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 Post subject: need test for 6526
PostPosted: Sun Nov 17, 2024 4:46 am 
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Joined: Sat Nov 16, 2024 9:04 pm
Posts: 1
Hello!

Who can share a list of resistance values ​​between different pins of 6526? Has anyone thought of measuring interpin voltage drops with a tester in diode continuity mode?

I have doubts that my chip is working properly. But I would like to make sure that this is NOT the fault of the power supply.


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 Post subject: Re: need test for 6526
PostPosted: Fri Nov 22, 2024 11:25 am 
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Joined: Fri Jan 25, 2019 2:29 pm
Posts: 193
Location: Madrid, Spain
vivat wrote:
Hello!

Who can share a list of resistance values ​​between different pins of 6526? Has anyone thought of measuring interpin voltage drops with a tester in diode continuity mode?

I have doubts that my chip is working properly. But I would like to make sure that this is NOT the fault of the power supply.


Hi!

I don't think measuring resistance and/or voltage drops between pins is going to give you a clear diagnostic. There are 1000+ transistors inside a 6526 and these values are going to vary wildly between different production technologies and even batches.

You should probably aim for a software test that tries every possible use of the 6526. Are you using it as a component for your own build? Or is it inside a Commodore computer?


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 Post subject: Re: need test for 6526
PostPosted: Fri Nov 22, 2024 8:04 pm 
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Joined: Thu May 28, 2009 9:46 pm
Posts: 8514
Location: Midwestern USA
vivat wrote:
Hello!

Who can share a list of resistance values ​​between different pins of 6526? Has anyone thought of measuring interpin voltage drops with a tester in diode continuity mode?

I have doubts that my chip is working properly. But I would like to make sure that this is NOT the fault of the power supply.

What Dani said.  In fact, measuring resistances between pins could subject the device to damage, depending on the polarity of the voltage applied by the DVM being used to do the measuring.  Your best bet is to put the 6526 into a working computer and see what happens.

BTW, the 6526 is notably static-sensitive.  Many of them were damaged in C-64s and C-128s by the exposed pins on one of the joystick ports being touched and being zapped by static.

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