+Nezgar Posted November 5, 2017 Share Posted November 5, 2017 I received a 2nd hand Necromancer XEGS Cart that does not work. It does take over the ram (16K?) above $8000 because basic gets disabled, and it goes straight to self-test. Self test only shows 2 rows of blocks in RAM test, instead of 2.5. My new Sys-Check II shows bad ram above $8000 with the cart inserted. I believe this is only a 16K game with no bank switching, hence no chip in the middle. I re-flowed the solder to pretty much all the touchable points on the pcb, no difference. I haven't looked to see if that 16K addressable space actually has anything in it yet.. Any other ideas? if the ROM chip is bad, can a 27128 EPROM be dropped in its place? Quote Link to comment Share on other sites More sharing options...
+MrFish Posted November 5, 2017 Share Posted November 5, 2017 You could check the traces for continuity. Although, I'm guessing a bad ROM is a more common problem for carts. Quote Link to comment Share on other sites More sharing options...
SignGuy81 Posted November 6, 2017 Share Posted November 6, 2017 (edited) Hard to tell in that pic but it looks like I see a cracked solder joint on C1 on the right lead in the middle picture but it is hard to tell. Also too C2, again hard to tell by the pic but the back side of the board it looks like that might not be a good joint, where the lead is coming through the backside of the board, and also it didn't flow to the top side of the board as well on that lead(basically that lead will need more heat to solder good because of the huge trace(ground plane) on each side). EDIT: All that being said I doubt it is your issue though as those are just decoupling caps, but there could be others as well that are too hard to spot from the pic. Edited November 6, 2017 by SignGuy81 Quote Link to comment Share on other sites More sharing options...
SignGuy81 Posted November 6, 2017 Share Posted November 6, 2017 (edited) Look at pin 22 of the ROM chip, on the back side of the board, I see looks like a ring around the joint indicative of a cracked joint. Looking at the back of the board that pin will be the 7th one going up(starting from pin 28) along the edge of the board, you should see that ring around the joint I'm talking about in the pic. Is there anyway you can get closer high res pic of the back of the board? Edited November 6, 2017 by SignGuy81 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted November 6, 2017 Share Posted November 6, 2017 (edited) you needs flux and lead based solder.... anyone know if u3 was or was not needed on this cart? or if the jumper pad belongs bridged or not... stranger things have been found when carts are located Edited November 6, 2017 by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted November 6, 2017 Author Share Posted November 6, 2017 Thanks for the ideas! I touched up most of the points again with a bit of flux and extra solder here and there, no difference. So since the computer is able to boot with the cartridge inserted, I loaded up Sparta 3.2f, and issued SAVE NECROMAN.OBJ 8000 BFFF and the resulting file does indeed have data there... I even repeated it to a couple separate files, and they all compare the same. (16KB with a 6-byte object code header) necromancer.obj a little forensics on this memory dump... transferred the OBJ file over to the PC - loading into notepad I can see the string "OMANOMANBYBYL WIL WIMSMS" .. and comparing with a known good XEX version of necromancer, its very clearly "NECROMANCER BY BILL WILLIAMS" .. So its partially there... Whats the other LS type chip do... could that be suspect? KS74HCTLS00N - googling says "TTL Quad 2-Input NAND, HCT-CMOS IC DIP 14PIN" Cheers! - Ryan 2 Quote Link to comment Share on other sites More sharing options...
Zap! Posted November 6, 2017 Share Posted November 6, 2017 I had the same thing happen to me the other day with Flight Simulator II. It booted straight to self-test and only showed 2 rows of blocks in RAM test. What I did next was literally pour 91% alcohol on both sides of the connectors, then scrub with a q-tip. While still wet, I put it in and pulled it out of my Atari 800XL about 15 times, which also resulted in cleaning the computer. Finally, I turned it on and it worked like a charm. 3 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted November 6, 2017 Share Posted November 6, 2017 true the card edge does not look all that clean 1 Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted November 21, 2017 Author Share Posted November 21, 2017 Thoroughly cleaned connectors... all other carts work, and same symptom when used in multiple machines. out of ideas of this one other than replacing the mask ROM. 16K game - would a 27C128 EPROM be pin compatible if I replaced it? Quote Link to comment Share on other sites More sharing options...
ndary Posted November 21, 2017 Share Posted November 21, 2017 Yes, you can.. But first i would replace the .1uf cap and check all traces from the ATARI Prom to the Cartridge slot and to the 74LS00 chip, You can remove the ATARI ROM and put there a 27c128 Eprom (just make sure that its faced down to the cartridge edge) those are not 'resistors' you see in R2 & R3, there are there to make a short. just Take out the 'LEFT LEG' of R2 and solder it to the 'LEFT LEG' of C4, this will take care of the 'CHIP SELECT' signal that is required for the 27C128 Eprom to work. if after replacing the PROM with an EPROM (that has the NECROMANCER GAME) you still don't get the game to work then replace the 74LS00, it may go bad. see image 2 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted November 21, 2017 Share Posted November 21, 2017 (edited) couldn't hurt to replace the ls and deleted the rest as ndary covered at the same time Edited November 21, 2017 by _The Doctor__ Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted November 21, 2017 Author Share Posted November 21, 2017 Thanks for the tips! Will acquire the parts, and see how it goes! Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted February 12, 2018 Author Share Posted February 12, 2018 This evening I replaced the Atari ROM with a machine socket, and moved the R2 jumper to where C4 was in the Rev 2 board. With cart inserted with this EPROM, the computer boots locked up to blue screen+cursor, no attempt to boot from SIO. With EPROM removed, it will boot with BASIC disabled, and go to self test or try to boot from SIO if a drive is on (like it used to with the Atari ROM) My rev 1 cart does not have a capacitor at C4, is it necessary? This HN4827128G-25 EPROM was successfully burned by the Ralf David burner and verifies OK, but I see it's rated at 250ns, is that too slow for the Atari? If so I have to find a different EPROM, either not many are compatible with the Ralf David/Dropcheck burner, or I many duds. maybe next step is to replace the LS chip, as previously suggested Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 12, 2018 Share Posted February 12, 2018 look at the modifications on ndary's cart, you must do the same. bridging the jumper pads, the caps in and the added wire.. compare the picture to your cart... Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted February 12, 2018 Author Share Posted February 12, 2018 D'oh - I see now I missed one wire! It's in Nir's picture, but not the text, so I added that. Also, the Rev 1 board I have is a little different around C4, but I moved that jumper to where the left leg would be. Voila, it works! Thanks for the help and nudges all! Cool to have a cart with a socket too. Attached is picture of working Rev 1 board. 5 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.