repairs for vicist

[mrr19121970]

yes, sure

[vicist]

Got my board back from @mrr19121970 today.

So happy to have a competely working s-video modded Vic cr.

Big, big thanks for this.

[mrr19121970]

It is good to hear that you are happy.

[tokra]

Regarding the problem with your 32k-expansion - could you run the crosstalk-check for a few times (at least 5) and see if it reports some crosstalk? It will first show which BLKs and segments are available, that's fine.

http://www.tokra.de/vic/doom/crosstalk.prg

[mrr19121970]

Regarding the problem with your 32k-expansion - could you run the crosstalk-check for a few times (at least 5) and see if it reports some crosstalk? It will first show which BLKs and segments are available, that's fine.

http://www.tokra.de/vic/doom/crosstalk.prg

Thanks for the info. I now saw here http://www.forum64.de/index.php?thread/ ... crosstalk/ can it be fixed ??

[tokra]

You should first determine if crosstalk really is the problem here. Please re-download the program from the URL above, I made some changes so that non-existing RAM-blocks are skipped. If you activate both BLK0 ($0400-$0fff) and BLK5 ($a000-$bfff) you will see crosstalk, since this expansion is only 32K and uses the same RAM for both areas. However there should be no crosstalk between other areas.

[mrr19121970]

I try tonight.

[tokra]

Hmm, I looked at the original results of the memory-test and the memory-test program itself. It POKEs a value and then immediately afterwards PEEKs it. Crosstalk should not be the problem in this case. Is the result of the memory-test consistent? In that case it looks more like a simply broken RAM-chip on the expander.

To be absolutely sure crosstalk isn't the issue you could do the following as suggested by brain in another thread:

dload crosstalk.,prg from the other thread
[...]
run prg
verify errors occur
take out cart
find CR/W pin
Look where trace goes to [...]
Find VR/W pin
See if there is a nice way or inconspicuous way to cut the CR/W trace and wire the VR/W pad to that pin [...]
rerun test
See if error persists

[mrr19121970]

I was home too late yesterday to try, and now I'm on holiday for 1 week. Will try when I'm back.

[k3ys]

Hi guys,

I just happened to find this thread by sifting through tokra's posts. I don't get email pings from your use of "@k3ys" and I'm not terribly active on the forums.
@mrr19121970, the last PM I received from you was on Feb 26 RE: the diagnostics cart. I'm not sure what PM you're talking about, honestly.

I've ran tokra's crosstalk checker and indeed there is crosstalk between the 3K config and other banks. This is due to the use of the CR/W line instead of VR/W. However, I ran it all night with Switch 7 up (3K off) and there were no problems, and the 3K config seems to work fine by itself.

I've made modifications to one of the boards, cutting a trace and running a wire and the crosstalk goes away. Future boards will have this fix.

I am *really* curious how this crosstalk manifests itself. Can it cause problems with other internal memory locations, perhaps at $1400?

Regards

[mrr19121970]

I just checked my sent box. There is no pm (I asked you to look at the thread incase you he an idea). Never mind. You looked now. Can you please post photos of the mod that we need to do too ? Thanks.

[k3ys]

Here is the mod I did. The yellow circle shows it.

Cut the trace going from CR/W to the via.

Then solder a wire from the adjacent cart pad (VR/W) through the via to the other side. I just used the lead from a small capacitor that I had clipped earlier. It fit through the small via hole nicely.

If soldering through a via is too tricky for you, you can also run a wire from the VR/W pad up to pin 27 of the RAM chip, circled in magenta color.

Let me know if you have any questions about it.

[mrr19121970]

Well I ran crosstalk.prg now.

i assume when I see "crosstalk blk4>blk0" and the screen scrolls over the maximum this is really bad ???

Update

Even with only BLK5 active, I still have crosstalk from 0 > 1,2 & 3. Strange.

[tokra]

I have amended the crosstalk.prg so that it disregards memory areas that are not found. Otherwise crosstalk is to be expected between BLK5 and BLK0 when you set all switches to RAM as they use the same memory area in the expansion. I also fixed a bug that would display BLK4 instead of BLK5. Please re-download and re-test:

http://www.tokra.de/vic/doom/crosstalk.prg

Did you already make the modification mentioned above to your expansion? This is unclear from your post.

[mrr19121970]

Mod not made just yet. Testing only the expansion on my vic