Spectrum Computing

Hi Andy

That’s great news if you should post some screenshots that would be great

Many thanks

Hi Andy,

Thank you, I have some new caps coming soon as i need to replace them but my guess is its still going to be the same but will keep you updated

If you do find anything then please let me know as it could be the same as my problem

Many Thanks

Hi [mention]andywilliamsuk[/mention]

Have you had any luck on yours?

I now have a Retroleum DiagROM and this picked up a bad IC17 so have swapped this and all tests run fine now, but still have the yellow tinted screen

I have also traced U and V to IC14 and these are fine as well

[mention]1024MAK[/mention] any ideas?

ok so now im getting this

anyone have any ideas?

It’s the rom or IC19 as pin 13 is grounded and think that should be data?????

I will replace it and see what happens

I have a 4B board and ram voltage is fine. Powers on but give black boarder and strips on paper, the rim is getting hot and so is z80. I have checked voltage on rom pin 16 is going to ground and I’m sure it’s meant to be +5 I have been trying to trace it but can’t so looked at the schematics and can...

Hi Mark,

Do you have any ideas what I can try next?

Sorry it’s as follows

Pin 2, 4.95
3, 4.45
4, 4.97
12, 11.67
13, 4.31
14, 11.67
15, 11.69
16, 11.66

Counted the pins wrong

Pin 2, 4.95
3, 4.45
4, 4.97
12, 11.67
13, 11.67
14, 11.67
15, 4.31
16, 11.66

Chip has already been change and tested working on another board

If I disconnect a leg from C65 I get normal grayscale so white shows perfect then

Thanks spider,

It’s the same colours as before

Ok so I have disabled the upper ram and this now shows the copy write message

But still has yellow boarder and colours are not correct

Hi Mark, Yes the border is always that colour, I have done as requested and still doing the same. Before the system was working fine but with yellow boarder and incorrect colours so did the following to try and fix it. Replaced TR1 and TR2 (same result) Replaced TV module (same result) Replaced TR8 ...

Thanks both, ULA is the same as the old one 6c001e-7 All pins are connected, I have put the old ULA in and getting the same This is what I see, sometimes the paper is just black https://i.postimg.cc/FYsrQZRy/image.jpg I am also getting this sometimes Many thanks https://i.postimg.cc/Thywy1JN/6471-BD...

Thanks both,

ULA is the same as the old one 6c001e-7

All pins are connected, I have put the old ULA in and getting the same

This is what I see, sometimes the paper is just black



Many thanks

Think i have messed up

I removed the old ULA and put the new one in and now get yellow boarder and black paper, reboot a couple of times and get pure yellow screen and white cursor on bottom right of paper.

Any help would be great

I can’t seem to find any documents on this board. Is it rare? It has trace damage where someone has removed all the lower ram chips. From what I can tell will just need lower ram chips replacing, find a ula chip as this has been removed as well, it has no case or power supply, do you all think it’s ...

Thanks Mark,

Managed to find one on eBay will let you know how it goes

Also where can I get a replacement?

Thanks mark

Is it worth change x1 and x2 as well or will this not help?

Ok

So black is blackish
Blue is a very dark green
Red is fine
Magenta is a little lighter red
Green is bright green
Cyan is bright green
Yellow is yellow
White is also yellow

I have replaced tr9 and tr8 from a donor bored and still the same and have also now replaced tr1 and tr2 still the same

Hi Andy, That's perfect thank you, I will give that a go later and update with the results, this was my grandads computer so will be nice if i can get this working, but this is what the screen looks like at the moment https://i.postimg.cc/Q9L7X6Dd/yellow.jpg Thanks for all your help so far everyone

Thanks mark,
I’m getting 4.9v on both
I am very new to spectrum so not sure how to run that

I have noticed that if I short R44 white shows correct but there is a lot of static on the screen, the resistor measures as 5.13 is that correct?
Comp mod was done with 100uf

Hi All,

I have a ZX spectrum 48K issue 4b

When powered on it loads and works fine but the screen is like a dull yellow, is there anyway to change this?

I have replaced the following, RF module + done the comp mod
replaced the LM1889N chip

Still the same

Any help would be great