[ICOM] R70 issue

[Mort Arditti]

Steve,

The R70 is a senior citizen.

One possible issue may be electrolytic capacitors causing DC voltage
problems.  These devices 'dry up' with time which causes 
capacity loss and high leakage.  If you have the means to check the various
DC voltages and ripple.  This will require an 
oscilloscope.  The power supply has large such capacitors.  Sometime as
capacitors age, you may see some bulging and/or
some build up on the positive end wire lead near the seal.  This is a sign
of bad capacitor.
If the voltages are proper and minimal ripple (guess at <50 mV peak to
peak), it is not the capacitors.  On the other hand if the 
much higher start replacing electrolytic capacitors.

If indeed it is capacitor issue, replace them all.  Observe proper polarity
- this is very critical.

For long reliable life make that the capacitor are rated for 85 Deg. C and
low ESR.

I hope this helps.

73,

Mort,  NA6MA


-----Original Message-----
From: Icom [mailto:icom-bounces at mailman.qth.net] On Behalf Of Steve Sutfin
Sent: Thursday, October 13, 2016 9:38 PM
To: ICOM Reflector
Subject: [ICOM] R70 issue

Hello to the list,
  My Icom (aged) R70 receiver started having a problem after xxx years of
good service. When I turn it on sometimes there is no signal, just the usual
background noise. But after a bit it comes to life like normal but the
signal dies after 30 sec. to 3 minutes. The voice doesn't get distorted when
it quits but sounds more like wind blowing across the mic. If left on it
comes back and sounds like normal for a bit then goes out. All voltages I've
traced on the schematic are fine but my test gear is basic.
Any thoughts?
tnx & 73,
Steve k7dna
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