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    ST-70 Rebuild Thread

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    sKiZo

    Posts : 1285
    Join date : 2013-04-01
    Location : Michigan USA

    Re: ST-70 Rebuild Thread

    Post by sKiZo on Thu Dec 03, 2015 4:34 pm

    Doctor Hugocat wrote:I put the bias pots in just to fill the holes in the chassis: the plan is to temporarily get some vintage-looking knobs for cosmetic purposes and in the longer term buy your triode/pentode kit which will fill the holes AND do something useful!!


    Might I suggest twin volume pots? Separate pots also give you balance control ...

    Doctor Hugocat

    Posts : 75
    Join date : 2015-08-19
    Location : Los Angeles CA

    Re: ST-70 Rebuild Thread

    Post by Doctor Hugocat on Fri Dec 04, 2015 1:47 am

    Tune wrote:Hi any progress?

    Thanks for asking Tune! I've been waiting for a new power transformer to arrive from the excellent Dynakitparts. In the meantime, here's a pic of my newly-built VTA board in the chassis:

    sKIZo, that's a nice idea about the volume pots........food for thought.......Thanks! Very Happy Very Happy


    audiobill

    Posts : 271
    Join date : 2014-03-13
    Location : Philadelphia

    Re: ST-70 Rebuild Thread

    Post by audiobill on Fri Dec 04, 2015 8:05 am

    I note your Visa card is close at hand!!

    Doctor Hugocat

    Posts : 75
    Join date : 2015-08-19
    Location : Los Angeles CA

    Re: ST-70 Rebuild Thread

    Post by Doctor Hugocat on Sat Dec 05, 2015 12:43 am

    audiobill wrote:I note your Visa card is close at hand!!

    lol! Yeah, it tries to hide when it sees me get another project!! Very Happy

    Doctor Hugocat

    Posts : 75
    Join date : 2015-08-19
    Location : Los Angeles CA

    Re: ST-70 Rebuild Thread

    Post by Doctor Hugocat on Sat Dec 19, 2015 1:53 am

    It's been a while since my last update.....I got the new transformer from the excellent Dynakit Parts: Thanks Kevin!! I also bought new tube sockets for all the old ones except the frnt 'bias' sockets. I've been seeing so many posts about problems with older sockets that it seemed to make sense.

    I bolted in the new power transformer and the output transformers tonight: here's the result!



    Next job: carry on the build according to the original Dynaco build manual until I get to hooking up the VTA board. More soon!

    Tubes4ever

    Posts : 59
    Join date : 2015-07-14
    Location : Star, Idaho

    Re: ST-70 Rebuild Thread

    Post by Tubes4ever on Sat Dec 19, 2015 11:33 am

    Excellent! Keep the updates coming

    Doctor Hugocat

    Posts : 75
    Join date : 2015-08-19
    Location : Los Angeles CA

    Re: ST-70 Rebuild Thread

    Post by Doctor Hugocat on Fri Jan 01, 2016 12:34 am

    Today I took advantage of some holiday time to strip and prep the cover for painting. Very Happy

    I flatted back the mesh part, but used paint stripper on the sides. I was unsure whether to flat or strip it, but I'm glad I used the paint stripper: under the old paint was a bunch of rust. Next up: paint with black satin (semi-gloss).


    Tubes4ever

    Posts : 59
    Join date : 2015-07-14
    Location : Star, Idaho

    Re: ST-70 Rebuild Thread

    Post by Tubes4ever on Fri Jan 01, 2016 12:42 am

    Are you really going to use the cover and hide the beauty of the tubes?

    Doctor Hugocat

    Posts : 75
    Join date : 2015-08-19
    Location : Los Angeles CA

    Re: ST-70 Rebuild Thread

    Post by Doctor Hugocat on Fri Jan 01, 2016 12:44 am

    Tubes4ever wrote:Are you really going to use the cover and hide the beauty of the tubes?

    LOL probably not! Laughing But I'm a bit of a sad case and wouldn't feel I'd done a complete job unless I'd refinished the cover as well Embarassed

    Tubes4ever

    Posts : 59
    Join date : 2015-07-14
    Location : Star, Idaho

    Re: ST-70 Rebuild Thread

    Post by Tubes4ever on Fri Jan 01, 2016 12:52 am

    Totally understand

    Doctor Hugocat

    Posts : 75
    Join date : 2015-08-19
    Location : Los Angeles CA

    Re: ST-70 Rebuild Thread

    Post by Doctor Hugocat on Wed Feb 10, 2016 10:15 pm

    It'a been a bit quiet on the rebuild front here recently: I have an arm injury which can make it difficult for me to work on it, but here's a pic of most recent progress. In total, there's probably only aabout 3-5 hours work left: audio in, bias sockets, NFB, a couple grounds, power cord and a few other small things. Hopefully I can get back to work on it soon.


    Tune

    Posts : 3
    Join date : 2008-12-12
    Age : 59
    Location : Augusta, Ga, USA

    Re: ST-70 Rebuild Thread

    Post by Tune on Sat Apr 16, 2016 11:30 pm

    Hi,

    Been awhile any updates?

    Tune

    Doctor Hugocat

    Posts : 75
    Join date : 2015-08-19
    Location : Los Angeles CA

    Re: ST-70 Rebuild Thread

    Post by Doctor Hugocat on Mon Apr 18, 2016 8:10 pm

    Tune wrote:Hi,

    Been awhile any updates?

    Tune

    Hi Tune -

    Thanks for asking!! Now moving house, putting another brake on progress Rolling Eyes

    I did get a NOS RCA rectifier tube from a friend of mine though: he was carrying a box of tubes and I jokingly asked if he fancied trading one rectifier tube for a bunch of vintage tubes I got from a Hammond organ amp (I'm a Hammond player). He pulled one out of the box and we're both damn pleased with the trade!! He needed the 12AX7s for one of his guitar amps.

    Hopefully I'll be moved in soon and I'm gonna start up again. Of course, now I'm in the position which I hate, where I've lost track of what I still have to do on the project (thus exponentially increasing the chances I'll mess something up).

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