Stephen Moss Posted March 10, 2016 Share Posted March 10, 2016 The fact that the new 6502 is no longer running hot and causing a major power drain indicates that there was a problem with it but the questions what other components caused it/were effected by it. I am running out of things I think could be check without the correct equipment & a diagnostic cart but you could try checking... J1 Pin 13 = High, Pins 14 & 30 = Low (cartridge power) With a cartridge in... Is Pin 35 of the 6520 constantly High or Low or another voltage and if so what? Although difficult to check the clocks without an oscilloscope what voltages are you getting on... U1 Pins 3, 4, 6 & 8 U2: Pins 3, 37, & 39 U9: Pin 39 U8: Pins 4, 11 & 26 From the trouble shooting flow chart linked to in a previous post with a cartridge inserted check... U1 (MARIA) pins 42 - 48 and U8 (TIA) pins 2, 5, 7, 8, & 9, if both chips are trying to operate at the same time that could mess up the audio/video. Quote Link to comment Share on other sites More sharing options...
alortegac Posted March 10, 2016 Author Share Posted March 10, 2016 (edited) Stephen. I want to thank you again for your follow up on this issue. I agree and I am almost ready to drop the towel on this board and use for spares. I am afraid the new custom IC's will get ruined in the trouble shooting....please see below more bad news. Yesterday, I was testing taking some voltage measurements to compare against the working board and once again sudden major power drains, just like before or worse. I think 7805 is a failure again or something is seriously affecting its output, I am only getting 2.6 volts out from it, incoming is ok at +9V. The power supply is fine., but then voltage is dropping at 7805 therefore I am reading lower voltages all over the board compared to the working board. I am still getting good 4.9 V at U10/CR3 in OFF state, that whole latch circuit seems to be running fine compared to the good working board in terms of voltage. I measured U10 pins and they are OK., Q10, MJE210, etc. I checked CR6, C59, C60, C61, L6 all are fine. New 6502 is not heating up, however I am not keeping the unit ON for long periods. This is turning into a power issue nightmare, power coming down from C61 is much lower than 4.90v.. thanks!!! Edited March 10, 2016 by alortegac Quote Link to comment Share on other sites More sharing options...
+xucaen Posted March 10, 2016 Share Posted March 10, 2016 Just curious, did it work with the 16v adapter? Any chance the previous owners modified the console internally to work with the 16v adapter? (where you have been replacing parts, you probably already considered this) I'd hate to see a 7800 get retired to the corn field. Quote Link to comment Share on other sites More sharing options...
alortegac Posted March 10, 2016 Author Share Posted March 10, 2016 (edited) Unfortunately, I do not have any history on this unit other than I was only told the unit led does power on (goodwill find). The original adapter blue end jack was spliced to a Yamaha 12V adapter 700 ma, not a huge difference to the 9V 1A ( sorry I thought it was 16V). Since the RF module was totally rusted, I thought that was the main issue for the lack of video and sound when I tested it with the correct ATARI 7800 power adapter. Then power switch failed, so I replaced all 4 switches, etc.....There was some rust crust inside the cartridge connector J1 (I thought that was the problem), but I removed it and cleaned it. I have replaced 75% of the major and minor IC's and checked a bunch of things with NO success. I am a very junior electronics enthusiast, and do not have all the equipment to test. thanks for your response! Al Edited March 10, 2016 by alortegac Quote Link to comment Share on other sites More sharing options...
Stephen Moss Posted March 11, 2016 Share Posted March 11, 2016 Stephen. I want to thank you again for your follow up on this issue. I agree and I am almost ready to drop the towel on this board and use for spares. I am afraid the new custom IC's will get ruined in the trouble shooting....please see below more bad news. It is sounding like it may be easier to give up and use it for spares especially as it could be an intermittent problem which are extremely difficult to find as they are there one minute and gone the next. However, if you want to continue, still have you old ICs and have sockets where they go what you could do to protect the new replacements during testing is put the old IC's back in, but not all at once. If you can first try connecting just power to the old 6502 and see it if gets hot of its own accord, if not it may have survived in which case re-insert it but with the 6523, TIA and MARIA removed, leave it on for say 15-30 minutes and see if it heats and/or you get a power drain - if you cannot just the power to the 6502 try inserting it on its own anyway. If there is no heating/power drain leave the 6502 in and try reinserting MARIA (the only IC you don't appear to have already replaced) and again leave it on for say 15-30 minutes and see if the 6502 heats/you get a power drain. If no problems remove MARIA, insert old TIA and repeat, if still no problems remove TIA, insert 6532 and repeat. You could also do this with the new replacement devices as limiting the number of inserted device limits the number of devices that can be damaged, hopefully one of these will help limit our search area however if neither the tests I suggested in my previous post or those above indicate somewhere to focus our attentions on I have reached the end as far as trying to get this unit working again goes. Quote Link to comment Share on other sites More sharing options...
alortegac Posted March 11, 2016 Author Share Posted March 11, 2016 I agree this unit its at the end of rope, I will do the tests and report back. I am awaiting to receive 48 pin sockets for MARIA. I will let you know!~! thanks again! Alberto Quote Link to comment Share on other sites More sharing options...
alortegac Posted March 23, 2016 Author Share Posted March 23, 2016 Quick update. I did a bit more testing with no conclusive results, one IC at time. I have been waiting for components/sockets.......I will receive them this week or next at the latest. I did test TIA and RIOT on a 2600 working unit. Both are ok. I will still pending to test Maria in a working unit. 6502 was replaced . I will socket and replace all the smaller ICs (14 and 16 pins) once I receive them. I will proceed with testing one at time as suggested. I checked continuity on all traces from cartridge to ROM and CPU for issues, nothing found to be wrong. Thanks! Quote Link to comment Share on other sites More sharing options...
alortegac Posted April 1, 2016 Author Share Posted April 1, 2016 (edited) After replacing most everything on this board, as stated in previous posts, now including U3, U11 and U12. I am declaring it a failure. This motherboard is going for parts. The other working mother board suddenly also stopped working with a similar black screen of death, after removing the cartridge guide I found many cut/damaged traces going from J1 o the U5, U6 and U7 due to friction between plastic shroud and the board itself, that one is also going to the parts bin. Count 2 less 7800's from existence. Thank you all for your support, assistance and great feedback. Edited April 1, 2016 by alortegac Quote Link to comment Share on other sites More sharing options...
Jinks Posted April 1, 2016 Share Posted April 1, 2016 Sorry to hear. I feel that way with my coleco. Was thinking of putting it on the clay pigeon thrower and blast it in mid air with the 12 guage. At least a guy would get some enjoyment out of the console for all the time and money spent fixing. Quote Link to comment Share on other sites More sharing options...
alortegac Posted April 1, 2016 Author Share Posted April 1, 2016 (edited) thanks!! this one was a money pit,,,, not even including ruining the other one I was using to compare against.......but hey I learned a lot on what to never try on fixing again..... Edited April 1, 2016 by alortegac Quote Link to comment Share on other sites More sharing options...
Stephen Moss Posted April 4, 2016 Share Posted April 4, 2016 (edited) After replacing most everything on this board, as stated in previous posts, now including U3, U11 and U12. I am declaring it a failure. This motherboard is going for parts. The other working mother board suddenly also stopped working with a similar black screen of death, after removing the cartridge guide I found many cut/damaged traces going from J1 o the U5, U6 and U7 due to friction between plastic shroud and the board itself, that one is also going to the parts bin. Count 2 less 7800's from existence. Thank you all for your support, assistance and great feedback. Shame we could not get it working after all the effort into it but these things happen. As for the one with the cut/damaged tracks at least you appear to know the cause of the failure in the one, could you not scrape off the solder resist with a sharp blade and repair the track with solder or a piece of wire? Edited April 4, 2016 by Stephen Moss Quote Link to comment Share on other sites More sharing options...
alortegac Posted April 8, 2016 Author Share Posted April 8, 2016 Hi Stephen, when I tried to fix it, it feels as if this board was cleaned with WD40 or some other strong solution solvent in the past, the cooper tracks are like peeling off the board...so I think it is not salvageable. I would need to remove the rom and most likely more tracks will come off...... thanks as always!! Quote Link to comment Share on other sites More sharing options...
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