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dc offset

  1. rickl

    Fisher 95 schematic or suggestions to reduce DC offset

    I’m looking my my neighbor’s 1966 Fisher 95 (serial #52826). This is an all in one unit with a solid state receiver and a built-in turntable on top. AUX Hi/low inputs, Record, and speaker RCA outputs. I’m looking for a schematic for an 85 or 95 or something made around 1966. She bought this...
    • rickl
    • Thread
    • 1966 all in one all in one system dc offset
    • Replies: 17
    • Forum: Fisher
  2. goldswimmerb

    Marantz 1152DC Offset

    Hey all, looking for some assistance here, I have a Marantz 1152DC on the bench with a rather "drifty" DC offset, it tends to start around 200mv when the relay closes and as things warm-up drops down to where I have the adjustment point set, once there it seems to drift around slightly (eg I...
  3. Hyperion

    B-2102 fault finding

    I have owned a Sansui B-2102 for about 5 years, and to be honest haven't used it much. I have given it a somewhat patchy restore, but there was a problem, not serious, with setting DC offset on one channel. I had a few cracks at solving it when I have had time, so recently I decided I would...
  4. NickArchdale

    Harman Kardon HK430 refurbishment - DC offset problems

    Hi there, I hope someone can help please. I'm restoring an HK430 twin PSU receiver and appear to be falling at the last hurdle. There was crackling and switch/pot noise so after some consultation here, I have replaced all the angular 2SC458, 2SC1344 & 2SC1345 transistors with new KSC1845 (from...
  5. toymanmsp

    SONY STR-7055 - NO OUTPUT - DC OFFSET & BIAS Values WAAAY out of spec.

    Greetings all, I'm rebuilding my 7055 but am in need of some HELP!! I am a novice/newbie to rebuilding vintage gear. That said, I have successfully rebuilt several Pioneers and Sansui's but this is my first go with a piece of SONY gear. I love the looks and particularily the sound from this...
    • toymanmsp
    • Thread
    • bias adjustment dc offset no output power supply issues sony str-7055
    • Replies: 13
    • Forum: Solid State
  6. ChrisPDX

    Evaluating Adcom GFA-2535 : DC offset question

    I recently acquired a used Adcom GFA-2535, which is two GFA-535 amps (MKII version, if I understand correctly) in one unit. These amps can be run independently in “stereo” mode or in “bridged” mode. This unit does not have input-level control dials. I wanted to check the amps' DC offsets before...
  7. klamsoss

    KR-7400 Offset

    I have a KR-7400 that is sounding pretty good aside from the fact that the balance/volume control has an issue (going in, the signal is nice and even... signal out isn't, and yeah, I have cleaned it several times), and the DC offset is.... okay but not great. My question is: with dc offset at...
  8. Theo A

    Adjusting DC Offset on Technics sa 400

    Hello all, After getting a dead technics sa 400, I narrowed the problem down to a shorted power pack and replaced it. Low and behold, everything was working alright, but the dc offset is pretty high now. This is a relatively higher model in the technics line, are there pots to adjust the offset ?
    • Theo A
    • Thread
    • dc offset sa 400 technics
    • Replies: 56
    • Forum: Solid State
  9. R

    HK DC Balance Problem

    I have been working on an HK6650R amp which is now working perfectly - almost. Both channels of the power amp showed distortion and the DC balance was WAY out on both (multiple volts). I reheated all solder connections on the power amp board and was then able to dial in the DC balance on one...
  10. R

    Sansui R-50 loud popping speakers when turning on

    Guys, when I turn on this sansui, there's a boom in the dc voltage across the speakers, sometimes 5V, 8V, 12V. After one or two seconds powered, the dc voltage drops and becomes stable at 50mV per channel. Already changed the filter caps on the power supply (2 x 6800uF 50V) and recapped the...
  11. G

    JungSon DA-120IA impressions and repair/tweaks

    Hey! I have acquired today a pretty interesting and at the same time beautiful amplifier from JungSon. I believe the company is sort of dead today, by this I mean it doesn't make new amplifiers today. They are still making OEM parts for the other companies (something I have read online while...
    • GytisB
    • Thread
    • china da-120 da-120ia dc offset hi end hi end audio hi fi jungson repair
    • Replies: 6
    • Forum: DIY
  12. A

    unusual power amplifier - DC offset etc

    Hi I'd appreciate some suggestions on an amp I'm working on. Works well, sounds good but there's some DC offset and no manual or schematics available. Background: The amp is made by an Australian business called Audio Assemblers Pty Ltd. Some of their stuff is reputed to be PA-grade but...
    • audiogymp
    • Thread
    • custom amplifier dc offset hifi modification power amplifier professional amp
    • Replies: 20
    • Forum: DIY
  13. S

    MCS 3223 - Right channel louder than left

    I recapped the power supply, changed the fuses and changed the bulbs of my MCS 3223. Now I realized that the right speakers sound a bit louder than the left ones. What could be causing this/how can I fix this? I also noticed that sometimes when I'm listening to records, the left channel...
    • sabalennon
    • Thread
    • bias dc offset louder louder than other speaker mcs receiver vintage
    • Replies: 0
    • Forum: Solid State
  14. M

    Marantz PM7200 Can't adjust Idle Current and DC Offset

    Thanks for reading me: After i repaired the speaker protection board of that amplifier, all was ok. So I then proceeded to adjust iddle current, got it, then DC offset. Oh, bboy. At that stage, on the left channel, after first seeing normal readings while moving the trimpot to get to the...
  15. mkneidl

    AU–X701 dc offset

    I recently fixed my 701, a broken 2SA1306 I could replace, some resistors with wrong values and at least I recapped the beauty. The amp sounds great and is not going into protection, bias is ok, dc offset for hot/cold is ok, voltages are as in the sm but I don‘t get cold/earth below 1V for both...
  16. Geek

    1122DC Offset Issues

    Hi Folks, So I have this 1122DC in for service. Everything is all good, bias, no oscillations, etc. but the DC offset is 6.5V one channel, 2.4V the other. Pretty far out, too out to trim. What my revision had was for R735 (and respectfully in the other channel) instead of 560R, was 270R and...
  17. B

    Pioneer SX-727 Left ch/pin3 on protect bd DC offset fluctuating.

    Hi guys. New to audiokarma. Been looking at a lot of your threads on pioneer SX 727 they are helping out a lot. Just bought pioneer SX 727. Recapped everything except for I still have to order three main power supply caps. My problem as mentioned in the topic. Before and after recapping. The DC...
  18. Taavip

    Kenwood KA-5500 left channel repair

    Hello from Estonia! Hope you are all well. Got my hands on this really sweet '77 year Kenwood amp. Unfortunately left channel is dead. I really like this amp, so I would like to repair and restore it. Hopefully you can give some little guidance needed to bring this amp back to life. Before I...
  19. ViperZ

    Rotel RA-1412 strange preamp problem

    I'll start documenting repair of my Rotel RA-1412 integrated amplifier. Sometimes it would just kick into protection randomly. Settings that I am measuring at: all tone controls are in 'out' position. AUX input is selected. I checked voltages on both power supplies, and all voltages are...
    • ViperZ
    • Thread
    • dc offset preamp problem ra-1412 rotel
    • Replies: 24
    • Forum: Solid State
  20. D

    Help with Modular Component Series 3222 Receiver

    I have an MCS 3222. When I scope it, it distorts at the bottom of the wave much sooner than the top. Both channels are equal now after I re-capped it but something must still be wrong because they both still distort at the bottom of the waveform much earlier than the top. Here are the other...
  21. rustyhusky

    Marantz 2270 unstable DC Offset causes?

    Well, I almost got through my second rebuild without tapping the AudioKarma brain trust, but I'm having an issue with the DC offset on the right channel P750 power amp board of my cousin's 2270 (S/N 53625). Without going into too much detail, this unit initially required a new power switch and...
  22. kristerj19

    Checking a Sonab R4000

    Hi Guys, I just started a checking a Sonab R4000 (quite an unusual amplifier) and it has really nice "heavy metal" knobs. All three inputs works nicely and the receiver plays OK. After replacing the bulbs and I measured the DC offset at no load and zero volume. The Dc offset was around 200...
  23. ScooterMcTav

    Arcam A85 - DC Offset issue

    I realize that 17 year old pieces are not as vintage as we normally see here, but have been stumped with a problem with my used Arcam A85. First off, I really like the piece. Not the most powerful integrated I own, but it has a lovely balance of solid sound, and detail without becoming...
  24. PROJECT 2501

    Does a high DC offset cause excessive heat?

    Marantz model 32 amplifier. DC offset of 89mv on the right channel and noticeably higher heat radiating from the right heatsink. Any correlation? Red flag?
    • PROJECT 2501
    • Thread
    • amplifier design dc offset heatsink marantz marantz amplifier troubleshooting
    • Replies: 11
    • Forum: Solid State
  25. JJ7212

    Yamaha B-2 owner looking for repair shop in Japan

    Hello! First post here. I am an American who has been living in Japan for the past 12 years. I bought a Yamaha B-2 a few years ago. It had LEDs and gold plated speaker terminals on the A channel. I paid about $100 for it junk because one channel had no sound. Deoxit fixed that easily! The...
    • JJ7212
    • Thread
    • dc offset japan repair vfet vintage amplifier yamaha b-2
    • Replies: 2
    • Forum: Solid State
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