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General Category => Technical Support => Hardware related => Topic started by: Shining on 22:11, 31 August 16

Title: 6128 not booting anymore
Post by: Shining on 22:11, 31 August 16
My 6128 is not booting anymore. When I turn the CPC on, the welcome message will appear and then the CPC resets, shows the message and so on in an endless loop. Has anyone an idea/suggestion how to fix this ?
Title: Re: 6128 not booting anymore
Post by: VincentGR on 23:22, 31 August 16
Maybe is the keyboard or Z80 needs to be pressed down or maybe just wait Bryce  ;D
Title: Re: 6128 not booting anymore
Post by: CraigsBar on 23:50, 31 August 16
Do you have any expansions fitted? Are your system ROMs socketed?
Title: Re: 6128 not booting anymore
Post by: Shining on 08:06, 01 September 16
Sadly, I think I exactly know why the CPC is damaged but not how and where:

I've put an extension at my Mother-X4 not exactly at the right pins (as you may know, these are not idiot (me  ;) ) save).

After that the CPC showed this behaviour.

If the ROMs are socketed, I don't know. I didn't open it for years, it is my main and first CPC and because of that I especially love this one. I've put many things into this CPC, for example ABBA-Switch, Reset-Switch, CPM-Switch, Pause-Switch but I never did something with the chips. So if they are not socketed by default, they are not.
Title: Re: 6128 not booting anymore
Post by: Audronic on 08:52, 01 September 16
@Shining (http://www.cpcwiki.eu/forum/index.php?action=profile;u=922)


Remove all peripherals, Mother x etc including external floppy drives.
Just the 6128 Power up as normal. Is the fault still there. ?
Ray
Title: Re: 6128 not booting anymore
Post by: Bryce on 09:27, 01 September 16
It could be a few different parts causing this, but you've definitely damaged either the ROM or some of the TTL logic. Most likely by feeding 5V into any output. Send the board over if you want.

Bryce.
Title: Re: 6128 not booting anymore
Post by: TFM on 17:25, 01 September 16
Sounds like a corrupt lower ROM (or the BASIC or AMSDOS ROM). Yes, Bryce can help.  :)
Title: Re: 6128 not booting anymore
Post by: Bryce on 14:21, 03 September 16
Board just arrived. I'll report back later in the week when I've had a chance to look at it.

Bryce.
Title: Re: 6128 not booting anymore
Post by: Bryce on 16:22, 04 September 16
Ok, a quick round of diagnostics later... 40015 (AMSDOS ROM) has D3 jammed high (not good). I'll put a socket in and replace it with an EPROM.

Bryce.
Title: Re: 6128 not booting anymore
Post by: Shining on 14:12, 05 September 16
Thank you very much. Also for the socket.... ;)


If you want to test it later, please note, that I soldered an ABBA switch to the board and sending it to you I just cut the cables.... Also there are two wires on the Jumper for the CPM-switch (AMSDOS to ROM 0).
Title: Re: 6128 not booting anymore
Post by: Bryce on 16:35, 05 September 16
Yes, I discovered that quite quickly, especially as you have also removed LK7 and added wires to that too.

Bryce.
Title: Re: 6128 not booting anymore
Post by: Bryce on 20:12, 05 September 16
All tests completed, your 6128 is back working as it should.

Bryce.
Title: Re: 6128 not booting anymore
Post by: Shining on 21:58, 05 September 16
Wonderful, thank you very much  :) .
Title: Re: 6128 not booting anymore
Post by: CraigsBar on 23:39, 05 September 16
Thank you very much. Also for the socket.... ;)


If you want to test it later, please note, that I soldered an ABBA switch to the board and sending it to you I just cut the cables.... Also there are two wires on the Jumper for the CPM-switch (AMSDOS to ROM 0).
What is the advantage of amsdos in slot 0. Surely the machine don't boot then?
Title: Re: 6128 not booting anymore
Post by: Bryce on 23:42, 05 September 16
What is the advantage of amsdos in slot 0. Surely the machine don't boot then?

It boots directly to CP/M when you have the right disk inserted.

Bryce.
Title: Re: 6128 not booting anymore
Post by: Duke on 23:43, 05 September 16
What is the advantage of amsdos in slot 0. Surely the machine don't boot then?
Autoboots CPM when in slot 0.
Title: Re: 6128 not booting anymore
Post by: CraigsBar on 00:13, 06 September 16
Autoboots CPM when in slot 0.
Really? Have to try that lol.
Title: Re: 6128 not booting anymore
Post by: TotO on 00:23, 06 September 16
Require a special jumper set on the mainboard, if I'm not wrong?!
Title: Re: 6128 not booting anymore
Post by: TFM on 02:08, 06 September 16
You are right. Just cut a metal wire on the PCB (or add a switch). Also putting FutureOS ROM A in slot 0 will cause autoboot of it. And cutting LK seven just "moves" AMSDOS from slot 7 to 0.  :)
Title: Re: 6128 not booting anymore
Post by: Audronic on 02:44, 06 September 16

.... Also there are two wires on the Jumper for the CPM-switch (AMSDOS to ROM 0).
Do You have link to the detail for this CPM Modification Please.


Thanks    Ray
Title: Re: 6128 not booting anymore
Post by: Shining on 09:11, 06 September 16

Here is a description of the LKs on the CPC-Mainboard:

LK Links - CPCWiki (http://www.cpcwiki.eu/index.php/LK_Links)


The CPM-one is LK7. When you cut it AMSDOS is switched to ROM0 and autoboots CPM.


I did this modification as a child as it had also the advantage that some games (e.g. Gauntlet) auto booted with this modification....
Title: Re: 6128 not booting anymore
Post by: Shining on 10:02, 06 September 16
For those who are interested just to list all modifications to my 6128 I found useful back then: