Thanks Guys!
Now the fun really begins.
I've taken voltage readings at most of the points specified on the sams schematics. They differ from amp to amp and I don't know how to interpret them.
Is some of it the variations in tubes?
Is some of it the changes in values in the MOD (see below)?
Sams Schematic
http://akdatabase.com/AKview/albums/...0Schematic.pdf
The modifications;
Quote:
GordonW,
I decided to go with your recommendations;
C1a & b - (1)47uf / 450v
C2a - 100uf / 450v
C2b - 47uf / 450v
C4 - 100uf / 100v
R12 - 5.1K / 1 watt
So with 30 min + at idle (source & speakers connected / no load), here are the numbers...I went thru them twice, just as a double check and they seemed to be holding within a few volts.
Tube------Pin-----spec'ed--------Amp A-------Amp B------
V1............1...........65V.................65V. ............71.5V
EF86.........3............1.5V..............1.34V. ..........1.22V
...............6............60V...............51.0 V............66V
V2............4............60V...............50.1V ............66V
6SN7........5............320V.............325.8V.. .........313V
...............6............75V...............64V. ..............76V
...............1.............60V..............59.1 V............66V
...............2............320V.............341V. ............300V
...............3............75V...............64V. ..............76.2V
V3...........3............425V..............407V.. ..........394V
6L6GB......4.............430V.............410V.... ........398V
..............8..............35V..............35.4 V............35.4V
V4...........3............425V..............401V.. ..........394V
6L6GB......4.............430V.............407V.... ........398V
..............8..............35V..............35.5 V...........35.3V
Tube descriptions...
V1 / EF86 / amp A / International Servicemaster - Germany
.................amp B / Eico - Mullard - England
V2 / 6SN7GTB / amp A / Eico - 6SN7GBT- USA
.................. / amp B / Eico - 6SN7GBT- USA
V3 / 6L6GB / amp A / Eico - 6L6GB - USA
............... / amp B / Executone - 6L6GC - ?
V4 / 6L6GB / amp A / Westinghouse - 6L6GC - Germany
................./ amp B / Westinghouse - 6L6GC - Germany
V5 / 5U4GB / amp A / General Electric - 5U4GB - USA
................../ amp B / Westinghouse - 5U4GB - USA
Like I said...a real mixed bag.
All the tubes tested as "good" on my Superior Instruments TD-55 emissions tester, with the exception of both 5U4GB's which tested as "replace". They had about the same measurements on both tubes.
(john...just saw your post...will look into it)
That's the low-down.
Any other places I need to get measurements from?
So, where do I start to get these numbers moving in the right direction?
Whew...!
thanks
martin