SignGuy81 Posted December 12, 2017 Share Posted December 12, 2017 Did you repair the traces on the board? Or were they completely cut open I couldn't tell for sure by the pic. Did you do a continuity check on each side of the traces affected? Quote Link to comment Share on other sites More sharing options...
Nmitchn47 Posted December 12, 2017 Author Share Posted December 12, 2017 Did you repair the traces on the board? Or were they completely cut open I couldn't tell for sure by the pic. Did you do a continuity check on each side of the traces affected? Yep, continuity is good on all three traces. Checked on both end origins while criss-crossing to see if they tapped into each other. Osgeld is sending me all three 3 chips for the reset circuit. Will update soon. Quote Link to comment Share on other sites More sharing options...
Nmitchn47 Posted December 17, 2017 Author Share Posted December 17, 2017 Update, the chips Osgeld sent me came in and the following was replaced with no change: - 4013 (U10) - 74LS174N (U11) - 74LS32N (U12) - 2N3906 (U8) Back to following the repair flowchart that I printed out for the system and it is saying to "check pin3 of 4013 goes low on depression of on/off switch". What does "low on depression" mean and how can I check that? Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted December 17, 2017 Share Posted December 17, 2017 Basically it just means that there should be a change in the state of the data on that chip. I could be wrong, but I think the easiest way to test this is to use a meter and see if you get continuity between the switch to that leg of the 4013 when you press the switch down, though I've not looked at the schemes to know for sure. At this point you might need to get some IC clips to attach to your meter so you can start to test for things with it powered up to look for changes like this. Quote Link to comment Share on other sites More sharing options...
tep392 Posted December 17, 2017 Share Posted December 17, 2017 Update, the chips Osgeld sent me came in and the following was replaced with no change: - 4013 (U10) - 74LS174N (U11) - 74LS32N (U12) - 2N3906 (U8) Back to following the repair flowchart that I printed out for the system and it is saying to "check pin3 of 4013 goes low on depression of on/off switch". What does "low on depression" mean and how can I check that? Use a voltmeter to check the voltage level on pin 3 goes from 5V to 0V when you press the power switch. I don't recommend doing continuity test on populated boards because it applies a voltage to do the check and you could damage an IC this way. I killed a POKEY doing continuity tests on a Ballblazer cart once. Stick to voltage level measurements when possible. Quote Link to comment Share on other sites More sharing options...
SignGuy81 Posted December 19, 2017 Share Posted December 19, 2017 When I say do a continuity test I'm talking about using a voltmeter set on ohms not a hipot tester so I think he'll be fine. I've done this for years and have never damaged a chip, nor have also using an ESR meter in circuit testing caps or any of my other test equipment I use such as my octopus circuit on my oscope(works like a huntron tracker). Quote Link to comment Share on other sites More sharing options...
Osgeld Posted December 19, 2017 Share Posted December 19, 2017 Update, the chips Osgeld sent me came in and the following was replaced with no change: - 4013 (U10) - 74LS174N (U11) - 74LS32N (U12) - 2N3906 (U8) Back to following the repair flowchart that I printed out for the system and it is saying to "check pin3 of 4013 goes low on depression of on/off switch". What does "low on depression" mean and how can I check that? well poop Quote Link to comment Share on other sites More sharing options...
Nmitchn47 Posted December 20, 2017 Author Share Posted December 20, 2017 (edited) Thanks guys for all the help so far. I think I will have to invest into a logic probe to see if the chips are functioning correctly for further diagnostics. But some good news after I'm almost giving up on this pile of plastic. Local gamestore is closing shop and I was grateful to have known the owner, so they let me look at their repair shop in the back and had a non-functioning 7800 for parts. I grabbed it alongside a few other 2600's to tinker with. It looks to be an earlier model with the expansion port but the board is the same layout. Now I can spend a day comparing both boards. I did snag a holy grail item that was sitting in a box over the side of the room. Early model Fairchild Channel F. Can't wait to look at this beast. Edited December 20, 2017 by Nmitchn47 Quote Link to comment Share on other sites More sharing options...
Nmitchn47 Posted December 26, 2017 Author Share Posted December 26, 2017 Spent a few hours on Christmas Eve comparing boards and I might be going crazy but both boards are doing the exact same thing. I relocated all the known good/new chips over to the newly acquired 7800 system, including the reset IC's Osgeld sent me, and so far no prevail. I'd much rather work on this new board due to it being a slightly older board with better traces and just cleaner looking. I'll keep the other board for parts. Moving forward, I've ordered DIP sockets to install on the board so I can swap out all the IC's. Need to check the Ram and OS chip first. Can the TIA and RIOT chips be interchanged from a known working 2600 to the 7800? Best Electronics is listing them too work. Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted December 26, 2017 Share Posted December 26, 2017 Yes the RIOT, 6507, and TIA from a working 2600 can be put into a 7800. Only the Maria is unique to the 7800. Quote Link to comment Share on other sites More sharing options...
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