madness77 Posted February 18 Share Posted February 18 I am diagnosing a problem with the Atari not detecting the memory extension. CA200519 board. Is it normal for there to be such a signal on line PB4 (pin 14 of the PIA)? On other boards I have a high state there. I have replaced the PIA with another one, but it is the same. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 18 Share Posted February 18 what memory extension, the picture shows empty sockets and no other pcb's or carts Quote Link to comment Share on other sites More sharing options...
madness77 Posted February 18 Author Share Posted February 18 2 minutes ago, _The Doctor__ said: what memory extension, the picture shows empty sockets and no other pcb's or carts 1MB SIMMext (by Pasiu/Mq), but it doesn't matter. It doesn't detect banks, whether I do a simple upgrade to the 130XE (GAL in U34) or connect an external SysCheck 512kB. This is the signal on a bare board fired into BASIC in base 64kB mode (jumpers on U34). Quote Link to comment Share on other sites More sharing options...
Beeblebrox Posted February 18 Share Posted February 18 Just out of interest which version of the simple 128k upgrade did you do? Just trying to work out there what might be going wrong. Tbh if you are having issues with several types of upgrade i wonder if the mmu could be a problem, especially if you believe it not the pia. Whilst I've only done 320k upgrades in both 130xe and 65xe machines with 8 or 16 ram chips, both use connections to the mmu among other things. Quote Link to comment Share on other sites More sharing options...
madness77 Posted February 19 Author Share Posted February 19 (edited) 40 minutes ago, Beeblebrox said: Just out of interest which version of the simple 128k upgrade did you do? Just trying to work out there what might be going wrong. https://ccomodore64.blogspot.com/2019/08/rozszerzenie-pamieci-ram-w-atari-65xe.html (simple one, only GAL) But the question was different, what states do you have on the PB[0..7] PIA lines? (no extended board in BASIC) I have signal (pulse) on PB4 (with or without any extension). According to what's in the service manual, and as I've checked on other boards (regular 130XE and 800XL), there should just be a high state there. https://atariwiki.org/wiki/Wiki.jsp?page=PORTB (4 CPU 0=CPU has access to extended RAM, 1=CPU has access to main RAM) Edited February 19 by madness77 Quote Link to comment Share on other sites More sharing options...
+kheller2 Posted February 20 Share Posted February 20 Any luck on solving this? Quote Link to comment Share on other sites More sharing options...
TZJB Posted February 21 Share Posted February 21 On 2/18/2024 at 10:31 PM, madness77 said: I am diagnosing a problem with the Atari not detecting the memory extension. CA200519 board. Is it normal for there to be such a signal on line PB4 (pin 14 of the PIA)? On other boards I have a high state there. I have replaced the PIA with another one, but it is the same. What PSU are you using for the 5V supply? Could this be affecting the result? What does the 5V supply ripple look like? As you suggest there should not be a nearly 900KHz signal on PIA pin 14 PB4 or am I reading that wrong? Have you changed the MMU and continuity tested MMU pin 5 and R24 3K3 Ohm to PIA pin 14 PB4 as they should be the only connections to PB4? Could you please post some high resolution pictures of both sides of the motherboard? I am suspecting a contact with something that shouldn't be there which we may spot when you upload the pictures. 1 Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted February 21 Share Posted February 21 @madness77 found a tiny short, that prevented the expanded RAM to work at all. It works in 130XE mode now. Now he's fighting with the expansion, which shows up now but acts weirdly. He'll write more after the problem is completly solved. Quote Link to comment Share on other sites More sharing options...
TZJB Posted February 21 Share Posted February 21 1 hour ago, Peri Noid said: @madness77 found a tiny short, that prevented the expanded RAM to work at all. It works in 130XE mode now. Now he's fighting with the expansion, which shows up now but acts weirdly. He'll write more after the problem is completly solved. I thought so. Thanks for the update. Quote Link to comment Share on other sites More sharing options...
madness77 Posted February 21 Author Share Posted February 21 Yep, microscopic tin residue short-circuited the PB4 to CASINH under the U34 socket: 3 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 21 Share Posted February 21 (edited) Yes it seems many of those are over filled, looks like flux and some removal is in order. something about the board says corrosion, I'd re-flow anything anything looking like it's not flat to the PCB and spray any socket that does not looks pristine with de-oxit. Any over fills need to be reduced using good lead solder and flux, re inspect for whiskers and dirt. Edited February 21 by _The Doctor__ 1 Quote Link to comment Share on other sites More sharing options...
TZJB Posted February 23 Share Posted February 23 On 2/21/2024 at 8:17 PM, madness77 said: Yep, microscopic tin residue short-circuited the PB4 to CASINH under the U34 socket: I don't think we would have spotted that from a picture. Not sure how that is possible, maybe too much solder and heat? Thanks for the update. Quote Link to comment Share on other sites More sharing options...
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