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PET 2001-8 Not Booting

StickyRice

Member
Joined
Dec 4, 2021
Messages
17
Location
London , UK
So if you have H7 working (aka F800 to FFFF) then theoretically you could get the tester I sent you via message working too. I actually like VOSSI a lot, it's the only tester I had to hand when I started out, PETTESTER is a bit more useful though... e.g. you can test the keyboard VIA as well...

anyway... Either the ROM you are putting in H3 is bad or it is selected at the wrong time... either BA11 is duff or... you have a bad socket or bad trace to H3... a lot of these chip selects are active LOW which is quite unhelpful sometimes as unconnected might result in the wrong device being active.

Send some screenshots as you progress to make the thread more fun!

The tester in message doesn't contain an image just a broken link , could you try again please?
 

Nivag Swerdna

Experienced Member
Joined
Jul 17, 2020
Messages
355
Location
London, UK
What a nice thing to find in a skip! Looks like you are making good progress!

Chuck maintains a list of serial numbers; it would be good to add this one into his database.
 
Last edited:

StickyRice

Member
Joined
Dec 4, 2021
Messages
17
Location
London , UK
What a nice thing to find in a skip! Looks like you are making good progress!

Chuck maintains a list of serial numbers; it would be good to add this one into his database.

Got the image now cheers!

My serial number is 1006033

Yes making progress but now have vertical collapse on screen. Just looked at vertical signal pin 3 J7 and I have 60Hz pulses so it may be the video PCB at fault !?

Thanks Nivag
 

Nivag Swerdna

Experienced Member
Joined
Jul 17, 2020
Messages
355
Location
London, UK
I have never had to touch my video monitor so other people are better to opine there.

The schematic is at http://www.zimmers.net/anonftp/pub/c...01/video-1.gif

If you have a scope then you can be systematic, or if you want to shot-gun replace then C9 the coupling capacitor is an obvious candidate... and then C12... but it could be anything in that chain.

Divide and conquer should work... base of Q6... base of Q8... base of Q9 and Q10...

PS
Check your V signal has the correct amplitude as well as frequency before going down the video rabbit hole.
 

StickyRice

Member
Joined
Dec 4, 2021
Messages
17
Location
London , UK
I have never had to touch my video monitor so other people are better to opine there.

The schematic is at http://www.zimmers.net/anonftp/pub/c...01/video-1.gif

If you have a scope then you can be systematic, or if you want to shot-gun replace then C9 the coupling capacitor is an obvious candidate... and then C12... but it could be anything in that chain.

Divide and conquer should work... base of Q6... base of Q8... base of Q9 and Q10...

PS
Check your V signal has the correct amplitude as well as frequency before going down the video rabbit hole.

Yes will do. I have vertical collapse and some of the width on the horizontal. Will post some pictures soon when I get some free time.
 

StickyRice

Member
Joined
Dec 4, 2021
Messages
17
Location
London , UK
Q8 went OC and was causing loss of vertical deflection, replaced transistor and its working again. I going to leave it running a diagnostic soak test and heat up for several hours and see if it holds up. Thanks Nivag for your help.

BTW the keyboard is working fine but I will need to service the tape deck for sure.
 

StickyRice

Member
Joined
Dec 4, 2021
Messages
17
Location
London , UK
Here's how many failed components I have found so far...

Some of the memory replacements I ordered from China arrived faulty the MM2114N-2 chips.

The PET 2001 is booting fine now but I'm having intermittent load errors from the C2N. May need a new belt and media.




20220101_151401.jpeg
 
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