Analogue-sequencer

Hi Fred, 

In the absence of Colin, who is now drifting away in marital bliss, 
I'll  see if I can help. 

First. Get yourself a multimeter that works :->) 

> my p3 is *almost* alive... there seems to be some issue with the  
fuse. 
> the only way i can bring it to life is to short the fuse (currently 

> being done via my multimeter). my power supply is 9VDC at  800mA... 


The psu is plenty powerful enough for the P3. Sounds like there is a  
fault with your fuse. 

> that's not enough power to trip the 1/2 amp fuse. however,  
measured at 
> the jacks, the power seems to be SIX AMPS!!! that should be  plenty 
to 
> trip the fuse...  

But this sounds like you are just shorting the psu with the meter. 
The  current will increase but the voltage will collapse to nothing, 
and  eventually your power supply will burn out. It's not a good idea 
to  short the input jack. 

but the strange thing is that, across the fuse, the 
> amperage looks exactly right... 800mA. the P3 also comes to life  
when 
> i've got the positive lead connected to the right side of the fuse 
and 
> the negative lead to the right side of D6.  

The fact that you're reading that much current through the meter  
indicates that the fuse is not working. 

(the reason i'm doing 
> amperage measurements is because my multimeter sucks and  won't 
read 
> voltage when the current is greater than 450mA.) 

I don't really understand this statement, but I reckon it's time to  
beg/borrow or steal a working meter. 

You could just try removing the fuse and inserting a wire link in 
it's  place. I know you say that you have tried shorting the fuse, 
but  maybe there is a broken track or solder pad around the fuse. You 
 don't *really* need a fuse at all. It'd just there as an extra 
safety  precaution. You need to check the continuity with a working 
meter.  Check that one end of the fuse pad actually gets to D6 anode, 
and  the other end actually gets to the input socket. 

Also check the voltage on the output of the regulator. It should be  
+5V wrt ground. 

Hope this helps 

Good luck 

Andy 

---

Andy Wilson
http://www.techman.synth.net
andy@techman.synth.net