Video problems when running games and... I am new

[bola_dor]

About ULA bridge with the capacitor is there any risk involved? Beyond me making any sort of short circuit and ending up in fire ?

Are you okay with knowing the numbering of DIL chip pins?

If soldering it on the bottom, this should be done with the computer switched off or disconnected.

Mark

I guess 40pin is 1st top to the right looking from above and then counting backwards..
I am aware that killing the ULA Is to kill the machine itself so I have a replacement ULA I've found, I have to test it before and probably USE this instead. I am not sure what ULA version is it..
(This is not the one actually fitted on)

[mrtinb]

In the signature of every 1024MAK's posts, there is a link to the ZX81 chips pinouts.

[dessony]

Bola_dor,

Thank you for an implied clarification!

Everybody,
http://www.sinclairzxworld.com/viewtopi ... fer#p25270 Horizontal track "line with its two (2) arrowheads attached" is a copper strip on the veroboard/stripboard. Also, notice that I put several numbers beside a board's vertical side, that is for the "track". I put "Top View" box on the drawing. Be considerable about the transistor's flat side on the board before putting a soldering iron near one of the transistor's leg. "c" is a collector. "b" is a base. "e' is an emitter. I am writing this one for Bola_dor and the potential future electronics newbies.

1024MAK,
How about both of us making a printed circuit board based on your excellent video buffer transistor circuit?

Thank you very much in advance.

Cheers,
Dessony

[bola_dor]

Can it be done directly over the ULA socket? Perhaps without soldiering? Do you suggest me to try different nF values? In that case which ones?

The value is non-critical, hence me suggesting a range of values, as I don’t know what is available to you. Ideally a larger value is better than a smaller value. If you have / can get a range of different values, by all means try each value to see what, if any difference it makes.

You could try holding it onto the pins to see if there is any difference (being careful not to accidentally short anything out), but for permanent fitting, I suggest putting it on the bottom of the board and solder it to the pins of the socket. You may need some insulated sleeving to guard against the leads of the capacitor any other pins or connections.

Please keep in mind, we are in the experimental game here. There are no certainties...

Mark

I've just tried the capacitor thing without any success..
With 100nF I couldn't see any difference..
I didn't find any 470nF so I used a multilayer 330nF and I didn't much but even worsened a bit..
Today I had better image than yesterday without any strong vertical banding anyway...
What did reallly improved image quality whas an ice cube into a latex glove directly over the ULA.. so heat is the principal problem...