Author Topic: CPC 464 -- all basic commands result in Syntax Error & a pinched y  (Read 353 times)

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Offline thomas

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Hi There!

I'm trying to revive my "Schneider" CPC from '84. It boots up, but I cannot issue (basic) commands.  Every command gives me a "syntax error".

What's also odd:
- the "y" character has a hole
- pressing ESC reboots the machine (is this normal?)- pressing "key up" (in the area with the "copy"-key) prints "fat up arrows" (is this normal?)

My experience with Amstrad is very little and besides a video cable I do not own any peripherals or software (but a Dandanator is on it's way).

Things I tried so far:
- cleaned everything up, including kbd membrane
- reflowed solder joints around RAM chips
- reinserted the two socketed chips (z80 + 40010)
- searched for broken traces and cold solder joints (magnifying glass, sunlight)
All ICs stay kinda cool.Board has PT No. Z70200.

if I had to guess, I'd say it's a bad ROM; with faulty RAM, it wouldn't even boot, right?
Any help would be greatly apreciated!
- thomas
« Last Edit: 18:02, 15 February 21 by thomas »

Offline GUNHED

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Looks like the lower ROM has problems / is corrupted. Should be easy to change (you can use an EPROM).
http://futureos.de --> Get the revolutionary FutureOS (Recent update: 2021.01.24)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.02.18)

Offline thomas

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Thank you!

Just to make sure: the ROM is the 400007?
- thomas

Offline Audronic

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@thomas


No NOT the 40007


The ROM is 40009 (Left hand side )


Keep Safe


Ray
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.

Offline thomas

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 :doh: ah yes -- I meant it! :-) The 40009 below the sond chip. Sorry!
- thomas

Offline thomas

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got a Dandanator and some of the preinstalled games run just fine! :-)
Now, I will have to wait for the equipment to arrive needed to burn and replace the bad ROM.  :-)

- thomas

Offline Gryzor

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Will no one mention the black and white mode? :D

Offline thomas

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hm yes ... I don't know why it is B/W. Using a cheap (Amazon, 20 €) SCART to digital converter which I blamed for the B/W picture. (?)
Hopefully it's not another fault of the machine (Chroma gone?). Any ideas on how to chase that problem are welcome! :-)
- thomas

Offline Bryce

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hm yes ... I don't know why it is B/W. Using a cheap (Amazon, 20 €) SCART to digital converter which I blamed for the B/W picture. (?)
Hopefully it's not another fault of the machine (Chroma gone?). Any ideas on how to chase that problem are welcome! :-)
- thomas

No chasing required, your diagnosis in the first sentence is most likely correct. There's another active thread here discussing / recommending which convertors work best. Yours most likely only converts the composite signal.

Bryce.

Offline thomas

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thank you Bryce! :-)

Offline thomas

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Morning!

Another minor problem: there is no Sound from internal speaker. Measured the resistance of the rotary knob between 8 and 12 Ohm.

I found some yellow stuff underneath a cap on the cassette PCB. First thought this would be leakage, but it is most probably some glue.

I'm kind of lost here, so if anyone can share some ideas how to debug that issue go ahead! :-)


Offline thomas

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what's nagging me more than the int. speaker: I replaced the ultra cheap Scart to HDMI box with one a little less cheap and RGB capability.
Color is good, but the picture is kind of "jumpy" (every other second it "jumps" to the left, next second it centers back; there seems to be some noise too).
Maybe a synchronization problem?

Waiting for a SCART cable for the C64 so I can test the upscaler with a different machine.
- thoma

Offline Animalgril987

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It wouldn't hurt to replace that cap, just in case.

Offline thomas

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YESS!!! :-)
After replacing this suspicious 22 micro cap and the "fat" one (C322, 470 micro) which had some "glue" underneath as well (but I guess it was ok) on the cassette PCB internal sound is working again! Yeah!

One down, (at least) two to go:
- replace the bad (?) ROM (waiting for a TL866II)

- figure out what's wrong with the sync signal; checked the traces for conductivity, lowered resistance of 317 to about 150 Ohm, everything seems OK. I guess my (new) converter box is not good enough for the Schneider (no problems with a C64, though); ordered a different upscaler, let's see if this will sync correctly
thomas

Offline Bryce

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YESS!!! :-)
After replacing this suspicious 22 micro cap and the "fat" one (C322, 470 micro) which had some "glue" underneath as well (but I guess it was ok) on the cassette PCB internal sound is working again! Yeah!

One down, (at least) two to go:
- replace the bad (?) ROM (waiting for a TL866II)

- figure out what's wrong with the sync signal; checked the traces for conductivity, lowered resistance of 317 to about 150 Ohm, everything seems OK. I guess my (new) converter box is not good enough for the Schneider (no problems with a C64, though); ordered a different upscaler, let's see if this will sync correctly
thomas

The C64 outputs a composite video or S-Video signal, the CPC outputs an RGB signal. Just because a converter works with a C64 is no guarantee that it will work with a CPC.

Bryce.

Offline thomas

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yes you're right .... (I forgot EVERYTHING about the different options for color output in the old days and just slowly regain some knowledge about RGB vs. Composite etc.  ... guess HDMI spoiled me somehow ...).   :o
Well, let's see if the new upscaler will fix my sync issue, people were prasing it for the Amiga (which has RGB as well, this time I'm certain! :-)
I also have one of the GBS 80-something boards (the newer model with HDMI out), but no means to connect it to the CPC at the moment.

- thomas