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    dynaco markiii cap rebuild

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    smalphurs

    Posts : 2
    Join date : 2016-06-12

    dynaco markiii cap rebuild

    Post by smalphurs on Tue Jun 14, 2016 8:37 am

    Any recommendations on what caps to buy to rebuild the can capacitor on the Mark iii. I'm new to the forum and rebuilding electronics. Also some links where to get them at a good price. Thanks in advanced

    Shawn

    Bob Latino
    Admin

    Posts : 2411
    Join date : 2008-11-26
    Location : Massachusetts

    Re: dynaco markiii cap rebuild

    Post by Bob Latino on Tue Jun 14, 2016 10:55 am

    A good exact replacement quad cap capacitor would be the Dynakitparts 30, 20, 20, 20 @ 550 volt cap. Check the link below ..

    Dynakitparts replacement Mark III quad cap

    For $5 more you can also use an upgraded 80, 40, 30, 20 quad cap. Just place the 80 section where the red wire from the output transformer connects. (the section of the quad cap that faces the rectifier tube socket). Link below ..

    Dynakitparts 80, 40, 30, 20 @ 550 volt quad cap

    Bob

    bluemeanies

    Posts : 129
    Join date : 2015-02-09
    Age : 66
    Location : Folsom Pa.

    Re: dynaco markiii cap rebuild

    Post by bluemeanies on Tue Jun 14, 2016 3:23 pm

    Welcome smalphurs

    Mark Korda

    Posts : 23
    Join date : 2009-12-29

    Re: dynaco markiii cap rebuild

    Post by Mark Korda on Tue Jun 14, 2016 6:42 pm

    Hi Bob and Shawn, thanks. I've seen those electrolytics and I might have to go that way. The cap boards I bought awhile ago from Chart Chong can be seen in a Mark 3 rebuild picture by PMarcin. There to good to give up on without a fight. Paul Marcin called me up and I have sent him the manual and installation instructions, Mike Samra too. I'm waiting to see what they say. The Chart Chong board has included many other components than just the caps.
    I thought Charts directions were a little over my head. I think I was right when Paul said Chart must of gone to Cal Tech, that made me feel a little better.
    Charts's instructions are easy but he neglects some loose ends which are shown in the pictorial diagram. To me it's 3 resistors and one stray transformer wire to figure out ....thanks guys...Mark.

    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    Re: dynaco markiii cap rebuild

    Post by Ernstmach on Tue Jun 14, 2016 8:52 pm

    Good to see you posting here Mark.
    Bob2

    Mark Korda

    Posts : 23
    Join date : 2009-12-29

    Re: dynaco markiii cap rebuild

    Post by Mark Korda on Tue Jun 14, 2016 11:44 pm

    Hi Bob2, besides doing the best job I can on these one thing is going to set these apart from the rest, the chassis. The chassis were slightly pitted. I found out an old high school teacher is doing powder coating. Their with him now. The color I picked was Bruce McClaren Can-Am sports car orange, the Bell X-1 sound barrier jet orange, or the Cleveland Browns football color orange. Thats the best way I can describe the color. With the brown cages they will look as good as I hope they sound.
    Bob2, this forum is a Godsend to Dyna fans. I've already received some great help and inspiration, specially from you Bob. When I first got my hands on these, 1982, the UPS driver wanted to punch me out. It was a c.o.d. package and I didn't have the money ready. I lived on the 3rd floor and both Mark 3's were in the same box...it was hot out too!....the story gets better as time went on. These must be built!....take care Bob...I will have pics...Mark.

    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    Re: dynaco markiii cap rebuild

    Post by Ernstmach on Wed Jun 15, 2016 7:46 am

    Hi Mark,
    this is a great place and the folks here are the best.
    Please keep us updated!
    Bob.

    smalphurs

    Posts : 2
    Join date : 2016-06-12

    Re: dynaco markiii cap rebuild

    Post by smalphurs on Wed Jun 15, 2016 11:52 pm

    Thanks for the quick reply. I like a forum where people actually pay attention. I need to clarify what I'm asking as I was leaving for work when I first posted. I want to rebuild the can capacitor. A lil back ground first.... When I got the Mark iii amp I knew nothing about the amp nor how to work on them (Mark iii and PAM-1). I have been doing ALOT of reading since. I have always wanted a vintage tube amp......I have also read and learned about the dangers of working with capacitors, how to discharge and check them.
     Without knowing any better I immediately fired it up. I hooked up some 8 ohm speakers. All the tubes lit up as it warmed up. It Had a loud hum....and then the can capacitor went up in smoke... literally.
    I now have the can out , I pried around the lid , heated it up and have taken the capacitor out.
     My question is, can I buy 4 40uf @ 600v...or is there some better options. I have read some about putting some lower voltage caps in " series or parallel " ( I don't understand that just yet) and still have the proper voltage?
    Second question is where is the best place to buy....good prices. I'm going to replace all of the caps and resistors.
    Third question....Does the high dollar audio capacitors and the low ESR ( think that's right) sound better? Sprauge seems a bit pricy as well....or just any capacitor with the proper voltage and UF rating?
    This amp and preamp is completely untouched as far as I can tell. I'm pretty sure it has the original tubes. They say Mullard KT69 I think ....hard to tell or is that wrong and they are possibly KT88. As soon as the trial period is up I would love to post some pics.....Thanks for any advice, as you can tell I have very limited knowledge about this subject but I'm like a spounge...

    GP49

    Posts : 733
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: dynaco markiii cap rebuild

    Post by GP49 on Thu Jun 16, 2016 12:39 am

    I would recommend that for now (especially with your not understanding series vs. parallel), you keep it simple. Either use a replacement quad capacitor as a drop-in, or one of the replacement kits that include a circuit board and separate capacitors. Yes, you can wire lower-voltage capacitors in series, but you then require double the capacitance AND equalizing resistors so that the voltage will be evenly applied to the two capacitors. You then also have to create a way to mount them, bearing in mind that they will probably take up more space than the proper quad capacitor or replacement kit. There isn't that much room underneath a Dynaco Mark III to cram in all those capacitors under the chassis.

    Don't think you can just replace the one capacitor inside the quad capacitor that has failed. Do that and you'll be back into it again in short order, as the other three are just as old and electrolytic capacitors do have a "median time before failure" which is measured in decades...which is how old your Mark III is.

    In the power supply, highfalutin' audio capacitors are a way to separate you from your money. Sprague is good...and NOT considered expensive. Many of the retrofit kits to replace the quad capacitor have used Panasonic capacitors, but they are not by any means the only good brand.


    Mark Korda

    Posts : 23
    Join date : 2009-12-29

    Re: dynaco markiii cap rebuild

    Post by Mark Korda on Sat Jun 18, 2016 11:46 pm

    Hi, I want to update my quest to find out how to tie up a few loose ends on a real nice Dyna Mark 3 cap board built by Chart Chong about 8 years ago.
    First, thanks goes to Bob Latino for getting me back on this forum and teaching me how to test Dynaco transformers.
    While looking thru the Dyna pictures I found a member who had installed the same cap board and had his Dyna compared to a Mac 275 that his friend owned. Thru the beauty of this forum I reconized the same cap board and blew the picture up. More important was I e-mailed him. He goes by PMarin, but Polish Power Ivan Putski said his last name is Marinciak.
    Paul called me up and told me to bear with him as he is going thru Parkinsons. He sound fine. I had 3 unanswered questions that Chart Chong was trying to make me understand but he gave up e-mailing me like I was the
    Geiko caveman. Paul jokingly said , he must of gone to Cal Tech and we both laughed.
    I sent a letter to Paul with the cap board instructions,schematic, and a pictoral diagram, where I colored in the wires with a crayon sometime ago.
    Paul called me tonight and explained every question I had written down ans also offered future assistance in my Dyna rebuild.
    Whats remarkable is me finding the answer on this great forum. Whats more really cool is a handicapped person with Parkinsons just bridged a communication gap with an Asian speaking person and a downeast Mainer. Paul is the greatest person and probably not reading this forum. I bet if you guys e-mail him thru this forum like I did we can keep him busy. He knows tube amps like the back of his hand and wants to get back to work...he sure helped me....thanks guys....Mark Korda

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