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Dynaco ST 400 bias


Someone can confirm if 150 mA. is the correct value to calibrate properly the bias in the Dynaco ST 400 Power Amplifier?.


Dynaco ST 400 bias

I tried downloading the ST400 file at another site and it won't open for me. Maybe someone can upload it here.
BTW, 150ma seems high to me, but that would depend entirely on how and where that is measured.

Dynaco ST 400 bias

Thank you Johnnysan.

How and where?:

Removing the + fuse, installing instead of it an ammeter and adjusting P2 trimmer on PCB 28. This is the way to do it, but I don´t know for sure if 150 mA. is correct. I am remembering you that MF 120D AVA´s Dynaco ST-120 rebuilt, bias is adjusted to 125 mA with only 2 and less powerful output devices, and Adcom 5800 is 800 mA but with more output transistors. In another hand Amber Series 70 (70 w/ch) with only one: 2N5684/86-( 50 Amp-300w devices per ch), bias is 150 mA.

Also I am not sure if ST-400´s Instructions for assembly indicate the bias value, may be someone with access to it can confirm it.


Dynaco ST 400 bias

I uploaded the Service Manual.