AR88 voltages
Thanks very much for the response Kevin! I refer to EMER E773. This shows
V10 as a 6SJ7 as you say and with Anode (Plate) at 40V, Screen 30V and
cathode0.1V. The cathode resistor is 11% high and therefore OK, but my volts
are A 60,and S 37.
Altogether, I have V1 with screen 32% up, and grid resistance 32% high; V6
(6SG7) with cathode volts at .87 (against .5 norm) which is 74%; all
resistances at V8 (6H6) too high; and V9 with Anode resistance 503 (33%
low).
"Kevin Dooks" wrote in message
...
Hi, which EMER are you refering to? In my 'original' RCAF manual (
E0 35BB-5GR17-2), dated 26 JAN 55, for the GR-17 (aka AR-88LF) the
first audio (V10) is a 6SJ7 which according to the manual should have
83V on the plate, 34V on G2 and 0V on the cathode. If V10 seems a bit
hot check R39 (100 ohm) from cathode to earth. The values for the
CR-91A are the same but the CR-88 is different, 1.1V for G1, 33V for
G2 and 50V for the plate. Which resistor went high, R40 (270k) or R41
(100k)? ........... Ok, just rulled my '88 out of it's case and
checked, I have 81V on the plate. 33V on the screen and 0V on the
cathode with a line voltage of 121V. Not bad for a 65 year old piece
of gear.
On Sun, 26 Jul 2009 04:28:18 +1000, "MoiInAust" wrote:
Hi all
Getting the beast working well. Have now traced many resistors that have
gone high, and apparently I did not fatally damage (see other post) C22 at
all (range 3 still works well though tuning may be a bit out. That's for a
later check). Now there some voltages I can't get right and I'm wondering
if there are any errors in the EMER fault finding tables. For example, V10
(1st AF) had an anode voltage that was much too low and of course that was
a
resistor that went high. But on replacng that I now have 60 volts on the
anode and according to the EMER chart it should be 40. I am allowing a +-
20% tolearnce but 50% is too much I feel.
Cheers
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