MSTE screen flickering after being ran for awhile

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christos
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MSTE screen flickering after being ran for awhile

Postby christos » Tue May 09, 2017 4:59 pm

Hi,
I've got this issue with my mste. After I run it for a few minutes (15-20) the image starts flickering left and right (but not up and down). Any idea what it might be? Also, it seems like my cache chips have an issue since the machine halts when I turn them on.
Thanks in advance.
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Re: MSTE screen flickering after being ran for awhile

Postby christos » Fri May 12, 2017 3:49 pm

Update,
I thought it might be the shifter overheating so I decided to check by putting a heatsink over it. If it took longer to cause the issue, I would have found the culprit.
However, the machine never started after that. It powers on but all I get is a black screen and a buzzing sound from the monitor port. Connecting with the L&R sockets doesn't produce the buzzing. I thought it might be that some thermal paste leaked in the socket so I removed the chip, cleaned it up and the socket with some isopropyl alcohol but there was no difference. I also reseated the rest of the socketed chips. No result. Any ideas?
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Re: MSTE screen flickering after being ran for awhile

Postby christos » Mon May 22, 2017 4:22 pm

OK, new blog entry:
I got a new shifter and it works! But I've isolated the problem to overheating since I get some flickering (much less severe than the previous one) only when the case is closed. An open case alleviates the symptoms. So I need to find what causes the system to overheat. Looking forward to reading your thoughts in the comments section below ;)
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Re: MSTE screen flickering after being ran for awhile

Postby exxos » Mon May 22, 2017 4:44 pm

Odd screen issues are normally bad caps in the video circuit. I cant speak for the MSTE as never owned one, but very common on STFMs.
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Re: MSTE screen flickering after being ran for awhile

Postby siriushardware » Mon May 22, 2017 9:07 pm

christos wrote:
However, the machine never started after that. It powers on but all I get is a black screen and a buzzing sound from the monitor port. Connecting with the L&R sockets doesn't produce the buzzing.



This problem was almost certainly a Red Herring (a false fault) caused by you plugging the 13-pin monitor plug into the socket upside down. It is very easy to do accidentally and produces the symptoms you describe, especially the buzzing sound from the monitor.

As you kept on faultfinding and removed the plug at some point and put it back in again, this time the right way up, that particular fault went away.

If you have access to some 'Freezer Spray', let the unit warm up until the fault comes on, then carefully spray individual components while the unit is on / fault is present to see if cooling any of them makes the fault go away. Note: NEVER use freezer spray on the PSU unit, use only on low voltage parts of the computer.

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Re: MSTE screen flickering after being ran for awhile

Postby christos » Tue May 23, 2017 5:50 am

@exxos: yes it's possible that there might be some bad caps, if they can cause the shifter to overheat.

@siriushardware: The plug was the first thing I checked, and I've used two different cables (composite and scart) so I've plugged it in and out quite a few times. The new shifter chip made the machine run again. I don't think that you can fry a shifter by plugging the cable upside down.

About the freezing spray, that would show me indeed which component overheats, but in all likelyhood that would be the shifter. I'll try to source some spray and see if I get a different result.
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Re: MSTE screen flickering after being ran for awhile

Postby exxos » Tue May 23, 2017 7:06 am

What I mean is, if the machine acts up faster with the "lid on" then its not necessarily the shifter.
4MB STFM 1.44 FD- VELOCE+ 020 STE - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - various clutter

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