[salb203]

Hi Everyone,
Just a little intro, my name is Sal Brisindi, I am into tube audio, tube radios and when time permits, R/C airplanes. I have been collecting and restoring tube radios for the last 12 years now owning over 200 radios, not to mention 6 Dynaco ST-70's, 2 Dynaco Mark IV's, PAS-3 etc... I have been restoring/rebuilding Dynaco ST-70's of late and below is a before and after photo of one I completed about 6 weeks ago (I actually did 2 of them at the same time). If you wonder how I got the chassis so shiny, its because I purchased a new stainless steel chassis from Dynakitparts.com.

I took photos along the way of the restoration, sooner or later I will write a restoration article. This amp was in very poor condition, some wiring modifications, broken switches, etc. I took apart the transformers, sanded them, gave them 2 coats of primer and 2 coats of semi-gloss black paint. Cleaned the printed circuit board, replaced every capacitor, a few resistors, replaced the selenium rectifier with a 1N4007 diode, new RCA jacks and new speaker terminals in the back.

Note: I didn't go as deep as Bill Thomas did removing all the components off the circuit board, I even used the same tube sockets. I did leave the 10k bias resistor and tried a few different brands of EL34's and the bias was able to be set with no problems, including a quad of "real" Mullard EL34's.

Regards,
Sal

[Rocket]

Hi Sal,

Great rebuild.  Do you intend of restoring anymore amps.

Regards

Rod

[Bill Thomas]

     AN EXCELLENT job, Sal.  I take it you used one of Kevin's new chassis' from Dynakit Parts, right?  (Believe me, I KNOW how much time *that* saves!  It takes several DAYS of polishing to get one of the stock chassis' back into presentable condition.  (And the "before" picture you posted showed a chassis that was WAY too far gone to save.)

     Well Done!

Sincerely,

Bill Thomas

[salb203]

Thanks Rod and Bill,
Yes, I will be restoring 2 more ST-70 in the near future and 2 PAS-3 preamps. Out of my 6 ST-70's, 4 of them are electrically restored, the two I completely restored with new chassis was for someone else. If anyone is interested, I took photos along the way pretty much step by step and I can post the photos here. Below is a before and after of the printed circuit board.



Bill,
Since I live in New Jersey I am lucky to live about 55 miles from Dynakitparts.com. I have visited Kevin twice this year.  He has everything you would need to restore a Dynaco tube amp.

The 2 amps I restored for "a customer" chassis were in terrible shape, when I told him I can replace the chassis he was thrilled. Go to http://www.tuberadios.com/davest70/ to see some more before pictures. You did a nice job polishing the chassis and electrically restoring the amps.

My next restoration will be a pair of Dynaco Mark IV mono blocks as soon as I get the Marantz 2252B receiver off my work bench, I am just waiting for the fuse bulbs to arrive. It had a bad driver transistor.

Regards,
Sal

[Bill Thomas]

Dear Sal,

     I'm an old "ex New Yawker" myself, but decided to hang out in the Blue Ridge Mountains for a while.  I have pretty much all the parts necessary to restore the existing amps, although there are a few that will require a chassis.  The saddest case is a factory-wired chassis.  It is totally beyond reclaiming.  Still, it is unmolested and helped to show how Dynaco did it back "in the day."  (As I'm sure you know, there are a few minor differences.)

     Your Driver Board "before" picture is pretty typical of what I find.  Getting that "crud" off the board is pretty troublesome, but essential.  Nice work!

     Well, back to the preamp.  Much to do, and miles to go before I...ZZzzzzzz!

Sincerely,

Bill Thomas

[martlet]

Hi Sal,

New member here.  I was amazed by the before and after pictures of your work.  Now, I am really curious about your efforts on the marantz 2252b - especially since I am working with my favorite repair/rebuild friend on the same model.  As you are so close to completion would it be possible for you to answer a few questions?...

Did you recap the entire piece?

Did you make any improvements or simply aim to replace original material when possible?

Can you offer any comments on the phono section?

I have read a wide range of comments about this receiver from it is nothing special to it is one of the best receivers one owner (who claimed to have compared it to many others) had in his collection.  Where does it stand in your opinion?

Thanks

Scott
aka martlet

[salb203]

Hi Scott,
Sorry I didn't respond sooner, I didn't check this forum this week.

Thanks for the compliment on my ST-70, it looks and works great.

To tell you the truth, all I did on my Marantz 2252B was to replace a bad driver transistor and a few bulbs. The receiver works and sounds great so I didn't go further. The phono section sounded good. Right now the 2252B is sitting in my basement with a pair of Bozak 301B speakers connected to it. I want to put it in my sons room replacing the Akai that is there now. I will connect it to a pair of KLH 6 speakers.

I bought it from the original owner who put it away in its original box with its manuals. Its in excellent condition.

Sal