Direct Coupled B-1 Buffer - Hypnotize troubleshooting

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Pboden

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Joined 2004
Been away from diy audio for years and yesterday I ran through some old stuff in the attic and found an old project that never was finished - among the B1 Buffer.

I started up the B1 buffer today, but I can not get it running - that is no music.
I see that there are some leds that do not start.

Appreciate any help on troubleshooting.
 

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AndrewT

R.I.P.
Joined 2004
if you are really careful you can measure the voltage across each LED.
You may find that one has a very high voltage indicating it has been inserted in reverse.
Can you see the flat edge indicating the -VE side of the pair of lead outs?
All the good ones should have around 1.7Vdc to 1.8Vdc across them. That is the Vf when current is passing.
 
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AndrewT

R.I.P.
Joined 2004
The DCB1 needs at least 5V and preferably 7V across the CCS part of the regulator.
This is required when the mains voltage is at it's lowest.
You can use a dual 15Vac secondary wired as a centre tapped secondary and in normal operation you will measure 20Vdc to 22Vdc on the main smoothing capacitors.
 
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