Recommendations for a tube amp tech in Arkansas or close by?

[avguytx]

I’ve got a Dynakit ST-70 tube amp that I acquired in a group of equipment last summer that I’d like to get finished up. Does anyone know of any reputable techs in the Arkansas area that would be recommended? I may end up having to just ship it somewhere, which adds a good chunk since shipping has gone up so much, but that may have to happen.  I'd like to get this working as it's a great looking amp with the cage.  At the least, I'd like to be able to listen to it in the winter time since it can help heat the upstairs room.  lol  I'd posted on Audiokarma about doing some troubleshooting on it but I know my limitations with electronics and especially amps.  The person I'd bought it from last summer was selling things off for his older brother, who was elderly and dementia was setting in and worsening.  This amp is practically new looking and the power transformer was mounted but never wired up.  

 

Here is the thread at Audiokarma if you would like to see/read what had been going on.

 

Thanks for any recommendations.

[seti]

That needs more than a tech lol. Check Durham electronics. My friend Chris works for him on a few jobs and he is as good as they get.

 

 

 

 

[avguytx]

1 hour ago, seti said:

That needs more than a tech lol. Check Durham electronics. My friend Chris works for him on a few jobs and he is as good as they get.

 

 

 

 

 

Chris did the repair work on a Mcintosh MC250 I had a couple years back and Arvel has worked on other things of mine.  Arvel doesn't really mess with tube amps, or amps with MOSFETs (ha) and Chris isn't doing as much work now is what Arvel last told me. Seems like I asked him about it awhile back. I agree, though...Chris is one of the best out there. 

[John Warren]

How to rate your service tech?  A wee test:

 

• Capable of working amps others have butchered, including those with highly regarded reputations.
• Has spectrum, distortion analyzers and other expensive, well maintained analytical instruments everywhere.
• Manages 20 pounds of unusable, trash shipping materials for each amp received
• Enjoys spending endless hours figuring how to pack each amp and get it shipped so the carriers can damage it. 
• Maintains vast inventory of difficult, hard to find electronic parts
• Has a source for free, low production rate transistors sourced from factory authorize distributors
• Buys nothing from NTE 
• Sees one-of-a-kind factory designed parts that break when touched a "challenge"
• Has a source for free shipping materials such as cartons, packing foam, tape
• Highly skilled, former McIntosh certified repair tech
• Somehow possesses a viable business model with shop labor rate $8/h

 

 

 

[Coytee]

C'mon Warren, he could simply send it to Jeff Medwin....  he'd be sure to only use approved red zip ties and capacitors that have been blessed by his French Chihuahua (Yes French, this is a highly specialized dog and uber rare).  

 

 

 

 

 

[avguytx]

My other option, if I can't find someone, is to order a new driver board and wiring, un-wire everything that's been done previously, then rewire everything and install the new driver board.  Hell, for that matter, I could order all new resistors and replace the originals just to make sure.  Why not start with a clean slate.  At least if it doesn't work, I've only got myself to blame.  I built a VTA ST-70 kit about 4 years ago, which I really enjoyed, and it worked like a champ.  All I really had to do with it was check tube bias once in awhile.

[Davecv41]

I read the last 2 pages of the AK thread. Fix the short in the power supply first. If that doesn't work, then I'd suggest unwire the whole thing, and start over, installing one wire at a time. Start with the power transformer. Unsolder and tape the secondary leads up for safety, and use the bulb test to make sure the transformer itself isn't shorted.

[avguytx]

3 hours ago, Davecv41 said:

I read the last 2 pages of the AK thread. Fix the short in the power supply first. If that doesn't work, then I'd suggest unwire the whole thing, and start over, installing one wire at a time. Start with the power transformer. Unsolder and tape the secondary leads up for safety, and use the bulb test to make sure the transformer itself isn't shorted.

 

Thank you for the input.  As time and bravery allow, I'll go back in and check the power transformer wiring again.  I've honestly been over it numerous times but there's always that chance.  When I first started going through it, the PT had not been wired to anything so it made it easy to wire.  However, I then started discovering where some things were reversed, wrong resistor values, etc., and it got tedious.  If diagrams are followed, it's really hard to screw this amplifier up if a person takes their time.  I had no issues when I built the VTA from a kit....but I had a hand in it from start to finish and didn't rush anything.  Maybe I can tinker with it more on Thursday or Friday since I'll be off work for the Holidays.

 

Just so I'm clear, which wires are the secondary?

 

Here's what the underside looked like when I got it.

 

[captainbeefheart]

If you can't find anyone or are worried about the included shipping costs I can help since it's not my day job I don't need to really make any profit on it just pay for parts and maybe a bottle pinot noir for my troubles. I have high quality lab equipment and have been designing and working on amplifiers since the 60's, I also know these amplifiers inside and out as I have worked on so many of these I can do it in my sleep. So basically your just paying for parts and shipping, I don't drink expensive wine either

 

Another bonus is I have a bunch of premium NOS 7199 tubes if needed, I have seen many of them weak in these amplifiers that need to be replaced. I also have the beefed up printed circuit boards that installs the new power supply filter capacitors too. I probably have more parts than a working tech since I have been doing this for a very long time, I keep a ton of resistors, capacitors, tubes, transistors, IC's, etc... from NOS to new, anything under the sun you can think of I probably have it.

 

PM me if interested, I just love working on tube gear and since I am not a back logged tech you will get it back asap. I remember the gold old days doing extensive mods to these and really making them into a real amazing amplifier.

 

 

[SWL]

If you can't find anyone or are worried about the included shipping costs I can help since it's not my day job I don't need to really make any profit on it just pay for parts and maybe a bottle pinot noir for my troubles. I have high quality lab equipment and have been designing and working on amplifiers since the 60's, I also know these amplifiers inside and out as I have worked on so many of these I can do it in my sleep. So basically your just paying for parts and shipping, I don't drink expensive wine either [emoji6]
 
Another bonus is I have a bunch of premium NOS 7199 tubes if needed, I have seen many of them weak in these amplifiers that need to be replaced. I also have the beefed up printed circuit boards that installs the new power supply filter capacitors too. I probably have more parts than a working tech since I have been doing this for a very long time, I keep a ton of resistors, capacitors, tubes, transistors, IC's, etc... from NOS to new, anything under the sun you can think of I probably have it.
 
PM me if interested, I just love working on tube gear and since I am not a back logged tech you will get it back asap. I remember the gold old days doing extensive mods to these and really making them into a real amazing amplifier.
 
 

Very cool. [emoji106]

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[seti]

I mentioned it to Chris he said take it on to Durham's.