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Blowtorch method of Speccy repairsI just did my first Spectrum repair (and successful at that). It was the Issue 2 spectrum I wrote about a while ago, I just hadn't got around to doin…
... I suspected either ROM or lower RAM to be bad, since my ... thought I'd try the RAM first.
I ... in all the now empty lower RAM positions, and a socket for ... I'm directly soldering the RAM in, in case the ... in for the full 48K RAM, and it still worked.< ... -
sinclair zx spectrum issue 6a (again) - how to repairHi All, Is there someone who may explain what these jumpers can be used for. [url]http://forest.no-ip.org/repair/jumpers.gif[/url] <- this is from …
Hi All,
Is there someone who may explain what these jumpers can be used for.
[url]http://forest.no-ip.org/repair/jumpers.gif[/url] -
48K specs boots, but THEN blinking blocks!Of all ZX problems I have seen, the 'blinking blocks' is the most common... Today I picked up a 48K, it boots and THEN it locks filling the screen wi…
... . That is weird... When the lower RAM i broken, it will never ... -
issue 6a faultyHi All I got issue 6a pcb from ebay with status faulty pcb had bad voltages when I power up I changed tr4 ztx650 and all voltages got back on ic6 I h…
... ltd.
I desoldered all lower ram chips and put new ... no ... -
issue 4s for reapirHi All, This time I have issue 4s for repair :) Here is few screen shots and small movie after boot. [url]http://forest.no-ip.org/issue4s/[/url] I kn…
... and have good voltages in lower ram
12,5,-5
lower ram, upper ram, cpu, rom.
And ... -
dead issue 6a boardI've just been back to the uk and found my old 48K + there - and bought it back with me to singapore - it's giving white border and red bars. From wh…
... 've read here this suggests lower memory. BUT 6 times out ... 's the stack. Upper or lower ram??? Thanks in advance... -
48K Speccy Repair Log.Some people may know my love for writing up my repairs of arcade PCBs on various forums so thought I would do the same for this little fella. Had th…
... ROM sits in the lower 16KB of address space ... and blow the entire lower 16K of RAM in one go. ... commonly taken to mean a lower RAM fault, ie something in ... back as OK, all the lower RAM was fine.
... a working ROM, working lower RAM and a good CPU, and ... -
repaired a 48K, yay :)I just managed to repair one 48K. After socketing all eight lower RAM chips (hard work!) and replacing few of them, it showed the familiar "Sinclair …
... 48K. After socketing all eight lower RAM chips (hard work!) and replacing ... /> question: does that mean all lower RAM is now OK? (if so ... -
ZX Spectrum Woes...In my endeavours to get my second Spectrum (Issue 3) working I have replaced the CPU, memory and lower ram. I have fitted sockets for the CPU and me…
... replaced the CPU, memory and lower ram. I have fitted sockets for ... the two previously assumed faulty RAM chips.
The only ... -
Repairing a faulty 48K issue 2.I am investigating one of a pair of non-working issue 2 48K Spectrums that have been sitting in a cupboard untouched for quite a few years. I haven…
... DC input.
The lower RAM chips are marked ITT 4116 ... RAS signals at all RAM chips (upper and lower).
- ... pins of all RAM chips
(upper and lower), though some of ... prime suspects are now the lower RAM chips or perhaps a
Issue 2 voltage troubleDear all, I got my hands on an old issue 2 from a friend. Price was close to zero so I did not hesitate to take it. After powering it up I was sur…
... this conditions. Temperature of the lower RAM seems to be not unusual ... or that some of the RAM or capacitors has a short ...Faulty rubber speccy - advice neededHello all speccy hardware gurus :) Recently I moved to a new flat and after a long time have some space (and time) to dig out my old Speccy hardware…
... right somewhere between upper and lower ram chips... maybe even ULA...
lower ram chips have faultered. This ... motherboard had upper ram chips socketed so I pulled ... and the voltages on the lower ram chips all seemed stable ...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…
... using a static RAM IC to replace the lower RAM 4116s in a ... installed, CPU access to the lower RAM seems to work perfectly. However ... bytes it reads from display RAM.My Issue 2 spectrum"IT'S ALIVE!!!!!" - Dr Frankenstein I got my issue 2 spectrum up and running, colours and all. I borrowed socketed lower ram from my issue 3 that is…
... and all. I borrowed socketed lower ram from my issue 3 that ... can not find its upper ram. It is quite possible that ... as well as it did lower ram and cpu. They are GM7164p ...4116 replaced with 4164 - ProblemsThanks to Velesoft I have some 4164s, and I have cut the -5V line below R9 where it pass from one side of the PCB to the other. I have cut the +12V a…
... to Pin 8 on the lower ram. And I have left +5V ...4116 replaced with 4164 - ProblemsThanks to Velesoft I have some 4164s, and I have cut the -5V line below R9 where it pass from one side of the PCB to the other. I have cut the +12V a…
... to Pin 8 on the lower ram. And I have left +5V ...Issue 2 problemHeres a video of what happens when I fire up an Issue 2 board ive had hanging around for ages, this is with Paul Farrows RAM test cart in btw If this…
... , this is with Paul Farrows RAM test cart in btw
lower RAM ill give it a go ...Issue 4S AnnoyanceRecently ive been going through a few interfaces testing them and I stupidly inserted a "key-less" interface (didnt know at the time but should have …
... in, quick voltage test of lower ram checks out but TR5 is ...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…
... the voltage tests on the lower RAM with the computer powered.
lower RAM chips, and finding pretty much ... now of replacing all the lower RAM chips, and then the ULA ...Spectrum+ Noisey Picture ProblemHi fellow Spec-chums I need your help! I've recently brought a 48K+ Spectrum(issue 6A) that I'm trying to repair. I did all initial tests on it prio…
... line that the feeds the lower ram and the tea(tv) chip ...Issue 4A issuesHi all, I've been trying to get the Issue 4A board that came DOA with the case I purchased for my Frankenspectrum to work. I've recapped and socket…
... chips, and verified that the lower RAM IC sockets IC6-IC13 are ... of a Speccy with no lower RAM present at all, however all ... 've also removed the upper RAM chips and the associated logic ...lower ram "new" replacement board.[url]http://www.ebay.co.uk/itm/230994088030[/url] I'm sure others have seen it .. but is it "like for like" compared to the original. .with regard …
[url]http://www.ebay.co.uk/itm/230994088030[/url]
I'm sure others have seen it .. but is it "like for like" compared to the original. .with regard timings etc ?Where do you stick the stack?...OK, so I've got a fair chunk of ASM code assembled from 24000 mark. The stack shouldn't get very big, just a few PUSHes and POPs of the main regis…
... right at the top of RAM while I was trying to ... probably go high up in RAM (does lower RAM contention affect it a ...Pimping an Issue 4SSo theres this 4S I have, its been a pain in the backside for ages, this and that going wrong then I stupidly broke it properly by inserting a keyles…
... all the lower ram and the regulator. So now the lower ram is all ... socketed and fitted with Zorns excellent ram module ... , the upper ram is in the ... in preparation for Zorns upper ram module, a recom unit ...Issue 4A black paper, white borderJust had one of these through, nice yellow pcb! Everything but the ULA soldered in. On power up I get black paper, white border and some intermitten…
... .
Testing with fruitcakes 128k RAM test cart brings up the ... normal display without the RAM cart which makes me think IC6 lower RAMI've had better nights...So I got a broken issue 2 today, case in good nick but the diags board showing multiple failures in both lower/upper RAM. Never mind, good as a spare…
... showing multiple failures in both lower/upper RAM. Never mind, good as ... multiple failures in previously good lower RAM and a pattern exhibiting a ... tests I can perform on lower RAM in the future out of ...Black Screen Spectrum 48kWas working ok, it came to me in a Fuller FDS keyboard, I had a nose inside and found a floating power lead connected to the keyboard, I removed that…
Calling people with Diagboards.....and who have toastracks or grey +2's with all socketed memory :) I'm finishing off modifications to the Diagboard firmware to expand its testing c…
... sample output when IC16 (upper RAM) is removed:
[IMG ... /> .. and when IC6 and IC8 (lower RAM) are removed:
[IMG ... to screen the specific upper RAM IC locations that have failed ...Scrolling Bi-Colour Engine for 4-Player GamesJust putting this code up for people to have a look at. Far from finished. Should simply compile and run a bit of a demo. Only good for 128K and +…
... ).
;
;Use central uncontended RAM block (32768-49152) for colour ... graphics down to top of lower RAM block for drawing sprites in ...
