[R-390] Audio Chassis mysteries

[John Wendler]

I'm doing some resistance probing on the dismounted audio chassis.  Setting
aside the out of spec carbon comp resistors that should really be replaced
with higher power metal film units.... oh, that would only be all of
them....

I measure the following:

FL601
Wh/Blk wire terminal to center: open (instead of 230 or 250)
Wh/Red wire terminal to center: 958 Ohms (instead of 230 or 250)
Wh/Red wire terminal to White/Black wire terminal: open (instead of 480)

In Fig 52 of the tech manual, which shows a bottom view photo of the
chassis, I note an R-628 that is missing from my Moto audio module.  Does
anyone know what is up with that?

My FL-601 would appear to be broken; I'm not sure how that can occur...  It
is a low power filter for such a big can - rated at 5 mW but with very
stiff I/O impedances.  I would guess miles of very fine wire.  I may take
this apart, yet.

In other measurements:

K601: spot on at 2.8 ohms
L601: somewhat low at 104.5 vs. 137 ohms in the manual; the can says less
than 137 ohms, and it is, but is it enough low to indicate shorted turns?
L602: slightly low at 117.7 vs. 125
L603: slightly low at 92.3 vs. 110

T601
1-2: 597 vs. 580
3-4: 27.3 vs. 28
5-6: 28.5 vs. 30

T602
1-2: 577 vs. 588
3-4: 27.4 vs. 28
5-6: 29.9 vs. 30

I do not know yet whether the difference in the measured transformer
primary resistances is caused by leakage elsewhere in the circuit - I would
otherwise expect them to be closer to equal.

Does anyone know what RT510 is?  the 5 in the number would appear to
indicate IF chassis, but it appears in audio chassis on pg 93 of the manual
in the resistance measurements.

The caps are going to get replaced; I will be doing the "Mellow Cap"
improvement.

73 de John N5CQU