[The UAV Rev. D Video Upgrade Thread]

The UAV manual instructs the user to replace the computer composite with the UAV composite. See post 96 of this thread.

[The UAV Rev. D Video Upgrade Thread]

On 7/3/2022 at 9:55 PM, Lakz said:

I've been eyeing the UAV to upgrade the video on my 800XL and had a question. Would it be possible to use the composite output from the UAV to improve/maintain RF output? If not, is there a way to keep RF output when installing UAV into a 800XL?

 

 

Any tips would be appreciated, thanks.

 

(Also first post, yay!)

You can solder the UAV on top of the 4050 chip and that will maintain UAV output. However, I can't imagine why you would want to use RF if there was any other option.

[800XL Boots intermittently]

This may be unrelated to the booting issue bit when the BAD computer does boot, the colors are off and dark.

[800XL Boots intermittently]

I think I have confirmed that the problem is a computer chip. I was swapping chips from BAD XL to GOOD XL and eventually BAD started working and GOOD kept working. I would work on other tasks then go back and power on both computers and after several repeats the GOOD stopped working and BAD continued to work. Now I have to backtrack and see if I can determine which chip is the culprit.

[800XL Boots intermittently]

My belief that the problem was solved was premature. The computer is back to the sometimes boot/sometimes not. I recapped it just in case, no joy.  

[600XL almost working. Advice needed.]

I thought I had tested the MMU but it was the culprit.

[600XL almost working. Advice needed.]

That's why I need to bring out the other working 600xl.

[600XL almost working. Advice needed.]

I also replaced the MMU, ROM, BASIC, and all of the 40 pin ICs. I need to dig out a working 600xl because there are several ICs that aren't common with the 800xl.

[600XL almost working. Advice needed.]

Syscheck says bad ram but I tried several sets of drams that work in another computer.

[600XL almost working. Advice needed.]

I have a similar problem with a 600XL.  It boots to a black screen but I often get the audio click that usually comes before a boot.  The really really strange thing is that Pole Position will boot.  I haven't tried to see if the program will run but it always boots.  No other cart boots.

[800XL Boots intermittently]

I never did run the on board Memory Check.  The SysCheck does a better job and it works when almost nothing else does.

 

[800XL Boots intermittently]

On 6/2/2022 at 6:05 AM, 1050 said:

I would have long ago changed out U18  for a 74HCT08 AND gate and since I bought a stick of them and the other one I like to change, U30 for a 74HC51 chip as well. Can't get the latter one anymore so it looks like someone will have to make something functional out of two smd AND gates and a smd NOR gate perhaps? U18 is often enough alone to give it a solid system clock, U30 just added to the RAM stability since it's creating /CAS and /RAS signals.

I installed a 74HCT08 and the computer has booted every time since then. I also tried a 74HC51 and the computer would not boot with the HC51 installed.

[New keyboard membranes]

16 hours ago, Simius said:

https://thebrewingacademy.com/products/atari-xe-keyboard-mylar?_pos=1&_sid=ef36a4531&_ss=r&variant=16908973736036

They are sold out. When I try to use the "contact us" link I get nowhere.

[New keyboard membranes]

Are there any of the folded 65/130XE mylars available?

[800XL Boots intermittently]

I checked the MMU and it isn't the problem. Disk drive has no activity on a nonboot

[800XL Boots intermittently]

I was mistaken when I said that SYSCHECK always comes on, and I only get the click on a nonboot if SYSCHECK is present.

[800XL Boots intermittently]

When it boots, it boots to the ready prompt. I have used two different power supplies. When it doesn't boot it still has 5.0xx on several points on the MB. I didn't check the MMU yet but I will today. I haven't tried it with a disk drive but I will. When it is on a non-boot streak, Star Raiders also won't boot. 

[800XL Boots intermittently]

Computer sometimes boots sometimes shows dark green screen. The good boot or no boot does not fit any pattern. It might fail to boot on 10 consecutive attempts or it may boot on 10 consecutive attempts. When it doesn't boot, I hear a click like it is going to boot but then nothing. I have tested all the 40 pin ICs in another computer and they all work.  SYSCHECK says the memory is OK. SYSCHECK always comes up so whatever is wrong must be something that SYSCHECK over rides when it is checking memory.

[What's the latest Atari related thing(s) you've bought on ebay?]

An 800XLF, I bought it so I could troubleshoot another one that isn't working properly.

[Atari 1200xl Keyboard Repairs]

Flashjazzcat's video is the standard for KB repair.

[What's the latest Atari related thing(s) you've bought on ebay?]

I bought a non-working 800XL MB with a RAMBO 256K memory upgrade.  Five of the eight MT DRAMS were bad and the ANTIC was bad. Now everything works.  I also bought a keyboard and a case.  I haven't tested the KB but the case is in good shape.  Total cost was $93.56.

[Atari 1200xl Keyboard Repairs]

I have restored 6 or 8 1200XL keyboards and I have never touched a spring and I have never tapped a key numerous times. I take the screws out of the PCB then with a Q tip I put a little bit of alcohol in each screw hole. That makes it easier to remove the mylar. After removing the mylar, I wipe the dots with alcohol then paint the traces where they connect with the PCB. Then I wipe the PCB with alcohol. I then place the mylar back on the PCB and check the operation by touching each dot to verify that all the keys are connecting. If any dots fail, I paint them with conductive paint. This seldom occurs. Once all the dots are working I place a tiny piece of electrical tape over the section where the mylar and PCB connect, replace all the screws and attach the keyboard.

[Atari 1200xl Keyboard Repairs]

My efforts have shown that the problem is almost always where the mylar traces connect with the PCB.

[The Worlds Smallest Atari 8-Bit?]

80 columns and the ability to use an 80 column version of Atari Writer Plus.

[The Worlds Smallest Atari 8-Bit?]

How about the HSIO slot?