N
N Cook
- Jan 1, 1970
- 0
Valve Reverb, 1U case prob. 1994 , no output.
One obvious problem. Seems to be C-R-C-R-C HT ps with
the first R overheated to partially white body and O/C.
Scraped back and remnants measure 4K and 12 K. Comparing
with other MO 1/2 W Rs, band positions on bodies, the band heated to black
was
probably gold and the first 2 Brown then blue , third is gone totally, .
so maybe 16K .
Supplying HT to 3 valves 12AT7 and 12AX7 so common enough.
Anyone know the correct value of this R, The second one in
the ps drop down chain is 22K and looks fine?
I've not dug out my Avo valve tester yet, as not really a valve-man, so any
ideas for this fault?
The wax around the 3 HV Cs is unmelted but as the 22K is fine at the moment
I suspect a powered-up-only short in middle 47uF,500V electro.
Apparently no separate secondary for heater voltage - seems to use the
same LV winding used for the transitor power rails - is that so ?
electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse
One obvious problem. Seems to be C-R-C-R-C HT ps with
the first R overheated to partially white body and O/C.
Scraped back and remnants measure 4K and 12 K. Comparing
with other MO 1/2 W Rs, band positions on bodies, the band heated to black
was
probably gold and the first 2 Brown then blue , third is gone totally, .
so maybe 16K .
Supplying HT to 3 valves 12AT7 and 12AX7 so common enough.
Anyone know the correct value of this R, The second one in
the ps drop down chain is 22K and looks fine?
I've not dug out my Avo valve tester yet, as not really a valve-man, so any
ideas for this fault?
The wax around the 3 HV Cs is unmelted but as the 22K is fine at the moment
I suspect a powered-up-only short in middle 47uF,500V electro.
Apparently no separate secondary for heater voltage - seems to use the
same LV winding used for the transitor power rails - is that so ?
electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse