1040STfm stuck in monochrome

[TheAtarianGuy]

Recently I started using my ST again, and it's been working fine using the RF output and my TV. But a few days ago or so, it started displaying in monochrome only. I'm not sure what the problem is, can anyone help me figure it out?

[tjlazer]

Recently I started using my ST again, and it's been working fine using the RF output and my TV. But a few days ago or so, it started displaying in monochrome only. I'm not sure what the problem is, can anyone help me figure it out?

Monochrome on RF? Try reseating all socketed chips.


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[ParanoidLittleMan]

I think that it is not monochrome mode - because it can't be displayed on TV - different frequencies.

It just lost colors. So, not reseating chips, but check around color encoder chip MC1377 - in some revisions it is together with RF modulator, not so easy accessible, by some others it is on main board, near to modulator. May try with adjusting chroma carrier freq - trim capacitor is under shield, near to shifter chip.

And something more: does TV show colors when using with other source ? Just to be sure that problem is not in TV .

[TheAtarianGuy]

I tried it again today on both my TVs, one's an old school CRT. And now, neither of them seem to be getting a signal from the RF... I got the desktop to show up on the old TV for a second, but it was still in black and white, then turned to static. The newer TV just says "no signal". I guess it's time for some maintenance?

[mdivancic]

6 hours ago, TheAtarianGuy said:

I tried it again today on both my TVs, one's an old school CRT. And now, neither of them seem to be getting a signal from the RF... I got the desktop to show up on the old TV for a second, but it was still in black and white, then turned to static. The newer TV just says "no signal". I guess it's time for some maintenance?

Many newer TV can’t lock onto the the ST’s RF output. None of the three TV in my house could. 

[TheAtarianGuy]

1 hour ago, mdivancic said:

Many newer TV can’t lock onto the the ST’s RF output. None of the three TV in my house could. 

It was working fine for weeks though, on the newer TV. It just stopped displaying in color one day, now it doesn't display at all, even on my old woodgrain Sears TV. I've been thinking about picking up one of those 13 pin to RCA cables from ebay, now I've got a good reason to go ahead with that. I also need to resolder the mouse ports, might as well check the chips and all that while I've got it apart. Thanks for the help so far everybody! I'll keep y'all updated.

[ParanoidLittleMan]

Using video instead RF cable is certainly better, or if possible RGB signals. 

In this case it looks that machine condition goes worse. For instance, it may be that colors gone because 12 V power went lower.  So, I recommend to check 12 and 5V power lines, and perform in later years a lot mentioned 'recapping' of PSU. It is elementary by so old electronic.

[tjlazer]

Get one of those VGA adapters that can do mono and color and a 15KHz LCD like the NEC 1970vx and you will be all set!

[oky2000]

I bought a used Mega STE around 2008 for 80 bucks and that did actually get stuck in mono mode, it would try to display the 31khz hi-res image on the SC1224 (which suddenly started releasing the 'magic blue smoke' from inside the components).

 

I never solved that one....so I sold it.

[tjlazer]

Maybe the monitor port had a short or something to force it into Mono mode?

[oky2000]

I thought that too and I used to repair, not replace, laptop LCD panels so I would have had a go at the simple stuff probably but I honestly can't remember much except smoke coming out from my coveted SC1224 monitor.

 

Came with a nice 80mb external hard drive with loads of stuff on it so I just kept the hard drive but then I lost the boot disk for it oops. The hard drive came with an Amiga 500 PSU which had the power connector changed to a 5 pin DIN.