do you have buzzing too? Pioneer SX 990 / SX 2500 ..??
- Thread starter Mi kki
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Tuner FM is selected on the video. but the same situation is with every input.
Tuner FM is also on in the first video.
Grounding is checked on each board.
The voltages were measured, they were all fine, so no transistor on power supply board was changed.
But maybe some transistor needs to be replaced...
2SC485 = KSC1845FTA
2SC627 = KSC3503DSTU
2SC971 = ?
2SC1061 = BD241C
Do you recommend to change all or only 458 and check the function, if necessary, change the device and solve the problem?
But maybe some transistor needs to be replaced...
2SC485 = KSC1845FTA
2SC627 = KSC3503DSTU
2SC971 = ?
2SC1061 = BD241C
Do you recommend to change all or only 458 and check the function, if necessary, change the device and solve the problem?
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Check Audiokarma list of known problem transistors and replace those. If It's like mine, 2 on the driver board and more on the head amp unit. I checked Hifi Engine for a schematic for the sx2500 not there. I see a transistor left of the 2 - c1061 could be a c458. A noisy transistor may still test good.
yes, the transistor with the black cooler is a Toschiba 2SC485
thank you, I will try to change them, I just have to buy new parts.
TO92 small transistor is Mitsubishi 2SC870 = KSC1845 ?
Maybe the trouble is from the pre amp / tone control. Have you tried disconnecting the pre amp out and main in? And then power up. Do not make or break these connections with unit on. If you still have buzzing trouble is in the main amp section. Wonder if you could have RFI interference? Your description almost sounds like noise from florescent or LED fixture.
yes, there are glue residues.Looks like someone recapped this but didn't bother to remove the 'glue'
Yes, I know it's not nice
do you clean it mechanically or do you use some kind of chemical preparation please ?
the buzzing is still there, even now no lighting was used when recording the video.
There is not a single LED in the device, there are only light bulbs.
The SX 2500 has a non-mechanical connection between the preamplifier and the power amplifier at the back, but there is a switch.
This switch was cleaned several times with a contact spray.
Now i disconnected the preamplifier and amp from each other and the buzzing increased.
As soon as I connected the CD player to the input for the preamplifier, the buzzing decreased by about 90 percent, even when the CD player was not connected to the electricity.
It depends on the formulation, reports vary but an Acetone based cleaner seems to work well for softening it, and making it easier to remove, and for mechanical removal, a fairly blunt scraper (screwdriver, blunt penknife, sharpened chop-stick) - and a lot of patience. And you need to clean every bit of it off, every piece, every scrap - because the glue turns corrosive and can even become conductive.
Thank you, I will try to clean it well.
RalphRaccooN
Active Member
maybe the RCA jacks need some reworking, I would measure each input ground for every RCA and make sure they're all zero. I've had to solder jumper wires between each one because the crimping Pioneer used fails after much use.
Do you have a 1/16 headphone to RCA cable? plug your phone directly into the main amp in and play a test tone.
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I will check the RCA again. but the signal from Tuner is connected through the switch, and I checked and measured it, and cleaned it several times with contact spray.
All RCA connectors are fine.
I connected the mobile phone to the Main IN and it made a buzzing sound almost nothing...
I connected the PRE OUT and MAIN IN with Cinch cable and the buzzing is even stronger than when the original connection is through the switch.
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