Dynaco power supply ST35

[soundz915]

I am looking for help designing a external solid state power supply for a Dynaco ST-35 with a DC heater supply. I know I will probable get a lot of why's for this its
just something I would like to do.

Thanks Scott Pike.

 

[rayma]

You mean for both the HV and the filaments?

 

[soundz915]

yes.

 

[rayma]

It's certainly doable if you want to.
The filaments need a total of 3.6ADC. The HV supply needs about 280mADC at 370VDC.

Notice that the original circuit floats the filament supply at +13.5VDC.

Have you considered changing to separate, fixed bias operation?
You'd need a new negative bias supply for that.

The standard circuit uses (and needs) a matched quad for the outputs.
At the least, it would be easy to convert to two matched pairs of output tubes,
instead of a matched quad, by using a separate cathode bias resistor/capacitor per channel.

 

[soundz915]

Would like to us Mercury Magnetics DYNA-PA60-P transformer. I have an adjustable bias circuit in the amp. 6.5V filament with center tap is what is supplied with the OEM Transformer and HV is 330v with center tap 660 rail to rail. I want to split filament supplies one left one right DC and over kill on filtering.

Scott Pike

 

[rayma]

Can you get a data sheet for that transformer?

Linear supply, or a SMPS for the filaments?
For a linear filament regulator, you'd only need much C at the input.
The output would have 1000uF or less, depending on the part.

 

[soundz915]

Yes

 

[rayma]

For developing/testing the filament supplies, use a 6.3V/1.8A = 3.5R, 20W load resistor for each supply.

 

[soundz915]

PDF Transhttps://www.diyaudio.com/forums/attachment.php?attachmentid=941629&d=1618233603

 

[soundz915]

https://www.diyaudio.com/forums/attachment.php?attachmentid=941630&stc=1&d=1618233897

 

[soundz915]

120 vac 50/60 hz primary, secondary 360-0-360 @ 300 ma, 55 volt bias tap, (2) 6.3 volt @ 5 amp taps and (1) 5 volt @ 4 amp tap.

 

[rayma]

This low drop out adjustable voltage regulator should be good for the two 1.8ADC filament regulators.
Use a full wave 35A bridge rectifier, with a capacitor input filter, on each of the two 6.3VAC secondaries.
See page 5/17 here:

Data sheet: https://www.st.com/resource/en/datasheet/ld29300.pdf

Digikey: Blocked

 

[rayma]

https://www.diyaudio.com/forums/att...d1618233897-dynaco-power-supply-st35-st35-jpg

Very nice amplifier.
You intend to remove the power transformer/rectifier/input capacitor from the chassis?

 

[lavane]

Have you looked at DG's board with EFB? tronola.com