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Offline orange

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problem and question about cpc
« on: 14:45, 15 April 10 »
from time to time picture 'jumps' on TV (using RGB SCART) connected to cpc464. there is some sort of 'glitch'. otherwise cpc464 works nice and loads fine games from tape (even if there is that glitch during loading).
I had bought it on fleamarket and washed the motherboard. I noticed one of the onboard chips has metal 'heatsink' on it. could the washing have removed any thermal paste? (was there such thing inside)?

(i am guessing that it heats up)

TIA for any replies.

Offline ukmarkh

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Re: problem and question about cpc
« Reply #1 on: 14:53, 15 April 10 »
It sounds like a connection problem, if you turn the sound right down does the screen still jump? If something is lose, or not quite connectiing, the sound vibration can have this affect, especially with a dry joint.
 
I noticed you said you washed the CPC, er what with and how?
 
 
 
 

Offline arnoldemu

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Re: problem and question about cpc
« Reply #2 on: 14:55, 15 April 10 »
from time to time picture 'jumps' on TV (using RGB SCART) connected to cpc464. there is some sort of 'glitch'. otherwise cpc464 works nice and loads fine games from tape (even if there is that glitch during loading).
I had bought it on fleamarket and washed the motherboard. I noticed one of the onboard chips has metal 'heatsink' on it. could the washing have removed any thermal paste? (was there such thing inside)?

(i am guessing that it heats up)

TIA for any replies.
Yes there is some thermal paste under the heatsink.
But I don't know if this will cause the problem you describe.
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Offline Gryzor

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Re: problem and question about cpc
« Reply #3 on: 17:41, 15 April 10 »
If it's the thermal paste that does it then the problem shouldn't start immediately after switch-on, but after a few mins...

Offline orange

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Re: problem and question about cpc
« Reply #4 on: 16:19, 16 April 10 »
oh, thanks for the replies.

er well i washed motherboard in the dishwashing machine! well it was very dirty, muddy from fleamarket.

yes, the problem starts after some time and repeats on every couple minutes. so I should put some (new) paste there?
a lot of that white stuff got removed.

also, i got some RAM heatsinks and stuff, maybe those would help

Offline OCT

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Re: problem and question about cpc
« Reply #5 on: 21:10, 16 April 10 »
er well i washed motherboard in the dishwashing machine! well it was very dirty, muddy from fleamarket.
If you are really talking about pulling off this feat, rather than pulling this forum's collective leg, ;) well... if you wanted to expose your CPC to some of the most aggressive household chemicals combined with high-pressure water at scorching heat, it has gone to the "right" wrong place.

Even if the machine was just set to "rinse cold" without detergent (it still has salts and a descaling agent inside), I'm surprised how much of the CPC actually survived.

Having asked your chemists to stage a little demo encounter between your dishwasher supplies and an acidity tester, you will too...

Offline orange

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Re: problem and question about cpc
« Reply #6 on: 14:43, 18 April 10 »
yes i actually did it. set it to lowest temperature and only small amount of detergent (or maybe none, can't remember now).
but I washed only motherboard. let it dry for couple of days and it worked. its a 'standard procedure' for keyboards.
i also washed many other stuff from flea market. some zx spectrums, cassette players and so on. it had to be done :)

motherboard looks a bit 'dull' on some places. there was some white stuff and i removed that with toothbrush and ipa (not diluted). it seems that some sort of lacquer was taken off (not sure). I shouldn't have left it drying in machine so long.
otherwise, its not such a bad idea. after all they wash PCBs in factory, too.
« Last Edit: 20:04, 18 April 10 by orange »

Offline Gryzor

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Re: problem and question about cpc
« Reply #7 on: 09:50, 19 April 10 »
'Lowest temperature' for dishwashers is, AFAIK, around 45 degs, which is still quite hot. Water has salts. And detergent is definitely not the way to go...

Maybe stuff does work afterwards, but you can bet you have shortened its life...

Offline Bryce

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Re: problem and question about cpc
« Reply #8 on: 12:25, 19 April 10 »
Forget the temperature :D , most PCBs can take 70°C without a problem, the real issue is that Dishwashers use salt which will corrode the copper off the board.

@ Orange, yes Dishwasher-like devices are used in the industry, but with ionised water and a little alchohol based cleaner, not the stuff you use to wash dishes. Dishwashing PCBs is definitely NOT a good idea!

Regarding the "jumping" on the TV, this may not be an error in the CPC at all, it may be that the TV is not syncing exactly with the CPCs video signal, have you tried the CPC and Cable on a different TV?

Bryce.

Offline Cholo

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Re: problem and question about cpc
« Reply #9 on: 14:47, 19 April 10 »
How long is your scart cable? If the cable is longer than 5m then it usually starts doing odd stuff like loosing colours and such (weak signal?). Probably best to hook the scart cable up directly to tv too (better not use extenders or similar).

Noticed that Dataserve has a 464 mobo for sale right now:
http://www.dataserve-retro.co.uk

But perhaps its even cheaper to just wait untill someone sells a 464 keyboard on ebay.

If it ends up being the scart cable that is bad, then ebay usually also has scart cables for sale.

Offline orange

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Re: problem and question about cpc
« Reply #10 on: 22:44, 19 April 10 »
well i made the scart cable myself; the damn plasmaTV needs voltage to set RGB (or else it would default to CVBS grrrr)
maybe I used wrong resistor there.

also, I'm using very old AT PSU that survived several short-circuits (after connecting -12V to GND...)
cable is about 5m, SFTP..

can you tell me what is the function of that chip with heatsink in cpc?

thanks for the replies, will do some more testing with normal TV (CRT).

Offline arnoldemu

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Re: problem and question about cpc
« Reply #11 on: 23:34, 19 April 10 »
well i made the scart cable myself; the damn plasmaTV needs voltage to set RGB (or else it would default to CVBS grrrr)
maybe I used wrong resistor there.

also, I'm using very old AT PSU that survived several short-circuits (after connecting -12V to GND...)
cable is about 5m, SFTP..

can you tell me what is the function of that chip with heatsink in cpc?

thanks for the replies, will do some more testing with normal TV (CRT).
That is the "gate-array". it's function is to display the picture on the monitor. It handles mode and colours, and also controls if the z80 sees ram or rom.
If that is broken.. then you are not lucky.
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Offline Bryce

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Re: problem and question about cpc
« Reply #12 on: 11:31, 21 April 10 »
Hi Orange,
       CPC Scart cables rarely work on Plasma TVs, even if you did add the voltage to switch Scart modes. Plasmas sample the Scart signals at a different rate than the CPC needs, so flickering, no picture or a scrambled picture is almost always Guaranteed.

Bryce.

Offline orange

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Re: problem and question about cpc
« Reply #13 on: 17:48, 23 May 10 »
well, I'm pretty sure the cable is OK. It works perfectly with CPC6128.

it seems this cpc464 has some issues. so far I tried only one game (Arkanoid). but that game would strangely slow down from time to time.
 i put some heat paste below the strange-looking 'heatsink' but it didn't help.

what game should i use to test the hardware? (one that should not slow down)

Offline Bryce

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Re: problem and question about cpc
« Reply #14 on: 16:54, 24 May 10 »
Ok, that is wierd, haven't heard of that problem before. Maybe the trip through the dishwasher really did mess something up.

Bryce.

Offline Cholo

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Re: problem and question about cpc
« Reply #15 on: 01:07, 25 May 10 »

it seems this cpc464 has some issues. so far I tried only one game (Arkanoid). but that game would strangely slow down from time to time.
... what game should i use to test the hardware? (one that should not slow down)
As Arkanoid is one of those few games that use overscan, its probably best to use any other game to test.

Offline MacDeath

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Re: problem and question about cpc
« Reply #16 on: 00:39, 27 May 10 »
Quote
it seems this cpc464 has some issues. so far I tried only one game   (Arkanoid). but that game would strangely slow down from time to time.
hahahahaha... :laugh: ;D

But this is an Amstrad CPC...It slows down a lot, especially for an Overscan-full screen game such as Arkanoid... this game dates back from 1986/1987...
You know ? the 16K Video Ram screwing with the Z80 performances, the   interrupts and so on...

They weren't as good as nowadays coders, lots of tricks have been discovered, and we no more have only 3 weeks to shit a shit with impossible deadlines and only 1 coder in his bedroom.



So Yeah, this slows, and this is normal. :'(
« Last Edit: 00:43, 27 May 10 by MacDeath »

Offline ukmarkh

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Re: problem and question about cpc
« Reply #17 on: 00:43, 27 May 10 »
hahahahaha... :laugh: ;D

But this is an Amstrad CPC...It slows down a lot, especially for an Overscan-full screen game such as Arkanoid...

You know ? the 16K Video Ram screwing with the Z80 performances, the interrupts and so on...

So Yeah, this slows, and this is normal. :'(

PMSL  :laugh: So true

Offline MacDeath

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Re: problem and question about cpc
« Reply #18 on: 00:45, 27 May 10 »
Just try Dead on time, it seems smooth and fast.
If it runs well, your CPC works perfectly.

Offline Devilmarkus

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Re: problem and question about cpc
« Reply #19 on: 00:58, 27 May 10 »
next 3D Mark 2010 for CPC? :D
When you put your ear on a hot stove, you can smell how stupid you are ...

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JavaCPC Desktop Full Release

Offline orange

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Re: problem and question about cpc
« Reply #20 on: 09:24, 27 May 10 »
ok, but IIRC Arkanoid run quite smoothly on my ZX+3, no overscan there though.

Offline ukmarkh

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Re: problem and question about cpc
« Reply #21 on: 17:55, 27 May 10 »
ok, but IIRC Arkanoid run quite smoothly on my ZX+3, no overscan there though.

This is typical of Spectrum games; nearly always seem to run at a slightly faster frame rate than their CPC equivalents. But today, the programmer isn't all alone, and can find help, use trickery he’d probably never thought possible. And ultimately create the best CPC game ever. The same is true of the other 8-bits, but its kinda evened the up the playing field, as the CPC was notoriously time consuming to program for back in the day and didn't always have the same resource pumped into a game as the other two computers.
« Last Edit: 17:59, 27 May 10 by ukmarkh »

Offline fano

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Re: problem and question about cpc
« Reply #22 on: 19:32, 27 May 10 »
ok, but IIRC Arkanoid run quite smoothly on my ZX+3, no overscan there though.
ZX vram is far smaller and owns better organisation (i love how is done the tile addressing) than CPC vram.More , at equal resolution , CPC will have to move twice data on vram to draw something.
"NOP" is the perfect program : short , fast and (known) bug free

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Offline ukmarkh

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Re: problem and question about cpc
« Reply #23 on: 22:05, 27 May 10 »
Its true, for years the perception was that the Amstrad CPC was superior... I think they were about level.

Offline MacDeath

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Re: problem and question about cpc
« Reply #24 on: 22:24, 27 May 10 »
The Amstrad is Superior in Graphics... That's all.

I'm not sure a Speccy would perform that well with 16k graphics...

The Speccy is a fake colour computer, actually its real Colour "resolution" is 32x24... with 8 colours from 15 on this.
Of course because those "colour pixels" are 8x8 you can dither inside each character to give a lot of variations so considering this 32x24 colour resolution, it's actually a lot of actuall colours.

Many Speccy demos use the 32x24 caracters attribute as a kind of screen, displaying pseudo 3D stuff and so on...but this remains a terrible blurred resolution, despite sweet effects can be performed.

[youtube=vbV4YqHsnRU]exemple 1[/youtube]
Sweet animations in mon,ochrome, nice ditherings too...but the plasma are big and blocky...

[youtube=sDIAE7C9uc8]exemple 2[/youtube]
Good 3D monochrome at a moment, but the plasma effects despite colourfull, are...32x24...sort of.
Also the still graphic pages are not that good IMO : poor colours and clashes... can certainly be done betterly in Mode0 or even rastered Mode1.


Those are not bad, good music too.
And those animations are fast and smooth But can we say "smooth" when colours/textures are moved by entire 8x8 pixels  blocks ?

Yeah, we must remember the Speccy 128 was released in 1985, after the Amstrad CPC Range and it was quite designed as a music computer (MIDI plug, better AY...) while AlanSugar had no thinking about Music making or games ofr whatever (bizness guy all the way...)
Or Else the CPC6128 would have featured some real improovements (real VRAM ? better AY ? some MIDI plugs ? oh sh....).

Just having a CPC getting its graphics elsewhere than in central memory from the z80...but this story is getting old and lot of awesomness can be achieved on CPC too.

The coloured resolution of the Asmtrad being more like 320x200x4 or 160x200x16...
I'm pretty sure if using a pseudo 32x24 miniscreen in mode0, with pixels actually of 1x2 (2x2 equivalent iin mode1) so a mode 0 32x48...you can certainly do a lot of those character attributes stuff yet on a smaller screen surface.  8)
« Last Edit: 22:37, 27 May 10 by MacDeath »