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dc offset

  1. mhz

    KR-3090 Adjusting DC Offset

    Hello everyone, I'm working on a KR-3090 and currently looking at bias + DC offset. This receiver was on the cheaper end, so adjusting the transistor bias involves swapping a fixed resistor and as far as I can tell there is no adjustment procedure for DC offset. Luckily, transistor bias seems...
  2. C

    Aiwa SA-P50 Distortion on both channels

    Hello and Good Day/Afternoon/Evening to everyone so my father has this Aiwa SA-P50H that he bought a few years ago and its all original but has an issue, sound comes out distorted (mostly on one channel, the other one its almost indistinguishable but its there) going by memory so the amp...
  3. T

    Restomod Dynaco Stereo 120 — high DC offset

    I am rebuilding a Dynaco Stereo 120, with UpdateMyDynaco power supply and replacement caps, and the eBay TIP-mod amplifier boards, and I am seeing two issues that I could use some help with. 1) High DC offset (~200mV), and 2) the #4 and #14 eyelets are reading 71.3V instead of 36 and 37V...
    • TXGardener
    • Thread
    • amplifer dc offset dynaco dynaco 120 upgrade
    • Replies: 5
    • Forum: Solid State
  4. X

    SUPER HIGH dc offset SX-1280. Full restoration - final straw !

    This has been a wild restoration. From no power at all to a full blown restoration. Original output were blown, PS resistors and thermal fuse blown. It’s all been recapped, cleaned, most known faulty transistors replaced… I’m on the final straw of setting the DC offset and it seems to be...
  5. ZeRask

    Yamaha A-1 high voltages

    Hello, AK’ers I hope some Yamaha A-1 experts here can help me troubleshoot a weird voltage issue with my receiver. I attempted a recap/servicing on my A-1, which went well until the Electrolytics board, which was supposed to be the last one. I studied everything related to the subject on AK...
    • ZeRask
    • Thread
    • dc offset idle current recap and restoration voltage yamaha a-1
    • Replies: 65
    • Forum: Yamaha
  6. D

    Recommended multimeter to set dc offset?

    Hello! Looking into how accurate a multimeter needs to be to set dc offset in amplifier? Today I’m using extech 355 which has an accuracy of +-0.5%. Is that not good enough? Im reading that you should at least have a accuracy of +-0.1% what do my fellow audiokarmas think?
  7. T

    Sansui B2101 - DC voltage goes crazy

    Dear All, My Sansui B2101 suddenly stopped producing sound. The display bars works, meaning peak levels up and down with a pre input. I have checked all the outputs are fine. About 300mV is in the speaker terminals. I checked the DC offset (see SM attached image) and have found that DC voltage...
  8. D

    Kenwood KR-9600 - Preamp problems?

    I recently bought a KR-9600. When I bought it, I was having a problem with the pre-amp. It would only work partially when you move the selector switch from one input to another. It would then play for a second then stop. It was not just a dirty connector as it was very systematic meaning that it...
  9. Carbsandcaps

    Dc voltage on on output kr-750

    Working on a kr-750 and the protection relay won’t come on. Testing around and I found 12v on the collectors of the output transistors. I can’t find anywhere it would be picking up 12v. The base and collector have the correct voltages. Is there any way to check for where the voltage is coming...
  10. CoreyS

    Pioneer SX950 DC Offset Adjustment

    When setting DC Offset are the 5.1k resistors really necessary? I’ve read on audiokarma that they are not. Never seen this before.
  11. Robergé

    Tandberg TR 2075 Speaker Pop

    Good morning everyone! Thanks in advance for any info you guys can provide, this site is awesome. I recently had a full professional recap done on my Tandberg TR 2075. Not the MK II, the original 2075. The speaker pops when I turn it on, and DC voltage spikes to about 500mv for a very brief...
    • Robergé
    • Thread
    • dc offset speaker pop tandberg tr 2075 tr 2080
    • Replies: 7
    • Forum: Solid State
  12. P

    SM Info about DC OFFSET and BIAS for the SX-828

    This subject has been discussed so many times, but I still didn’t find some kind of a ONE-Pager with all pins and millivoltage settings from an official Pioneer Service Manual. Has anyone from this forum got ALL information or can help identify the correct pins to measure DC Offset and BIAS?
  13. kasbah512

    Kenwood KR-4070: DC offset

    There is no DC offset adjustment on this device and Im trying to figure out how to correct the issue. Im getting -17 mv on the left channel and +35 mv on the right. Here is the circuit:
  14. H

    New thread on DC offset protection and B&K 200.7

    Hi, There are many (inexpensive) aftermarket DC protection boards you can buy to cover you if your amp does not happen to have protection. Youtuber xraytonyb has several videos on them. However, you would need 4 of these boards in this case. There are many different designs for these boards...
  15. J

    ACCUPHASE E-205 HELP NEEDED

    Hi all, I have just purchased an Accuphase E-205 which apparently has a channel with the output transistors having problems. The other channel seems to have been fixed previously. I would like to know if someone could help me to make it functional. 1. Help me know if the modified channel could...
    • Joan Biel
    • Thread
    • accuphase accuphase e-205 dc offset mos fet transistors
    • Replies: 13
    • Forum: Solid State
  16. AmpRa

    Sansui 907 DC at speaker terminals

    Hello all, I have a Sansui AU-a907 audio amp. It sounds really really good!! A little problem is that there's about 250mv DC output at speaker terminals. I adjust it close to 0mv few times but when I turn it on the next day, it's out of wack. Both sides This amp has Integrated and Power amp...
  17. jefferylhenr

    Luxman R1050 -168mv on both right and left terminals?

    I just acquired a fairly clean R1050. I powers up with no shorts. I set the bias fine and then tested the DC. -168 mv both channels! I have restored 8 of these luxmans and have never seen this. Fast forward, recapped the pb1062 board, replaced the differential transistors, zener diodes… still...
  18. Burialcloud

    SAE 2400L dc offset question along with recap, restoration tips and recommendations.

    I bought a SAE 2400L this week for 350. It was in “working” order but I figured it would probably need an overhaul before use. Got it on my bench today and channel B seems great. Was able to get the offset and quiescent dead on. (Don’t have a distortion analyzer to check bias unfortunately)...
  19. jFF_Bulbo

    2330b help!

    hello AK'ers I´m working on a 2330b. previously repaired without succes. power supply recapped, new transistors, new relay, single diodes an double diodes as well preamp, phono recapped power amp recaped BUT after changed capacitors, transitors, new mj´s 95/96 output.... one chanlles refuses...
    • jFF_Bulbo
    • Thread
    • 2330b dc offset help p700 q710 repir restoration upgrade
    • Replies: 10
    • Forum: Marantz Audio
  20. goldswimmerb

    G-8000 Pop when relay closes

    Trying to figure this one out, when my protection relay closes, especially if the unit was turned off, left for a minute or so, and then turned on I get a pop of DC out of both my left and right speakers. Measuring the DC shows roughly 100-200mv when the relay closes, quickly dropping to 0. If I...
  21. J

    NEC AUA-8000e

    Hi everyone, this is my first post but I have been following you for a few years now. I must say that you are doing a great job and I thank you in advance for everything you have already done for us. Thanks. My question is about a NEC AUA-8000e amplifier. It turns out that I have adjusted the...
  22. PROJECT 2501

    Model 32 amplifier with 100mv DC offset in the right channel

    Left channel is steady at 35mv Right channel went from 75mv to 98mv Right channel produces a disgusting buzz/humm through the right speaker that is constant no matter the amount of attenuation. Needless to say that it's in need of repair, that's a given. I'd just like to know if these...
    • PROJECT 2501
    • Thread
    • amplifer bias dc offset magic smoke marantz model 32 recap repair restoration
    • Replies: 2
    • Forum: Marantz Audio
  23. P

    Basic Question about DC OFFSET and BIAS for the SX-737

    This subject has been discussed so many times, but there is one information missing I like to find the answer. Every reply covering DC Offset and BIAS points to a millivoltage range with 20mVDC for Bias and DC Offset close to 0 mVDC. BUT sometimes it’s very hard to get the DC Offset close to 0...
  24. Fleime

    Rotel RB990-BX amplifier repair / revision

    Hello, I have acquired a Rotel RB990-BX amp which appears to have been sparsely used, compared to another which I have lying around. Being a beginner in this hobby, I first researched the amp for technical experiences. I have checked all the components individually and not in circuit (never...
  25. Spendor

    Help with DC offset and Bias on amp. Soundcraftsmen circuit?

    I have a power amp made in Australia that i believe was used as an install amp in Cinemas. It's made by Auditec or AVE. It sounds kind of good, but on checking DC its showing around 350mA. There are 2 1k adjustment pots which i assumed were for DC and Bias but they're wound fully anticlockwise...
    • Spendor
    • Thread
    • 2sk176 bias dc offset soundcraftsmen
    • Replies: 11
    • Forum: Solid State
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