[R-390] Still deaf below 8 Mc

[Bob Camp]

Hi

Item number 4 on your list sounds like your problem. I don't have a  
manual in front of me, but that section sounds like it's checking the  
oscillator output. If so your oscillator is dead.

Bob


On Oct 27, 2007, at 3:26 PM, Jim Green 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)
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