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Faulty 48+ Help NeededHi, This is what I get when I plug in the spectrum, this is tuned in. Vid shows a reset. Any ideas, or pointers on the first thing to check. Keyboa…
... that it has a rom/ram check feature, so time to ... /> TR4 and TR5 replaced.
Lower ram replaced
Z80 replaced
Faulty 48+ Help NeededHi, This is what I get when I plug in the spectrum, this is tuned in. Vid shows a reset. Any ideas, or pointers on the first thing to check. Keyboa…
... suspect I have a dodgy lower ram module, or there's something ...Faulty Issue 1Hi all, thought I'd document my efforts in getting another speccy working. I've never done this before so please bear with me... I recently took a p…
... where if I ordered a lower RAM module he'd send me ... some info on how his lower RAM performed.
A few ... in.
Zorn's Ram module plugged straight in and ... 16K speccy? (8K ROM, 8K RAM?) The manual didn't bother ...Issue 3B woesHello there, I currently have a Issue 3B for repairs around, it used to have broken upper and lower RAM, which I replaced with 41256-120 DRAMs (hac…
Oh ... and if I'm quick I can verify that the ZX sees both the upper and lower RAM banks (print peek 23732/23733).
I've also tried to isolate the issue by removing the upper RAM & ICs 23-26. Problem persists.Faulty Issue 1Hi all, thought I'd document my efforts in getting another speccy working. I've never done this before so please bear with me... I recently took a p…
... RAS, /CAS, /WE) on the lower RAM end. But I'm unsure ... Especially since for reads from RAM, you can't be sure ... to check though: (with that RAM replacement module inserted)
... you can find a decent RAM test program: results of ... or ULA reads from the lower RAM.Faulty Issue 1Hi all, thought I'd document my efforts in getting another speccy working. I've never done this before so please bear with me... I recently took a p…
... a report of problems with lower RAM before and as the ULA ... a SRAM to replace the lower RAM.
[b][i]Mark ...Faulty Issue 1Hi all, thought I'd document my efforts in getting another speccy working. I've never done this before so please bear with me... I recently took a p…
... certain that, with the lower RAM module installed, the computer ... corruption; CPU use of the lower RAM is not affected.
... addressing one; sometimes the lower RAM module latches an incorrect address ... have this problem when the lower RAM module is used. I ...Issue 3B woesHello there, I currently have a Issue 3B for repairs around, it used to have broken upper and lower RAM, which I replaced with 41256-120 DRAMs (hac…
... the "isolation" resistors between the lower RAM and the rest of the ... of chips used for the lower DRAM like you have done ... SRAM is being used as lower RAM (a LRR module) and they ...No colors on screen, issue 2.I have a 48k issue 2 with composite mod. When i first pluged it in after i bought it, the screen went yellow and after restart there were no colors a…
Check your power supply voltages on IC13, pin1 = -5v. pin 8 = 12v. A missing 12v rail would cause a B/W display, as well as being none too healthy for your lower RAM.
BFaulty 48+ Help NeededHi, This is what I get when I plug in the spectrum, this is tuned in. Vid shows a reset. Any ideas, or pointers on the first thing to check. Keyboa…
... above, I purchased some 4116 ram chips. I got them from ... /> I'll save the replacement Lower ram module for another fix.
Faulty 48+ Help NeededHi, This is what I get when I plug in the spectrum, this is tuned in. Vid shows a reset. Any ideas, or pointers on the first thing to check. Keyboa…
... />
TR4 / TR5 replaced
Lower Ram NOS replacement
Z80 replaced ... to fix broken trace from lower ram to ULA
Changed all ...NTSC Compatibility?Correct me if I'm wrong, but wasn't the Timex 2068 the only NTSC clone built of the ZX Spectrum? And I use clone lightly... From what I underst…
... the data bus for [the lower RAM and ULA] and the CPU ... is reading data from the lower RAM, a I/O read by ... to be reading from the lower memory for use in displaying ...NTSC Compatibility?Correct me if I'm wrong, but wasn't the Timex 2068 the only NTSC clone built of the ZX Spectrum? And I use clone lightly... From what I underst…
... only reads data from the RAM when it needs said data ... read any data from the RAM.
The ULA only stops ... when the CPU addresses the lower RAM, or certain I/O ports ...NTSC Compatibility?Correct me if I'm wrong, but wasn't the Timex 2068 the only NTSC clone built of the ZX Spectrum? And I use clone lightly... From what I underst…
... when the CPU addresses the lower RAM, or certain I/O ports ... contend just 7K of graphics RAM. It has to contend at ... any memory in the 16K lower RAM), then the ULA doesn't ...Sudden death of ZX Spectrum 48KHello A friend gave me a 48K rubber keyed Spectrum. I brought it home, hooked it up to my little TV and powered it up. I was very happy to see t…
The problem might be the lower RAM or ULA judging by the ...Sudden death of ZX Spectrum 48KHello A friend gave me a 48K rubber keyed Spectrum. I brought it home, hooked it up to my little TV and powered it up. I was very happy to see t…
... . It's to allow OKI RAM to be used as upper ... RAM rather than the Texas Instruments ... for TI or OKI upper RAM.
Check for a ... one or more of the lower RAM ICs. It's a very ...Sudden death of ZX Spectrum 48KHello A friend gave me a 48K rubber keyed Spectrum. I brought it home, hooked it up to my little TV and powered it up. I was very happy to see t…
... make me suspect a faulty lower RAM IC or possibly a faulty ...Sudden death of ZX Spectrum 48KHello A friend gave me a 48K rubber keyed Spectrum. I brought it home, hooked it up to my little TV and powered it up. I was very happy to see t…
... fault is indicative of faulty lower RAM. To be honest, it could ... pointed out that the upper RAM and that several of the ... /> As Zorn has said, test lower RAM, it's all you can ...Sudden death of ZX Spectrum 48KHello A friend gave me a 48K rubber keyed Spectrum. I brought it home, hooked it up to my little TV and powered it up. I was very happy to see t…
... /> As Zorn has said, test lower RAM, it's all you can ... of more of the 4116 "lower" DRAM chips has gone faulty ... ROM/EPROM, a ROM based RAM test program should confirm this ... firmware? Also, I have a RAM turbo interface which takes ROM ...Composite picture qualityI have read many many discussions here about the composite video modification of the Spectrum 16/48K models. I have choosen one of the simplest comp…
... I have the upper and lower ram modules installed (in my case ...Composite picture qualityI have read many many discussions here about the composite video modification of the Spectrum 16/48K models. I have choosen one of the simplest comp…
... I have the upper and lower ram modules installed (in my case ...Composite picture qualityI have read many many discussions here about the composite video modification of the Spectrum 16/48K models. I have choosen one of the simplest comp…
Best thing I found for reducing video interference was replacing C5 to C8 (the 12v decoupling caps for the lower RAM) with 1nf ceramics. On mobile at the moment, but if you search my post history you'll find it :)
BComposite picture qualityI have read many many discussions here about the composite video modification of the Spectrum 16/48K models. I have choosen one of the simplest comp…
... 12v decoupling caps for the lower RAM) with 1nf ceramics. On mobile ...Dead issue 3b with black and white barsHi all, I've been donated an issue 3b which has some nice black and white bars with a few flashing blocks. I've done a few RAM tests and could spo…
From the symptoms, I think it's highly likely the CPU is faulty, though I couldn't rule out a RAM (upper or lower) fault. It's very rare for the ZX Spectrum ROM to fail. While you're at it, also check the -5 and 12 V power supply rails at the lower RAM.Dead issue 3b with black and white barsHi all, I've been donated an issue 3b which has some nice black and white bars with a few flashing blocks. I've done a few RAM tests and could spo…
... -5 and +12 on the lower RAM, they're all showing 5 ...Dead issue 3b with black and white barsHi all, I've been donated an issue 3b which has some nice black and white bars with a few flashing blocks. I've done a few RAM tests and could spo…
... I'm looking at the lower RAM now then? I'll need ... . I've got some upper RAM replacement chips but I tried ... on each of the upper RAM chips and there wasn't ... 't use those for the lower RAM.Testing 4116 type DRAMsHappy New year All! I'm managed to find some time to repair some more Spectrums :) woo hoo. I have a couple with busted lower RAM, Sooo, I appr…
... feasible to actually make a ram module replacement with ease?[/quote ... 64K*4 DRAMs, or a lower RAM replacement module.Unresponsive Spectrum with Magenta border.This Spectrum is taking an age for me to repair, thank for all the help thus far! So after I switch on the ZX Spectrum+ I get the familiar white…
Thanks, not what I wanted to hear! :)
However I swappned the ULA to a known good one and it still did the same thing, the ULA in the other rmachine worked fine :)
So I wonder if the lower RAM is still borked?Issue 3B turning offI'm trying to save a Spectrum Issue 3B. I restored the power supply section, changing the 7805, TR4, and TR5, besides all electrolytic capacitors. No…
... a faulty chip in the lower ram was putting down the voltage ... already replaced it with a ram module. The stability of the ...Opus Discovery "the big switch on" (after 20 years)I have a few of these Opus Discovery's with different Eproms in that have not been swiched for 15-20 years or so . I am in no rush to switch any on …
... a new 48k rom and lower ram chips to try and fix ... is fit twin floppies and ram
