hueyjones70

I recently bought a 65XE with the 4 memory chips on Ebay. It has been modified and boots directly to Self test. When it finishes the memory test, the screen goes crazy with lots of characters and a rapidly rolling screen. It also has a mod on the BASIC chip and it has a ROM that is different from all of the other ROMs I have seen. It will boot STAR RAIDERS, POLE POSITION, ATARIWRITER, from a cart. With a BASIC cart inserted, it boots to Self-Test. I have a picture of the BASIC mod. Is it possible that the BASIC mod is the cause of the problem.

My work bench/solder station and my monitor table are 20 feet apart. I have to disconnect everything to do any soldering on the MB. How are the traces being stressed?

I crossed the resistors (110 and 111) and the computer wouldn't boot so I used SYSCHECK and it showed 3 bad DRAMS. I replaced them and got the computer to boot. I switched the resistors back to stock position and the computer would not boot. SYSCHECK doesn't do anything. By turning the computer on and off repeatedly, I did get SYSCHECK to show up one time and it showed all DRAMS as being bad. I know that is not correct because they were all good before I crossed the resistors. I crossed the resistors once again and the computer boots but it exhibits the same odd behavior as before. No extra RAM, won't respond to DOS command. Both resistors show 33 Ohms and both resistors have approx 5 V on each end. I have switched out the MMUs so it must be a bad connection to PIN 10 of the MMU. I just remembered something, while I had the resistors in stock configuration, R111 showed a slight negative voltage.

I removed the upgrade and everything seemed to be working OK. MYDOS booted, the RAMDISK showed more than 32K sectors with no strange characters showing up. Then I experienced some other unusual results. When I boot with DOS 2.5 the computer shows the RAMDISK being set up; then when I get the READY prompt and type DOS, I just get the ready prompt again. I tried several different DOS disks with the same result. Another thing, when I run the self-test, the computer doesn't recognize the extra RAM. I switched ROM chips and the PIA and got the same results.

No, I haven't changed the PIA, I tested it in another computer and it worked OK but the other computer didn't have a memory upgrade and I didn't know about the unused pin.

I have seen instructions that call for pin 1 of the 256 RAM chips to be bent up and connected by wire. I have also seen instructions that call for the pin 1s to be connected on the bottom of the board. Does it make any difference?

Would that be at the power jack?

Thanks, that gives me a starting point.

The switch is standard replacement from BEST. I haven't checked the filter cap, is it the large upright cap nearest the switch (C1)?

I don't think this problem is peculiar to the 130XE. I am getting power to the power connector and to the switch. When I place the switch in the ON position I don't get any power. The power connector and the switch show zero voltage. I replaced the switch and got the same results. I can't imagine what is causing it. I thought maybe there was a short to ground but nothing gets warm and there is no voltage reading anywhere on the board.

I tested the DRAMS in another 130XE computer and they checked out OK. I completely removed the RAM upgrade and the RAMDISK worked OK. I can't imagine what was wrong with the upgrade, I even unsoldered all of the wires from the LS158 and replaced the LS158 with no change in the results.

I did separate pins 15 and 16 from the MB. I don't remember if I tested the 256 Drams but I will.

I have the diagnostic cart from Best, it checks several different functions of the GTIA and IIRC the ANTIC. Do those other diagnostic carts perform the same checks.

The disk was formatted and the results were the same with DOS 2.5 and MYDOS

Changed to D3, don't remember if I formatted or not, wrote DOS files. I will check the format and run the XRAM.

This is MYDOS 4.54. I haven't tried 2.5 yet.

I just installed the 320 RAM upgrade and I get this when I execute the choice for RAMDISK directory. I have not installed a switch. Anyone have an idea as to what is causing the extra screen characters. Also, I did not mount the 74LS158 on top of the 4050 because I have a UAV installed. I glued the 158 chip to the top of the 61618I ran a wire from pin 16 of the 158 to what would be pin 14 of U21 and another wire from pin 8 of the 158 to what would be pin 7 of U21. I was also wonder If the 74LS158 could be mounted on top of the 25953 chip.

Where does rhe switch go?

I am a little embarrassed to admit this but the problem with the 130XE was my failure to solder all of the socket pins. I had added a socket and just tacked a couple of pins to hold it in place then forgot to finish the job.

The screen is black, I get two pops when I turn it on. It worked after I socketed the extended RAM bank. Would a problem with the extended RAM keep it from booting?

I just got a new (to me) 130XE. It has mt RAM chips. I had planned to put in the 320K RAM upgrade so I immediately took out the extended RAM bank and put in non mt RAM. I checked everything out and the computer booted successfully. A couple of days later it wouldn't boot; so I hooked up syscheck. Syscheck says RAM is good but it doesn't do the next step where you get the rainbow screen. Star Raiders boots but nothing else. I socketed the ROM and that chip was good. i socketed BASIC and that chip is good. I have to socket everything I need to troubleshoot so what is the most likely culprit that I should socket. I plan to replace the rest of the RAM once I get it working again.

I have voltage.

I don't have a scope. Yes diodes are directional and the silk screening makes that easy to get right.

I have only one complaint about the PCB and that is that the holes for the power port and the monitor port were too small and I had to spend a considerable amount of time filing down the pins so they would fit.

I did use an old delay line IC but it worked in another computer. I made sure that my directional capacitors were oriented correctly. Resistors are not directional.