Looking for a M8330 or a couple of SN74194's

[Christian Corti]

On Mon, 31 Mar 2008, Tony Duell wrote:
> I don;t know what test gear you have, but I find a simple logic probe to
> be more use than a 'scope for this sort of problem. The former can easily

Yes, logic probes are very handy. They are small and easy to use, and I 
have found faulty devices most of the times just with the logic probe. The 
seven-segment display show transitions and illegal voltage levels (or no 
voltage at all), very useful e.g. for dead totem pole outputs (in this 
case the voltage of the signal will be determined by the input stage(s) 
and lies around 1-2V).

>> I also return all systems to working order. Apart from a couple of
>> VT420's with ticking SMPSU's everything I have restored runs. (Three
>
> Any reason you';ve not fixed those? Ticking SMPSUs are often quite simple
> to fix, maybe just dried-up capacitors.

I think ticking PSUs in displays are a sign of a shorted HOT and/or 
flyback (had this case several times).

Christian