[johnnymac]

I look forward to learning more from this community. I have been involved in music my whole life. As a Live SOund Engineer as well as small recording studio owner and now getting back into vinyl and old turntables, and all things tube for the most part. I do enjoy tripath solid state amps too. I have a VirtueOne2 as my 2 channel set up on my computer mated with some Fostex 8" studio monitors.

I bought a Dyna ST70 and it has a obviously aftermarket board on it that i cannot find a schematic for. One of the input RCA jacks is missing but I do not think it is a mono amp. It does not have the Stereo / Mono switch. The star grounding wire for the jack that is missing is still just hanging there inside the chassis but I do not see where the signal wire should connect to the PC board. A schematic would make this trivial for even a novice like me.

The board is the Super Seventy PC189.

What year was this board made?

Is the schematic available and how much does it cost?

Once I know if this amp works I think I am interested in keeping it. I have a lot of other tube gear.

If it works can I upgrade it further to become a Ultimate 70?

thanks ! I am glad to find this place!

John

[JerryM]

Welcome to AudioCircle, John. 

Reach out to Frank Van Alstine, here on AC. He's the master of Dynaco ST-70s.    http://www.audiocircle.com/index.php?board=48

[mresseguie]

Welcome to AC, John.

I'll second Jerry's suggestion. Frank van Alstine has decades of experience with your amp (or models like it).

Michael

[Maritan]

Welcome! You should also look into Bob Latino - he has some experience with these older Dynaco amplifiers and offers kits to upgrade them too if desired.

[ArthurDent]

Greetings & Welcome to AC john      There is almost always someone available for counseling 24/7/365 for your vinyl & tube 'interests' (does that term work better Michael ?). 

Have fun. 

[Guy 13]

A warm welcome to AudioCircle Mr. John

Guy 13
Also a Tube-a-holic.
(Decware SE84C+ and Bottlehead Crack)

[OzarkTom]

Welcome John, FVA is the King of ST-70's. He has modded them from the mid 70's or earlier.

[TrungT]

Welcome to AC 

[brooklyn]

[dB Cooper]

Welcome to the sweet spot.


 Frank Van Alstine will no doubt be able to help you get your "70" rocking again.

[Phil A]

Welcome to AC!

[johnnymac]

thanks for the welcome everyone, I am getting help here and at audiokarma where i have been a on and off member over time

I emailed FVA on saturday and he got back to me right away!

I am working on a couple projects at the same time. I was deep into working on an Empire 298 turntable when I luckily grabbed up this ST70.

It sounds good but over the weekend has developed a bad hum/vibration I think something is amis here perhaps on of the transformers is now screwed tight enough either to the chassis or the thru bolts thru the plates of the tranny are loose?

John