Finding replacement transistors for Pioneer SA-8100

[nintendoeats]

Hiya,

I have a Pioneer SA-8100 with an phono preamp that is "f***ed" as a previous owner so elegantly put it with sharpy (now removed). Since I recently got a couple record players, I'd like to fix it. They do pass signal, but something is generating a huge amount of noise on both phono preamp and mic inputs which isolates the problem to the equalizer board.

My first thought is to replace the transistors as I think they are the most likely culprit, but of course they haven't been made for decades. I would prefer not to buy equally ancient NOS transistors of unknown origin, though I will if I have to.

I don't really know what's important to look for as far as specifications in a transistor. I was hoping for somebody to please give me a few pointers. I did ask my embedded dev buddy, and he just went "Agh, amplifiers, I know as much as you do".

I was thinking of replacing the 2SC1345 with the BC550CTA.

I was thinking of replacing the 2SA774 with the 2N2907. (Yes I know that site sells them, but once I get those in Canada it's going to be very expensive and they will be either very old or fake).

Any advice appreciated, thanks!

 

[Ralph_Cramden]

Probably better to ask in the Pioneer forum on AK.

Audiokarma Home Audio Stereo Discussion Forums

Home stereo and general audio discussion forums.

audiokarma.org

 

[Philbo King]

You want to replace transistors you have not tested? A bad idea...
Get a DVM with a diode test range and check each pair of leads in both directions. One direction should show 0.5 to 0.7Vdc (assuming bipolar transistors) the opposite direction should show OL or open.

Actually, unless you have soldering skills and pick up some knowledge of electronic components, I strongly recommend you have a professional tech take a look at it.

 

[JeffS7444]

What kind of noise, hiss, hum, or something else? If you are getting a loud buzz or hum from both channels, I might investigate the +/- 24 volt power supplies to that board. Electrolytic capacitors are one of the biggest sources of trouble in older electronics, and that amplifier is 50+ years old.

For now, leave those transistors alone: They might be matched pairs, often identified by dabs of colored paint. I normally wouldn't expect bipolar front-end devices to be the source of trouble.