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Component Equivalents/substitutionsA while ago, I mentioned to somebody in a thread that we should have a list of component equivalents and substitutions so that it's easier to fix our…
... the USA and Europe, but not essential.
Foggy, ... (Inmos) chips work in any upper RAM position (IC15-22)
... work in place of 4164 upper RAM chips
V53C256P80L chips ... work in any upper RAM position (IC15-22)
... -
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] -
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…
... have good voltages in lower ram
12,5,-5
not i go to standard way, will change lower ram, upper ram, cpu ... -
VERY annoying (DVD drive not detected)My 'puter seems to have forgotten that I have a dvd/cd drive. It has done this before and I thought it may be some virus or other and I took it in…
... 'm relatively sure I have not downloaded owt dodgy, but you ... -
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…
... chips off as they would not desolder without risking damage ... I originally thought it was not making contact with the socket ... originally soldered in that would not account for the initial problem ... machines, as each of the upper RAM chips contributes a single bit ... -
Help and Advice with DivIDE PlusHi Guys, Really struggling to get any reliable actiivty with my DivIDE Plus and am looking for some pointers. I am trying to get it to work with on…
... boot sequence up (Unit 0: Not detected; Unit 1: Disabled) but this ... because the CF card is not inserted. Inserting the CF card ... power on and the screen/RAM consistently stays in a static ... -
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 found its voltage regulator not to be working so I ... one is a
replacement (not by me and it appears ... looking RAS signals at all RAM chips (upper and lower).
the upper RAM chips, which I imagine is ... -
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…
... faultered. This motherboard had upper ram chips socketed so I pulled ... was the same as with upper ram fitted - black paper with ... 2000k, as with other upper ram chips), and not below 20k, which ... the upper ram chips, the pattern on the screen is not static ... -
ZX Spectrum not working... issue 4S?Hi, I've bought a "new" broken ZX Spectrum +. The idea was to put an harlequin board inside, but for the moment I'm trying to put it in working order…
... and the logic chips for upper RAM mounted in sockets.
- Lower ... get some 4116s?
- Is upper memory more resistant or it ... -
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…
... all. I borrowed socketed lower ram from my issue 3 that ... great, except it can not find its upper ram. It is quite possible ... well as it did lower ram and cpu. They are GM7164p ... -12, but I can not find any data sheet on ... -
Replacing Upper RAM in 48KHi Folks Well, my fun continues :) After sorting the display issues with this machine I found I couldn't load software meant for 48K machines. Havin…
... here it looks like an upper memory fault.
Before ... -
Broken Spectrum 48k: Faulty rams?Hi! I recently bought a used Spectrum 48k which works perfectly apart from not recognizing the upper 32k ram (so making it a Spectrum 16k that way).…
... works perfectly apart from not recognizing the upper 32k ram (so making it ... that it's exactly the upper 32k which are failing ... be a connection between the upper ram failing and that missing capacitor ... , so I assume it's not completely essential.
... -
Faulty 48K Issue 3 motherboardHi I have a faulty Issue 3 motherboard and would appreciate it if somebody can steer me in the right direction of where to begin with the fault find…
... black screen. I removed the upper RAM and interface chips so that ... possible that the CPU does not start at all. Have anybody ... -
POKEs on 128K "upper RAM"?I've been working lately with some 128k games, and I've got this question about RAM in games. I guess most games use RAM pages 5 and 2 to store the …
... 've got this question about RAM in games.
I ... guess most games use RAM pages 5 and 2 to ... the main program, and other RAM pages are used to store ... that needs POKEs placed in RAM pages 1, 3, 4, 6 ... -
Question about 48K DRAM refreshHi guys. Can anybody tell me how the 48K spectrum refreshes the upper ram. RAS only? CAS before RAS? I've got a bunch of 41256 DRAM that i would lik…
... the 48K spectrum refreshes the upper ram. RAS only? CAS before RAS ... almost impossible if it does not. -
Interesting 48K failureI thought I'd recount a failure I've not seen mentioned before that I saw tonight while fixing a 48K issue 6 board. The background: The initial fail…
... a failure I've not seen mentioned before that ... peripheral (errm, I'm not saying which :-)) was plugged ... voltages and -5v was not present and all the ... 1. A fault in upper RAM causing incorrect instructions to get ... ) but most of the time not.
Since ... -
My Boxed ZX Spectrum For Sale On EbayHi spec-chums. I have listed on Ebay a boxed ZX Spectrum which is a rubber key model. It is in a tatty condition but is all working. It would be a ni…
... a 16K, but all the upper ram is socketed and populated with ... are still working. It has not been composite modded yet either ... -
Help put this back to 16kSo this issue 2 arrived today and ive opened it up just to nosey and confirm that infact it is an issue 2. Now from the help offered in an earlier po…
... know I have to remove upper ram oki's and some logic ... old Avometer 8 and im not sure it has the necceserry ... my collection so am probably not going to use it but ... -
Upper Memory LinksI've got an 1982 Issue Two Spectrum 48k with an upper RAM fault. I've narrowed down the faulty IC and I'm in the process of removing the 8 IC's, sock…
... Two Spectrum 48k with an upper RAM fault. I've narrowed down ... -
48k - Why Won't it Buzzzz?Hi WOS ;) I bought a load of Spectrum games off eBay and thrown in for good measure was a 48k 1984 Issue 6a circuit board that I was told was for sp…
... /> The voltages around the lower RAM ICs are all wrong however ... and the thing is still not buzzing like I believe it ... appears I know the lower RAM is faulty (alternating black & ... they all work fine. The upper RAM has been removed and donated ... -
ZX81 internal RAM board?Just a quick question to Zorn (amongst others). What would the issues be with fitting one of Zorn's RAM boards into an unexpanded ZX81? Seems to me…
... fitting one of Zorn's RAM boards into an unexpanded ZX81 ... a lot of the official RAM pack's internal circuitry is ... fit one - preferably the 32K upper RAM board, 'cos I never had ... -
Issue 2 Spectrum - Black screenHi I have an issue 2 spectrum which I'm having some issues with. I bought it on ebay so have no idea of the history or how it came to be broken. Whe…
... appear that this is an upper RAM fault.
As ... a very low reading (not the one I replaced) ... to get the corresponding upper RAM location and sure enough ... I replaced the offending upper RAM chip but it made no ... the same to the upper RAM and the fault stayed ... -
128K RAM tester as .TAP?I was sure that I've seen a RAM tester that can be loaded with e.g. DivIDE or DivMMC EnJOY! as .TAP. But I can't find it (been searching through the …
... that I've seen a RAM tester that can be loaded ... only a small error in upper RAM.
I have a ... -
Finally got round to itFinally got round to giving my old speccy a close look. Details 1982 Issue 2 Seriel No 001 196193 Hmm... Followed the initial tests on You tube w…
... fail then
Lower ram tested on 200Kohm range
not IC 3 and 4 ?
Upper ram socketed
TR4/TR5 replacementHi guys, I've got another Spectrum I'm working on now - an Issue 4S this time. When I originally got it, I powered it up and did the basic tests a…
... a fault with the upper 32K of RAM. Not surprising, and I've ... the voltages on the lower RAM IC's show they are ... still wrong on the lower RAM IC's, so I'm ...Bizarre ZX Spectrum faults (also possibly relevant to Spectranet compatibility problems).I'm attempting to repair an issue 4A 48K ZX Spectrum and am encountering some very strange problems. For my own records I've given this computer the …
... works correctly. ZX285 would now not initialise (or sometimes would, but ... the DivIDE is connected, but not the Spectranet. I have ... , only when the original OKI upper RAM is fitted.
- Spectranet: ... (any) quite often, but not always, produces a very brief ...Issue 4A, tests complete fine but get odd crashing problemHi all, I've got an issue 4A which has had all of its lower RAM replaced, TR4, TR5 as well as its CPU. It originally had quite high voltages (20-3…
... and some very questionable RAM. TR4 and TR5 were ... replaced and with new RAM it appeared a lot ... 've tried swapping the RAM chips around and have ... difference. The voltages on the RAM appears fine.
upper RAM or the logic chips but they're not ...48K Issue 2 Spectrum showing exactly 16KI've acquired an issue 2 and it quickly became clear that only 16K of memory is available. I've read that some early 48K Spectrums with malfunctionin…
... early 48K Spectrums with malfunctioning upper RAM were sold as 16K versions ... populated and the upper RAM are all TI and not socketed.
upper RAM has been disabled? If the lowest upper RAM IC is ...ZX Spectrum 48k issuesHi all! A couple of days ago I bought my first 48k Speccy off ebay (I already own a beautiful QL expanded with QubIDE interface and 640k ram). It was…
... with QubIDE interface and 640k ram). It was advertised as "it ... , power connector) and the socketed upper ram, fully recapped it, added composite ... reports faulty reads from ram (removing the upper ram does not resolve).
ZX Diagnostics v0.35 ReleasedHi all, I'm pleased to announce the release of zx-diagnostics v0.35, downloadable from [url="https://github.com/brendanalford/zx-diagnostics/relea…
... /> -------------------------
New ROM sets detected in this release:
- Spanish ... failure beeps if a RAM issue is detected in soak test mode ... multiplexer ICs if all 48K upper RAM is faulty (as opposed to ...
