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Successfully updated Issue 2 48k to 128k?Thanks to the donation by PMSR and through the very patient teachings of Velesoft, I have updated the Issue 2 to work with 128k. However. I have yet …
... . However when measuring A7 on lower ram the signal is remaining on ... ram A7.
Perhaps this is the problem? I am not ... -
Successfully updated Issue 2 48k to 128k?Thanks to the donation by PMSR and through the very patient teachings of Velesoft, I have updated the Issue 2 to work with 128k. However. I have yet …
... pins on one of the lower ram sockets through a tiny bit ... was why A7 VRAM would not be pulled low. As soon ... -
Successfully updated Issue 2 48k to 128k?Thanks to the donation by PMSR and through the very patient teachings of Velesoft, I have updated the Issue 2 to work with 128k. However. I have yet …
... pins on one of the lower ram sockets through a tiny bit ... was why A7 VRAM would not be pulled low. As soon ... was thinking, if it's not the GAL, has he got ... -
Replacing ZTX650 with BD139Today I blew up one of the GALs on one of my DivIDEs while testing on my Toastrack. Shorted M1 with 12V and the 12V circuit broke. I had to replace T…
... work if the lower RAM is replaced with RAM that does not need 12V ... -
Diagnosing a strange software fault in a 48kHi, A friend gave me a 48k, which I am very keen to restore. The spectrum 48k was my first computer over 20 years ago and I owe my ability to code t…
... has the originals. It's not unusual for these to be ... the power supply to the lower RAM and cause some/all of ... -
Diagnosing a strange software fault in a 48kHi, A friend gave me a 48k, which I am very keen to restore. The spectrum 48k was my first computer over 20 years ago and I owe my ability to code t…
... old even quality ones are not much good anymore, and ... do even for a newby (not saying you're one! ... is on 4116 RAM IC's in lower left corner ... amp; shows image (which needs lower RAM + video encoder to work), ... -5V missing can kill lower 16K chips in short order ... -
Diagnosing a strange software fault in a 48kHi, A friend gave me a 48k, which I am very keen to restore. The spectrum 48k was my first computer over 20 years ago and I owe my ability to code t…
... advice here if you're not used to de-soldering DIP ... /> IC6 is part of the lower RAM and we have no reason ... -
WIP: ULAPlus hardware implementationThis aims to be an "almost" plug-in replacement for the Sinclair ULA chip fitted in Spectrum 16K/48K/Plus machines. It comes in a form of a small PC…
... font), and only uses the lower RAM to display the game. I ... ohm (it's not advisable to put a lower value due to ... to run fine, but maybe not always fine.
But ... -
My 48K Speccy has died.Hi fellow WoSer's! Wondering if you could help me with my rubber key 48k Spectrum, which died on me this afternoon. It is one I prevoiusly fixed up j…
... the supply voltage to the lower RAM, make sure all voltages are ... are getting warm that ought not to. The ULA will warm ... from radiated heat, but the RAM should not.
Removing ICs ... soldered to boards is not terribly easy. The best way ... -
SPECTRA New from Paul FarrowLooks good! Read about it [URL="http://www.fruitcake.plus.com/Sinclair/Spectrum/Spectra/SpectraInterface.htm"]here[/URL]
... (not 18K) of RAM, basically mirroring the Spectrum's lower (read "video") RAM. ... offer any other rom area ram modes please [/QUOTE]
lower RAM and separately, you choose ... br />
SPECTRA does not change the ULA contention in ... -
Successfully updated Issue 2 48k to 128k?Thanks to the donation by PMSR and through the very patient teachings of Velesoft, I have updated the Issue 2 to work with 128k. However. I have yet …
... . However when measuring A7 on lower ram the signal is remaining on ... ram A7.
Perhaps this is the problem? I am not ... -
Difference between brands of 4164 chips?I have gotten my hands on a batch of several brands of 4164 chips. Examples are NEC D4164C-3 and Mitsubishi M5K4164ANP-15. Anyone knows if any type …
... operation is achieved.
Not sure if this is related ... use these as a 4116 (lower RAM) substitute.
They seem fine ... -
Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …
... replaced. Even if that's not where the fault lies, they ... -5V and 12V for the lower RAM (and 12V for part of ... of a problem with the lower RAM. It's possible you've ... got one or more RAM ICs that are failing only ... -
Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …
... a fault in the upper RAM, not the lower. This is certainly possible ... gets detected as faulty and not used, but it interferes on ... 're able to, try the RAM test program I created and ... it against the upper and lower RAM and leave it running for ... -
Composite video for 48k Capacitor orientationHello, My multisystem TV is acting up and I'm unable to navigate the menu to tune in the RF signal for my speccys. However the A/V input still works.…
... a filter. However, it is not enough in the case of ... have something to do with lower ram. But I can find nothing ... -
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…
... or related to it, is not specified on the site.
how did you check the RAM ic's ULA, CPU and ... flashing, etc. as with a lower RAM failure.
I tested ... the RAM IC's, ULA, CPU and ... -
48k fuzzy screen errorHi all, I just got a ZX Spectrum 48k (rubber keys) from eBay and when I plug it in the main screen on the TV is all fuzzy and garbled in the middle.…
... like what happens when the lower RAM is completely broken or missing ... with the 4116 RAM ICs. Fortunately, it's probably not very difficult ... -
48k + Spectrum Issue 4S Display IssueHi all! Brand new user here. Growing up I had a zx spectrum for a little bit, and recently I have bought a working 48k + Spectrum (Issue 4). I was…
... 't use capacitors with a lower voltage rating than the originals ... coil (though you may not with the lower RAM removed)?
I ... -
48k fuzzy screen errorHi all, I just got a ZX Spectrum 48k (rubber keys) from eBay and when I plug it in the main screen on the TV is all fuzzy and garbled in the middle.…
... , you say it's probably not very difficult to put right ... the necessary voltages at the lower RAM ICs (as I mention towards ... risk killing any of the RAM ICs that may still be ... -
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…
... , everything seems fine with the lower RAM and the Voltage regulator. Looks ... I have been using is not as healthy as I thought ... !
Voltages on the lower RAM now are:
0V Pin ... -
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…
... my failures are with the lower RAM chips, and sometimes with the ... upper RAM chips. Occasionally I find a ... faulty ULA, but that is not the norm. I have also ... ZTX650 transistor if it was not fitted with the necessary mods ... -
Poorly Issue One 16k spectrum diagnosis?Hello, everyone. :smile: I was lucky enough to buy an Issue One 16k rubber key the other week; I didn't know it was an Issue One till I opened it up…
... there's the typical Spectrum lower RAM fault, but that still has ... due to a faulty CPU; not necessary completely inactive, but ... -
Which ULA?Just a quick question, more of interest rather than immediate need... I am thinking ahead about the repair of an Issue 2 board, and also an Issue 6A …
... anywhere. However, none of the lower RAM chips are heating up any ... /> Z80 okay :)
Not a ULA fault :)
Not a membrane fault ... the system is working (including "lower" 16k DRAM).
What ... solder joints for them are not likely based on 5 connections ... -
ZX Spectrum 48k Issue 2 Faulty Ram?Hi, I have a faulty ZX Spectrum Issue 2 motherboard. Looks in very tidy condition. Though I'm getting random columns of blocks and flashing cursors…
... .zigg.net/LRR"]ZX Spectrum lower RAM replacement module[/URL]. [URL="http ... be other faults, but overheating RAM ICs clearly suggests a problem ... it offers any resistance, do not force it. If you do ... by measuring voltages at the lower RAM's PCB pads - look up ... -
ZX Spectrum 48k Issue 2 Faulty Ram?Hi, I have a faulty ZX Spectrum Issue 2 motherboard. Looks in very tidy condition. Though I'm getting random columns of blocks and flashing cursors…
... replacement of the power RAM. It does not matter if you replace ... the current RAM with other 4116 ... chips or use the lower RAM replacement module, you still have ... -
ZX Spectrum 48k Issue 2 Faulty Ram?Hi, I have a faulty ZX Spectrum Issue 2 motherboard. Looks in very tidy condition. Though I'm getting random columns of blocks and flashing cursors…
... replacement of the power RAM. It does not matter if you replace ... the current RAM with other 4116 ... chips or use the lower RAM replacement module, you still have ... -
Cascading transistorsMiguel (mcleod_ideafix) alerted me on an aspect of a design I'm working on where I am cascading transistors, which may give problems. This is the par…
... stabilize, but it is not the only element that ... CPU clock and reading lower RAM to display the image. ... 5V supply rails to feed lower RAM. The DC-DC converter ... data from nowhere because lower RAM won't be ready ... 5V rail, ULA and lower RAM are ready and working, ... -
Issue 2 colour problemsHey all, I've got a slight colour problem with my Issue 2 Spectrum, as can be seen below: [IMG]http://www.bennyalford.com/images/issue2a.jpg[/IMG] …
... , a new membrane, 8 4164 RAM chips from my old, long ... voltages good, but not booting. Looks now like a lower RAM problem. Fun ... -
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…
... /> I swapped this around the lower RAM sockets until I got a ... bytes - these sometimes appear, sometimes not.
Anyway, next check ... -
Spectrum +2(grey) rf problem not tuning inHi lads, first of all a quick intro. Im a speccy enthusiast in Ireland, had my first speccy when i was seven in 1987(grey +2). Eventually it got repl…
... power supply oscillator for the lower RAM chips, the ZTX651 mentioned is ... to why the thing may not be working, but if you ... probably good - it simply may not be getting to where it ...
