Re: Dead PET 2001

Re: Dead PET 2001

From: Philip Lord <>
Date: Tue, 11 Aug 2009 23:38:53 +0900
Message-id: <>
I was just about to say that Pin2 is connected to one of the red leads  
that goes to the capacitor, therefore with the red leads disconnected  
there would be 0V at pin2, but instead I decided to test it anyway...I  
got 0.5VDC!!!!  Then I realized what is happening:

When I disconnect the two red leads from the capacitor, but still have  
the two leads connected together the voltage reads 0.5VDC at pin4 and  
pin2. When the red leads are disconnected from the capacitor, and also  
disconnected from each other I get just over 8VDC at pin4, and 0VDC at  
pin2 (as expected). for a glow from the monitor filliment, I had to turn off all the  
lights to see it, but yes indeed, there is a glow.


On Aug 11, 2009, at 10:48 PM, William Levak wrote:

> On Mon, 10 Aug 2009, Philip Lord wrote:
>> Thanks William,
>> I did as you described.
>> I removed the red wires from the capacitor and re-measured the  
>> voltages on either side of the two diodes.
>> As before I get just over 8VAC on the anode side, but now I get   
>> just over 8VDC on the cathode side.
> That's good!  I assume you mean the side that is pin 4 on J8. What  
> about pin 2?
>> I also tested the large capacitor using the ohm meter on my digital  
>> multimeter. It starts at Zero ohms and slowly rises.
> That's also good.
> By the way, you should not run the computer for any length of time  
> with the big capacitor disconnected.  That provides most of the  
> filtering on the power supply.  However, since you have no power  
> output, it is safe, for now.
> Also, I don't thik you mentioned whether the filiment on the CRT  
> glows.
> SDF Public Access UNIX System -
>      Message was sent through the cbm-hackers mailing list

       Message was sent through the cbm-hackers mailing list
Received on 2009-08-11 16:55:04

Archive generated by hypermail 2.2.0.