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Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


    ST-70 Dual Rectifier V2 install questions

    James_Weir
    James_Weir


    Posts : 18
    Join date : 2016-07-01
    Age : 50
    Location : Los Angeles

    ST-70 Dual Rectifier V2 install questions Empty ST-70 Dual Rectifier V2 install questions

    Post by James_Weir Wed Sep 13, 2023 7:33 pm

    Looking for advice from someone who has installed the 2nd version of the tubes4hifi dual rectifier.

    Step 4 says to install the 3 lug terminal with the B+ resistor, which I did, but there’s no more mention of attaching any wires to it? From the pic it’s clear that the red lead marked B+ on the VTA pcb goes to the terminal on one side of the resistor, but the other side looks like 4 wires? If I had to guess it looks like 1 of the 2 leads from the Choke (black), an orange that presumably is the extended choke wire mentioned in step 5, the red transformer lead from the output transformer on the left, and then that leaving and going into the old bias pot hole? If that’s correct, great, but it seemed strange that one choke lead and the lead from one transformer would attach to the terminal strip while the other choke lead and transformer lead would not. And those are all just soldered together at the terminal on the other end of the terminal lug?

    I also noticed that in photos of V1 there are 2 B+ locations on the DR PCB, but on V2 there is one contact point labeled B+ with three holes for wires, and at the other end of the pcb, between contacts of one of the new smaller caps, there is an unmarked contact? Another post mentioned only needing one B+ but then what do I do with the B+ lead from the other output transformer?

    Thanks in advance.

    PS I have emailed Dan Willoughby, but I'm sure he's busy and I thought someone here might have some first hand experience solving the issues I'm coming up against.

    MechEngVic likes this post

    James_Weir
    James_Weir


    Posts : 18
    Join date : 2016-07-01
    Age : 50
    Location : Los Angeles

    ST-70 Dual Rectifier V2 install questions Empty Re: ST-70 Dual Rectifier V2 install questions

    Post by James_Weir Fri Sep 22, 2023 3:25 am

    Had a great call with Dan that cleared up these questions. Here's what I found out.

    As far as the 3 lug terminal. One end of the resistor connects as I thought to the B+ connection point on the via pcb. The other end of the resistor connects to one of the 3 connected B+ connection points on the dual rectifier (DR) pcb. The red leads from each of the output transformers connect to the other 2 connection points.

    Choke leads can bypass the terminal lug, contrary to the photo, and connect directly to the DR pcb in the labeled connection points.

    There is an unlabeled connection point within one of the circles of the caps. This is an oversight and can be ignored.

    Tubes4ever and MechEngVic like this post


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