My Schneider CPC 464 don't work.

[twox]

Hello, i have a Schneider cpc 464 (german version of Amstrad). It don't work, when i turn it on it shows big green rectangle (1) on screen (i have monochrome monitor) and sizzle. When i unplug video cable, it don't show the rectangle on screen (2). Sometimes it shows something another (3, 4). I cleaned the CPU a few times, but without effect. Any ideas?
Cheers.
1.

2.

3.

4.

[Devilmarkus]

Did you already swap the Z80A?

[twox]

No, i have not changed. I found this one: Z80A DART DIP40 STM Z8470AB1 (3943375658) - Allegro.pl - Więcej niż aukcje. (this is Polish auction site), will it work?

[gerald]

I found this one: Z80A DART DIP40 STM Z8470AB1 (3943375658) - Allegro.pl - Więcej niż aukcje. (this is Polish auction site), will it work?

No, the Z80A DART is an (dual) UART controller. You need a Z80A CPU.

But before changing the Z80, you can do the following :
   - Report us which version of the motherboad your CPC has from this page Mainboard Versions - CPCWiki, or just post a picture of it.
   - resettle the gate array on its socket.
   - Check for RAM device hotter that others. If so, you may have a failing RAM device

[twox]

1. I don't know which version of motherboard i have, it's late and dark in Poland so i will check tomorrow.2. So i have to turn on my CPC while it's disassembled and check if the RAM is hot?
3. And please simply explain how to resettle the gate array on its socket, because i don't know how to do it. It means i have to unplug gate array and plug it again?

[gerald]

1. I don't know which version of motherboard i have, it's late and dark in Poland so i will check tomorrow.2. So i have to turn on my CPC while it's disassembled and check if the RAM is hot?

Basically yes. You may need to disconnect the keyboard matrix (cable(s) on the left side of the CPC) to ease the opening, but you must keep the tape cable connected. The tape connector is also used for the power switch.

3. And please simply explain how to resettle the gate array on its socket, because i don't know how to do it. It means i have to unplug gate array and plug it again?

Resettling can be either pushing it back on its socket or getting it out and putting it back. start with just pushing it 


If you already opened you CPC, try to remind if the PCB filled most of the unit or just a fraction of if.
Big PCB is either version 1 or 2 : Mainboard Versions - CPCWiki.
The gate array is the 40pin component on the right top of the PCB. On revision 1 and some revision 2, the gate array has a heat sink on it. The 8 ram device are just below.

Small PC is either version 3 or 4 : Mainboard Versions - CPCWiki. Version 4 use a SMD asic, so there is nothing to do. For version 3, the gate array is on bottom right of the PCB. the 8 ram devices are just in the middle of the PCB.

[twox]

Here are photos of inside my CPC.









I can even play with mouse



I think this is version 3 or 4 of mainboard, im right?
Sorry for the bad quality, i dont have good camera.

[Devilmarkus]

For me it really looks like the Z80A doesnt write the correct CRTC values and even cannot start any ROM etc...
I'd swap the Z80A first.

[gerald]

This is a version 3 PCB.

From the 1st post picture you've posted, we can
   1. CRTC is properly set
   2. CRTC is not set OR CRTC set and GA paper/border color set
   3/4 CRTC is not properly set (wrong H/V sync timing)

The CRTC configuration is one of the early things done at boot. CRTC parameter being copied from ROM to RAM, problem can be either in ROM, Z80 or CRTC.
The next thing is initialise the RAM, and from there, the Z80 will use the stack and any corruption due to bad RAM will make the computer crash.

- Trying with a know working Z80 can be done. However, none of the symptoms clearly point to it.
- Resettling the Gate array (40 pin IC ref 40010) has to be tried, as it is dealing the all RAM access.
- Check for hotter than other RAM chip.

Also, it seems that the power connector has been patched


You should check that the board is properly powered (ie check voltage and bad contact)

BTW, avoid using your USB to PS2 to RS232 adapter on the joystick port 

[twox]

So i need to check voltage? If yes, tell me what voltage is correct and where i should check.
Im not expert on electronics, btw this is the first computer which i repair, so tell me what i should do like if you had to explain it to your grandmother 
EDIT:
I pushed the gate array into its socket, but without effect.

[gerald]

So i need to check voltage? If yes, tell me what voltage is correct and where i should check.
Im not expert on electronics, btw this is the first computer which i repair, so tell me what i should do like if you had to explain it to your grandmother 

Not sure I would explain how to check voltage on a computer to my 90 years old grandmother 

You need a multimeter. Then check voltage between GND and VCC on  IC :
   Z80 : pin 11 (VCC)  - pin 29 (GND)
   RAM : pin 8 (VCC)  - pin  16 (GND)

Voltage should be 5V +/- 10% (ie between 4.5V and 5.5V)
     

[twox]

Sorry for the bump of old thread, but during a long silent period i have found this processor:
Z80 IC Baustein DIP40 CPU Zilog 84C0004PEC Microprozessor 8 BIT 110510001 | eBay
Will it work?
I don't have paypal nor internet bank account, so this one fits ideally.

[TFM]

.

[gerald]

Looks like a 4MHz part, according to Zilog Z84C0004PEC

[TotO]

Sorry for the bump of old thread, but during a long silent period i have found this processor:
Z80 IC Baustein DIP40 CPU Zilog 84C0004PEC Microprozessor 8 BIT 110510001 | eBay

The good one is Zilog Z84C0004PSC
I have it in stock (new) for half the price (and half shipping too):
Circuits - Cent Pour Cent

[Bryce]

The C in the name means it's a CMOS part and there was never a CMOS Z80 below 4MHz. The 2.5MHz version was an NMOS part and was labelled "Z80 CPU" (no proper chip number on the part) or "Z8400". Also, most of the 2.5MHz parts were in a ceramic case and I doubt you'll find many of them any more.

Bryce.

[twox]

Hello, i found a cheaper one, plus its Z80B not Z80. Will THIS work?
IC Z80B CPU Zilog Z8400BPS | eBay

[TotO]

Yes, it should work.
The first CPC use Z80 APS (4MHz). This is a Z80 BPS (6MHz).

My CPC uses Z0840004PSC. The cpcwiki pages shown Z0840004PSC too.
Best that you check here: Mainboard Versions - CPCWiki

[twox]

Today i have made a few photos of my CPC and the patched power supply. I think i destroyed the patch (of power supply), the CPC dont even show green box on screen. Im so ashamed to myself...
Here are the photos:
When i was a kid i painted the cassette reader with marker. May this caused damage?


Shielding seems to don't fit in some places.

Here are patched power supply:

[Bryce]

The Marker in the tapedeck (other than looking shit) won't have caused any damage, but the wires on the power connector don't look good, you may need to replace them.

Bryce.

[twox]

Can you give me a (Hi-Res) photos of what the power supply should look like? And can the RAM be replaced in Schneider 464?
Aha, and i before i destroyed the power supply a Led marked EIN (i think this means POWER) was shining when i turn the CPC on.
I have read in other topic, that if you press ENTER and it does not make sound, something is wrong blablabla. In my CPC, after pressing ENTER no sound comes out of the speaker.

[robcfg]

It's the DEL key that you should press and listen if it beeps.

[twox]

It's the DEL key that you should press and listen if it beeps.

Sorry, my mistake. After i repair the power supply, i will see if it beeps.

[twox]

Hi, the fuse in power connector was faulty so i replaced it. I found amstrad cpc 464 service manual, and i followed basic hardware analysis like so:
Red led lights on?
Yes
Is wake up message displayed?
No
RGB Video connector connected?
Yes
Any picture at all?
Yes
This leaded me to the solution, that either of those 4 guys are broken:
Video connector (this one is most propably no)
Cable assy (can someone explain what is it?)
ULA (again, can someone explain what is it?)
PCB (yeah, this time i know what is it)

[twox]

bump