My lost 600XL!

[walter_J64bit]

Ok I've just found one of my old 600XL with a 64K upgrade but the picture is super dark, anyone have an ideas what's going on with it? 

Edited April 1, 2023 by walter_J64bit

[JR>]

Did you try adjusting the color pot?

 

[ACML]

Does it look like that immediately after turning it on?  If it was on for nine minutes, it might have gone into screen saver mode.  If so, it will alternate colors every 10 seconds or so.

 

 

[Beeblebrox]

It could be the colour pot but I think I had an XL which had the same issue last year. I am struggling to recall what the issue was. Have a feeling it was either a chip gone bad or a bad transistor. I'll have a look at my old screenshots and see if I can recall. Might help.

 

In the meantime try adjusting the colour pot as mentioned whilst the machine is on. Use a small flat headed screwdriver through the access hole on the underside.

 

EDIT: it could be attract mode (screensaver) but I get the impression this is the case on initially booting up(?)

Edited April 1, 2023 by Beeblebrox

[walter_J64bit]

5 minutes ago, ACML said:

Does it look like that immediately after turning it on?  If it was on for nine minutes, it might have gone into screen saver mode.  If so, it will alternate colors every 10 seconds or so.

 

 

Yes, immediately after turning it on.

 

[walter_J64bit]

3 minutes ago, Beeblebrox said:

It could be the colour pot but I think I had an XL which had the same issue last year. I am struggling to recall what the issue was. Have a feeling it was either a chip gone bad or a bad transistor. I'll have a look at my old screenshots and see if I can recall. Might help.

 

In the meantime try adjusting the colour pot as mentioned whilst the machine is on. Use a small flat headed screwdriver through the access hole on the underside.

Thanks!

 

[walter_J64bit]

16 minutes ago, JR> said:

Did you try adjusting the color pot?

 

Not yet.

 

[walter_J64bit]

Ok I've tried the color pot that just made worse.

 

[BillC]

3 hours ago, walter_J64bit said:

Ok I've just found one of my old 600XL with a 64K upgrade but the picture is super dark, anyone have an ideas what's going on with it? 

It appears likely one or more of the luma signals isn't getting through, which reduces the brightness of the LUMA/Composite outputs.

This could be caused by a faulty GTIA, 4050, or some other bad component/connection in the signal path.

[Beeblebrox]

13 minutes ago, BillC said:

It appears likely one or more of the luma signals isn't getting through, which reduces the brightness of the LUMA/Composite outputs.

This could be caused by a faulty GTIA, 4050, or some other bad component/connection in the signal path.

I agree. The great thing is the 600XL is fully socketed. So I'd open it up and maybe start with replacing the 4050 first. You can buy 4050 chips very cheaply. Remember if you've never opened up the machine before it will have it's internal metal shielding in place. To remove it is simple, although remember there is a hidden screw which is accessible around the top left of the sheilding through a hole in the sheilding itself. 

 

Do you have another machine with sockets you can pop the 600XL's gtia in to test it? 

 

If gtia and 4050 check out it could be a transistor in the video circuit maybe. 

[walter_J64bit]

1 hour ago, Beeblebrox said:

I agree. The great thing is the 600XL is fully socketed. So I'd open it up and maybe start with replacing the 4050 first. You can buy 4050 chips very cheaply. Remember if you've never opened up the machine before it will have it's internal metal shielding in place. To remove it is simple, although remember there is a hidden screw which is accessible around the top left of the sheilding through a hole in the sheilding itself. 

 

Do you have another machine with sockets you can pop the 600XL's gtia in to test it? 

 

If gtia and 4050 check out it could be a transistor in the video circuit maybe. 

Does the 5200 have the gtia and 4050? I do have a dead 5200.

 

[_The Doctor__]

Yes

[walter_J64bit]

The 4050 is solder to the board of the 5200 but the gtia isn't.

 

[TGB1718]

Just a thought before you start pulling the 600 apart, I have 130XE's and an 800, when I connect to

the same monitor using S-Video or Composite, I have to adjust the colour/brightness settings on the monitor.

The difference between the 800 and the 130XE is quite extreme, some day will fix the issue

[Beeblebrox]

@TGB1718 I think based on the fact i'd had this before myself as well as the fact the prompt text is darker, I still think this is a chip/component failure issue.  Afaik whatever the pot settings or display equipment's brightness the text should always be a lighter shade than the background for a stock machine. (Correct me if I am wrong here). 

 

I vaguely remember tweaking the colour pot as well as the TV display settings when I had the same issue and it made no difference at the time Iirc.

 

I am trying to find an old post of mine as pretty sure I posted about it when it happened. Or at least I'd replied to another thread. (

Fixed quite a few machines so it blurs into one. (Memory ain't waht it used to be heh heh).

) 

@walter_J64bit

The 4050 chips can be bought for peanuts so I'd recommend to OP just order one, and also try and swap out the gtia. 

Passive components such as transistors are dirt cheap also.  The AA forum member will gladly help out I am sure with guidance if it comes to that.