CPC 464 Light Grey picture - no beep when pressing DEL : (

[jclark1]

Hi All,

Been reading loads of these threads and amazed at the knowledge found here!

Just joined today so please so easy on me

I recently got a CPC 464 that initially worked fine apart from could not get tape deck to work at all.

Fixed this with a new rubber band woohoo!

Main problem started about 30 mins later when testing Oh Mummy after Harrier Attack,,, screen well kind of fizzled in middle of playing.

Turned off and on again and now just a light grey/blue screen.

New to this but got a multi meter to check the 5v output on chips.. all showing 4.90 to 5v apart from the Z80 chip showing 4.18v & the Amstrad 40010 showing 1.38v ...

My question is .. do you check for voltage output the same way on these chips as all the other ones on board??

Sorry if I am asking a silly question but new to this.

Thanks

Jason

[Bryce]

Are you talking about a completely grey/blue screen with no text? Does it have a square in the middle? If so, your RAM has most likely failed. A picture of the screen would be useful.

Bryce.

[jclark1]

Hi There Bryce ,

You very much a legend on this site from what I have read and thank you for replying : )

Yes the grey/light blue screen is showing with no text with a black border..

Was totally fine with BASIC loading and running couple games until the screen fizzled in front of my eyes

Fixed tape deck then this ha .. but totally enjoying the mission to find route cause of fault, with any kind help that comes my way.

I have included a screen shot showing the display.

Oh and I have read a lot of your replies on here and remembered one , with you saying 1st rule to check voltage output on IC's.

This this I got a multi-meter to check IC's for the 5v output , all good apart from the Z80 & 40010 chips... am I on a wild goose chase on this with the lower voltages through chips?

Your help kindly appreciated Bryce.

Jason

[Bryce]

Don't bother checking the voltages, that's a classic RAM failure. Have you the equipment / practise to replace them?

Bryce.

[jclark1]

Cheers for that, yes I have basic soldering skills , just need to get some sockets etc regarding the RAM chips you mention .. just to clarify are these the 8 chips on bottom tight of board guessing at 1bit per chip...?

Bryce where would you recommend getting quality sockets & ram chips from?

Thanks for you help with this

[betpet]

I, too, would like to socket my chips at some point. It makes me sad to say but with the machines being around 30-35 years old, parts are going to wear out and I'd like to make replacing them as easy as possible in future.

[jclark1]

Evening All 

I have ordered for chips via ebay from Chine .. 10PCS NEW MT MT4264-15 4264-15 DIP16 IC Chip

Exact same ones that are on circuit board.. also some 30PCS 16-Pins DIP IC Sockets Adaptor Solder Type Socke JE EH

The sockets will come quickly so I can prep the board yay!

The IC 4264 chips sound like will take longer but no worries .

Do the technical people on here think these will be good replacements for what already on board??

Cheers for every bit of advice on here too.

Jason

[Bryce]

If you are using 4264 chips you will need to replace the entire bank of 8 chips. Mixing 4164 and 4264 chips in one bank can cause problems.

Bryce.

[jclark1]

Thanks Bryce

Got my socket and same chips last week.

Just started taking the old RAM chips out , my eyes are not great so working with massive magnifying glass!!

Slowly getting the old ones out.

Noticed the sockets I got have very fragile legs.. no holding much faith this will insert very well without snapping

Thinking of buying some different ones that may have stronger legs , any suggestions on where to purchase good quality socket anyone?

Thanks for any help regarding this

Cheers

Jason