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General Category => Technical Support => Topic started by: Dinorast on 19:23, 27 January 21

Title: GX4000 maybe fried ?
Post by: Dinorast on 19:23, 27 January 21
My 14 year old daughter gave me a "cleaning voucher" for my mancave to my birthday and some days ago, she started to clean some light dust from my collection. Unfortunatly the power cord of my gx4000 (alternative 9V power supply because of the C4CPC flashcard) dropped out and I guess she plugged it in on the outer port of the console. I switched it on and got a very unhealthy smell from my little beauty gx4000 when I turned it on today. The green power lamb still shines bright in green so I guess its not just a fuse which went up...screen is black and no sound ???

Is it still saveable ? What can I do...please help me...many thanks





Title: Re: GX4000 maybe fried ?
Post by: Bryce on 19:37, 27 January 21
Ooo, it may be fried. You could send it to me (I'm in Köln) to check it out. If you are really lucky she only fried a RAM, but if the ASIC took the over-voltage it's an ex-GX4000.

Bryce.
Title: Re: GX4000 maybe fried ?
Post by: Dinorast on 20:08, 27 January 21
That would be fantastic - many thanks for your help !!! I will send you a pm.


We can show the results here to help also other users, which are might having also a helpful daughter, as I  ::)




Title: Re: GX4000 maybe fried ?
Post by: Bryce on 20:16, 27 January 21
"Helpful" children are always a challenge. My son (9), who's doing his best to learn electronics, accidentally shorted the output of my (relatively expensive) function generator with all protections turned off and I couldn't even be angry with him, because he was trying his best to impress me. It's hard to be angry in those circumstances. That's part of parenthood.

Bryce.

And just for him, here's his first attempt at drawing a schematic designed by him. Bonus points if you can guess whether it works and what it does...


Title: Re: GX4000 maybe fried ?
Post by: Dinorast on 20:25, 27 January 21
Yes, I could also not be angry with my daughter, even when the "fishy smell" hit my nose, when I turned on the console today. >:(


Nice drawing schematic of your son-I guess you can use this as a part of the flux compensator from back to the future and travel back in time   ;D
Title: Re: GX4000 maybe fried ?
Post by: Animalgril987 on 20:47, 27 January 21
Hi Bryce.
Flashing LEDs, maybe? Not sure about the function of the LH transistor, though, as the base isn't connected to anything.
Do I get the bonus points?



Title: Re: GX4000 maybe fried ?
Post by: Bryce on 21:06, 27 January 21
Yes, I could also not be angry with my daughter, even when the "fishy smell" hit my nose, when I turned on the console today. >:(


Nice drawing schematic of your son-I guess you can use this as a part of the flux compensator from back to the future and travel back in time   ;D

Oh, fishy smell is a good sign! That could mean that a capacitor shorted and saved the rest of the components.

@Animalgril987 (https://www.cpcwiki.eu/forum/index.php?action=profile;u=3936): The LH transistor is a photo-transistor. It gets biased by light = no connection.

Bryce.
Title: Re: GX4000 maybe fried ?
Post by: Animalgril987 on 00:07, 28 January 21
Oh, yes, my bad. I didn't spot that they were arrows ( eyes getting older).


So, automatic light switch?
Title: Re: GX4000 maybe fried ?
Post by: Dinorast on 11:08, 28 January 21
Oh, fishy smell is a good sign! That could mean that a capacitor shorted and saved the rest of the components.

Very good news  :) I keep my fingers crossed, that the little beauty can be rescued
Title: Re: GX4000 maybe fried ?
Post by: Bryce on 16:16, 30 January 21
Oooo, parcel just arrived... That smells nasty! Something is badly fried inside. I'll take a look at it tomorrow (with the windows open).

Bryce.
Title: Re: GX4000 maybe fried ?
Post by: Bryce on 16:33, 30 January 21
Repair tip No. 287: If a RAM IC is running at 115°C !!! Then there's a good chance it's no longer working. Now lets hope it failed fast enough to protect all the other bits on the board.

Bryce.


Title: Re: GX4000 maybe fried ?
Post by: Dinorast on 12:33, 31 January 21
Wow, I still have the nasty smell in my Gameroom. 115 Degrees  :o Ist now -8 here, I could have used the GX4000 as a heater for the house…

I still keep my fingers crossed, that it will not go in the rubbish bin...

Thank you very much
Title: Re: GX4000 maybe fried ?
Post by: Bryce on 14:25, 31 January 21
Alas, the news is not good. I swapped the RAMs first because it's quick and easy to do, but the ASIC isn't putting out any video signals at all :(

Looks like your daughter owes you a GX4000.

Bryce.
Title: Re: GX4000 maybe fried ?
Post by: Dinorast on 15:01, 31 January 21
What a bummer... But many thanks for your help.


If anyone wants to sell one, please let me know  :)
Title: Re: GX4000 maybe fried ?
Post by: Bryce on 15:23, 31 January 21
Hold my beer! I have a crazy idea. I have a fried CPC+ here. The ASIC was the problem...buuuut... It way a keyboard scanning problem and it was a Row that the GX4000 doesn't use!

I'll try swapping the ASICs out and see if I can get a working GX out of it if you like? May not work, but it's worth a try?


Bryce.
Title: Re: GX4000 maybe fried ?
Post by: Dinorast on 15:31, 31 January 21
Would be grand if it works  :D 
Title: Re: GX4000 maybe fried ?
Post by: Bryce on 15:32, 31 January 21
Nothing to lose, stay tuned...

Bryce.
Title: Re: GX4000 maybe fried ?
Post by: Bryce on 16:18, 31 January 21
So, I removed the damaged ASIC using a rather old-school method, so I thought I'd document it here as a tip to my fellow finger-burners...

This is called the wire method. It's only useful when you don't want to save the chip you're removing. It's really good though, when you are working on an old PCB with very small/thin pads. You thread a thin enamelled wire under the row of pins and solder one end of the wire to some point on the PCB (I usually use some exposed ground plane as the anchor), then heat each pin while pulling the wire slowly on the loose end under the pins. The advantage of this method is that there is no pressure applied to the pads, so they all survive. It's also good if you have plastic parts close by that would get damaged from a heatgun. I used 0.15mm enamelled wire here. It has to be enamelled, otherwise it will get stuck in the solder.

You can see the wire on the left row of pins.

Bryce.

Title: Re: GX4000 maybe fried ?
Post by: TotO on 16:35, 31 January 21
Does the ASIC circuit has been decapped?
Title: Re: GX4000 maybe fried ?
Post by: Bryce on 16:54, 31 January 21
Does the ASIC circuit has been decapped?

If not, they can have the one I just removed.

Bryce.
Title: Re: GX4000 maybe fried ?
Post by: TotO on 17:04, 31 January 21
If not, they can have the one I just removed.
Exactly what I tough. 8)

Sean Riddle does the job for the Gate Array: http://www.seanriddle.com/ (http://www.seanriddle.com/)
Title: Re: GX4000 maybe fried ?
Post by: Bryce on 17:54, 31 January 21
Well, it was a longshot, but it didn't work. The other ASIC has failed too, probably too sensitive to survive the removal and resoldering :(
It now just fails differently.


Bryce.
Title: Re: GX4000 maybe fried ?
Post by: Dinorast on 20:05, 31 January 21
It was worth a try... I will see where I get a different one. I will deduct it from her pocket money  8)


No of course not...my daughter is ashamed enough already and she will never clean up again  :D
Title: Re: GX4000 maybe fried ?
Post by: Bryce on 20:17, 31 January 21
It was worth a try... I will see where I get a different one. I will deduct it from her pocket money  8)


No of course not...my daughter is ashamed enough already and she will never clean up again  :D

You're right, you need to be fair and balanced. I'd suggest letting her out of the locked basement next weekend and the bread and water diet should only be until the end of March.

Bryce.


Bryce.
Title: Re: GX4000 maybe fried ?
Post by: eto on 20:25, 31 January 21
Why did the 9V adapter fit into the 5V socket?
Title: Re: GX4000 maybe fried ?
Post by: Dinorast on 20:31, 31 January 21
No no-no butter-she must learn from her mistakes  :D
Title: Re: GX4000 maybe fried ?
Post by: Dinorast on 20:34, 31 January 21
Why did the 9V adapter fit into the 5V socket?


It was not he original Power unit anymore... I used the C4cpc Flashdrive so I took a 9v alternative unit, unfortunately it was fitting in both sockets
Title: Re: GX4000 maybe fried ?
Post by: Bryce on 21:10, 31 January 21
Why did the 9V adapter fit into the 5V socket?
Because Amstrad stupidly used similar sockets and didn't even bother labelling them!

Bryce.


Title: Re: GX4000 maybe fried ?
Post by: dragon on 01:46, 01 February 21
Exactly what I tough. 8)

Sean Riddle does the job for the Gate Array: http://www.seanriddle.com/ (http://www.seanriddle.com/)


But it's not clear as de 40007 or 40010.i think the logics gates can't be read and reversed. Because is more modern and more little. In nm




We know now is a thosiba by eBay protype action. One thosiba chip less in the world.
Title: Re: GX4000 maybe fried ?
Post by: tjohnson on 22:53, 04 February 21
If you use an 8pin din to scart and 5v supply you can remove the risk of this happening, alt remove or cap the 5v input.