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  1. Matt Mincer

    dbx 20/20 display issue

    Hey folks, I have this EQ a guy brought me to fix. The 250 and 2khz displays don't respond even when I inject those frequencies directly into the input. He's also saying the pink noise generator isn't working but I haven't gotten that far yet. All of the chips are plugins so I've been able to...
  2. Matt Mincer

    I don't replace a lot of radio parts

    Yeah, in a receiver and also solid state.
  3. Matt Mincer

    I don't replace a lot of radio parts

    Hey, I have noticed that I replace a lot of transistors and caps in amps and power supply circuits but rarely in radio circuits. Is this a known thing or am I imagining it? If it is a thing, why? Do OEMs use better components in radio circuits? Is it because radio circuits use less power so...
  4. Matt Mincer

    Pioneer SX-3600 with no FM

    Hey folks, I have an SX-3600 with no FM. No static regardless of where it's tuned, mute on or of, no deflection on the tuning meter. All of the other functions on the receiver work. Any ideas? I'm going to poke around with my meter but I'm wondering if there's a known issue. Thanks Matt
  5. Matt Mincer

    Marantz 4270 Relay Delay

    Hey All, I have a 4270 on the bench and when I turned the power on, the speaker relays took a super long time to engage. And when both speaker switches were on, it was painfully slow. I replaced C806, 807, and 808 on the power supply board and it now works perfectly. I also replaced the...
  6. Matt Mincer

    Sansui G-7000 Protection Light

    Hey Folks, I'm working on a G-7000 that is working perfectly. The owner swears up and down that the power light should switch from red to green depending on whether it is in protect mode but this one stays red. The relay clicks as expected and the thing sounds perfect. Idol current and voltage...
  7. Matt Mincer

    Kenwood 700M speaker switch

    So the pictures below were the speaker switch from a 700M. The 4 parts sitting on the transformer were originally 2 parts that have broken (not by me btw). Does anyone know where I might find a replacement switch? I’ve checked eBay but with no luck. Thx Matt
  8. Matt Mincer

    Kenwood Basic M2 channel distorted

    I think we got it figured out. There were several cold solder joints, particularly around the heatsinks for Q25, Q27 & Q26, Q28. Each channel has a shared heatsink for 2 transistors. There were a few others too but those were the main issue. Thx for all the help! Matt
  9. Matt Mincer

    Marantz 2330B with a noisy left channel.

    Well, it turns out that I'm a freakin' idiot! One section of one of the power supply caps was shorted. Soooooo, BUZZZ! This model has dual power supplies. Each channel has one cap with two sections. One for B+ and one for B-. B- was dead. Thx Matt
  10. Matt Mincer

    Marantz 2330B with a noisy left channel.

    Yeah, I know it's not a good way to test transistors. Still, you can sometimes tell if they are shorted. I plugged my iphone into the main in and still got the buzzing. Also, when I pull the signal input plug (J21-J23) off of the power amp board, I still get the buzz. So it's got to be on the...
  11. Matt Mincer

    Marantz 2330B with a noisy left channel.

    Hey All, I'm working on a 2330B where the left channel of the power amp is distorted and buzzy. I am positive it is the power amp because it does even when the signal input on the board is disconnected. I replaced all of the electrolytic caps on the board. All of the transistors test good (in...
  12. Matt Mincer

    Kenwood Basic M2 channel distorted

    Hey all, I'm working on an M2 where the right channel is intermittently distorted. When I put a 1mhz signal into the input, the output is only the bottom half of a wave. But the kicker is that it's intermittent. As I'm typing this, the scope shows a perfect signwave and the audio sounds great...
  13. Matt Mincer

    SD-434 blowing fuse 5 but only after it's been running a while

    C 4 & 5 both test okay with my ESR meter. Agree that they are underrated but they seem to be okay. Power supply voltages are 13.5, -23.5, + 25.5. Diodes test okay in circuit. 1.3 V across R1. The stereo bulb is blown so it's not that. I'll let it cook a while and see what happens. Thx Matt
  14. Matt Mincer

    SD-434 blowing fuse 5 but only after it's been running a while

    Hey All, I have an SX-434 on my bench for the 2nd time. I replaced F5 a few weeks back and it worked fine for about 30 minutes. Then it blew the fuse again. Any ideas as to what might cause the issue? Thx Matt
  15. Matt Mincer

    JVC QL-A7 with speed issues

    Hey all, A guy brought me a QL-A7 and said it will work fine for a while but will speed up to super-fast after running for a while. So far, I haven't been able to recreate the problem but I'm wondering if it's a known issue or if there's something I should be looking at? Thanks Matt
  16. Matt Mincer

    G-7000 smoking ballast resistors

    Yeah, I saw that 8.2 was on the schematic but the ones that were in the receiver were 10 and looked original. You know how it goes, the mfg uses something different than the manual.
  17. Matt Mincer

    G-7000 smoking ballast resistors

    Hey all, I'm working on a Sansui. When I first got it, it would light up and the relays would click, but no tuning and almost no sound on either channel. On AUX and at full volume, I got a very low sound out of the left speaker only. I was thinking it was a power supply issue but after a few...
  18. Matt Mincer

    Marantz 4100 with an audible speaker pop in the power amp

    Hey All, I have a 4100 where the left channel has a popping sound along with the music out of the speaker. It's only the left, only at higher volume, only when the amp is set to 60W and is definitely on the power amp board. I know because it happens whether I used the pre or unplug the jumpers...
  19. Matt Mincer

    4100 refurb

    Hey all, I'm working on a 4100 Quad. Are there any components that are known for going flakey that I should replace while I'm inside? Thx Matt
  20. Matt Mincer

    A followup to my RT-909 question. It was the capstan motor

    I took the motor apart and little bits of carbon and a brass ring fell out. Does anyone know where I can buy a replacement motor or get this one fixed? Thx Matt
  21. Matt Mincer

    Pioneer RT-909 capstan motor not running

    Hey all, I've got an RT where the capstan motor won't turn. I've tested the motor and it seems to be fine. Here's what I have found. The voltage is 24V to both sides of the motor. Take a look at the screenshot I have attached. If I'm reading it correctly, Q208 & Q209 toggle back and forth to...
  22. Matt Mincer

    Receivers and dead FM stereo lights

    Hey All, I've got 3 or 4 receivers that work perfectly except the FM stereo lamp doesn't come on. I have replaced the bulbs but it hasn't fixed the problem. I've checked and there's just no voltage even when a station is perfectly tuned. There are no problems tuning to a station, the sound...
  23. Matt Mincer

    sansui AU-20000 randomly goes in to Protector mode

    Hey all, I've got this beast on the bench and randomly the speaker Protector light and relay go into protect mode. The thing works perfectly when it's working and no random noises precede the "switch over". I replaced all of the known bad transistors 2 years ago and it's worked since then. I've...
  24. Matt Mincer

    Altec Lansing 912 service manual

    Hey folks, I have a beautiful 912 Stereo Music Center on the bench but can't seem to find the service manual online. Does anyone know where I might find it? It's actually working great but I would like to replace the cassette belts and adjust the speed and it's not obvious how to do either of...
  25. Matt Mincer

    7591 SE stereo amp

    I've tried it in several positions but it doesn't seem to help.
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