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Spectrum not working, can anyone help this lady?[URL="http://www.retrogamer.net/forum/viewtopic.php?f=6&t=29734#p674152"]http://www.retrogamer.net/forum/viewtopic.php?f=6&t=29734#p674152[/URL]
... 's probably a damaged RAM in the lower bank. If not, it ... rails, and if the 16K lower RAM bank is not being fed ... -
Spectrum not working, can anyone help this lady?[URL="http://www.retrogamer.net/forum/viewtopic.php?f=6&t=29734#p674152"]http://www.retrogamer.net/forum/viewtopic.php?f=6&t=29734#p674152[/URL]
... possibility that one or more lower ram chips will be dead (and ... -
Dead Spectrum SocietySo I'm getting back into real Sinclair computers rather than emulators. During the summer months I was lucky enough to buy a working ZX81 and was giv…
... the lower RAM chips (4116) are quick to die as well. Lower RAM and ... voltage conversion circuitry busted -> lower RAM chips dead (or vice versa ... before trying further tests. The lower RAM chips are a lot more ... -
Requesting a little help to identify the purpose of this 'add-on' to my Issue 2Hi everyone First of all it's my first post here so please go easy on me! I'm grateful to be accepted into your fine little club :smile: I probabl…
... problems with the upper 32K RAM. The 'dead cockroach' ... fix & upper 32K RAM are unrelated. I myself ... test program that checks lower RAM, to make sure there ... . A machine with lower 16K RAM okay is better than ... , and fix upper 32K RAM problems.
[*]Be ... -
Requesting a little help to identify the purpose of this 'add-on' to my Issue 2Hi everyone First of all it's my first post here so please go easy on me! I'm grateful to be accepted into your fine little club :smile: I probabl…
... levels across both the 8 lower RAM chips and the 8 upper ... it, thereby doing a rudimentary ram test. I assembled it to ... me to believe that upper ram is definitely suspect. Unfortunately I ... -
Requesting a little help to identify the purpose of this 'add-on' to my Issue 2Hi everyone First of all it's my first post here so please go easy on me! I'm grateful to be accepted into your fine little club :smile: I probabl…
if ur gonna desolder the ram chips, you will need wick. some peeps like pumps but i could never get results from them. it took me a couple hours to remove the 8 lower ram chips and i broke 2 traces, but after re[lacing with sockets it all seems worthwhile! -
Dead Spectrum SocietySo I'm getting back into real Sinclair computers rather than emulators. During the summer months I was lucky enough to buy a working ZX81 and was giv…
what sort of pattern?
Have you gone through the steps in the repair guide to isolate the lower ram so you can test the supply circuits? If so are you getting all three voltages correct now? -
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…
... shows the default contents of lower RAM, so it causes activity on ... -
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…
... I will next remove the lower RAM and fit sockets. I would ... -
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…
... /> On the other hand: having lower RAM on sockets surely is a ... -
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…
... start the Spectrum with the lower RAM all removed, then the display ... the CPU (still with the lower RAM removed) doesn't have any ... -
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…
... the CPU (still with the lower RAM removed) doesn't have ... br />
With all the lower RAM missing, a "working" Spectrum shows ... />
So, in absence of lower RAM, shorting C27 and leaving it ... seen some schematics about replacinig lower DRAM with SRAM at ... -
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…
... wire up an SRAM as lower RAM. But to fit on a ... -
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…
... CPU.
Removing the lower RAM was time consuming and fiddly ... m almost certain is a lower RAM failure (it only sometimes ... address line connections from the lower RAM to the ULA are ... on the Spectrum with the lower RAM removed, it does sometimes show ... -
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…
... less plain white screen when lower RAM removed? Don't know for ... -
Canny use of the 'r' register?Seeing Sokurah's code in the [URL="http://www.worldofspectrum.org/forums/showthread.php?p=583188#post583188"]crunch sound thread[/URL] has made me th…
... . Probably won't work for lower RAM since ULA is refreshing that ... it's 100% functional (all RAM replaced with SRAM :D ).
Z80 Cross-assemblersI need to build some code which contains sets of routines which run at one address but are stored elsewhere. Unfortunately, neither of the assembler…
... at the top of RAM, copy it to lower RAM, then page the ... original RAM bank back in and ...Z80 Cross-assemblersI need to build some code which contains sets of routines which run at one address but are stored elsewhere. Unfortunately, neither of the assembler…
... at the top of RAM, copy it to lower RAM, then page the ... original RAM bank back in and ...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…
... the Spectrum+ that had faulty lower RAM rather than the one I ...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…
... 5V, -5V and 12V from lower Ram bank. Target was to see ... whether a faulty ram draws to much current and ... TR4 and thus a faulty lower Ram -> non working Speccy.
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…
... not caused on consumption side (lower RAM, video circuit), but in production ... very likely to damage the lower RAM when supply voltages are off ...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…
... board for speccies with socketed lower ram would almost certainly work out ...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…
... Spectrum mostly works with 4116 RAM installed, but suffers from corruption ... of data in this RAM (as described earlier).
< ... about the same with no lower RAM installed.
I ... /CAS) as applied to the lower RAM on a problem free Issue ...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…
... the CPU to refresh the lower RAM when the ULA isn't ... over the upper part of lower RAM), so the problem wasn't ...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…
... refresh (or otherwise) of the lower RAM. If the description is correct ... that's what affected the RAM, causing a risk of corrupting ... arrangement of connections between the lower RAM and the ULA on the ...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…
... would be happening on the lower RAM address lines when the border ... , but not the contents of RAM. Perhaps it's a 'feature ...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…
... when the CPU accesses the lower RAM.
I've made ... the address lines at the lower RAM changing in what seems to ...faultyi 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 …
... some or all of the lower RAM chips have failed, which can ...BeginnerIm having a go at fixing a spectrum which has been in the loft for 20 years and would like some advice please.... I have downloaded the 'spectrum se…
... again if there is a lower RAM fault....
How can I ... test for a RAM fault if TR4 blows again ...BeginnerIm having a go at fixing a spectrum which has been in the loft for 20 years and would like some advice please.... I have downloaded the 'spectrum se…
... can I test for a RAM fault if TR4 blows again ... cut the -5v legs of lower ram chips until it's not ...
