Author Topic: Problem CPC6128 Fixed Thanks to all who Contributed.  (Read 7651 times)

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Offline Audronic

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Re: Problem CPC6128
« Reply #25 on: 08:51, 06 February 20 »
Hi All

Ok after replacing the 74HC240 IC203
The machine now boots  Phewww
BUT I have phantom keyboard input on the machine.
If I boot with my xmem attached I go straight into SOS's Yancc on the second restart But its working
I will look at the keyboard input tomorrow

Interesting project

Thanks to all who offered assistance

Ray
« Last Edit: 08:53, 06 February 20 by Audronic »
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Offline Bryce

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Re: Problem CPC6128
« Reply #26 on: 09:49, 06 February 20 »
Cool. So, if it also gives those phantom keys when the keyboard isn't attached, then it's either the AY or IC101 (74LS145). The AY is the most likely candidate as they are much more prone to failing.

Bryce.
 

Offline TotO

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Re: Problem CPC6128
« Reply #27 on: 10:01, 06 February 20 »
I got the "96RUN ..." text displayed when my AY "BC2 pin" was not connected to VCC... But, I think that can be another problem around that.
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Offline Audronic

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Re: Problem CPC6128
« Reply #28 on: 11:00, 06 February 20 »
@Bryce @TotO

Yes no keyboard attached.

Thanks I am cutting out the AY as the emails arrived.
I will power it up soon without the AY then fit a socket and try again.


Thanks All


Ray
 
Procrastinators Unite,
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Offline Audronic

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Re: Problem CPC6128
« Reply #29 on: 11:15, 06 February 20 »
Hi All


Interesting with the AY removed I get on the screen :-


63RUN". Then drops down a line and backspaces the cursor to the normal position


Ray
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Offline Bryce

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Re: Problem CPC6128
« Reply #30 on: 11:41, 06 February 20 »
That might be just due to floating inputs on the 8255, but if it still does that with a new AY installed, then the 8255 is bad.

Bryce.

Offline Audronic

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Re: Problem CPC6128
« Reply #31 on: 02:14, 07 February 20 »
Hi All

Nearly there ?

Normal Boot screen, Keyboard input NOT WELL.
Ok So on with the saga. The next victim will be IC101 74ls145 Keyboard decoder.
Where did I put those snippers.

Ray
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Offline Audronic

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Re: Problem CPC6128 RESOLVED thanks
« Reply #32 on: 07:43, 07 February 20 »
Hi All

Fixed

Ran out of Ay3-8912 (NOT A), only had an AY3-8912A so on this Motherboard Z70290 there is provision (Holes for a socket)
 for some 9 pin 2.2k Resistor Arrays (A222J) pullups , Fitted.
Keyboard works. no double characters.
I was unable to get the Dandanator to work Grrrrr
Had a broken track (trace) near the 50 Way expansion connector.
It turned out to be the /RD (Pin32) line. Replaced with appropriate wire Now OK Dandanator works.

What an interesting Sheep of Hit this project was.

Thanks to all who helped, Every comment has some merit.  Thanks

Ray
« Last Edit: 12:12, 07 February 20 by Audronic »
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Offline Bryce

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Re: Problem CPC6128
« Reply #33 on: 09:26, 07 February 20 »
Well done. Another CPC back working.

Bryce.

Offline TotO

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Re: Problem CPC6128
« Reply #34 on: 12:36, 07 February 20 »
I have not spoke about AY /A version, because I though that you was using the original AY.  ;D
Nice to know your CPC is now working again!
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Offline Bryce

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Re: Problem CPC6128
« Reply #35 on: 13:26, 07 February 20 »
I have not spoke about AY /A version, because I though that you was using the original AY.  ;D
Nice to know your CPC is now working again!

He was using the original AY, but he only had an A version as a spare when he went to swap it.

Bryce.

Offline TotO

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Re: Problem CPC6128
« Reply #36 on: 14:01, 07 February 20 »
He was using the original AY, but he only had an A version as a spare when he went to swap it.
I have understood that he got the "63RUN" issue with the original AY, because this may occur with the "A version" w/o resistor network. By the way, it is good thing to have recovered his CPC.
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Offline Audronic

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Re: Problem CPC6128 Fixed Thanks to all who Contributed.
« Reply #37 on: 04:43, 08 February 20 »
Hi All

An overView of what went on:-

Amstrad CPC6128 Components Changed :-

1)   8255
2)   40025
3)   4164 (1) Ic 120
4)   40015
5)   74HC240 (FDC Circuit)
6)   AY-3-8912(A) and Resistor array

7)   74LS145 IC101. 
8)  Trace repaired /RD to 50 Way expansion connector
     Trace Repaired as Dandanator would NOT work,

NB:- Sockets were added for the I/Cs.

Test Equipment used :-

Voltmeter.
Digital Probe.
Soldering Iron & Solder.
Solder Sucker.
Schematics.

Memory Bank Change (HAL Socket).
Lower Rom board with 2 Ram Tests (Geralds)
Dandanator as a test device.
Eprom programmer to replace the 40015 and 40025.

Brains.
Good sense of Humour and Coffee.


Ray
« Last Edit: 05:29, 08 February 20 by Audronic »
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.