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New guy with sick pet

W

webman

New Member
Joined
Oct 28, 2008
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I was recently given a pet 8032 that has some issues, namely does not beep on power on. What I am wondering is I am new to testing beyond power and from reading will need a logic probe to look further. There is a 16 in one probe on eBay that looks good as it will test logic and frequency, but not sure if this is the route to go. Any feedback is appreciated.

http://www.ebay.ca/itm/Super-Probe-...unter-Volt-Signal-Generator-PWM-/320900889215
 
Hey there, welcome to the PET repair forums..

First guess, without other information, is one or more bad RAM and/or ROM chips. If you have spare RAM sometimes you can temporarily 'heal' bad RAM by piggybacking a good chip on a bad one. I had an 8032 with a bad kernal ROM, which kept the beeps from happening. Other possibilities - faulty reset or clock. If you have access to a scope it will help quite a bit.
 
That's what I think is wrong from Reading other posts, but I do not have acces to a scope so was hoping to use a logic probe to try and find the defect.
 
Nothing. No beep or anything on the screen. Voltage looks ok on the mb and all chips that could be reseated were. It is a universale board so not much to reseat.
 
If you can get a multimeter, then you can check the clock out from the 6502. That will tell you if the CPU has been reset and is running at least. I believe you'll find that on pin 3 (phi 1) and pin 39 (phi 2) on the 6502. With a voltmeter you should see something close to 2.5v if the clock is running, since it will basically average the voltage over time. If it's up at 5v or down at 0, then your 6502 is not running.
May be more money than you want to spend on this, but the Saleae logic is a nice USB logic analyzer, very useful for debugging such things..
With the 8032, the CRTC init routines need to run in order for you to see anything on the screen, unfortunately. So before you get at least that part running, you won't see anything on the screen. But if you can at least get key portions of RAM and the kernal ROM working, then you'll hear the start beep.
 
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