faulty
i have a zx48 that will not tune in it allways seems to be just out of tune what could cause this fault also half of the keyboard doesnot work there has been a repaire done on a diode and it looks like its shorted i woud post a pic but cant work it out lol
Post edited by ozzyzx on
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Besides most people seem to bypass the modulator and use composite video anyway :)
rwap sells reproduction menbranes
It is fixable though :)
Have a look here:
http://womblesretrorepairshack.blogspot.com/2008/11/zx-spectrum-composite-video-mod.html
how can i put a pic on here i will post the board in its state now
you will have to find somewhere to put the photograph online, and then post the url here in img tags.
e.g.
[noparse]
this is the repair that was done before i got my grubby paws on it
as u can see who ever did this repair left that end one to long so when the lid was put down it connected its self to the 2 next to it and gave it a nice black mark on the back
Store the picture somewhere online, get the URL to its location, then create a post here with this:
[noparse]
Here is an example:
The URL to the picture in the top left of this page (black square that says "FORUMS World of Spectrum") is [noparse]http://www.worldofspectrum.org/forums/images/custom/forums.gif[/noparse] so I just copy that URL and plop it between the IMG tags, like so [noparse]
And when I submit my post it comes out like a regular picture:
( PS "But how are you able to use the IMG tags in this example without it being interpreted as an IMG tag???" I hear you cry ... well, I am able to use the [noparse][img][/img][/noparse] tags without the forum software parsing it by putting [noparse][noparse][/noparse][/noparse] before and after the IMG tags for demonstration purposes (and so can you))
EDIT: HAHA, you beat me to it by a minute ... good job! And I see guesser helped out too.
Is that R55? it should be a 56 ohm resistor as far as I can tell...
If so it looks like the -5v supply has probably been shorted out and if so that will have caused a cascade of problems for you :(
I would be possibly expecting to see TR4 being overloaded and almost certainly ram being damaged if the -5v supply disappeared :(
so your opinion is it a scraper or something that can be saved
If the ULA works then the spectrum can be saved basically. Whether it's economical to do so is another matter but it doesn't look to me like your board is damaged at least not in the bits you photographed. All the components can be replaced except the ULA
It probably can be repaired, but it sounds as if there has been quite a lot of damage. Don't scrap it, in the worst case it can provide spare parts to help repair another.
http://womblesretrorepairshack.blogspot.com/2008/11/zx-spectrum-composite-video-mod.html
another thing is only half of the keys work dont know if thats down tot he board or the ribbon cables
This was already answered back here
And here is the answer you're looking for: [noparse]http://www.rwapsoftware.co.uk/[/noparse]
The ULA is generating a video signal, so that component at least isn't completely dead. I'd say there's a decent chance it can be fully repaired.
what do you thinks gone on this thing
Did you even read comments no 20 or 5 ???
If I were repairing it, I'd start by checking whether the power supply circuitry is working and whether the various voltages it produces are present where they should be. If not, it's likely some or all of the lower RAM chips have failed, which can produce a display like the one you posted, though so can other faults too.
Thanks for all your paitance and help