Help - My CPC suddenly has all kinds of weird inputs!

[bolton80]

Hi All,

Last week I successfully cleaned the membrane of my 'new' (to me at least) CPC464 and it worked perfectly. However, I was still having a few issues with joystick inputs.

So when I loaded a game I decided to unplug the joystick so I could use keyboard controls without any possible interference from a dodgy joystick. When I did this the CPC crashed. I restarted it and since then, every time I turn the CPC on, I get the following inputs, immediately.  You cannot view this attachment.   

I opened up the CPC again and disconnected the keyboard membrane ribbons (both) and powered it on. No change, so I'm confident it isn't the keyboard itself that is causing problems. I checked the motherboard and made sure the whole area of the controller port and surrounding chips was clean, but nothing has made a different. 

Any idea what is happening and what I need to do to fix it please? I'm really frustrated with myself!

[darkhalf]

Unfortunately may be the AY sound chip which takes joystick and keyboard might be damaged. Pio generates the signals and AY reads them in

[pelrun]

Agreed - the AY-3-8912 (which is the chip right next to the joystick connector on the 464) is toast. Did that to my 6128 as a kid, after I got a zap picking up the joystick and touching the monitor at the same time.

Replacements are available, though sellers are gouging the market at the moment. You will also probably end up with an AY-3-8912A, which is a drop-in replacement *except* that it also needs an additional 9-pin 10k SIL resistor network to be soldered into the row of solder-filled holes next to the keyboard connector. ( https://www.cpcwiki.eu/forum/technical-support/6128-ay-3-8912a-works-in-cpc-6128/ )

There's a thread elsewhere on here that has an adapter for using a cheaper AY3 variant with a different pinout, but I can't find it at the moment.

[eto]

There's a thread elsewhere on here that has an adapter for using a cheaper AY3 variant with a different pinout, but I can't find it at the moment.

https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/ay-3-8910-adapter-for-amstrad-cpc-to-stop-exploitation-for-ay-3-8912!/msg224245/#msg224245

[bolton80]

Thanks @darkhalf and @eto .

Unfortunately this type of thing goes beyond my levels of soldering knowledge, so I've contacted a professional (Mutant Catapillar) for a price.