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Amstrad 464 plus (no video output)

Started by elBeton, 22:43, 04 April 24

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elBeton

Hi,
I have problem with Amstrad 464 Plus bought on ebay.
After power connection there were no signs of action (no led, no video).
I found a problem with the switch plug connector and I fixed this, now the LED is on, tape deck is working at least rewinding the tape. After pressing play motor is working, tape is moving (I'm not sure if it's supposed to work like this or after entering the run" command ?!).

But my main problem now is no video output so I don't know it is working or not.

First I checked input voltage on power plug there is 5V (I have power supply from jbl speaker 2,5A) but I checked also voltage on CPU and on pin 11 there is only 3.13V, on RAM there is 4,6V.

The CPU should probably have a voltage of 5V.
I want to chceck also CLK pin 6 on CPU and there is something I don't get it. On oscilloscope I have 757 Hz on it but on other cheaper multimeter I have 3,998 MHz on CLK pin 6 (?!).

Should I immediately replace the capacitors in the power supply area?
Any idea what I should check and do next or what is wrong at that point?



andycadley

I'm assuming you actually have tried with a cartridge in the machine? A Plus won't do anything without one.

elBeton

I don't get any cartridge with this computer. Really should I have it to get any video output?? So for what is a tapedeck??

Deevee

Quote from: elBeton on 23:30, 04 April 24I don't get any cartridge with this computer. Really should I have it to get any video output?? So for what is a tapedeck??
Yes. The computer boots its firmware and OS from the cartridge. Without one, nothing in the computer will be initialised. Including the chip that generate video signal.
ORIGIN 320,200:FOR r=1 TO 360:PLOT 5*(16*(SIN(r))^3),5*(13*COS(r)-5*COS(2*r)-2*COS(3*r)-COS(4*r)):NEXT

McArti0

Remove z80 and check pin11 again.
CPC 6128, Whole 6128 and Only 6128, with .....
NewPAL v3 for use all 128kB RAM by CRTC as VRAM
TYPICAL :) TV Funai 22FL532/10 with VGA-RGB-in.

eto

Quote from: elBeton on 23:30, 04 April 24So for what is a tapedeck??
Once the 464plus boots from cartridge ROM, you can use the tapedeck. 

Where are you located?

elBeton

Ok, I'll wait until the cart "Burnin' Rubber" I bought on ebay arrives. 
Thanks for that info I didn't know that. :picard:

I have also an Amstrad CPC 464 and I thought they start similarly, I didn't know that the plus model had to have a card to start and get any video output.

Quote from: eto on 09:41, 05 April 24


Once the 464plus boots from cartridge ROM, you can use the tapedeck.
Where are you located?

To run the tapedeck I need to have a basic rom on the cart, right?
I'm from Częstochowa in Poland.











McArti0

CPC 6128, Whole 6128 and Only 6128, with .....
NewPAL v3 for use all 128kB RAM by CRTC as VRAM
TYPICAL :) TV Funai 22FL532/10 with VGA-RGB-in.

eto

Quote from: elBeton on 16:43, 05 April 24To run the tapedeck I need to have a basic rom on the cart, right?
do you have an Eprom burner? If yes you can also create your own cartridges. There are quite a few PCB designs. All you need is an Eprom of the right size (128K for the original firmware), a cheap logic IC and 2 capacitors. 

McArti0

on the oscilloscope you have a long time base set at 2ms/div. set manual 1us or 100ns. Fnirsi has very stupid software.
CPC 6128, Whole 6128 and Only 6128, with .....
NewPAL v3 for use all 128kB RAM by CRTC as VRAM
TYPICAL :) TV Funai 22FL532/10 with VGA-RGB-in.

Anthony Flack

Quote from: elBeton on 16:43, 05 April 24
Ok, I'll wait until the cart "Burnin' Rubber" I bought on ebay arrives.
Furthermore, I hope you got the one with the yellow top that says "Burnin' Rubber & Locomotive BASIC", which is the cart that should have come with your Plus machine, and not the one that came with the GX4000 console with the orange top that just says "Burnin' Rubber". 

If you got the orange one it will work, and you will be able to see if your Plus machine boots up at least, but you'll only be able to play Burnin' Rubber. 

elBeton

Quote from: eto on 21:12, 05 April 24do you have an Eprom burner? If yes you can also create your own cartridges. There are quite a few PCB designs. All you need is an Eprom of the right size (128K for the original firmware), a cheap logic IC and 2 capacitors.
Yes I have T56_TL866II I will be making my own cart, but I'm waiting for the PCB's to arrive.
Quote from: Anthony Flack on 02:46, 06 April 24Furthermore, I hope you got the one with the yellow top that says "Burnin' Rubber & Locomotive BASIC", which is the cart that should have come with your Plus machine, and not the one that came with the GX4000 console with the orange top that just says "Burnin' Rubber".

If you got the orange one it will work, and you will be able to see if your Plus machine boots up at least, but you'll only be able to play Burnin' Rubber.

Unfortunately, I bought a red/orange one without basic (I have never seen yellow/blue/green ones on sale) but I will program it with my own rom.



darkhalf

Congrats on your 464 plus. Had the same thing happen (purchase from ebay, green screen and then waiting for the cart to arrive!)

I've put some info together on testing this and upgrading which should come in use once you get everything working
https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/cpc464-build-thread/
CPC464/GT64, CPC464 Plus/CTM640, 2 x CPC6128/CTM644

elBeton

Quote from: darkhalf on 11:33, 06 April 24Congrats on your 464 plus. Had the same thing happen (purchase from ebay, green screen and then waiting for the cart to arrive!)

...
I have orange/red screen without any cart. I hope it works even though I have a different color on the screen.


andycadley

Quote from: elBeton on 09:36, 07 April 24
Quote from: darkhalf on 11:33, 06 April 24Congrats on your 464 plus. Had the same thing happen (purchase from ebay, green screen and then waiting for the cart to arrive!)

...
I have orange/red screen without any cart. I hope it works even though I have a different color on the screen.


Yeah, that looks like the kind of thing you get from a working Plus with no cartridge in it IIRC. Which is no guarantee of course, but not something to be concerned about.

elBeton

I already get my cart from ebay and everything is working fine :) My Amstrad 464 Plus is fully working :) Now time to RAM and DDI interface upgrades.
Thanks for Your support

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