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  1. KilgoreCemetery

    Sansui 7000 Receiver with weak FM

    Well, I found at least one bad part.. CF202, which is a three legged.. capacitor? I'm not at all familiar with this type of ceramic, but it doesn't have anything going on between any of the legs. I tracked it down by checking for signal at the transistors. Collector of TR201 had signal, but the...
  2. KilgoreCemetery

    Sansui 7000 Receiver with weak FM

    Update: I found a parts unit! One channel blows the speaker fuse, but FM works and it will even pull in stations in Stereo! So.. I disconnected the wires between boards F-1323 and F1243, then jumpered from the working unit to the non-working one. Long story short, board F-1323 works on both...
  3. KilgoreCemetery

    Sansui 7000 Receiver with weak FM

    :D:D:D Thanks, Edd. I needed that on this snowy Monday. Surprisingly, adding a wire in didn't make any difference. I tried a regular wire, then I tried half of a dipole antenna just to be sure.
  4. KilgoreCemetery

    Sansui 7000 Receiver with weak FM

    Thanks, Bertus! I hate to be a bother, but I'm having some trouble finding anywhere that I can buy either a 3SK39 or a BF960. When I click on the BF960 link, it takes me to the AllAboutCircuits website where, if it's the right part, they're asking $80 and it doesn't even look like they have any...
  5. KilgoreCemetery

    Sansui 7000 Receiver with weak FM

    I'd have to look into availability and possible replacements would be for the FET. It's a 3SK39. Here's the schematic of the front end
  6. KilgoreCemetery

    Sansui 7000 Receiver with weak FM

    That would make sense. There's nothing charred or visually out of place, but maybe it's more subtle. What would I be looking for? Open coil? Bad FET maybe? Or is it just kind of random?
  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

    Singing Machine Power Port Replacement

    I didn't search for a datasheet for the old port, just the new one. Places like Digikey or Mouser will have them. I should have measured the pin spacing for the old port and checked the datasheet for the new one before ordering it. Instead I had to modify the new one to make it fit. If I...
  10. KilgoreCemetery

    Nakamichi RX-505 Low 12V + and - Rails

    The rectifier on the 5v regulated supply side is the same part number. I pulled them both and tested out of circuit. They tested the same. I swapped them when reinstalling and there's still no change to either regulated supply. The 5v side always measures 5v with a maximum deviation of about...
  11. KilgoreCemetery

    Nakamichi RX-505 Low 12V + and - Rails

    So.. I went ahead and used my scope to see what the output of the rectifier actually looks like and I did find that the positive side has less amplitude than the negative side. Would this indicate a problem within the rectifier?
  12. KilgoreCemetery

    Nakamichi RX-505 Low 12V + and - Rails

    I typically measure voltages with my DMM with the black probe to chassis ground for DC. I do have a Tektronix 335 scope and while it does help me quite a bit, it's not great at providing detailed voltage measurements. I've successfully used my DMM to find faulty capacitors before by testing...
  13. 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...
  14. KilgoreCemetery

    Help! With troubleshooting SMPS for a Denon reciver. (Low output voltage)

    I'm no expert when it comes to this sort of stuff (read noob), but from what I understand, the optocoupler is supposed to regulate the amount of voltage that the SMPS puts out. If it's reading wrong it could throttle the output. Something like a bad zener mentioned above could certainly cause it
  15. 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...
  16. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    Just to cross all my eyes and cross all my tee's, the replacement A798's did fix the voltage issue. The relay clicks after about 3-5 seconds and the bases and emmitters of the output transistors are back down where they should be. Sine wave looks good on the scope too! Thanks again for your...
  17. KilgoreCemetery

    Sherwood Power Amp Crossover Distortion

    Sorry for the slow replies, I was out of town for a few days. This is a Sherwood AM-7040 power amplifier. I'll be going down the troubleshooting list as soon as I can, but this part definitely stands out: *sigh* This has been a learning project and I remember asking before I bought them...
  18. KilgoreCemetery

    Sherwood Power Amp Crossover Distortion

    That makes sense, BobK. I did notice a non-populated spot on the circuit board right around D107R that was for a trim pot. I suppose the earlier releases of this model must have had them, then they started using diodes to save cost. Either that, or maybe the board was used in higher models that...
  19. KilgoreCemetery

    Sherwood Power Amp Crossover Distortion

    It took me a while to find it, but I did add another diode to one side only. Unfortunately, I can't tell any difference between the two channels. The original is a 1n4148. Do I need to have another one of those, or is there something similar that I can use. I do have some 1n4007's on hand, but...
  20. 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...
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