Fender Concert PR244 amp

N

N_Cook

Guest
Distorted output, half wave. I've not dismantled to get to component
side of the board yet, nor tested the valves yet.
Output 6L6 have matching , good, DC on K,G and A, but with test sine V7
grid scoping shows a rectangular wave of the test f period and 1/3 mark
to space. Swapping splitter valve , distortion remains.
Swapping 6L6, distortion stays at V7 position. o/p matching tx primary
measures 56.3 and 51.3 ohms to standby sw, so nothing suspicious there.
I've forgotton what this is symptomatic of, is it a leaky cap on the
relevant side of the splitter valve?
 
Before dismantling, remembered to check the DC on the splitter valve. p1
anode of about 7V, gives a good target. What inside an older Fender will
give a good idea of its date?
 
Failed anode dropper, discoloured to unreadable and o/c, presumably
100K as its fellow. Have to presume the DC blocking cap has failed to
cause that and replace that too, along with its fellow, and test the
valves just in case internal problem shows itself, but unlikely.
Dating JRC4560D has a code 3024D = 1993?, after year 2000 I thought 30**
on JRC meant 2003**
Standby sw has 9345
7W w/w has number 9153 on it.
General feel is 80s or 90s
So I'll settle on 1993 unless (wherever it is) that site for translating
Fender Tx numbers and Ser nos to dates , I can find again.
 
July 1994 via
http://www.fender.com/support/articles/amplifier-product-dating/
and the QA label
 
Anyone know if R61 of a PR244 is 100K or 82K like other flavours of
Fender Concert ?
 
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