• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

CR-800 Tuner issue

P

pa_200

Well-Known Member
I have three questions for all, regarding my CR-800.

First, every time I power up the unit with Tuner selected and tuned to a good Stereo Station, I get a plop after around 1 minute, a second one after 2 minutes and a third and last one after 2:30 minutes.

No plops with the tuning needle off center and the stereo light off.

Everything else works and the sound is great. Made several test with AUX, Tape and Phono, no plop at all.

I haven't recapped or touched the tuner board in any way so far. Only the Power Supply has got new electrolytic 3 years ago.

Any idea where to look at and start?


Second question is about these three transistors, the unit has quit a lot of them.

2SA706, 2SC458, 2SC1124 are well known for failure after all these years and listed on the top-ten-worst-transistor list.

Are there some transistors in positions, which are well known as trouble makers and should be replaced as precautionary measure while the unit is on the bench?

Lastly, where can I find a good scan of the service manual?
 
Register to hide this ad
Can anyone offer some help to solve my issue with the plop when playing the tuner in Stereo??

“First, every time I power up the unit with Tuner selected and tuned to a good Stereo Station, I get a plop after around 1 minute, a second one after 2 minutes and a third and last one after 2:30 minutes.“
 
I could narrow the issue down to the Tuner board, it’s not coming from any other area.

Can anybody give me a hint, if this "plop sound" is typically caused by a bad capacitor or a bad transistor? After a warm up time, around 3 minutes, everything is fine for the rest of the playing time.

On that board there are many 2SC458 and quit a few low value capacitors. I don’t want to change all of them if it’s not necessary.
 
Last edited:
pa_200 said:
I could narrow the issue down to the Tuner board, it’s not coming from any other area.

Can anybody give me a hint, if this "plop sound" is typically caused by a bad capacitator or a bad transistor? After a warm up time, around 3 minutes, everything is fine for the rest of the playing time.

On that board there are many 2SC458 and quit a few low value capacitors. I don’t want to change all of them if it’s not necessary.
Click to expand...


If they are the outhouse style 2SC458's you need to replace them with either of these KSC1815 / KSC1845 .

33076963846_ed86705598_o.jpg


2SC1124> KSC2690 / KSC2073

2SA706> KSA1381ESTU / BD136 / KSA1220
 
I have already replaced some of the 2SC458, (TR129-134) but the plop is still audible.
But the main question for me, is this plop typically caused by a bad capacitor or by a transistor?
 
You must log in or register to reply here.
Back
Top Bottom