    Hello all, I have what seems to be a bit of a rarity; A Nikko TRM-1200 preamp-amplifier (approximately 1970). Which I am having a couple of issues with. First, the VU meters seem really insensitive. They move a little if I turn on the loudness switch. Any thoughts? As a note: I did replace...
  4. A

    Regular, Sharp Pops Through Stereo

    Friends, Just posted about my system for a different problem (crackling on input changes and volume pot), but here's a new one that I started tracking. Managed to read some threads about this issue, so let me go through facts: Quick, assertive pop through the left and right speaker...
  5. Connor G

    Sansui AU-717 Restoration and Upgrade

    Hello fellow AKers! I just finished a comprehensive restoration of a beautiful Sansui AU-717. This thread is dedicated to showcase the steps I took during the restoration process. There will also be a video posted to my YouTube Channel showcasing the work I did there. Once it is uploaded, I will...
  6. Schmurpy

    Hitachi HMA 7500/8500MKII power meters needed.

    Hello, Hitachi HMA 7500/8500MKII power meters needed.
  7. G

    Looking for B&K ST-2140 Power Amplifier Service Manual

    Hello - I am looking for service manual of B&K ST-2140 Mosfet Power Amplifier. In 2020 I contacted ATI who owned B&K then and I got this reply: "Thank you for contacting us. Did a search of our legacy B&K database and could not find a service manual or any schematics for the ST2140. Sorry...
  8. C

    AU717 power stays on

    My amp stays on even when power turned off.Must be in the protection circuit, maybe.Red power light on always. Any idea?
  9. J

    Custom Terminal Build

    I'm finally addressing an issue that started, round about ten years ago, broken speaker terminals on my Fisher CA-2120 Integrated amplifier. I've been using this as a pre-amp for the Hafler P500 amplifier since the speaker terminals were junk. After the first two, the A and B R+'s broke, I wired...
  10. cuboid

    MC2105 Speaker thump

    Hi all I've got a well-loved but frequently-serviced MC2105. The current concern is that when it's powered on, I get some major speaker thump. Though it's just a single oscillation and my speakers are now pretty high power, they're now too expensive for me to risk damaging them from something...
  11. Connor G

    Sony TA-5650 VFET Integrated Amplifier Restoration (Video)

    See below to check out the restoration I just finished on a gorgeous Sony TA-5650 VFET integrated amplifier! I’m starting to post more and more restoration and repair videos to YouTube. Hope you all enjoy!
  12. S

    looking for a power transformer for Philips Laboratories AH 578

    Hello dear DIY in HIFI, Everything is in the title, I'm looking for a power transformer for Philips Laboratories AH 578 to bring back to life my power amp. Sadly, I don't know anything about it and its specs. There is no information written on mine (the picture below is what I found on the...
  13. C

    Sansui au717 or au7900

    I have a chance for either if these if I act quickly,need your expert advice. Neither have been redone.
  14. C Hart

    Testing amps

    Hi AKers. I hope you can help me with a question that has nagged me for a while. Among other gear, I have a .08% THD 5x120wpc-rated receiver. It just doesn't seem that clean when it's turned up and I would like to verify whether it is performing to its ratings. I'm sure there are high end test...
  15. W

    Harman Kardon HK640 broken left channel

    Hello, Quite a while ago I asked my dad for his old HK640 that we used to have at home. I remembered it having some problems and was interested in fixing it up and using it. I have made some progress, but am currently somewhat stuck. I've been working on it off and on for quite a while, so I...
  16. ocdecio

    2238B noise on power amp (both channels)

    Here's something that is puzzling me. It is a spiky wave 20mV / about 520Hz with the amp running in idle and shorting plugs at Main In. The noise was there before replacing capacitors and diodes at the power amp and power supply. I doubt it is anything at the amp itself since both channels...
  17. A

    Peavey CS 1000 Hiss

    Hey guys, and girls ofc :) Recently started learning how to repair faulty amplifiers. My very first project was a Peavey CS 1000 Power Amp that i purchased off ebay. Took me a while to get to grips with what im doing, But i eventually figured it out... But to cut a long story short.. The amp...
  18. woodhous

    Help picking out a stereo amp for Infinity RS IIBs

    Hi there! I recently came into ownership of a pair of beautiful Infinity RS IIBs. Believe it or not, I found them on the street being thrown out!!!! I managed to get them repaired professionally and they are truly a wonder. That said, I'm currently powering them with a really underpowered...
  19. david winter

    Heathkit AA-40 - strange voltages at 6AN8A plates

    Hi, I have been working on a Heathkit AA-40 amp for which I did the following works: - Set to 230V mode (powered at 240Vac). - Surgistor replaced with CL-90 varistor - Tubes: two NOS Sylvania 6AN8A + four good EL34 - All electrolytics and coupling caps replaced - Most resistors replaced (out of...
  20. O

    Why does Luxman recommend installing different capacitors?

    For some reason, Luxman recommends installing different capacitors C506 and C507 (30000uF x 71V, 15000uF x 63V) in the power supply of Luxman L-503 amplifier. I installed two 22000uF x 80V capacitors. One of them started leaking after 5 hours of using. Possibly bad Chinese quality. Now I have to...
  21. Dav3

    Little mystery amp

    Picked up a box of interesting junk for $10 from a yard sale today including some nice ham tubes, an Admiral 6S12N console pull, and a funky little amp I was wondering if anyone could identify. It 'boasts' a single 6X5WGT rectifier tube, an old style speaker out socket, and a Kenyon T157...
  22. Hollow_Man

    The right channel of the National Panasonic SU-3400 amplifier gets hot.

    Hello everyone. I definitely have a problem with this amplifier, when I bought it it was very neglected, it was reassembled with parts from other appliances, it had 4 diodes tied together as a power supply, etc. So I started to repair and replace everything (or almost everything) that was not...
  23. R

    Kyocera A-710 puzzle

    Hi all - I have been banging my head against the proverbial wall with a Kyocera A-710 integrated amplifier. It originally came to me with a blown output transistor, which was addressed easily enough (though I was surprised that the emitter-collector short did not take out the .22 ohm emitter...
  24. S

    Do the Yamaha CR-1020 and 2020 have the same output amps?

    Hi all, I feel kind of silly asking this but where comparing pictures the amp output assemblies and parts look identical. I have not been able to compare parts lists for these two and thought I would ask since a lot of parts are interchangeable on these.
  25. JDSmith

    Pioneer SA 7500 restoration

    Recently began working on an SA 7500 in good condition. (Not MK II) Unit appears to be in original condition and the boards have required minimal cleaning. So far only changed out speaker inputs for modern binding posts. Planning to recap and restore the unit to its best self. The interior...
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