• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Dynaco ST 70 mods restoration, number 1

gkargreen said:
Thanks gadget, that was one of my concerns. Right now, I am looking at the VTA boards and going with that as I will have documentation and a clean build, the PS will be rebuilt by getting rid of those big caps and returning to a more reasonable PS build.
Click to expand...
The 80/40/30/20 quad cap works well with the 40 first, then the 80 after the choke.
 
Thanks, all! Yes, Pio, I believe the PS cap should be connected with the 40 first as that is the most allowable for the first cap coming off a 5AR4. After looking this one over, I decided to rebuild back to original replacing the 5AR4 with the SS plug-in you showed earlier,, removing the monster caps, and using a new VTA driver board which will also take care of the bias supply as it is built into the board, the VTA site shows a typical rebuild, and it is nice and clean looking underneath and has IBAMs for the output tubes. This one (and the next one) has chrome that was pretty oxidized, just needed some Wenol polish to get them looking much nicer, so removing most of the parts off was necessary.
 
The plexy covers for the VTA boards are nice.
There two I believe. The other being a mirror instead of being clear. It helps to keep little finger and dust out. I put one on mine
 

Attachments

  • 20220901_111613.jpg
    20220901_111613.jpg
    130.6 KB · Views: 45
gkargreen said:
Thanks, all! Yes, Pio, I believe the PS cap should be connected with the 40 first as that is the most allowable for the first cap coming off a 5AR4. After looking this one over, I decided to rebuild back to original replacing the 5AR4 with the SS plug-in you showed earlier,, removing the monster caps, and using a new VTA driver board which will also take care of the bias supply as it is built into the board, the VTA site shows a typical rebuild, and it is nice and clean looking underneath and has IBAMs for the output tubes. This one (and the next one) has chrome that was pretty oxidized, just needed some Wenol polish to get them looking much nicer, so removing most of the parts off was necessary.
Click to expand...
Do consider a CL-90 or two for the PT primary. Also consider changing the two 1.5 meg screen resistors for 1.2 meg if using the 6CG8 or 7199 driver boards.
 
Last edited:
Not sure about the jumper 4 to 6, I have never seen that one, would that not short the red windings? Please explain.
 
Hi all, been working on this as I get parts in. I do have a question regarding the resistors (6.8K and 22K) wattage value, the wattage is not listed in the manual, I can only see the physical size on the image from the Dynaco build manual, looks like a 1 watt and a 2 watt, respectively. Is that right, or should I go higher in wattage? Thanks.
 
You must log in or register to reply here.
Back
Top Bottom