• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Conrad-johnson Line (B6-15)

Hi,
I bought the blank pcb with the attached schematic and picture from ebay. The seller sent the schematic as an e-mail. However, what exactly are the diodes that appear as D-V on the pcb and D4,D5,D6,D7 in the schematic. I ask the seller and he does not answer. Please what can I use instead of these diodes. Information please.
 

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Those are Zener diodes that set the output voltage of the bipolar transistor series regulators.
No DC voltages are marked on the schematic. I would guess each Zener should be 100V to 150V rating at 2W or 3W,
but this depends on the transformer used. Is there no bill of materials given?

Use a lab DC power supply to get the board working and to make sure the regulator transistor dissipation is reasonable.
Maybe someone else here has built one of these and can tell you what voltages they used.
 
Hi Rayma,
High voltage ac input 220v ac in the description on the product's sales site. I will use a 200-220v ac transformer. There is only the attached diagram. I keep sending messages to the seller, he does not answer. What do you think the value of these zeners should be if I use a 220v ac transformer.