Calculate voltage divider for Citation II separate bias transfomer

[gvocale]

I am restoring a Citation II I bought on ebay few years ago, where the two windings powering the diode for the negative bias seem not working.

When I bought this amp for parts, there was installed inside a little extra transformer marked Dynaco 464018 used to power just the diode of negative bias.

This transformer has the following wires:
- Black
- Black / White
- Violet
- Violet / White
- Red
- Red
- Red / Yellow

Black and Black / White were wired together and connected to one the AC wire.
Violet and Violet / White were wired together and connected to the other AC wire.

I tried adding 115v AC to Black and Violet, and on the other side I get:
- 96v AC measured between Red and Red
- 46v AC measured between Red and Red / Yellow

I have another working Citation II and I've measured across the White and White / Orange windings going into the negative bias diode 74v AC.

I am not very familiar with voltage dividers yet. Can I use one to lower the voltage from 96v AC to around 74v AC?

I tried using this calculator http://www.ti.com/download/kbase/volt/volt_div3.htm and it suggests to use a 340r with 1k150.

What wattage would these resistors need to be?

 

[gadget73]

easier to rectify it and drop it afterward. Makes the calculations much easier.

Need to see where the rest of the supply goes. Changing the 1.8k to drop more voltage will get it done, but without knowing what the load is and what the voltage ought to be its hard to guess. Quick and dirty method if you don't feel like doing the math, just power it and sub resistors until its where you need it to be.

 

[kward]

What Gadget said.

If you wanted to drop voltage in the AC domain it's easier on a high current secondary to do it with another transformer or another winding on the same transformer used in buck configuration. But if this is for a bias circuit, it shouldn't be pulling a lot of current, so it should be straight forward to drop what you need in the DC domain (after rectification).