hueyjones70

Thanks a lot, that should save me some time.

Which chip would contain bit 0, or do I just swap chips until the problem goes away.

Thanks for that information, I did check another of my 130XEs later and it didn't do an extended ram test either. The problem computer seemed to do OK with DOS 2.5 and only acted up with MYDOS. I switched the resistors and did the memory self test and nothing came up bad and when I booted with MYDOS almost everything was OK but the RAM disk showed that there were two programs in memory that I have never seen before.

Started working on a 130 XE and I thought everything was fully functional but when I do the self test there is no check of extended ram. When I boot with MYDOS and check the RAM disk, the computer prints out 5 or 6 lines of letters , symbols, and numbers; then it tells me there are just over 2000 available sectors. Does this mean that I have bad extended RAM or could the problem be with the MMU or with the Freddie.

This has been a great day for 800XL repairs. One MB had a bad delay chip, the one that fits in a 14 pin socket but only has 8 pins. Another had bad socket for the POKEY, and a third had one bad memory chip.

I have been doing the Super Video 2.1 mod on most of the 800XLs that I upgrade and I have noticed that sometimes the image is actually too sharp and it makes the Last Word difficult to read. Has anyone else noticed and is there a way to fix the problem other than using the UAV.

I recently bought a non-working 800XL on ebay that only had one socketed IC. Since Star Raiders would boot I figured the problem was OS ROM or the memory ICs. I removed those Components and added sockets and the problem was corrected after replacing the memory. I couldn't help but notice that the video was sharper than most XLs. I know this is a later model because of the lack of sockets and the fact that it has BASIC rev C. After hooking up the chroma I was really surprised at the video quality. I am still going to do this video mod but I know there isn't as much room for improvement as there usually is.

I will check the sockets. I am using a white brick power supply that gets checked just about every time I work on a computer; if not directly, then indirectly because one of my checks is to verify voltages through the connector, the switch, and caps near the switch.

Yesterday I was troubleshooting an 800XL MB that gives nothing but a black screen. While I was checking memory chips, my test board suddenly went the way of the bad MB and gave nothing but a black screen even with its original supposedly good chip set. Today when I turned it on I still got the black screen but it was making a noise like a screeching sound. It will boot Star Raiders but nothing else and it still makes the screeching sound mixed with the sound that Star Raiders usually makes. I tried swapping our the ROM and BASIC but I haven't had time to recheck all of the ICs. What besides the ICs would be a good thing to check.

I drew a circle on the case and then used a dremel tool and successively larger grinding wheels to make the hole.

If you push all of the resistors and capacitors to the left or to the right about 45 degrees you can fit the UAV in and it will still fit under the shield.

Thanks, I will check both ways, voltage and frequency.

I think the oscillators may be bad on the last two boards that I populated. I have a multimeter with a frequency tester and I don't get 8.0 when I check the pins but I am not sure if I am checking them correctly. I have tested the meter on the 2 pin crystals on a 800XL board and I get the correct reading. I am not sure which pins I check on the 4 pin crystals on the 314/354 boards. Can anyone enlighten me? I have googled and did not find any info about testing 4 pin crystals.

I just finished installing a UAV-D and the video is really clear. I had tried to do a SuperVideo 2.1 but I couldn't get a picture after I had installed all of the components. Everything is so confined in the 600XL that I could have made any one of many soldering mistakes so I would rather install a UAV than try and find the error(s). Where can I find information on the RAM upgrade? One other thing that is puzzling is that I can't get my Sdrive to work with the 600XL. Is there something that makes the Sdrive incompatible with the 600XL?

I have tried to do SV 2.1 mods on two different 600XLs and was not successful so I just installed a UAV in each one and got a pretty good video.

I struck out with another 551/314 PCB. If there is anyone out there that is really good and confident about populating a 551 PCB, I would be willing to trade some materials for a finished board. I send you two PCBs, all of the parts required to populate the PCB, a working 3.5 drive and a SF354 case. Then when you finish, you just send me one of the PCBs

The SV 2.1 does not interfere with the UAV. The UAV bypasses all of the SV2.1 circuitry. I am pretty certain that this is true because I did a SV 2.1 on a 600XL and totally screwed it up, I wasn't able to get any video at all and rather than try to find my mistakes I just installed a UAV-D and the video was great.

I now converted a SF314 drive to 8-Bit use. This was extremely simple once I was finally able to put together a working PCB. Just insert the PCB in the case and connect the cables. Works nicely. I have considered having a new model label made and label it as an XF315A or XF315M, but I don't know if that would be legal if I decided to sell one.

I have made 4 or 5 SIO cables. I have to use a lighted magnifying glass to do most of my soldering. I wish I could afford one of those magnifying glasses like dentists use.

I am having mixed success with assembling a working PCB. I don't know if it is due to salvaged parts, or poor soldering skills but my success rate is about 50%.

I have discovered that my inability to run the Atariwriter+80 on the Sdrive2 was because of some fault with the Sdrive2, probably associated with reading double density files. I finally tried the program on another type of Sdrive and it worked correctly.

The SuperVideo 2.1 changes some resistors and capacitors in order to separate the Luma (black&white) signal from the Chroma(color) signal so that you don'd get colored objects bleeding into each other. It also sharpens the pixel definition. The UAV (Ultimate Atari Video) does this with an add-on board that is plugged in to the motherboard. The Wiztronic and Rambo upgrades increase the RAM from 64K to 256K.

I tried the files and one of them has DOS 2.5 built in as the boot file. When I loaded the file I got a ready prompt so I had to load DOS then use the L command and load LW.EXE.

I like to buy 800XLs, upgrade them and resell them for a small profit. I can do video upgrades (usually SV 2.1), install UAV, install memory upgrades, (Wiztronics or Rambo), and generally clean them up. I usually sell on eBay but I would be willing to do business with forum members without the fees associated with eBay. Anyone interested can message me and work out details.

I know that this program requires a DOS, how do I load it from a disk emulator like an Sdrive?