[orthobiz]

I recently received unannounced in the mail my college roommate's Dynaco ST-70! Pretty amazing, eh?

I am planning on sending it to Frank soon for a rebuild but am wondering how much I should worry about the appearance. My initial thought is that some patina is cool. There's some pitting and a little rust...Some input is appreciated. Like, should I buy a new chassis from dynacoparts?

Some pics of your projects are much appreciated.

Thanks,

Paul

[Wayner]

Where are the pictures???

[orthobiz]

I've loaded some pics below. I'm also hoping to see some other people's completed projects to get an idea of what a fully electronically restored 50 year old amp on an unrestored chassis looks like! Wayner, I know you have an Ultravalve but how about a restored Dynaco?

Thanks,

Paul

[avahifi]

The one in the link below is about as clean as an Ultimate 70 is going to get after we are finished with it.

The metal parts are 50 years old are thereabouts.

http://avahifi.com/index.php?option=com_content&view=article&id=171&Itemid=172

Frank Van Alstine

[orthobiz]

Now that I look closely at the picture, Frank (and I've been looking for the past several days!) I can see that it is a nicely cleaned up older unit. Thanks.

Paul

[orthobiz]

[orthobiz]

More:
 



Anybody wanna see inside?

Paul

[ArthurDent]

Anybody wanna see inside?

Paul

Well of course we do. At least I'd like to. 

[orthobiz]

These are all I have right now. If only the whole thing could look like the underside!






Paul

[avahifi]

this looks more like just layers of dirt rather then corrosion.  It should clean up reasonably well.

You might want to vacuum it before shipping.

Frank

[sfox7076]

Does the conversion of an ST70 to an Ultimate 70 still cost $999?

[avahifi]

Correct, the Ultimate 70 factory rebuild is $999.

This includes the assembled new mother board with multiple regulated power supplies installed, the new AVA input and output jack sets installed, a complete new tube set (7 tubes) and a new three year parts and labor warranty.

I am actually building one right now, they are still fun for me to do.

Frank Van Alstine

[jtwrace]

Correct, the Ultimate 70 factory rebuild is $999.

This includes the assembled new mother board with multiple regulated power supplies installed, the new AVA input and output jack sets installed, a complete new tube set (7 tubes) and a new three year parts and labor warranty.

I am actually building one right now, they are still fun for me to do.

Frank Van Alstine

How about some in progress pics?   

[orthobiz]

OK, I started to clean the chassis with a greasy wadding material made for alloy car wheels:
There is still a fair amount of corrosion present and I have not used anything abrasive.



"After" closeup:


"Before" (other side) closeup:


Windex on the black stuff (BTW it takes the writing off the glass of the Mullard tubes, don't ask me how I know  ):


So, what do you think? Perhaps Frank and Larry will weigh in...

1. Keep the chassis? Frank: should I continue cleaning it up or is it something you do during the rebuild?
2. Is there a favored cleaner/abrasive for the old chassis?
3. I think you source your Ultravalve chassis from the Dynacoparts people? Can you order a new chassis for me at the time of the rebuild?

Thanks. Still waiting for more pics of AC members' Ultimate rebuilds!

Paul

[Wayner]

The www.Dynakitparts.com folks do make the chassis for the Ultravalve, the problem is that its not just a Stereo 70 chassis, but the Ultravalve chassis, which then needs a faceplate. They are 2 different animals, from a physical point of view.

A new clone copy of the original Dyna chassis can be had from Dynakit for about $125. http://www.dynakitparts.com/dynakit-products/chassis/DYNAKIT-ST-70-CHASSIS





The Ultravalve chassis looks like this:



Wayner

[orthobiz]

The www.Dynakitparts.com folks do make the chassis for the Ultravalve, the problem is that its not just a Stereo 70 chassis, but the Ultravalve chassis, which then needs a faceplate. They are 2 different animals, from a physical point of view.
Wayner

Nice additional pics of the Ultravalve, thanks Wayner.

I knew the chassis were different, I was mainly wondering if AVA could order the chassis for my rebuild rather than me ordering it from Dynakitparts, shipping it to my house and then shipping it to Frank.

Paul

[Wayner]

Do a direct ship?

Wayner

[avahifi]

Note that chassis replacement is a VERY labor intensive project.  There are many transformer leads to unsolder, tube socket wiring to undo, and then redo and a lot more.

The Ultimate 70 rebuild assumes we are starting with a wired and working original Dyna ST-70.  The rebuld uses almost all of the original tube socket and transformer wiring, with connections fixed on an as needed basis, not a wholesale replacement.

The Ultimate 70 rebuild removes the quad filter capacitor, the bias supply, and the audio board and replaces these parts, along with the input and output jack sets, but does NOT include the time to strip the transformers and all tube sockets and other parts from the original chassis.  By the time we do all that at extra cost you would be better off with a new Ultravalve amplifier.

Frank

[orthobiz]

Thanks Frank! I didn't realize all that was involved. So do I need to try to clean it up more or is that something you do with the rebuild?

Appreciate it,

Paul

[orthobiz]

"You MUST use your variac to bring the AC line voltage up very slowly, over a period of hours, a small bit of voltage increase at a time, to avoid destroying the power supply electrolytic capacitors.  A "hard" turn on to full line voltage will likely short out and damage these old parts, especially if they have been unused for many years."

Meanwhile, my roommate plugged it in and turned it on (also the preamp he sent me) so when you say "working," I would say "probably?" I didn't dare do it again!

Paul