All us old Commodore types used to hit Akihabara whenever we were in Tokyo.  Rumor has it that CBM-J would occasionally run down there to buy a few scoops of 7407's to keep production flowin.

Bil

-----Original Message-----
From: owner-cbm-hackers@ling.gu.se [mailto:owner-cbm-hackers@ling.gu.se] On Behalf Of Philip Lord
Sent: Wednesday, August 12, 2009 9:37 PM
To: cbm-hackers@ling.gu.se
Subject: Re: Dead PET 2001

Great!
I'm going to race into Akihabara this lunch time and get all the CR3,
C11, C12, C13, VR3, VR4, VR5, and VR6 parts.
Hopefully I'll have time this weekend to attack the board starting
with the CR3 diode.

Thanks again for your help, and I'll let you know how I go.

Cheers
Phil



On Aug 12, 2009, at 2:40 PM, William Levak wrote:

> On Wed, 12 Aug 2009, Philip Lord wrote:
>
>> 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).
>>
>> ...as 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.
>
> This is good!  This means that the transformer, the big filter
> capacitor, and CR1 and CR2 are all good.
>
> The problem is localized to CR3, C11, C12, C13, VR3, VR4, VR5, or
> VR6. One or more of those is bad.  The prime suspect is CR3.  If it
> was working, you should see 8V on pin 2.  These diodes get hot when
> operating. If it is cold, it is probably open.
>
> Now would be a good time to remove the circuit board.  Small things,
> like paper clips, sometimes get trapped under there, and short
> things out.
> The screw on the left rear of the board is a ground to the chasis.
> The others should not contact any circuits.
>
> wlevak@sdf.lonestar.org
> SDF Public Access UNIX System - http://sdf.lonestar.org
>
>      Message was sent through the cbm-hackers mailing list


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