JP: Save me again, help.

[JamesHealey]

Question for john philips:

Based on the schematic that is here:-
http://www.drtube.com/schematics/marshall/1987prem.gif

Yet in my amp i read the following values:
r7 = 33k
r8 = 33k
r13 = 230k
r14 = 230k

which are different to the schematic.. any ideas why? value drift? one strange thing i've noticed is the colour coding on the R7 &R8 is identical to that of R3 & R4. Which confuses me, doesnt look like they've been replaced.

[AdmiralB]

You can't measure those resistors without lifting some part of the circuit. You're measuring them in parallel with each other, which makes their values appear to be halved.

[JamesHealey]

wicked no problemo, thats all i needed to know.. just kinda stumbling in the dark here.. well in that case every value in the amp is original.

I can't find any reason why this amp isn't stock, although i'm not 100% the pre-amp tubes have been wired up stock.. any ideas?