so as noted couple of posts ago the "thing" had not rectified ±5VAC transformer plugged to 9V.DC.IN (initially not my speakers - donno if "they" ever sold such sets F;i) -- after it sever'ly ended up it mal-design it became what seems to be a working instance at least it didn't exploded or anything in 1h test
teh TF (no'the ®) appears to be the "hottest word" here (over 42°C - i wonder if it's a problem , should be cooled , swapped to more powerful 1) . . . otherwise it's quite HUM3 witch the ~AC1 definitely wasn't
... quite a lot of stuff to pack onto PCB-s & i donno about the thermal nor RFI design techniques - thus must include automated timeout- & therma-l switch-off-s - - - the relay - which me think is most reliable for such - uses apx. the power of the supply -- alternate would be motorized switch - that 'd need autonomous power or there should be more tests to verify the design's secure enough to be left ON for ages
? ? ? ? i don't remember the ±5VAC had a fuse or anything (! usually the primary is protected with thermal fuse - usually ? not with double ...) - must read some stuff about from www ...
about the Z-up ::
Vtg.-2-bler ► voluntary filter ► supposedly 150mA current limiter (not fully tested) ► 16V voltage limiter ► 2-ry filter ► 9V regulator
-- note: some stuff may be prev. cfg.-s leftover and are not strictly requred by this v.
-- this v. may be not consistent at all possible modes e.g µ-blackouts , ~AC transients ... specific sound input to SBS20 . . . otherwise it seems to draw power LE to 50mA if the VOL is not set above apx 67%
[EoF]
