[R-390] Silver Mica capacitor failures

[Larry H]

I'm hoping to put together a clearer picture of the SM cap failure rate and
need your help.  The R-390xs are packed full of SM caps, most of them in
the RF deck and conversion oscillators (in  R-390As, there are 99 there and
22 in the IF deck for a total of 121).

What I thought would be interesting to know is what are the DC voltages
applied to the SM caps in As.  So, here it is: high: 23, low: 27, and zero:
71.  High voltage is between 150 and 200 volts, low voltage is AGC and bias
around +10 to -20 VDC.

Even if you haven't worked on one for a while, your input will be helpful -
just let me know when the last time was.

No research is necessary, just what you can recall.  I'd like to know the
year, # of R-390As worked on, # of SM caps you HAD to replace in each DC
voltage category, and the symptoms.  If you'd like to group years together,
that is fine, but please keep it to a maximum of 5 years.  If you didn't
change any SM caps, say 'none'.

Example:
2001, 1 A, none
2005, 2 As, hi: 1, lo: 0, 0: 2, leaking: 1, changed value: 2
2011-2015, 9 As, hi: 2, lo: 4, 0: 9, changed Q: 3, leaking: 4, changed
value: 7, shorted: 1
Last repair: 2015.

And one more thing, please - include how many As you have and how many are
in use any amount of time.

If you send me an email directly (larry41gm 'at' gmail 'dot' com), the info
inside will not be divulged - just tabulated for a total.  The totals I
will publish.

Thanks a lot for taking the time to do this.

I hope you had a good July 4th, Independence Day.

Regards, Larry