Vintage tube amp restoration. Dynaco MK 3- mono blocks

[Ar9Jim 6,234]

 

The first photos (if I didn't screw up the order) is the old boards with the black caps. I built up the new driver boards from a kit and gave these old girls a refresh. Had fun doing it and it turned out great. The speakers in the pics are AR9s as you may have guessed. The AR90s behind them are in need of a crossover recap but have new surrounds. Those are my next project. Sorry for the sideways view. I'm not much good at this and the wife isn't home to help.

[4krow 5,168]

I appreciate the photos Jim. Looks like this is one project that has easier access than some. Now I forget, but what is the part that looks like a domino? I was thinking a diode.

[Ar9Jim 6,234]

Hi 4K,

Yeah, it was nice and easy, about my level. The board with eyelets made the soldering easy too.. I'm just a rookie at best and this was my first project since High School electronics class. I paid attention here, and armed with my Carver site education and a U- tube video on "how to solder", pulled it off. Looking forward to some more of it. It was certainly no achievement like a MKII or a BillD but it was a great "baby step" and fun.. That domino thing was likely a capacitor, guessing by what replaced it on the modern board, but I'm totally making an assumption. I'm just a greenhorn. Certainly no Old Texas Dog.

[4krow 5,168]

 Well, Let me be the first to say that you have quite a knack for making things look good. I mean that theleads on the resistors are bent exactly, as well as the other wiring. I still shake my head at some of my work.

[zumbini 6,140]

Nice clean work Jim. 

[oldtexasdog 2,371]

Very Clean and tidy there Jim!!

 

I could say even SEXY

 

 

[BillWojo 542]

Nice work Jim. I'm glad your getting into the Dark Side (tube amps). I bet those Dynaco's really sound great with the new caps. Believe it or not, they may take a few hours to break in and smooth out. I was never a believer in "caps breaking in" but after I recapped my Klipsch Heresy's I was a bit disappointed at first. After a few hours they smoothed out and now they sound great. So even though I can't explain it, I have experianced it.

One of the best pieces of advise I can give you when soldering is to use flux on every joint. I picked up a bottle of Kestor 186 with the needle tip on it and use it on every joint. I still have to finish up my Dynaco PAS3X preamp but I built a complete new set of upgraded PCB's for it. This was my first time building a PCB kit. I used the Kestor on every joint and when I was done I took them over to Kevins to have him inspect my work. I think he was a bit surprised and never even hinted that a solder joint needed to be touched up. I give the use of flux most of the credit for that. Twice I forgot to flux a joint and knew right away. Added flux and the joints flowed in perfect. 

Next you need to find some horns, they are great with dynamic music. Plus they are made for tubes.

Winter is a great time for tube amps................

 

BillWojo

[4krow 5,168]

Bill,

 

    I just started using the Kester product on larger joints in my work. I couldn't be more pleased with the results. I have used paste flux and the like in the past, but will stick with this product. Probably, just as you, I find some solder to be more friendly to work with in the first place. 

[soulofsound 40]

Looks like some fine work you did Jim.

[Ar9Jim 6,234]

Thanks so much guys for checking out my project. The work that CS members post is inspirational to me. After hanging with you guys for just about a year now, and looking back at old threads from many years back, it was time to do something. Hopefully this inspires other guys to do the same.

 

Thanks Dennis Miller for posting pictures of your work. Pics of your fine work are truly worth 1000 words, and your attention to detail, awesome.

Thanks Kevin P for the hardware and the support. Knowing I have a friend on the other end of the phone, that I can call for help is "priceless" and enabling.

Thanks OTD for sharing your projects. I watch all of them, and enjoy them very much. I learn something valuable every time. Very inspirational.

Now, I have enough confidence to be dangerous. New guys ( like me) remember to discharge the caps. Just cause the cord is unplugged doesn't make it safe! If you don't have a variac for start up, its a good idea to replace the fuses with ones of maybe 1/3 the normal rating, and use fast blow instead of slow blow, until it checks out ok..

Jim 

[Rockster2U 668]

Really nice project Jim - truly inspirational. Now all you need to do is spend a little time polishing that seat in front of your speakers. Enjoy.

[Ar9Jim 6,234]

 

 

Nice work Jim. I'm glad your getting into the Dark Side (tube amps). I bet those Dynaco's really sound great with the new caps. Believe it or not, they may take a few hours to break in and smooth out. I was never a believer in "caps breaking in" but after I recapped my Klipsch Heresy's I was a bit disappointed at first. After a few hours they smoothed out and now they sound great. So even though I can't explain it, I have experianced it.

One of the best pieces of advise I can give you when soldering is to use flux on every joint. I picked up a bottle of Kestor 186 with the needle tip on it and use it on every joint. I still have to finish up my Dynaco PAS3X preamp but I built a complete new set of upgraded PCB's for it. This was my first time building a PCB kit. I used the Kestor on every joint and when I was done I took them over to Kevins to have him inspect my work. I think he was a bit surprised and never even hinted that a solder joint needed to be touched up. I give the use of flux most of the credit for that. Twice I forgot to flux a joint and knew right away. Added flux and the joints flowed in perfect. 

Next you need to find some horns, they are great with dynamic music. Plus they are made for tubes.

Winter is a great time for tube amps................

 

BillWojo

Thanks Bill.. I must admit I was just using Radio Shack 60/40 rosin core.. You were likely using the high silver, solid type and separate flux with a higher melting temp? I cheated, but don't tell anyone.  I hope you enjoyed building up those new boards as much as I did. Really enjoyable work. I really like the idea of audio upgrades and complete products in kit form.. You can take as much time as you want, because its your baby. Not like in a production environment, trying to make a quota or a certain number per hour or day.. Also your not receiving a product that may have been built by someone in an unknown state of mind at the time, like personal issues, mad at the boss, hates the job they have, and on and on.. I bet the techs here at CS have opened up more than one unit full of cold solder joints and though "what was the assembler thinking about when they built this"? The DIY stuff lets you put a bit of your "heart and soul" in it.. Does that make it sound better? Maybe.