power supply

  1. ocdecio

    2238 Power Supply

    As per the Service Manual, I should be getting 46V at the collector of Q803. However I am getting 47.6V which I believe is responsible for the regulator becoming too hot (around 160F). The voltage before R801 is 50V. I am pondering if I should up the R801 resistor a bit to get it to the 46V...
  2. D

    Harman Kardon A-30K (A-300) power supply

    Hi! I just picked up a Harman Kardon A-30K, the kit version of the A-300. It works but someone replaced the power transformer from a 110V primary to a 250V but in doing so he also replaced the doubler circuit with a classic half wave rectifier fed from a 250-0-250v secondary winding. Only...
  3. baconbadge

    Combining Filter Caps?

    Greetings, I have a Fisher 500c here where the previous owner combined the three sections of the C92 (50uf, 50uf, 50uf) filter can cap into a single 150uf cap. First pic is schematic, second pic is how it’s rewired: The numbers are the same, but does this configuration have any real-world...
  4. I

    Philips GA 212 Power Supply Problems -- voltage too high

    So I've been working on this Philips 212 recently. I picked it up and it seemed to work OK as is powered up and I could select between 33 and 45, etc. I didn't think much of it. There were two axial electrolytic caps that I decided to replace. Upon removing the PCB one of the trim pots simply...
  5. cicada_17

    230V Avid Volvere turntable for U.S. use with 110V power supply?

    Hi, first post, am in need of advice regarding an overseas turntable. I have the opportunity to bring back a U.K. spec Avid Volvere turntable. My question is, can I simply purchase an Avid power supply that takes 110V/60hz U.S. voltage to power the turntable motor? Or would the motor be wired...
  6. James Cox

    Citation II help!

    Alright guys so I'm pretty bummed out here. I have a citation II that I picked up about 6 months ago that had been restored to stock values and worked perfectly aside from a little more background noise than I expected. I decided since I had pretty good luck restoring a few tube amps and...
  7. mrk229

    EICO HF-89 Power Supply Modifications?

    Greetings. As noted in many places the EICO power supplies were mostly built to a just adequate specification. I am currently rebuilding an HF-89 and want to upgrade the power supply. Looking at various threads here at AK and other places has given me some ideas and they are presented in the...
  8. ikonw8

    Pioneer SX-828 Power Supply Heat Question

    Thank you all! I am restoring a Pioneer SX-828. While it's not my first time restoring a receiver, it is my first Pioneer. At this point, all the boards have been re-capped, new semi-conductors on the Main, AF, Head, Protect and Power Supply. The unit operates normally, protect relay...
  9. M

    Hafler DH-220 Strange "External Capacitor Bank" Mod?

    Hello Everybody! Exxtreeemely long time lurker here Very quickly, let me introduce introduce myself. I've been lurking on here for years, and I've gleaned so much valuable information from you guys and gals! I just want to say thank you for the absolute treasure trove of valuable information...
  10. M

    Questions on less-than-common issues

    Hello all, joined some time ago and have not been doing much... Until recently. Helping a friend set up a new restaurant/bar in town, and trying to make a clean install at the centralized "command center". One big issue, he's running five TV's, each using a Comcast box, all said boxes are...
  11. Beavs

    JVC JA-S71 Protection / Power Supply Troubleshooting Help

    Need some help as the amp won't come out of protection mode and my troubleshooting knowledge has a long way to go. Got this amp knowing that the left channel was out. Turned out to be the same issue others have had with the wire connection to the volume pot (see post #5 here...
  12. guinypig

    Bogen RP60 Power supply resistors

    Hi, I am currently working on a Bogen RP60. I just noticed that 2 resistors in the power supply do not have the value indicated in the schematics. R84 and R87 are supposed to be 33K but have apparently been replaced with 10K like R85 and R88. Can anyone confirm that the value of the factory...
  13. sean sweeney

    Carver 1.0t Repair (variac issue? yes or no?)

    OK>>>> pretend I said TRIAC.... ugh... sorry I've done a fair amount of work on this, and did the complete MKII upgrade and attempted to set the bias and voltage, but the supply voltage came on at about 60v and then started to decline... I pushed the main voltage reostadt just a little and the...
  14. flatlinenj

    Marantz 4240, Back panel fuse blows when powered on.

    Problem: Marantz 4240, Back panel fuse blows when powered on. Troubleshooting: Test 1: Transformer: Disconnect input power leads on bridge rectifier 5B2. Power up unit. Measure voltage at transformer output: 42.0 Volts AC, Front panel lit. Conclusion: Transformer is good. Test 2: Power...
  15. crkeith65

    Kenwood KR4010 I killed it and need help

    A friend asked me to service his Kenwood KR4010. It played but was real noisy so I knew it needed the usual De-Oxit treatment. I recapped the Power Supply section and had it sounding pretty good with one small problem. Sometimes the left channel sounded like a broken speaker. A little freeze...
  16. crkeith65

    Kenwood KR4010 I killed it and need help

    A friend asked me to service his Kenwood KR4010. It played but was real noisy so I knew it needed the usual De-Oxit treatment. I recapped the Power Supply section and had it sounding pretty good with one small problem. Sometimes the left channel sounded like a broken speaker. A little freeze...
  17. Fusion9

    KLH-3 Analog Bass Computer Power Supply

    Will this plan work for a KLH-3 Analog Bass Computer (ABC) wall wart? From everything I've read the ABC requires 13 - 14 VAC, 220ma, it draws 9 watts, and is an ac to ac adapter. I think the adapter below is correct, and I can just replace the connector with the one listed, or similar. Am I...
  18. M

    Trusted Brands for a Phantom Power supply

    I've got a condenser mic and I've been using it without a power supply for a while but it's a bit annoying to use. The audio I get from it is very noisy and with noise canceling on I have to be right up on the mic to get decent volume out of it. I started to look around for a power supply hoping...
  19. MBuras

    Pioneer SX-950 PS Rebuild or Not?

    I know, that's a loaded question. :rolleyes: I've restored a few SX-950's over the years. A friend recently picked one up and just wants the bare minimum to get it into a reliable state, not trying for a full restoration. Was planning to rebuild the power board (usually very toasty in my...
  20. Richard P

    Denon AVR-1609 Power Supply & Speaker Popping / Relay Repair

    Just a quick summary of a couple of easy fixes i did to resurect a clean but dead Denon AVR-1609 in case anyone else wants to work on one of these: - Checked the power supply expecting the typcial 7815/7915 regulator failures and found no voltage feeding them. Traced the problem down to a...
  21. D

    Hum in Pioneer SA5300

    Hi, I have a considerable hum (or buzz?) coming from the SA5300. Somewhere in the 100 Hz range. In both speakers, also in the headphone. The hum is present when no inputs are connected and when volume is down. Doesn't turn up when turning up volume. So all these aspects points at the filter in...
  22. S

    Did I burn this power supply?

    I have just took the capacitors out of this power supply, and I'm a bit worried about those brown-ish spots that formed around the connections, do these look like I burned the board? and if so, anyway to "fix" it? I have read that burning things is unlikely if you're careful because not many...
  23. Brian Seeley

    Magnavox 8601-20 Amplifier question

    Hello. My first post. I recently came across an old Magnavox Tube radio. Model OFM-026 that has a smoked amplifier Power Transformer. I sent it in to have it recapped and reconditioned. Model 8601-20 amplifier and my technician tells me the Power transformer is cooked. My question is; does...
  24. internauta20

    Nakamichi 700 II PCB Power Supply problem.

    Hi to everyone... A few days ago I took on the task of rescue my old Nakamichi 700 II (1973-79) and the first thing I come across is a lack of 12 Volt output from the power supply PCB, the voltage It is not stable and varies randomly to such a degree that in the multiple measurements I made I...
  25. C

    2275 Power Supply Troubleshooting

    I just now have also found a smoked R801 resistor on my 2275 PS board. The resistance measures over limit (OL) and it is burned. What related issue may have caused this resistor to burn? Is this R801 resistor intended to fail in order to protect other components? I was planning to replace it...
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