Hi,
Yeah, it looks like you're correct there were brown epoxy impregnated
transformers in the 561B series. The manual I have (from Shannon Hill's
collection) lists 3 different revisions of the transformer in the 561B.
RPR & Transformer Diagrams show 4 different versions of the 120-0466-xx
transformer.
I did a little research against the transformer diagrams and what they were
coated/impregnated with.
120-0466-00 ( to B099999 ) Epoxy 252-0089-00 (Un-curiously this is the
same epoxy used on the 547 transformer 120-308.)
120-0466-01 ( to B159999 ) Silicone Varnish 252-0169-00, Silicone
Resin 252-0198-00
120-0466-02 ( and up ) Silicone Resin 252-0213-00 & 252-0214-00
120-0466-03 ( ??? ) Epoxy 255-0479-00
The same 120-0466-00 was used in the 564B, and the 568, per the RPR.
I found a couple of pictures of the -00 version in this EEVBlog thread:
Looks brown to me... As Chuck said, mine, serial # B19xxx, is a -02, and
Black. I can't speak further to -01, and -03, but definitely there were
quite a pile of 561B/564B/568's made with now known bad epoxy.
The 567 was mentioned at one point in the transformer discussions recently,
per the transformer diagrams, the 567 transformer ( 120-292 ) was
impregnated with wax 256-508 (neither epoxy, nor silicone). My RM567 is
not in a position for me to look and confirm.
That's my contribution to the thread.... Cheers!
David
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On Fri, Mar 5, 2021 at 5:04 PM Chuck Harris <cfharris@...> wrote:
Hi David,
Thank you for the picture.
The 561B tranny shown is in black epoxy, which isn't usually
a problem, and has turret posts, which adds to my expense.
I will probably keep the tranny open frame, and use an FR4
terminal board to handle either eyelets, or turrets... likely
eyelets.
-Chuck Harris
David Holland wrote:
I directly emailed Chuck a picture of the 561B HV Transformer from my
B19xxx. (I hope he didn't mind.)
But I'll also freely admit it is a fairly late SN'd 561B.
David
On Fri, Mar 5, 2021 at 2:50 PM Chuck Harris <cfharris@...> wrote:
