Yet Another get*set*go

[TomMcNally]

I built this one this evening ... a couple hours on the metalwork,
an hour on the circuit board, another couple hours wiring it up,
10 minutes figuring out why it didn't work
Can any eagle eyed guys figure it out ? haha

I used Edcor output transformers, Triode PA-774 power
transformer, Triode shielded choke, Auricap coupling caps,
everything else is standard Mouser BOM.
Sovtek 6B4G's and 6SL7, NOS RCA 6AX5.

[TerrySmith]

Nice layout Tom!

What's the part# on those Edcors and how do they sound compared to the James?

[TomMcNally]

Thanks Terry -

They are the Edcor XSE15-8-5K, I've used a lot of them in
Darlings and various other amps. They are much better than
the Hammonds, and I'd say almost as good as the James -
at $ 110 a pair cheaper. I need some more listening time
on this new one - I finished it late last night.

... tom

[Ty_Bower]

Wow Tom, you really bang them out, don't you? Do you even need to follow the assembly manual, or do you just stuff the parts by memory?

I like that layout too. I might have to try that and see if it works with the parts I've got.

I've stared at the photo, but I can't spot the mistake. Is it a wiring issue or something on the board?

[EWBrown]

Perhaps on the AC primary side ?

The small photos and my cheapo crummy LCD monitor turn eagle eyes into bat's eyes....


I need a little favor, please, would you measure the DCR of these OPT's primary for me? I am trying to run a sim on SE CAD. I can SWAG the primary inductance, which I guess is arounfd 10-15H.

I've noticed on the Edcor support forumk, that many of the questions about these trennies DCR and inductance seem to get somewhat "evasive" replies...

Sometime real soon, I;ll order a pair of GSXE and also XSE 5K: 8 ohmers for general experimentation.

/ed B

[TomMcNally]

I need a little favor, please, would you measure the DCR of these OPT's primary for me? I am trying to run a sim on SE CAD. I can SWAG the primary inductance, which I guess is around 10-15H.

I measured the primary and see:

128 ohms end to end
57 ohms B+ to screen tap
71 ohms screen tap to plate end

... tom

[EWBrown]

Thanks, Tom... I appreaciate your efforts.

/ed

[TomMcNally]

No prob Ed -
I have lots of test equipment ... if you need anything,
or know a way to test the inductance, I'd be happy to
give it a shot. I have a Heathkit bridge, one of the later
models in a blue plastic box - but I've never tried it ...
maybe I should fire it up and check it out.

[nyazzip]

i see a missing resistor at the bottom of the board, right side, just under the big filter cap....

[Ty_Bower]

It's not missing, it's installed on the other side of the board.

[battradio]

Whats above the power cord looks like one wires doen't make it all the way over .

Mark

[TomMcNally]

Hint: think green

[battradio]

You didn't leave the fillament windings off the output tube did you i can't see any twisted wires .


Mark

[TomMcNally]

Close ... but no cigar.

The g*s*g filaments are DC ... so twisting isn't critical,
but the filament leads are twisted - the violet/white pair at the bottom.

[SDS-PAGE]

Ok, shouldn't you have brown paired up with white and green paired up with the other white? I see two whites paired up which would have given you no continuity across the filament windings.

Min

P.S. If I got this right, I am building too many amps.