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Some problems with 2 ZX Specturm board'sHi, last week i got some ZX Spectrum stuff. Also 2 ZX Spectrum 48K's, one in the orginal case the anoter one in a DK'tronixs case. Both have problem'…
... in one of the lower RAM chips can cause this problem ... . (less than 7V of input voltage)
2) The +12V ... usual 8-9V (9V supply voltage minus 0.7V) that is ... .
I would check voltage on the power supply jack ... -
Toasted +3Oops.. I shorted one of my +3 (being clumsy with multimeter, doh) when measuring PSU connector pins :D Any immediate guesses what exactly died on thi…
... and shorted ground and some voltage (say +12V), you could have ... 12v then the 7812 linear regulator (IC2) is probably destroyed.
Toasted +3Oops.. I shorted one of my +3 (being clumsy with multimeter, doh) when measuring PSU connector pins :D Any immediate guesses what exactly died on thi…
... power supply (represented here by regulator chip IC1) to the load ... conductors is long enough, this voltage can rise to significant levels ... .
So the voltage measured across the load (+5V ... you will get a negative voltage indicated!
[I ...Toasted +3Oops.. I shorted one of my +3 (being clumsy with multimeter, doh) when measuring PSU connector pins :D Any immediate guesses what exactly died on thi…
... :D
So the voltage measured across the load (+5V ... somehow put a high voltage anywhere on the GND ... path to the supply voltage (R1 in your diagram ... and outputs of the linear regulator but (a) they are ... were to measure the voltage on GND immediately upstream ...My first composite mod.Thought it was about time I gave the composite mod a go. I used a youtube video, the bloke in the video took 10 mins, I took about 2 hours :) but it…
... lower and upper RAM module replacements, a Recom regulator replacement, and (given ...My first composite mod.Thought it was about time I gave the composite mod a go. I used a youtube video, the bloke in the video took 10 mins, I took about 2 hours :) but it…
... lower and upper RAM module replacements, a Recom regulator replacement, and (given ...Using a Euro Sinclair PSU in UKI've got a EURO1400 PSU with a Euro plug. Am I right in thinking I can just cut the pug off and change it to a UK plug, and it will work fine? The on…
... ,
Just check the voltage on and off load.
regulator in the PSU that the ...Born again Speccy user with problemsHello all, Firstly I'd like to say a big hello - this is my first post! When I was 8 or 9 or so my dad bought a ZX Spectrum 48K and a whole bunch o…
... very first byte of upper RAM and sometimes that is enough ... if it detects all upper RAM is faulty). However, I ... bit 1 of all upper RAM and your test does suggest ... 4164 or all of upper RAM with one of these: [ ... has applied too high a voltage to one of the audio ...IF1bis StabilityI just thought I would start a different thread relating to the IF1bis, and leave the copyrighters to it elsewhere...:-P I've had mine for a few mon…
... ?Interface 1bis? has its own voltage supervisor and a dedicated microcontroller ... plain simple crashing programs overwriting RAM that's being used for ...PlusDlite problems with 128K modelsLast year I developed the PlusDlite, and already shipped out a couple of them. Only recently I discovered some problems with 128K models. I remember…
... TTL chip, and checked minimal voltage for a 27C64 ROM (allthough ... the PlusDlite's ROM and RAM and disconnected /CSROM.
This ...Faulty 48+Hi I picked up a pile of Spectrum kit including a boxed "untested" 48k+ The Speccy boots to this screen... [IMG]http://www.scotek.net/zx spectrum/…
Thanks Balford,
I'll get some new RAM and run voltage checks.
Image of interface added above. I've been trying for an hour to edit/reply... So slow.Weird tv output by spectrum 48kI recently got a spectrum 48k and hooked it up to my tv. After finding channel 36, I get a really weird picture for the spectrum, why is that? Below…
... =flopping;752186]Check the memory voltage, 12v, -5v and 5v, probably ... get flickering pixels as the RAM send always-changing data to ... the ULA for the screen RAM.
Big black and white ...PSU Overvoltage?Going through a pile of 48k PSU's today, rewiring and fitting new plugs, testing each one as I go I came across one that outputs 14.85v, usually im g…
That on load voltage seems ok.
I ... when I placed a 12v regulator in the PSU that the ...Grey +2 DiedHi all, Thrashing my +2 playing Mugsy last night and it did this... [URL="https://m.flickr.com/photos/83515822@N05/13012551693/lightbox/"]https://m…
... output, then you know the voltage converter circuit is operating and ... 48K Spectrums, all of the RAM only requires the 5 V ...Another "untested" dead spectrum...Hi, I'm looking for some suggestions on a faulty Spectrum I have picked up. I'll need to wait until tomorrow before posting pics, but the screen is …
... one or more faulty lower RAM ICs or failure of their ... be essential, but sometimes the voltage converter circuit fails because of ... supply voltages at the lower RAM. If they are present, but ...Another "untested" dead spectrum...Hi, I'm looking for some suggestions on a faulty Spectrum I have picked up. I'll need to wait until tomorrow before posting pics, but the screen is …
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Voltages at Regulator and all lower RAM chips are present and ...Another "untested" dead spectrum...Hi, I'm looking for some suggestions on a faulty Spectrum I have picked up. I'll need to wait until tomorrow before posting pics, but the screen is …
... ;759961]Voltages at Regulator and all lower RAM chips are present and ...Harlequin clone...PCB manufactured!Using Chris Smith's detailed schematics and project notes from the Harlequin... a Speccy fan in the United States by the name of Don (Superfo) has de…
... out 11v).
The regulator (7805 on the Speccy, LM2596 ... regulator will need to dissipate more heat the higher the input voltage ...Harlequin clone...PCB manufactured!Using Chris Smith's detailed schematics and project notes from the Harlequin... a Speccy fan in the United States by the name of Don (Superfo) has de…
... the regulator of the harlequin will not rise while rising the voltage ... at input. It is a switching regulator with high ... efficiency. If you use a higher supply voltage ...Harlequin clone...PCB manufactured!Using Chris Smith's detailed schematics and project notes from the Harlequin... a Speccy fan in the United States by the name of Don (Superfo) has de…
... there. You can swap the RAM chips and see if the ... .
And measure the voltage - it should be 5V +/- 0 ...Harlequin clone...PCB manufactured!Using Chris Smith's detailed schematics and project notes from the Harlequin... a Speccy fan in the United States by the name of Don (Superfo) has de…
... there. You can swap the RAM chips and see if the ... .
And measure the voltage - it should be 5V +/- 0 ... ,
I think the RAM has gone, same problems with ... mine. I'll get the RAM and ask for professional help ...Totally random idea for the hardware nuts to exploreWhen it comes to multi-player games, how hard would it be to generate a second display from a single Speccy, instead of trying to link up machines, s…
... so I connected it's regulator up to the +2a's ... mapped over the bottom of RAM.
If you want ...Weird output...Last week I found my old ZX Spectrum 48k and I tried to connect it to my tv... After tuning it (at 583MHz - C35, it's the only one with signal) it s…
... very much like the lower RAM in the computer has had ... tells me that the onboard voltage conversion circuitry also has problems ... caused the other (shorted lower ram can kill TR4, or a ... supply failure can kill the RAM)
On the plus ...Harlequin clone...PCB manufactured!Using Chris Smith's detailed schematics and project notes from the Harlequin... a Speccy fan in the United States by the name of Don (Superfo) has de…
... measure the current of input voltage?
Did you measure the ... is OK
- the input voltage on the power plug connector ... ZX Spectrum PSU)
- the voltage at pins 7 and 14 ... [/URL]
Freezes after boot RAM test in PAPER 0 screen.+2a no sound from rfHi, finally got my +2 working, the sound was working through the TV, then it started to crackle, which got worse and then the sound went. Sound is w…
... and obligatory exchange of the regulator.
I thought I ... pretty quickly one of the RAM chips was dead so socketed ...Using VAC PSU in DC deviceHaving fixed the dead Issue 3B, I began to wonder about the PSU that came with it. It was pretty obvious what had killed the poor Spectrum as the PSU…
... hole gets blown in the regulator case then all bets are ... pin.
Also, this voltage would have been applied to ...Fixing my old ZX Spectrum 48K issue 4AHi Guys, I trying to fix my old Spectrum 48K. Looks like my dad used a wrong power supply as the ULA had a bit missing and so did the 7805. So I rep…
... 'd be suspecting an upper RAM fault causing the machine to ... other thread to check the Voltage on R9 to R16 and ...Plea for new hardwareI'm posting this as a poll as I want to judge if I'm a solo loon going on about this, or if people really are interested in either of the following S…
... embedded RAM blocks. I've been put off by the low voltage ... ? Will it have any extra ram in addition to whatever the ...eBay 128K Spectrum RGB cables overheat the Spectrum!?Hi everybody, For a long time I've wondered why Spectrum 128K Toastracks were overheating when using my Retro Computer Shack RGB SCART cable. Today …
... take that through an additional regulator - a small one offering 3v ... to try and drop the voltage - the problem with that is ... you don't drop enough voltage.
Hope this helps ... test first, particularly ensuring the regulator isn't getting too hot!
