[R-390] Saturday's Line & Local Report

[Craig Heaton]

To the faithful followers of the R-390 e-mail reflector:

The short version, gonna purchase some caps? 

Long version: Several hours were spent tracing all the wiring, connections,
resistors that go to V601A/B. Nothing there except a small wire harness is
pinched between TB601 and a stud from L603.  No easy way to twist the
harness and get a good look. Applied two layers of tape just in case. It was
time to warm up the O'scope. Lucky the plugs going to the AF section are
long enough to set it on its side and turn on the juice. 

With no antenna connected the voltage at the junction of C603B & R606 stayed
around 0.1VAC; Local gain adjusted from 0 to 10. Now, with an antenna
connected there was about 1.0VAC with the Local gain set at 4. Then for
grins & giggles, KKNX a local AM BC station was tuned in at 840KC. The
Beavers basketball team from OSU was playing and I could watch the wave form
on the O'scope bounce.  

The Amelco (boombox) has been here around five years and I've been thinking
maybe the magic smoke would escape. Then the problem might be easier to
find. Might add, since the AF module from the Motorola has been placed in
the boombox with no change. I'd say the Amelco is picky about its diet of
capacitors. At present both R-390/A's have Xicon 33uF 350V caps in them. The
Motorola is happy with its diet. 

Yesterday evening C603 was examined every which way. It just isn't good
enough. Maybe?

Any recommendations of other caps???? Both sets have been ordered from
Mouser, part # 140-XRL350V33. If you don't mind, I'll rebuild C603. 

Best Regards,
Craig