[R-390] Still deaf below 8 Mc

[Walter Wilson]

I always replace C327, especially if signals below 8MC are a problem:
See http://r-390a.us/R-390A%20Restoration%20Checklist%20v2.htm for a
more detailed checklist.

Chuck Rippel's site also has this listed as a common problem:
http://r390a.com/Commonfail.htm#I%20was%20finishing

Walter - KK4DF



On 10/27/07, Jim Green <jagreen3 at sbcglobal.net> wrote:
>  I'm still plugging away with my R-390/URR (Not R-309A/URR). The main
> struggle is the deafness below 8 Mc. I am following the Third Echelon
> troubleshooting procedure in TM11-5821-357-35. I've made it to Signal
> Substitution Part e IF sub-chassis tests Step 2 where the procedure
> is to apply a modulated 2Mc signal to E-210 with the receiver in
> standby mode. I am supposed to hear a signal in the headphones. I
> hear nothing. If nothing is heard the procedure is to:
>
> 1) check V205 (checks good),
> 2) check V701 (checks good)
> 3) check the V701 circuit components by voltage and resistance
> measurements. All voltages seem within range except Pin 1 at -0.46
> VDC (should be -1 VDC to - 2.3 VDC). All resistances are OK except Pin
> 1 at 178K (should be 150K) and Pin 5 at 19.8K (should be 8.5K,
> however the voltage at pin 5 is right on the money at 178 VDC).
>
> Does anyone see any major issues with these readings? Note I'm using
> a Fluke model 77 to take the measurements.
>
> 4) Check the vfo operation by measuring the DC voltage at E210
> (measured 0.000 VDC). The manual goes on to say: The voltage should
> be between -3VDC and -11VDC. If the voltage outside these limits
> check J223 and P723. J223 looks OK, but the cable P723 is connected
> to has a kludjy splice in it. When I measure the voltage from the
> center pin of P723 to ground I get 0.000 VDC. Perhaps this is OK
> since it's likely an AC signal (I measured  0.01VAC). When I measure
> resistance I get a dead short to ground. Are these measurements normal?
>
> Jim (KG9MM)
> _____________________________________________________________
> R-390 mailing list
> Home:  http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:R-390 at mailman.qth.net
> Unsubscribe:  http://mailman.qth.net/mailman/options/r-390
>