Tillek Posted Tuesday at 11:36 PM Share Posted Tuesday at 11:36 PM 12 minutes ago, sideburn said: OK i talked to Evie who makes the chip tester and I am picking the right one 44256. 64Kx4-bit = 32KB SO looks like both rams are bad. Can someone point me to some replacements that aren't crazy pricey. there's only a couple LH2464's on ebay out of country and shipping is $$$$ That would make sense since the ingot failure usually took out the ram. Quote Link to comment Share on other sites More sharing options...
Tillek Posted Tuesday at 11:38 PM Share Posted Tuesday at 11:38 PM 13 hours ago, sideburn said: I wonder if my U1MB is dead If there are any Atarians near you with a U1MB already installed it might be a simple plug and replace solution that could be easier for you than having to desolder chips on a 130xe. Just put yours in its place and see if things still work. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted Tuesday at 11:41 PM Share Posted Tuesday at 11:41 PM Nope, the u1m needs base 64K, which is why I had him pull and test them. Quote Link to comment Share on other sites More sharing options...
sideburn Posted Tuesday at 11:55 PM Author Share Posted Tuesday at 11:55 PM 17 minutes ago, Tillek said: If there are any Atarians near you with a U1MB already installed it might be a simple plug and replace solution that could be easier for you than having to desolder chips on a 130xe. Just put yours in its place and see if things still work. Nope, I am the only weirdo spending way to much time and money on "e-waste" in my circle... Quote Link to comment Share on other sites More sharing options...
Tillek Posted Tuesday at 11:57 PM Share Posted Tuesday at 11:57 PM 1 minute ago, sideburn said: Nope, I am the only weirdo spending way to much time and money on "e-waste" in my circle... Ah, that sucks. Quote Link to comment Share on other sites More sharing options...
sideburn Posted Tuesday at 11:57 PM Author Share Posted Tuesday at 11:57 PM (edited) OK so now, looking at the board more two more chips to pull and test but in the meantime even with the chips removed shouldn't I be seeing a 14mhz & 4mhz sine wave off the two oscillators? Board is DEAD... just downloaded the schematics. got to start digging deeper now. * spoke too soon just looked at schematics.. Looks like Freddy and Antic are required for y1 and 72 oscillators. but freddie checked out good so not sure whats up there. Need to pull and test antic next and then ill get the 800xl out and maybe I can use that to really test the chips. * ANTIC passed... so far only the ram has failed. Edited Wednesday at 12:49 AM by sideburn Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted Wednesday at 02:38 AM Share Posted Wednesday at 02:38 AM (edited) I'd check the 4050, GTIA and transistors since the Sophia fried Edited Wednesday at 02:41 AM by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 02:52 AM Author Share Posted Wednesday at 02:52 AM (edited) 39 minutes ago, _The Doctor__ said: I'd check the 4050, GTIA and transistors since the Sophia fried I have a good GTIA since it was removed for the Sophia. all chips pass. Sally, Freddie, gtia, antic, pia, os rom, basic rom. but when I put them all back in the sockets there’s no clock on the oscillators or the cpu. dead 💀 what’s the 4050? intested all transistors in circuit with my DMM. Good. Also I checked the voltage tolerances and most are above 11v I will pull U21 (74LS74) even though its spec say it can handle 15v but it is tied to the y1 oscillator and freddie with is tied to the y2 oscillator.. Something is definitely wrong here. got to get those oscillators running before anything. Edited Wednesday at 03:20 AM by sideburn Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted Wednesday at 03:18 AM Share Posted Wednesday at 03:18 AM (edited) 26 minutes ago, sideburn said: I have a good GTIA since it was removed for the Sophia. all chips pass. Sally, Freddie, gtia, antic, pia, os rom, basic rom. but when I put them all back in the sockets there’s no clock on the oscillators or the cpu. dead 💀 what’s the 4050? intested all transistors in circuit with my DMM. Good. Also I checked the voltage tolerances and most are above 11v The 4050 is a buffer chip used for the video. I'd go back to the clock and figure out why you don't have a clock signal. (I assume you have a scope here....) Check all the way back to the oscillator circuit. Edited Wednesday at 03:19 AM by reifsnyderb Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted Wednesday at 03:20 AM Share Posted Wednesday at 03:20 AM I meant for the GTIA to be put in which you did, if it's known good and already tested then you can skip that step. 4050 is the video buffer. Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 03:26 AM Author Share Posted Wednesday at 03:26 AM Gotta take a break. Still need to find some ram if anyone can help me find some that would be awesome. here’s a pic of the board now. Every chip except the glue has been pulled, socketed, tested and passed. Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 03:30 AM Author Share Posted Wednesday at 03:30 AM 9 minutes ago, _The Doctor__ said: I meant for the GTIA to be put in which you did, if it's known good and already tested then you can skip that step. 4050 is the video buffer. Ahh the 4051 on the bottom right by the keyboard connector? Ok but got to get the oscillator going #1 priority so whatever is in that path…. Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 03:32 AM Author Share Posted Wednesday at 03:32 AM (edited) 35 minutes ago, reifsnyderb said: The 4050 is a buffer chip used for the video. I'd go back to the clock and figure out why you don't have a clock signal. (I assume you have a scope here....) Check all the way back to the oscillator circuit. Yea exactly that’s what I’ve been working on and so far it’s looking like I need to pull and test that 74LS74. Yeah I have a scope. And a logic analyzer if it comes to that after I manage to get a clock! 🤦♂️ * 7474 passed… Edited Wednesday at 03:54 AM by sideburn Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted Wednesday at 04:25 AM Share Posted Wednesday at 04:25 AM (edited) You have crystals forming your oscillator and clock. check the caps and energizing path. even if the back bit tester says chips are all good, make sure nothing is pulling the clock down including those chips. consider the sophia may have distorted the socket so the chip may need splaying to contact the socket better. also I see some solder on legs of chips in other sockets I'd clean and flatten them ensure they make good contact as well. CD4050BN is not uniform in color anymore, even if it were to marginally pass, I'd replace it. Edited Wednesday at 04:36 AM by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 05:20 AM Author Share Posted Wednesday at 05:20 AM (edited) 1 hour ago, _The Doctor__ said: You have crystals forming your oscillator and clock. check the caps and energizing path. even if the back bit tester says chips are all good, make sure nothing is pulling the clock down including those chips. consider the sophia may have distorted the socket so the chip may need splaying to contact the socket better. also I see some solder on legs of chips in other sockets I'd clean and flatten them ensure they make good contact as well. CD4050BN is not uniform in color anymore, even if it were to marginally pass, I'd replace it. Good eye on th 4050.. yeah i semi cleaned the solder on the pins but they need another round. I have made some discoveries. but the schematic and board part numbers are not completely matching even though I am looking at the right one for my board. there are several. I found two open resistors right in the clock circuit. R26 and R18 (R33 on my board and the board in the snapshot provided to me). Anyway it looks very much like this would be why I have no oscillator action.... EDIT: NOPE.... swapped them out.. out of circuit only R18 was open. Weird now in circuit it's 0 ohms across R18. Maybe thats a clue and what might have blown it out. Edited Wednesday at 05:46 AM by sideburn Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 08:01 AM Author Share Posted Wednesday at 08:01 AM I lifted Y1 (the 14mhz crystal) and put my DMM across it and i measure no resistance open as well... So i guess the crystal is dead. and hard to find apparently... Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted Wednesday at 08:10 AM Share Posted Wednesday at 08:10 AM on the PAL models, you have 2x options here. replace the 2-pin crystal or go with the 4-pin oscillator variant and remove the local components to the right maybe the same applies to NTSC with just a frequency difference? Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 08:19 AM Author Share Posted Wednesday at 08:19 AM I’ll do whatever it takes. I lifted the 4.43 Y2 and it’s an open circuit as well then I though I’m being stupid because I’m about to pass out so I grabbed a bunch of crystals out of my bin and made sure my meter measures resistance on those! 😆 it did. so I have two bad crystals. And two bad rams. And both are unobtainium… almost… Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 08:21 AM Author Share Posted Wednesday at 08:21 AM 9 minutes ago, xrbrevin said: on the PAL models, you have 2x options here. replace the 2-pin crystal or go with the 4-pin oscillator variant and remove the local components to the right maybe the same applies to NTSC with just a frequency difference? This is a pal board… insaw there was also some other modern solution but didn’t dive into that. whatever I can do to get this back up in order I am willing to try. any links & pointers appreciated for the crystal situation and the ram. im calling it quits for tonight. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted Wednesday at 08:31 AM Share Posted Wednesday at 08:31 AM You were pointing to a capacitor that is not r33 Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted Wednesday at 09:48 AM Share Posted Wednesday at 09:48 AM heres a couple, ive used NEC brand before without issue (i think i stuck it in my CoCo2 also...) TMS is good too https://www.ebay.co.uk/itm/176224630245 https://www.ebay.co.uk/itm/176516920665 £7quid for 2x is quite reasonable 🙂 Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 09:56 AM Author Share Posted Wednesday at 09:56 AM 1 hour ago, _The Doctor__ said: You were pointing to a capacitor that is not r33 There’s a resistor in that spot on the my board. It was open. I put two 1m resistors in series there to replace it. Screen on the board may say c33 then but it’s r18 Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 09:56 AM Author Share Posted Wednesday at 09:56 AM 8 minutes ago, xrbrevin said: heres a couple, ive used NEC brand before without issue (i think i stuck it in my CoCo2 also...) TMS is good too https://www.ebay.co.uk/itm/176224630245 https://www.ebay.co.uk/itm/176516920665 £7quid for 2x is quite reasonable 🙂 Thanks but they both say item doesn’t ship to United States Quote Link to comment Share on other sites More sharing options...
sideburn Posted Wednesday at 10:04 AM Author Share Posted Wednesday at 10:04 AM 7 minutes ago, sideburn said: Thanks but they both say item doesn’t ship to United States 16 minutes ago, xrbrevin said: heres a couple, ive used NEC brand before without issue (i think i stuck it in my CoCo2 also...) TMS is good too https://www.ebay.co.uk/itm/176224630245 https://www.ebay.co.uk/itm/176516920665 £7quid for 2x is quite reasonable 🙂 Will these work? https://www.ebay.com/itm/134774816551?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=OdKtb0NMSL6&sssrc=4429486&ssuid=vQ425jH5TBq&var=&widget_ver=artemis&media=COPY 1 Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted Wednesday at 10:59 AM Share Posted Wednesday at 10:59 AM they look good and i'd like to say yes they will but i vaguely recall that 100ns (the '-10' suffix) has been reported as a bit on the fast side for our A8s. maybe someone can clarify. if you can find 150ns i think theyre the sweetspot. Quote Link to comment Share on other sites More sharing options...
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