[sdiy] Odd question about Lexicon 224xl

[Tim Curtis]

I should probably mention one other factor -

Unfortunately, I don't have an extender card for the Lexicon either.  
(Think how easy this would all be with a service manual and an extender 
card....)

Of course, those aren't available from Lexicon either.

I'm thinking that if I can't nail ths soon I might have to make an 
extender card - might not be a bad thing to have anyway.

So, is it normal for the 74s163 to drop the resistance between +V and G 
by about 10 ohms?

Also, I'm a big believer in replacing just about any tantalum of this 
vintage with an electrolytic.  I know this is a controversial topic, but 
if we're not talking about the audio path, what does everyone think?

Tim


Ken Stone wrote:

>Replacing the Tantulums is always a step in the right direction. Use low ESR
>electros if you can. Old tants are a common source of failure.
>
>A quick "test" for misbehaving chips is to feel the temperature they are
>running at. If one is unusually hot, it may be in a state of partial or
>complete failure.
>
>If any capacitor is part of a reset circuit, replace it.
>
>Ken
>
>  
>
>>The board has eight 4.7uF and two 22uF tantalums spread around between 
>>+5V and ground.  I put a meter on it while it was out of the mainframe 
>>and found that between +V and Ground I'm only reading about 170 ohms of 
>>resistance.  This seems awfully low to me.  Perhaps a leaky tantalum 
>>that's not completely shorted out?  Or is this possibly correct?
>>    
>>
>_______________________________________________________________________
>Ken Stone   sasami at hotkey.net.au or sasami at cgs.synth.net
>Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
>Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>
>
>
>
>  
>
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