Jump to content
IGNORED

Bad Necromancer XEGS Cart - fixable?


Nezgar
 Share

Recommended Posts

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?

 

post-53052-0-55727000-1509918898_thumb.jpg

Link to comment
Share on other sites

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 by SignGuy81
Link to comment
Share on other sites

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 by SignGuy81
Link to comment
Share on other sites

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

  • Like 2
Link to comment
Share on other sites

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.

  • Like 3
Link to comment
Share on other sites

  • 3 weeks later...

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

 

 

post-1423-0-36180900-1511248759.jpg

  • Like 2
Link to comment
Share on other sites

  • 2 months later...

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

post-53052-0-43739900-1518418013_thumb.jpg

Link to comment
Share on other sites

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.

post-53052-0-41244600-1518421190_thumb.jpg

  • Like 5
Link to comment
Share on other sites

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.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...