[Premium-Rx] RA1792 Problems. Help Please!

[David Schofield]

Hi Stuart,

The short answer to your question is YES. There are very well known 
faults on the RA1792. Basically suspect "every" tantalum capacitor in 
the unit.
The easy way to fix the unit is to replace all the tants. Unfortunately  
there are a lot of them. The other way to go about it is to check all 
your supply rails, one of them will almost definitely be low, then 
unplug one PCB at a time. When the voltage comes back replace every tant 
on the PCB you unplugged last.
You can also check each tant with a meter the faulty one will nearly 
always measure short circuit. The problem with this is that as they are 
supply decoupling capacitors, they are all in parallel so unless you 
lift one leg they will all appear short. By the time you have lifted one 
leg you may as well change the cap.

If you are in the North West UK and still having problems, feel free to 
contact me off the list and I'm sure I can help.
I have at present got 10 of these receivers, all of which I have 
successfully repaired. All bar one were capacitor faults.

The only other thing to check is, has the memory backup battery leaked 
on the CPU board. This is the first board on the left hand side top of 
the unit viewed from the front.

Cheers,
Dave.S


Stuart Lamb wrote:
> Hello Premium RX Group,
>
> About five years ago I purchased a Racal 1792 (non-BITE). It worked fine for
> a couple of years then the FAULT bar started to flash occasionally. However
> I’ve hardly used it in the last three years and when I came to fire it up
> recently I was met with the following:
>
> *	The FAULT bar on the LCD is blinking continuously. 
> *	Channels and frequencies can be entered via the keypad but the TUNE
> function of the VFO doesn’t increment frequencies or channels. 
> *	There is no audio output and the S meter shows no deflection in
> response to local strong signals. 
> *	Mode, bandwidth and AGC selection is possible. 
>
> Please can anyone give me an indication of any known faults that may account
> for this behaviour, or clues as to where to start looking?
>
> Thanks very much,
>
>
>
> Stuart
>
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