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SX-64 white screen

Taffer

Taffer

Experienced Member
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Jun 24, 2019
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Buffalo, NY
I'm heavy into IBMs and know very little about Commodores. I recently was given an SX-64. It works when a game cartridge is inserted, sound, video, screen work, keyboard and joystick work.

However, without a cartridge inserted, it just goes to a blank white screen with a blue border. Pic attached.

What needs to be replaced? Is it SX-64 specific?

I do have a C64 breadbin that works except has no sound I'd be willing to take parts from. From my research on that breadbin, it's an "early" model.

Thanks for the help.
 

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If cartridges work, I would guess a bad basic rom.

See the following site: https://www.pictorial64.com/

But be aware the colors are slightly different on SX-64 to improve contrast on the tiny screen. Or so I’ve heard.

If it is a basic rom problem, I think they are the same as on a breadbin, but you’d want to confirm that. Here is a list of part numbers and rom images: https://www.zimmers.net/anonftp/pub/cbm/firmware/computers/c64/index.html

But also know that the roms in these systems are old style 2364 or 2332 (depending on size) so you may need an adapter or special eprom that is kind of rare, if you cannot use an original part.
 
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Thanks, this seems to describe my problem pretty well: https://www.pictorial64.com/fault.htm?id=u3_1

Unfortunately I do not have an eeprom programmer or chips and I don't want to break the bank.

My most readily available solutions are either trying to swap in a Basic rom chip from my breadbin or buying a new chip that already has the SX-64 ROM image on it.

This guy seems to sell new chips, but doesn't carry any for SX-64 https://diychris.com/product-catego...n-replacements/rom-chips-modern-replacements/

I'll see if my breadbin is the same size chip. Any risk of just popping that in there?
 
I’ll bet they are the same. They should have part numbers on them. Is the chip on the breadbin socketed? I think I had to desolder one of mine when I replaced it, but I could be wrong. It’s kind of the luck of the draw as to what has sockets and what doesn’t on these.
 
Pulled out my "parts" C64 with the bad sound chip and took what I believe is the basic ROM chip out (highlighted with square in pic below).

This C64 has a 5pin video port which was a pain. It does have the ROM chips socketed, so that was easy.

This website says: "326298 Rev A – C. 1982. Schematic # 326106. These boards turned up in silver label C-64s, and later versions of it turned up in the first rainbow-label breadbins. These boards are notable for their 5-pin video ports"

https://dfarq.homeip.net/commodore-64-motherboard-revisions/
 

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After stealing the BASIC ROM from the C64, I popped it into the SX-64 UD4 socket, highlighted in pic below.
 

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That did the trick! Now I get text on the screen.

2 questions:
Why does it say "SX-64 BASIC V2.0"? Shouldn't it not say SX-64 since the chip is from my C64?
The keyboard seems quite unresponsive. Sometimes it will work, sometimes it will take a couple hits, sometimes it seems like there is a delay. Not all keys are working. Will investigate, but it seems most of the right half of the keyboard doesn't work.
 

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I’m glad you got it working!

I think the basic rom is the same. The kernal rom is different so that is probably what displays the different colors and the sx-64 text. Just my guess.
 
I cleaned my floppy with the Wang Cleaning Kit by repeatedly hitting reset to make it run/seek the drive. It sounds pretty good so I'm hopeful that works.

This keyboard definitely has a problem. I've seated the keyboard cable multiple times (it's commodore branded). The spacebar works every time, but most of the letter/numbers don't do anything or require multiple presses. Is there a known issue on these, like the foam-and-foil replacement I did on my Compaq Portable's Keytronic keyboard? Will research.
 

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The keyboard membrane in the SX-64 is notorious for failing. These can be replaced with a modern replica; if I recall correctly there are two different sources for these. I restored two SX-64 keyboards to full functionality by replacing the membrane. I'll check my notebook and provide you with the sources ASAP.

Found it:

www.sellmyretro.com

New Commodore SX-64 Keyboard Membrane / Mylar

This is a replacement Commodore SX-64 Keyboard Membrane (or Mylar) - manufactured to a high quality using the latest techniques and should outlast the original membranes. Keyboard membrane failure is the most common problem with a Commodore SX-64 (SX64) 'luggable' computer (also known as the...
www.sellmyretro.com www.sellmyretro.com

I bought several from this source and they worked flawlessly.
 
Lardlad said:
The keyboard membrane in the SX-64 is notorious for failing. These can be replaced with a modern replica
Click to expand...
Thanks, sure enough I found lots of people had keyboard issues with this portable. I ordered a new membrane and will replace/update if that does the trick.
 
Thanks for the help. I ended up buying the membrane on Amazon from "Retro Fuzion". It was around $25. It did not include the clear spacer I've seen in videos. I installed it and now have full functionality on the SX-64.

As I've said, I have no real Commodore background. I don't have any commodore floppies and only have 1 cartridge. I do have huge amount of blank NIB floppies and a couple tweener machines (I've wrote images for my TRS-80 line of computers before).

Can I write floppies from MSDOS on PC with a 360k or 1.2mb 5.25" floppy drive?
I also have 1541-II and 1571 floppy drives.


Is there a better, modern way to check out old software?
What are some key demos or games I could enjoy? I love modern demos on old hardware (example: Area5150 on the IBM PC)

It may be better for me to open a new thread for those questions.
Thanks
 

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There are cables and devices you can use to connect the external floppy drives to PC, such as XE1541, XU1541, ZoomFloppy, XoomFloppy and probably a few others. Yiu may struggle with copy protected disks, but this method would probably let you make lots of floppies.
 
As noted by Jafir, the Zoomfloppy is a good choice if you have a 1541 floppy drive - you can connect it to a PC and write a D64 to a floppy disk. Another option is a flux reversal reader/writer like Kryoflux or the Greaseweazle. These devices will allow you to connect virtually any 5.25", 3.5" and even 8" floppy drive to a PC and read/write disk images. They ignore the metadata and simply reproduce the pattern of flux reversals on the magnetic media. Doesn't matter which OS wrote the disk image. I just received the Greaseweazle (RetroFuzion carries them), haven't tried it out yet.
 
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If you're looking for information about games and demos for the Commodore 64 I would recommend lemon64.com, they have an extensive database of C64 software with reviews and screenshots as well as a great community of C64 enthusiasts. There are various archives of C64 software around the net, csdb.dk is a good one. In addition to having a few 1541 floppy drives I invested in a 1541 Ultimate II+, which is a cartridge for the C64 that does cycle-exact emulation of the 1541 floppy drive. It allows you to plug several USB sticks into it and mount D64 floppy images as if they were actual floppy drives as well as running cartridge dumps (CRT files) and has a host of other functions including connecting to wireless networks or ethernet networks. These can be found at ultimate64.com.
 
Thanks. I took a look at some options.

I'd like to keep my costs low, as I see myself only occasionally doing C64 stuff and so I'd have trouble justifying the Ultimate64. I'd be surprised if I find a dozen games/demos that I'd like to try out .

The zoomfloppy is about on the high end of what I'm willing to pay to mess around with this (considering I'm already into this SX64 for $125 with the membrane).

I might investigate this parallel to IEC cable since I have plenty of early PCs
 
Still working through the inscrutable instructions on how to write a C64 image. Does this fatal error mean anything for my 1571?
 

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Behaved a little better after trying a format command. I'm using some NOS DS,DD floppies.
But upon typing what I think is the correct incantation,
LOAD"$",8,1
it just briefly flashes some garbage characters on the top row and then says ready at the bottom where you can type.
 

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Yes, error 20 usually means the disk is unformatted. cbmcopy does not format the disk for you.

In the second case, the disk is probably working. On the SX-64, try pressing SHIFT-RUN/STOP to run the first file.
 
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