New Project ST70

Hope everyone is doing good !!

I'm here in Dallas with a ST70 I bought 10 years ago.
I knew it was in very poor shape, ( as in wires all cut up )
but because of money, job stress, etc.. I am just now
getting to assemble it. ( After seeing the VTA board )

I would appreciate some help in deciding what to replace,
which options to choose on a VTA basic board, and also
have some backup when I have a question about assembly.

I'm so glad I didn't buy other upgrade kits ( like Van Alstine )
or such, and feel pretty good about buying a VTA board with
whatever else I need.

This amp basically only has the original tube sockets, power transformer,
audio transformers ( the board is original but I don't trust it at all,
seems some people think putting 100 wonder caps will make an amp 100
times better ) and some hardware. There is some rusty pitting on the frame
but the cage looks pretty good. I don't really mind it is not in perfect
cosmetic shape, I just want good reliable sound.

I have another ST70 in original shape ( yes still has the selenium diode that
I know I HAVE to change ) so I do have a physical model to compare to.

If only someone could enlighten me as to the electronic schematic
and functioning of a 3 inch solid copper wire, I could just maybe
get this done.

I'm going to continue on the next post to separate
my ramblings with my proposed purchases and questions about
assembling the new amp.

I'm not sure I fully understand the condition but I think it is probably similar to one I had a few years ago. The best advise I can give is to sell it on ebay. Without tubes you will probably get about $150 for it. Then buy a full kit. Or buy a kit minus the transformers. But you need to know if your transformers are good before you do that. Buying parts will cost you more than a full kit.

( Could be double post )

Let me see...

From tube4hifi..

I buy a VTA basic board, - $89
upgraded caps option, - $10
3 new board tubes, - $39
probably needs a cap can - $40

Do most people upgrade to those Russian caps?
My concern, other than money, is, are they available
soon, and reliably so recently.

This amp had no bias pots ???? and I know the VTA board
has 4 separate, so maybe it would be good to put
those pentode/triode switches in the holes ?

Tubes, big honkin output TUBES !!!!!!!!!!!!

This amp came with 2, I assume to be normal tubes with
lettering ( 6ca7 el34 ) and greenish PhilipsECG kj
made in USA. One other tube says ( 6ca7 el34 )PhilipsECG j
made in USA but the lettering is grey.
These three all look the same to my eye.

Now we come to the odd one out ( I orignally thought they were
all the same ) that is fatter, taller, and the bottom round
support has small star pokey dingies like the top support plate.
I just noticed this one also has one ( I give you permission to laugh
just this once ) little round antenna sticking straight up instead
of slanting inward like the other one, and gives a vibration when I gently tap it.

I'd like to use these tubes to get the amp running and then later
buy those $110 tubes on tube4hifi.

Okay, I'll let you rest

Thanks for reading and hopefully responding...

thanks so much

Thanks for the candid opinion, Sailor.

Firstly, I've read about ST70 years ago, but have forgotten much.
Just how can I verify the condition of the audio transformers,
hopefully close here in Dallas, with minimal cost ?

Can I verify the power transformer using a DMM and how
safely ?

I'll research on the net for this, but just asking for a quick
reply to get me started.

Unfortunately, I've already started complete stripping and have
put everything but the transformers in a little box.

I used to see tube testers a couple of years ago in drug stores,
errrrr,, more than a couple years ago, huh ?
How to test the tubes here in Dallas ?
Anybody know of some kind soul who can do this for minimal cost ?

Sailor, what kit would cost less than rebuilding this amp?
All the ones I have recently seen ( as in tube4hifi ) are beyond
my reach or do not make economic sense ( at least in my mind )
in comparison to rebuilding. I know the transformers would have to test
good for that comparison.

Thanks again Sailor..

Looked at Ebay and found audio transformers going
for $225 a pair.
Not besmirching any individual at all ( since I don't know
about testing audio transformers ) but some say these
come from a working amp. To my mind a person would have to
send some signal and hook up a scope to see the true
characteristics of such a transformer ?

Newbie ramblings, if you want just ignore........

I'll research a little more, but if I could verify
my transformers, that's some savings right there.

Thanks

Thank you muchly for your succinct and pertinent
information.

This is why I'm very seriously considering using
your VTA upgrade parts for my rebuild.

You go the extra mile for us DUIyers,,,,, DIYers, yeah that's it.

I'm going to put this power transformer on a
wood base, connect the fuse holder, clamp down all
the wires with 1 inch spacing under a small strip of
wood and not touch anything except with my Wavetech DMM.

Does that sound safe ???

Thanks