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128K heatsink no color in composite video and bad antenna outputI am currently repairing a ZX Spectrum 128K heatsink model. It gives no colors on composite video output, and very bad antenna output. I opened it a…
... the TEA2000
- replacing the ULA
- disconnecting the composite video ... use 12V to ignore any faults in those circuits
- replacing ... /> So, if the TEA and ULA are ok, what could possibly ... -
Interface 1 cloneIs there any Interface I clone shematic avalible for me to build from? ZXnet and RS232 is the important part for me.
... hardware, and it has the typical sinclair lazy port decoding.
ULA's functions. -
4116 SRAM replacement (and ULA timings).As mentioned in another thread, I have spent quite a lot of time experimenting with different circuits and components for using a static RAM IC to re…
... is used to invert the ULA's /RAS signal:
typical small silicon diode here made ... the power supply and the ULA's /RAS line.
ULA (see the previous posts in ... tried that have a 6C ULA. -
ZX81 with black screen and some white dots.Was gearing up to do a composite video mod on my ZX81, and today was going to be it. Unfortunate when started my ZX81 seems faulty. I get a back scre…
... needed for the ZX81 (buggy ULA version)
BTW ... storage box. Both have developed faults and/or need some work ... . My ZX81 has the buggy ULA, and it's the one ... -
Issue 2 Failed 48k to 128k upgradeI have been trying to upgrade my Issue 2 with the help of Velesoft, using this schematic; [IMG]http://i764.photobucket.com/albums/xx284/arioch1973/4…
... is the PCB (which has faults since I got it). But ... is not usable to the ULA even though the data lines ... -
Semi-Dead Spectrum - Help RequestedI have finally got my hands on my two old Spectrums - neither of which work, but ideally I hope to get both of them working again. Spectrum number o…
... hours, but it found no faults. I then hooked up a ... have been due to the ULA's reading of the display ... -
RAM Diagnostic ROMhi all, i burn this ROM from here [url]http://www.fruitcake.plus.com/Sinclair/Interface2/Cartridges/Interface2_RC_New_RAM_Tester.htm[/url] and i a…
... open circuit and short circuit faults.
If it is ... all ram ic's cpu ula rom and anything goes where ... about the +5 volts on ula 4 pin
what he ... finally found a DMA0 line (ULA pin 4) stuck to +5V ... -
Keyboard Membrane Speccy +Grrrr! I'm having real problems getting the keyboard on my resurrected Spectrum+ to work reliably. I changed the keyboard membrane, and all seems to…
... to something else - the main faults when replacing keyboard membranes tend ... help with this.
c) Faults on the molex connectors (into ... the motherboard, or a dodgy ULA
I had a ... -
Issue 3 board... How to resurrect?Dear Everyone, Now I have a working 48k Issue 3, a sort of working Speccy+ (still having problems with the keyboard, more of that in another post) a…
... watch television.
The ULA clearly isn't completely dead ... the displayed pattern suggests a typical fault in the lower RAM ... the possibilities:
1. ULA: Hopefully you can insert another ... properly with the ROM and ULA. This can often be ... -
Poorly Issue One 16k spectrum diagnosis?Hello, everyone. :smile: I was lucky enough to buy an Issue One 16k rubber key the other week; I didn't know it was an Issue One till I opened it up…
... />
If the Z80, the ULA and the ROM are working ... short circuit or open circuit faults affecting the data, address and ... -
16K/48K Lower RAM (4116) replacement.You may want to read [URL="http://www.worldofspectrum.org/forums/showthread.php?t=37957"]this thread[/URL] for background information on the quest t…
... Spectrum + coming that may have faults and I would rather change ... adding a heatsink to the ULA chip than changing it for ... to risk the introduction of faults.
Bottom line - fix ... -
Poorly Issue One 16k spectrum diagnosis?Hello, everyone. :smile: I was lucky enough to buy an Issue One 16k rubber key the other week; I didn't know it was an Issue One till I opened it up…
... />
There are currently two faults:
1. On power ... />
Perplexing. I hope the ULA is okay. There's less ... -
ZX spectrum 128K + 2 (Grey one :)Hi all, I'm trying to revive a dead ZX 128K +2 (the grey one). The regulator was damaged and seemed to be feeding 7.8Volts onto the pcb. Yikes ! I…
... of a typical +2 set up (plus some manufacturing faults) [URL="http ... -
The Spectrum Resuscitation ThreadKicking off this thread as a place where people who are fixing/restoring Spectrums (or indeed any other piece of related hardware) can show off their…
... address lines between the ULA and RAM for faults before I entertained ... -
Born again Speccy user with problemsHello all, Firstly I'd like to say a big hello - this is my first post! When I was 8 or 9 or so my dad bought a ZX Spectrum 48K and a whole bunch o…
... path in the Spectrum are faults in one or more of ... 'll see why. Occasionally the ULA's internal audio I/O ... than to install a different ULA. Any of these problems suggest ... is handled by just one ULA pin. -
Homebrew ZX Spectrum kits for DIY builders !Hi. I'm considering selling Homebrew ZX Spectrum kits on ebay... hopefully at a low price ! They'd consist of : Z84C0020PEC Z80 CPU …
... they'd squeezed the Spectrum ULA into just under 120 macrocells ... timing compatible with the original ULA? I suppose it depends on ... using typical static RAM and flash devices)
The ULA doesn ... -
Weird tv output by spectrum 48kI recently got a spectrum 48k and hooked it up to my tv. After finding channel 36, I get a really weird picture for the spectrum, why is that? Below…
Everthing except the ULA on that looks soldered directly ... may have similar or worse faults (or may develop them within ... -
Loading from/saving to Zoom H2NI have recently acquired a Zoom H2N Handy Recorder for various audio-based purposes, and I am interested in loading my Speccy games from the H2N (Wav…
... ports adress the same one ULA pin, but EAR input is ... impedance EAR output of a typical tape recorder. Therefore it is ... -
Grey +2 DiedHi all, Thrashing my +2 playing Mugsy last night and it did this... [URL="https://m.flickr.com/photos/83515822@N05/13012551693/lightbox/"]https://m…
... supply must be present. The ULA is at least partly working ... can be caused by RAM faults and I'd probably start ... -
Poorly Issue One 16k spectrum diagnosis?Hello, everyone. :smile: I was lucky enough to buy an Issue One 16k rubber key the other week; I didn't know it was an Issue One till I opened it up…
... high voltages produced by the ULA when a corresponding address multiplexer ... , though the symptoms are not typical of a lower RAM fault. -
New user with a dead 48k issue 2Hello all I've found my way here from watching some excellent youtube videos by Joulesper Coulomb in an attempt to fix a issue 2 rubber key 48k I bo…
... the Spectrum has a working ULA and a working Z80 CPU ... no address or data bus faults that are show stoppers), it ... only socketed chip is the ULA then?
[B][I ... -
Dot crawl?Hi, As I'm rather new to the hardware of the spectrum, just to confirm: is this video showing "Dot crawl" ? [url]https://www.youtube.com/watch?v=_U…
... Spectrum has a 14 MHz ULA clock (which is divided by ... .43MHz colour clock as is typical for PAL.
There ... />
However the ZX Spectrum ULA display is not interlaced and ... -
Spectrum+ keyboard issueHi I have a spectrum+ (issue 4s board) where the 1-5 keys do not work. I have replaced the membrane and checked for continuity. I have also tested …
... those pain in the ass faults then :(:confused::x
ULA (which is addressed using A0 ... -
RAM issue for potential 48k buy?Hi guys I've got a 48k in my sight for ?20 but... it has an issue: [QUOTE]"I tested the computer and only displayed a distorted screen. Coloured …
... advice above is just the typical most likely fault.
ULA).
[B][I]Mark ... -
RAM issue for potential 48k buy?Hi guys I've got a 48k in my sight for ?20 but... it has an issue: [QUOTE]"I tested the computer and only displayed a distorted screen. Coloured …
... the L type (all have faults in the same half) and ... 48K model.
1 ULA suitable for use in an ... -
48K Ram Check Command not workingI am trying to repair my Spectrum 48k. It is having issues loading games, sometimes they load all the way to launch and then the speccy resets. Oth…
... has faults in the last 255 addresses only. A typical DRAM chip ... -
'Interesting' Issue 2 modSo I've been lurking on this forum for a while and I've got to the point where I want to see if I can repair a speccy.. so I bought me a 'broken' one…
... are good (no open circuit faults like dry joints) as this ... />
Ben has some spare ULA's. You may want to ... -
Issue with Issue Two[img]https://dl.dropboxusercontent.com/u/25300140/Spectrum/Edited_ImageEasyImageEditor_20141111_84.jpg[/img] I'm working on an Issue Two that was sh…
... as this where lower RAM faults are suspected then it's ... swapping in a known good ULA.
I neglected to ... state that the ULA I mentioned that had the ... -
48K Not booting properlyBought another faulty spectrum from Ebay. This one, when you turn it on, it looks like it's going to boot OK, but when it gets to the point where it…
... /> Could this not be a ULA problem?
Thinking of ... pretty much straight into the ULA (I may be wrong, please ... also be caused by the ULA being at fault?
faults on a Spectrum and it turned out the ULA was ... -
48K Not booting properlyBought another faulty spectrum from Ebay. This one, when you turn it on, it looks like it's going to boot OK, but when it gets to the point where it…
Faults with the ULA either manifest themselves very obviously, ... RAM fault and that the ULA is ok.
B
