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  1. KilgoreCemetery

    RCA Console Protection/DC Centering Mod

    I've been fixing up an RCA MHT67W receiver (Amp chassis: RS-209c). It has germanium output transistors, about 100mV of DC at one speaker terminal (only about 20mV at the other), and no way to adjust it. Is there an easy way to add a trim pot or should I just add an output coupling capacitor, or...
  2. KilgoreCemetery

    Yamaha A-960 II Integrated Amp Won't power on

    I've been troubleshooting this one for a while. First, it has a special power supply similar to what made Carver amps famous. I don't fully understand what each part does, but I know that it chops up the line voltage using triacs, almost like a slow version of a switch mode power supply. I've...
  3. KilgoreCemetery

    Sansui B-2101 Calibration Woes

    I've been having some trouble getting this power amp finished up and I'm hoping someone can help me out. Initially, all I found wrong with it was a broken ground trace on the power board and some nasty, corrosive/conductive brown glue, which is common for this era of Sansui equipment. I ran a...
  4. KilgoreCemetery

    Marantz 2230B with Weak FM

    I've been troubleshooting this one for a while, but I'm no radio expert. Basically, strong stations won't tune in Stereo and a lot of weaker stations don't come in at all. The stereo light works when I switch to Phono, Aux, and Tape, but won't come on with even the strongest local station. Plus...
  5. KilgoreCemetery

    NAD 304 Integrated Amp Post-Repair Question(s)

    I had an NAD 304 integrated amp that was stuck in protect mode. I measured about 14vdc in the signal path at the speaker relay and backtracked to the power amp section. Nothing looked physically damaged and, long story short, I found an open resistor. It wasn't burnt or cracked. I'm assuming it...
  6. KilgoreCemetery

    Fisher tube amp distortion

    I'm trying to rebuild a Fisher 400-CX tube amp, but I'm having some trouble with the signal while under load. What I've done so far: Replaced all of the electrolytic/film/mylar capacitors Replaced some resistors that had drifted beyond their tolerance Replaced the original rectifier diodes...
  7. KilgoreCemetery

    Sansui 7000 Receiver with weak FM

    I have an otherwise working Sansui 7000 amp, but FM is incredibly weak and AM gets very strong bleed-over from Aux. I'm hoping to correct both problems, but I'm assuming that they have separate causes and I'm far more concerned with the FM. At first, I thought FM was just completely out. I...
  8. KilgoreCemetery

    Onkyo TX-8050 Stereo Receiver, Bad Transformer

    So, I have an Onkyo receiver that will no longer power on. No standby light or anything. Long story short, I've discovered that the primary side of the standby transformer is open. It shows NPT-1520JQ on a sticker on the side, but I can't find much info about it. Luckily, I was able to find a...
  9. KilgoreCemetery

    Nakamichi RX-505 Low 12V + and - Rails

    I've been working on a Nakamichi RX-505 cassette deck. Long story short, the door wouldn't open or close on its own like it's supposed to, and I've found that the regulated + and - 12v rails only measure about +3v and -3v. If I disconnect all the wires that are supposed to supply +12 to the rest...
  10. KilgoreCemetery

    Klipsch Powered Sub Won't Come On

    I'm trying to fix a Klipsch SW-450 Powered Subwoofer. This has been a learning experience for me as I didn't really know a whole lot about switching power supplies when I started. Hopefully, that's changing as I go. I have not been able to find a schematic, so this is gonna be a bit wordy to...
  11. KilgoreCemetery

    Sherwood Power Amp Crossover Distortion

    This has been an ongoing project for quite a while, but long story short, I had to replace all of the output transistors (2SK1058 & 2SJ162) with modern ones (IRFP9240PBF & IRFP240PBF). The pinouts are different, so I had to twist the legs to get them to connect properly and was very careful to...
  12. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    At first, the protection relay would click on and off sporadically and I was able to trace the problem down to the driver board having voltage spikes in the signal path of one channel. The board mounts vertically, so I had this bright idea of removing it and putting it in the freezer for a...
  13. KilgoreCemetery

    Kenwood Receiver Heating Issue

    I've been trying to figure out this Kenwood KR-70 receiver. The guy I bought it from said that the volume drops to zero after you run it for a while and, although it hasn't done it to me yet, there are some other signs that something is wrong with the receiver. There's one power transistor that...
  14. KilgoreCemetery

    Marantz 2015 Receiver Distortion

    Everything on this receiver seems to work fine except when you hook up a load to the speaker connects. I just finished recapping and replacing a couple of bjt's in the FM section and finally hooked it up to some speakers so I could start enjoying it, but the music sounds horrible. It's not just...
  15. KilgoreCemetery

    MPS U56 BJT Replacement Comparison and Options

    I'm trying to find a proper replacement for an MPS U56 transistor and I'm starting to feel a little lost trying to decipher apples and oranges. First, this is from the power amplifier section of an HH Scott receiver. It goes right before the main output transistors. I've been comparing...
  16. KilgoreCemetery

    Kole Audio TRAX1-5500D Missing Component?

    I have a mono block amp that won't power on. It doesn't light up at all. I pulled and checked the fuses and verified that they are good. Also, when I supply power, they do have about 12V all the way across. When I first started looking at it, I did find 6 swollen 25V, 220uF capacitors and one...
  17. KilgoreCemetery

    Technics SA-818 FM Muting Problem

    Everything on this receiver works great except for one little thing. The FM Muting cuts out to the beat of the music or when commercials get too loud. It's not dependent on the actual decibel rating coming out of the speakers, just the incoming FM signal. Like, if it's a quiet song or a mono...
  18. KilgoreCemetery

    Philco Radio Parts Identification

    These parts are from a 40-180 console radio that I'm looking to restore. I'm hoping someone on here can tell me what kind of components these are and possibly their values as well. This looks like a foil capacitor covered in wax, but there are absolutely no markings on it: Are these two...
  19. KilgoreCemetery

    Noisy Otari MX5050 BII-2 Tape deck

    As soon as the unit is powered on, there is a constant static noise in both channels. You can hear it through the headphone jack, as well as the output connection. It doesn't register on the VU Meters, but it also makes any playback with known good tape extremely quiet. I've been using an...
  20. KilgoreCemetery

    Pioneer SX-838 Protection Relay Clicking

    This particular Pioneer receiver has a protection circuit that actuates a relay to prevent things like DC voltage going to your speakers. The problem is that the relay randomly clicks on and off. I've checked for DC voltage at the output transistors and found, what I would consider, a normal...
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