Re: Pet64 DOA

From: Philip Lord <>
Date: Thu, 09 Dec 2010 12:15:05 +0900
Message-id: <>
Yes, thats a good idea, I'll have to see if I can't find a C64 PSU  
here in Tokyo(!), even if it's just for testing as I'd really like to  
get the original hardware working.

I'll take some direct readings from the transformer (before it goes  
into the little PCB) and see what I get. Maybe then I can figure out  
if the problem is in the transformer itself, or one (or more) of the  
components on the small PCB.

Thanks again.


On Dec 9, 2010, at 12:04 PM, Pete Rittwage wrote:

> Hi Philip,
> The voltages might be a little high when not under load, but it  
> looks like your transformer might be bad, hence the buzzing/ 
> humming.  :)

> You should be able to retrofit any old C64 power supply into the  
> unit to get it working, although you could also probably easily  
> repair the existing one.


> Pete
> On 12/8/2010 9:53 PM, Philip Lord wrote:
>> Oh...Hi Pete, you just read my mind.
>> I was just looking at some schematics and it seems that the C64  
>> needs 5vdc and I decided to recheck using AC setting on  
>> my multimeter.
>> White: - 5.8 vac
>> (KEY)
>> White - 0.5 vac
>> Black (I'm guessing this is ground)
>> Red - 4.98 vdc
>> I was also wondering if this type of power supply needed some draw  
>> to measure the voltages correctly (I know the Apple II does, but  
>> this transformer arrangement looks much simpler than the II's, so  
>> maybe not.
>> P
>> On Dec 9, 2010, at 11:45 AM, Pete Rittwage wrote:
>>> On 12/8/2010 9:15 PM, Philip Lord wrote:
>>>> I just got myself a PET64 from Yahoo Auction Japan. Quite a rare  
>>>> machine I hear, so I'm not sure how one ended up in Japan. I got  
>>>> if for a decent price as I don't think the Japanese knew exactly  
>>>> what it was.
>>>> Anyway, It arrived the other day, after a quick internal  
>>>> inspection, I powered it on. I can hear the transformer  
>>>> buzzing(!), but no action at all on the screen at all, and it  
>>>> doesn't seem like the chips are getting warm at all Maybe need to  
>>>> leave it on a little longer to make sure, but I didn't want to do  
>>>> that incase bad voltages kill anything more).
>>>> There are 4 wires leading from the small PCB which is attached to  
>>>> the transformer to the C64 motherboard, and I have measured the  
>>>> voltage from the black wire (GND?) to the 3 others. Here are the  
>>>> reading i get:
>>>> White: - 100mv
>>>> (KEY)
>>>> White - 100mv
>>>> Black (I'm guessing this is ground)
>>>> Red - 4.98v
>>>> That's as far as I have gotten. Next I will remove the  
>>>> motherboard and see where exactly these 4 wires go.
>>>> Anyway, I was just wondering if anyone had any insights or  
>>>> thoughts.
>>>> Cheers
>>>> Phil
>>>>     Message was sent through the cbm-hackers mailing list
>>> I believe your white wires should be 9VAC, so I would remeasure in  
>>> case you used a meter on DC setting.
>>> -
>>> Pete Rittwage
>>> C64 Preservation Project

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Received on 2010-12-09 04:00:15

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