How do you check a TIA chip?

[yelrah39]

Hi short of pulling suspected bad chips and swapping them out with known good chips. Can a continuity test (?)be done , if so how do you do it? I'd like to be able to check all the Atari 2600 chips. Being able to just bench test the chips would be great. Thanks

[Stephen Moss]

It depends on what you are trying to test it for as to what type of test would yield the best result.

As for continuity testing, when in circuit you can test that there is a connection between a specific pin and another component but that is all a continuity test can tell you, it cannot be used to determine of a chips if good or bad per say. It could be used to check for a short across the power pins and potentially for a short between and I/O pin and a power pin when out of circuit but current can flow strangely through unpowered IC's and so without having first taken a comparison set of measurements form a known good IC the results you get could be misleading.

 

Search the forum for a link to the 2600 field service manual, that may have some tests that you could perform, but they are likely to be limited buy not having the correct equipment or the specific test program running as specific tests are often carried out with the unit in a know states as determined by the test cart output.

 

Assuming the Cart, controllers and RAM are functioning correctly... 

Direction control issues are likely to be either bad connections or the RIOT

Fire/Paddle, video or Sound issues are likely to be the TIA, or in the case of fire the buffer IC on those 2600 that have them.

 

Beyond that generalisation you have to form the correct set of test relevant to the specific issue to determine if the IC or something else is causing the issue.      

[yelrah39]

That's what I though. Thanks for the input.

[+-^CrossBow^-]

Well, I actually pull them and test with on my BackBit Chip Tester I bought over the summer. But unless you do this kind of stuff routinely, you might not have much use for the expense of it?