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No CLK on issue 2 ULA pin 32I'm trying to fix an issue 2. The symptoms are as follows:- Black and white bars on screen, colours near impossible to tune in, although these po…
... board as tested on the lower ram chips.
It will ... -
48k Issue 6a Very sick indeed.Hi Guys. I have a 48k Issue 6a board that shows a white screen with grey border. The white screen has three black squares spaced equally on the le…
... 7805 regulator, socketed lower and upper RAM, switched ram from another board, without ... the coil.
My lower RAM voltages are -5V = -029.5mV ... -
Character wobbleHello, I have an Issue 2 board which shows vertical character wobble. This happens for a few minutes followed by a few minutes of character sta…
... to fail (taking out the lower RAM) and also causing the 12V ... -
Broken Issue 2 - likely culpritsI've just got hold of an issue 2 spectrum with an interesting layout (heatsink is vertical and goes down to the speaker, some variable resistors and …
... get that far and a lower RAM issue is also questionable as ... -
divIDE interface not workingA while ago I bought a divIDE interface for my two spectrums (one is a 48k rubber keyboard one, the other is a 48k Spectrum plus). Sadly I never actu…
... , I replaced both upper and lower RAM with a new replacement boards ... -
Fixing a poorly Issue 3 - Odd faults.Here's one for you Spectrum fixers, I warn you it's a long one. I've spent a couple hours this evening doing several repairs on a rubber keyed Speccy…
... detected the 2 previously replaced lower ram IC's as suspected ... beeper started working, and the lower ram test reported IC13 as suspected ... disc capacitors around the upper/lower ram IC's. I know ... right over where the previous lower ram IC's were replaced, ... -
Another Spectrum is brought back to life.Hi Spec-chums. I have been having bit of busy afternoon with repairs today. I've brought back to life a Panasonic Super-VHS recorder, and more intere…
... only were there two failed ram IC's, but the previous ... an attempted removal of IC15 lower ram, with damaged pads/vials/tracks ... Smartcard, and this Speccy passes ram tests.:-
[img][IMG ... -
Modifying a speccy to +5v only operation.Just a thought experiment so far. Let's say i wanted to make a more resilient spectrum by getting rid of the DC-DC converter circuit. This would remo…
... rails from the speccy. The lower ram is easy to get around ... -
Help request for an injured Issue 4A spectrumHi folks, I'm hoping to resurrect an issue 4A spectrum that has been in my hoard for a couple of decades since buying it for spares. Someone ha…
... found 4 of the 8 lower RAM banks were nackered.
lower ram, but not inserted it yet ... to require 12v aside from lower ram was the LM1889 - should I ... -
48k issue 4B display problem etchi,, i have a zx spectrum 48k issue 4B with a display issue it has wavy lines in both the border and paper,some colours seem worse than others ie red…
... ,, ie replaced video encoder,new lower ram module.different ULA,crystals,full ... re cap,disabling upper ram.it passes ram tests left in sink ... -
zx spectrum 48k low -5volt raili have just received a 48k issue 3. initial tests show that all voltages are there but the -5V rail is only showing -4V. it does boot but i have tur…
... any further possible damage to lower ram.i have not experienced this ... the zener diode? maybe bad lower ram chip holding it down ? -
zx spectrum 48k interference during first two minutes of warm upi have a issue 3B 48k that i am looking at during the first two minutes (approx.) of warm up there is interference on the screen (tried to take a pic…
... ?? i was thinking maybe a lower ram chip was on its last ... -
boot fail .. bad address lines A7,A12,A13anybody have any ideas what could be wrong with this specie issue 3B .. work done : removed rom, upper ram & logic put lower ram multiplexers in sock…
... ram & logic put lower ram multiplexers in sockets (ic3 & ic4) , put lower ram ... s & ULA's. fitted lower ram module ... still no boot,tried ... regular ram...checked all the data & ... . . if i use regular ram it is more random.. if ... -
Building a ZX Spectrum and I have some voltage questionsI've posted about this before looking for parts, but now I've found all the hard-to-get stuff (thank you Retrolium!). So I figured new questions, new…
... Lower RAM: +4.98V
+12V to Lower RAM: +12.56V
-5V to Lower RAM ... : -4.31V
+5V to Upper RAM: +4.98V ... something to do with the lower voltages I'm seeing? -
TAP files for the TS 2068Hi, just recently bought a TS 2068 and found "Taper" on the web. Downloaded it and began to use it only to discover that it would not open TS 2068 fi…
... 's BASIC uses more lower memory and may overlap ... and the "OS RAM Routines" in lower RAM below the BASIC program ... started much later in RAM, and why the maximum ... of free RAM was 38652 bytes, much ... less than Spectrum's free RAM.
Finding ... -
16k spectrum crash?Hi, I have just been given a spectrum 16k. I plugged it in and it worked, but after turning the machine off and connecting the 32k (cheetah) memory …
... likely is part of the lower ram has packed in - either 4116 ... for the lower 16k, and this can fail when the ram packs ... -
Broken ZX Spectrum + (48k)Hi! I just got a ZX Spectrum + from a friend. He said it was working around 8 years ago when he put it into the cellar. It was in great condition - …
... .
upper/lower RAM faults are far more common ... problems often occur together (well, lower RAM & -5v anyway, for ... reasons)
the lower ram can often *almost* work with ... an 'almost boot' - genuine lower RAM faults generally give rise to ... -
Ecstasy & AgonyWhile checking out the area around Chennai Central station on Sunday, I came across this crowded narrow road taken up entirely by roadside vendors se…
... -5v supply to the 4116 lower RAM ICs is faulty, or one ... of the lower RAM IC's themselves - I've ... -
Want a Speccy Repaired?Maybe it's time to put my 'skills' to use.... Now that I've sourced some of the nastier transistors, I've fixed about 6 rubber keyed Speccys in the …
... yes I can. :) Probably the lower RAM has lost its -5V and ... -
broken ZX SpectrumHi there I was given a dead ZX Spectrum years ago, and being bored today thought I'd try it again. Its a Sinclair ZX Spectrum with lovely rubbery key…
... you say, it's probably lower RAM and/or Z80 but could ... -
broken ZX SpectrumHi there I was given a dead ZX Spectrum years ago, and being bored today thought I'd try it again. Its a Sinclair ZX Spectrum with lovely rubbery key…
... to be the Z80, the lower RAM block, the power converter that ... supplies the lower memory block, the ULA - in ... -
Nooooo my speccy died!??!!Hi! I am quite sad. :( Tonight I got a kempston interface so I rushed home to try it on my spectrum+ The edge connector of the interface was narrower…
... likelyhood as:
4116 lower RAM block 90% likely
4164 ... upper RAM block 50% likely
Z80 ... voltages needed to run the lower RAM, then the PSU section is ... .
Then check upper RAM, then the Z80 and then ... -
48k one dead, one dodgyhello everyone. I have 2 48k spectrum +'s (the one with the QL case). Both boards have issue 3B on them near the speaker. The first will power up …
... the board? Especially under the lower RAM chips? -
Black paper, white border. Ram fault?We have a speccy that wont work properly. When we power it up, we get white border around a black screen. We swapped the rom and ula with a working o…
... could be the Z80, lower RAM or upper RAM.
The best ... the voltages on the 4116 RAM first because you can immediately ... -
Spectrum Issue two problemI managed to bring back to life a issue two spectrum (at least the power supply cirquit). The screen is now crystal clear (after replacing all the el…
... a couple more things than RAM, but if the machine ...
I'd try the lower 16KB bank, as it's ... down, then you have bad lower RAM.
I had ... I thought it was a lower-bank chip (since the ... that someone replaced the lower eight 16Kx1 RAM chips with a ... -
Opus Discovery and +2A?Can anyone tell me if the Opus Discovery is compatible with the +2A. I've just bought a +2A off Ebay and couldn't find any info on compatability. If…
... to kill it, or the RAM/flash ROM and various other ... , the ULA and some of lower RAM just for good measure. -
Dead Spectrum +Hi all, I've recently dug out my old Spectrum + with the idea of repairing it. When I last looked at it, when I was much younger, I was soldering a …
... voltages required to run the RAM. +/- 5V and +12V. ...
test and replace lower RAM. The RAM can be sort of tested ... /> test and replace the upper RAM. Same procedure - remove, socket, ... replace with known good RAM, test removed RAM.
Test ... -
toasted soeccysHello, ive jsut bought a pair of speccys on ebay (one 16k issue 2 & a prob 48k issue 3) unfortunaly the genius who sold them tried to see if the wor…
... voltages required to run the RAM. +/- 5V and +12V. If ... />
test and replace lower RAM. The RAM can be sort of tested ... /> test and replace the upper RAM. Same procedure - remove, socket, ... replace with known good RAM, test removed RAM.
Test ... -
toasted soeccysHello, ive jsut bought a pair of speccys on ebay (one 16k issue 2 & a prob 48k issue 3) unfortunaly the genius who sold them tried to see if the wor…
... and GND to the 4116 RAM with the +12/-5v supplies ... is likely to fry your lower RAM! Hideous devices, these 4116s...not ... can be replaced with static RAM!
