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VD1212 on Yamaha C4

H

Hifibythekg

Super Member
Checking these.
With one leg lifted should they read

Diode test : 1184
Ohms: 5.61M ohm

With leads reversed, (Black lead on black end, red on red red end of diode) on the DMM at 20M ohms it climbs to ‘I’

I know these things have a dreadful reputation but just wondered if this one was obviously faulty or not.

If replacing with two 1n4148 diodes, does one just twist two ‘ends’ together and insert with them looking like a capital ’A’ shape?
 
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Hifibythekg said:
I know these things have a dreadful reputation but just wondered if this one was obviously faulty or not.
Click to expand...
Actually they don't have as bad a reputation as MV12's . In all the C-4's, maybe 20 or more, that I've reworked. I have only actually found 1 noisy VD-1212 in the +/-30 vdc power supply. Thats it..1 diode in one unit.
 
avionic said:
I use to replace them all the time.. But I don't any more. They are actually a very reliable diode.
Click to expand...
Yes indeed! :thumbsup:

Unfortunately people always confuse them with the Sony V-FET amp VD-1221 death diodes because of the similar PN's.
 
Last edited:
If... I should need to extract the phono wafer switch..
What’s the most pain free effective way / order of doing things to get it off the board and disconnected from the articulated arm?
 

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Hifibythekg said:
If... I should need to extract the phono wafer switch..
What’s the most pain free effective way / order of doing things to get it off the board and disconnected from the articulated arm?
Click to expand...
Unsolder it...KEY !!!

Then just slide the u-joint couplers on both ends of the extension shaft toward the front of the C-4..
 
Great, thanks for the advice.
If I do need to extract it in the pursuit of finding the source of my ‘phono hum’ I might ask if there’s a way of testing the wafer contacts with a DMM to save pulling them apart?
Possible?
Or do you happily pull ‘em apart and reassemble?
 
Phono hum... Check your phono RCA jack ground connections.. Never had a wafer switch creating a hum.
 
Does the hum disappear if you short out the phono inputs with a shorting plug ? How loud is the hum..

Does the hum disappear with a TT hooked up ?
 
Thanks for showing some enthusiasm on this.
Yes, the hum is present with aTT hooked up.

Loud when Phono is selected.
Even louder with MC selected.
Comes through on Aux and Tuner, at about one third of the level of ‘pure’ Phono.
If a source is connected it comes through as a bass hum.
Doesn’t stop with the use of shorting plugs.

I’ll check the RCA solder connections before checking the Phono wafer then.
 
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