A Plea For A Solution To The Paddle Issue

Pedro Lambrini · Post by **Pedro Lambrini** » Sun Mar 14, 2010 5:14 am

There's been a fair bit of talk of late regarding all the breakthroughs in tech such as the venerable Mega-Cart, the uIEC and the FE3. There's even interest in possible future developments such as a 40 column card and voice synth solution.

While all this is fantastic there is one hole in the Vic's technical growth that has slipped through the net. I desperately want the jittery paddle issue fixed. I love paddles and the Vic has a number of great paddle games. It's such a shame that these games are rendered almost unplayable on the real hardware these days. I would also love to see a revival of these wonderful and under-utilised controllers. However, for that to happen there needs to be an elegant (and affordable) remedy to the Vic's jitters!

I therefore make this plea to the Vic community to try to resolve this problem. There is a ridiculous amount of talent on this forum and I'm sure there must be a real solution. I realise this subject has come up before but there's never been any real work done on it.

So, please, please, please can someone bring their skills to this and find a simple and usable solution once and for all. If you do I will donate £40 to the Denial forum in the 'conquerors' name!

ral-clan · Post by **ral-clan** » Sun Mar 14, 2010 7:46 am

You're right about this. There is a software fix, as has been used in Orion70's PONG port of a few years ago. That results in very smooth, non-jittery paddle motion.

However, that's only good for newly programmed games. There are all the older games that almost can't be played because of paddle jitter.

It is kind of an embarrassing gap. All this new great, complicated, and previously thought impossible hardware has come out for the VIC-20...yet a fairly basic afflication that affects all VIC-20s still remains "uncured".

Vic20-Ian · Post by **Vic20-Ian** » Sun Mar 14, 2010 9:18 am

I assume you want an external solution and not one that means desoldering the capacitors on the VIC motherboard?

It might be possible to put a smoothing filter on the two pins in between the joystick port and the joystick

female plug --- filter x and y pins --- male socket

What sort of frequency is the jitter?

ral-clan · Post by **ral-clan** » Sun Mar 14, 2010 9:36 am

Actually, both solutions (external and internal) had crossed my mind.

I'm no stranger to opening up and soldering inside my VIC, so I'd prefer an internal fix. But I can see how an external solution might be better for some people.

I'm not sure how to determine the frequency of the jitter. I looks fairly random on screen, but that's probably not an accurate measurement.

Pedro Lambrini · Post by **Pedro Lambrini** » Sun Mar 14, 2010 9:38 am

If the only internal solution is to change caps and the like then, yeah, an external solution would do.

It needs to be something elegant and simple so that everyone can re-obtain the paddle functionality. Desoldering old caps on the mobo is a little hardcore methinks, though if this was the only solution it would be better than nothing...

Vic20-Ian · Post by **Vic20-Ian** » Sun Mar 14, 2010 11:27 am

To quote Eslapion from 2008

"Replacing the two small capacitors between the paddle lines and the 6560 is the only solution I can think of.

These degrade over time. Perhaps using military grade ones would help the solution last longer."

It seems like my idea for an external filter would not be useful as the noise is introduced inside the Vic. This has been verified by using good paddles on Atari and C64 that jitter on the Vic. The jitter varies from Vic to Vic.

I will take a look at mine next weekend and see how jittery it is.

ral-clan · Post by **ral-clan** » Sun Mar 14, 2010 2:09 pm

Vic20-Ian wrote:To quote Eslapion from 2008

"Replacing the two small capacitors between the paddle lines and the 6560 is the only solution I can think of.

That's just the standing theory for the cause of the jitter right now, though. It's never actually been verified that those capacitors are the cause of the jitter (although it seems like a good theory).

Marstedt · Post by **Marstedt** » Sun Mar 14, 2010 5:17 pm

Can anyone point to documentation on how the circuit is used? I always thought it was a just a voltage-divider type of circuit and the jitter was just noise due to a poor implementation.

Also, has anyone tried using Deoxit on the pots?

ral-clan · Post by **ral-clan** » Sun Mar 14, 2010 8:50 pm

Marstedt wrote:Also, has anyone tried using Deoxit on the pots?

I have tried TV-tuner contact cleaner on the pots inside my paddles. It does help somewhat, but there is still a small amount of jitter. The same paddles when plugged into an Atari operate smoothly.

Marstedt · Post by **Marstedt** » Sun Mar 14, 2010 9:32 pm

ral-clan wrote:I have tried TV-tuner contact cleaner on the pots inside my paddles. It does help somewhat, but there is still a small amount of jitter. The same paddles when plugged into an Atari operate smoothly.

Well I know that Deoxit is one of the best contact cleaners / enhancers that is available and I've had it do wonders everytime I've used it on a problem. But, it does sound like the VIC20 is somehow overly sensitive or noisy in this situation.

Pedro Lambrini · Post by **Pedro Lambrini** » Mon Mar 15, 2010 2:56 am

Indeed, it's definitely an internal problem. I have 3 sets of paddles (both Commodore models and the Atari ones) and they all work perfectly on other systems. The Vic is the only machine with the jitters...

Schema · Post by **Schema** » Mon Mar 15, 2010 7:43 am

I agree, it's internal. Quite a while ago, I rigged up a circuit with a tiny resistor network giving the same resistance as paddles/potentiometers at the center of their range and plugged it into the VIC. Yet, the jitter was still there.

ral-clan · Post by **ral-clan** » Mon Mar 15, 2010 7:55 am

Schema wrote:I agree, it's internal. Quite a while ago, I rigged up a circuit with a tiny resistor network giving the same resistance as paddles/potentiometers at the center of their range and plugged it into the VIC. Yet, the jitter was still there.

Well, I guess that nails it then.

If it's just a matter of a couple common capacitors, that sounds easy enough to replace. Perhaps though they are not common or in hard-to-reach locations?

Pedro Lambrini · Post by **Pedro Lambrini** » Tue Mar 23, 2010 11:50 am

My offer still stands.

PaulQ · Post by **PaulQ** » Tue Mar 23, 2010 6:21 pm

ral-clan wrote:
Vic20-Ian wrote:To quote Eslapion from 2008

"Replacing the two small capacitors between the paddle lines and the 6560 is the only solution I can think of.
That's just the standing theory for the cause of the jitter right now, though. It's never actually been verified that those capacitors are the cause of the jitter (although it seems like a good theory).

In my own experience, Eslapion's "Theory" is never without considerable thought on his part. I'd take his word on it and just replace the caps.