Old Dyna amp -- Worth Repairing??


I was given an old Dyna tube amp which seems to work well except, on occasion, there is an intermittent hiss or hum in one channel. Does this sound like a common or simple problem? I enjoy the use of this amp in my painting studio, so ultimate fidelity is not absolutely critical. However, I don't have the money to spend on a major repair. Typically, will I be charged a fee to even have someone open up and look at this piece of equipment? Or, should I ask for a free estimate? Any bits of advice on finding a fair and competent repair shop?

I am very glad I found this forum, as I enjoy music, but know very little about electronics, etc. (am a newbie), but am learning as I go. TIA.
dog581b
I assume by Dyna you mean Dynaco? Dynacos are great old amps! Some of the best values in all of audio if you ask me. They can be very musical if taken care of. Well worth repairing and one of the favorite hobbyists amps of all time.

Take a look at www.Curcioaudio.com. Joe Curcio invites you to e-mail him with a description of the problem at his site. He is also a regular at the audioasylum.com DIY tube section. If you ask your question there he is likely to answer you online.

What model Dynaco do you have? I'll assume an st70 as it is the most popular.

There are a number of things you can do to identify and fix the problem like swapping tubes and speaker wire and things like that. I am not going to go through it all because it is all available in very nice manual form at Joe's site. At the first page of Joe's site click on "Doctor Dynaco". At the new page scroll down until you see "Stereo 70 Repair Guide." This guide walks you through step by step method to identify and eliminate hum if you have a ST70.

There may be other guides there for other models but I am not sure.

Be careful poking around because tube amps carry high voltage even when unplugged.

The first thing I would do is read through the manual completely. Then do the simply things advised. Remember that there is lethal voltage even when the amp is unplugged. If you do not fix it post your question at the www.Audioasylum.com diy tube section. You will have narrowed down the possible problems a great deal by going through the process described in the manual and it will be easier to diagnose the problem over the web if it still exists. Joe has been there in the last day or two answering questions about hum and stuff in Dynacos. There are a lot of other folks who know a lot about Dynacos there too. Also you can e-mail him at his site.

If it's not an ST70 look at Joe's site for your model and ask at the Asylum in any event. Let us know what model it is too!

I'll look for you post at the Asylum but I hope all goes well and I don't see it!

Cheers,

I remain
Good advice, even though you remain "Clueless". BEWARE working on the amp yourself unless you do your homework as it contains "lethal" amps (even many weeks after being unplugged). Though Clueless remains so, he/she is far from, again good advice.
Contact Audio by Van Alstine,he has been modding these amps for years,he's reliable and priced right,good luck,Bob
Dog, the first thing to look at on a Dynaco amp would be the tube sockets for an intermitent "hiss/hum". Try wiggling the driver tube gently(the small one, it's a 7199 if it's a ST 70)on the channel that makes the noise. If it goes away or makes the same noise when wiggled, you found it. Clean the tube sockets and the pins on the tubes. Feel free to e-mail me with questions, I dont know everything there is to know about them but I fooled around with Dynas for a very long time and know some of their "habits".
Thank you for your responses. The amp is an SCA-35. Unfortunately, I'm having trouble locating info. on it.