C128D displaying random characters on startup screen (plastic case model)

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banman
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Re: C128D displaying random characters on startup screen (plastic case model)

Post by banman »

Hi Gyro Gearloose,

Thank you. You may be correct that there's an issue in the jellybean logic IC chips.

Yes, I agree regarding the diagnostic cartridges. I used several different types and got mixed results.

I have checked the power supply power and I get 12.02v and 4.94v respectively.

It is interesting to note that when I type in a small program in C128 mode I get a program listing that has the line numbers all scrambled.
The program will run for a short time before crashing.


In C64 mode the same program seems to be fine.
In this mode the program will work for considerably more time. However, on rare occasions it will crash.


Unfortunately I can't seem to upload any screenshots to this post for some reason.


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Gyro Gearloose
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Re: C128D displaying random characters on startup screen (plastic case model)

Post by Gyro Gearloose »

It occurrs to me that these days it should be totally possible to have troubleshooting sessions by Zoom or something similar.
The price one pays for pursuing any profession, or calling, is an intimate knowledge of its ugly side.
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Re: C128D displaying random characters on startup screen (plastic case model)

Post by rcade »

Mine did that also- it easily breaks free during shipping. It does fit in the holes, or at least mine did and I resoldered it.
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Re: C128D displaying random characters on startup screen (plastic case model)

Post by banman »

Hi Gyro Gearloose and rcade ,


Gyro Gearloose wrote: Sun Jan 22, 2023 3:35 am It occurrs to me that these days it should be totally possible to have troubleshooting sessions by Zoom or something similar.
Yes! that's a great idea. :)

rcade wrote: Mon Jan 23, 2023 1:36 am Mine did that also- it easily breaks free during shipping. It does fit in the holes, or at least mine did and I resoldered it.

I have checked mine carefully and it really does appear that at least in the machine I have here that it never made it thru the PCB. I can't seem to find solder on the mounting tabs of the RF cage shield. Also the PCB holes for the RF cage are too small, no doubt with a layer of solder, as result of the wave soldering machine.

I am surprised that the VIC IIe chip survived since 1986 without much contact to the heat sink.
I would even hazard a guess that it was barely making contact with the thermal grease. I think it does say something about the advances in manufacturing processes at MOS semiconductor plant compared to the very first versions of C64 chips that were manufactured.
I think if you click on the pictures hi res images can be viewed.

If I can manage to up load images again to this forum thread I will get some better shots. At the moment I can't seem to upload any files.
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Re: C128D displaying random characters on startup screen (plastic case model)

Post by banman »

This is the error I get when I try to upload a file.



'ERROR
Sorry, the board attachment quota has been reached.'
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Melon
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Re: C128D displaying random characters on startup screen (plastic case model)

Post by Melon »

banman wrote: Mon Jan 23, 2023 3:24 am This is the error I get when I try to upload a file.

'ERROR
Sorry, the board attachment quota has been reached.'
Try again, I've relaxed the attachment quota.
.oO( MELON64 - ONE SLiCE AiN'T ENOUGH! )Oo.
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Re: C128D displaying random characters on startup screen (plastic case model)

Post by banman »

Hi Melon,


Thank you very much for this. Very much appreciated.

Maybe I'm using up too much storage. Is there a way I can cut back some of my uploaded files?
I'm happy to delete some older posts too. I am sure that they aren't needed any more.

Any helpful tips would be kindly received. :D
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Re: C128D displaying random characters on startup screen (plastic case model)

Post by Melon »

banman wrote: Tue Jan 24, 2023 5:23 am Maybe I'm using up too much storage. Is there a way I can cut back some of my uploaded files?
I'm happy to delete some older posts too. I am sure that they aren't needed any more.

Any helpful tips would be kindly received. :D
We've got unlimited storage here. Absoultely no need to delete anything.
.oO( MELON64 - ONE SLiCE AiN'T ENOUGH! )Oo.
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Re: C128D displaying random characters on startup screen (plastic case model)

Post by banman »

Thanks Melon!

Perfect :D
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Re: C128D displaying random characters on startup screen (plastic case model)

Post by banman »

Hi Gyro Gearloose,

I will include some images.

I have checked the power supply power and I get 12.02v and 4.94v respectively.

It is interesting to note that when I type in a small program in C128 mode I get a program listing that has the line numbers all scrambled.
The program will run for a short time before crashing. Notice how the line numbers are all messed up when I try to list the program.....

IMG_20230118_145002.jpg




In C64 mode the same program seems to be fine.
In this mode the program will work for considerably more time. However, on rare occasions it will crash.
IMG_20230118_145231.jpg


Note the vertical lines running up and down the screen. I am sure this is a digital artifact not an RF related problem.
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