st70 start up problems (smoking)

[kheper]

pin3 of V3 = -12.30V
pin8 of V3 = -12.30V

pin3 of V2 = --12.00V
pin8 of V2 = -12.00V

The voltages have been going down
slightly as the amp heats up.

My new year's resolution was to build
3 amps in 3 months. Next, I'll be
building an ST70 clone with
custom wound transformers.

You seem to advocate the use of
ceramic sockets in your docs. Why?
I have not found a good source for
these.They seem too cheap to be
any good.

[mesherm]

I use and recommend the Micanol sockets instead of the ceramic sockets. Also if you get the Cinch style, they have 4 ground lugs on the outside ring that come in handy when wiring cathode resistors and the like. You need the 1 1/8" diameter ones to fit a Dynaco type prepunched chassis.

[kheper]

Yes. I purchased the cinch, Micanol sockets
from dynakitparts.com.

Pics of the amp:

http://nekhbet.com/new_amp

[Shannon Parks]

pin3 of V3 = -12.30V
pin8 of V3 = -12.30V

pin3 of V2 = --12.00V
pin8 of V2 = -12.00V

The voltages have been going down
slightly as the amp heats up.

All looks good and normal.

My new year's resolution was to build
3 amps in 3 months. Next, I'll be
building an ST70 clone with
custom wound transformers.

I think only Ed Brown and Tom McNally are that prolific! I shoot for one project a year.

You seem to advocate the use of
ceramic sockets in your docs. Why?
I have not found a good source for
these.They seem too cheap to be
any good.

I love the octal Micanol chassis sockets and haven't used one of the ceramic ones yet. I do like the one piece ceramic PCB style 9-pins.

[EWBrown]

The Russian made 26mm ceramic octal sockets are too large for a 1" diameter hole, and too small for a 1 1/8 inch hole, otherwise they are very nicely made... Bottlehead uses a rather interesting technique for these sockets, the socket hole is the standard 1 1/8 diameter, then the socket is mounted, using a fat rubber o-ring as an "isolator".
I cheated on my last build, and used regular "micanol" NOS US made octals, and kept the Russkis for some YTBD future project...

The last couple evenings have been "marathon" plinker testing sessions... Yellow_Light_Colorz_PDT_09

/ed B in NH .