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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…
... way off. If the voltage regulator, capacitors, and TR4 and ... switching on and off at the normal operating frequency, ... that some will read low, due to them being ... circuit.
At this stage, I would not ... the Z80 CPU has at least started running the ... -
Power supply voltage regulator circuitRelating to [url="https://www.worldofspectrum.org/forums/discussion/56142/"]this topic[/url] I have managed to acquire this little accessory, which I…
... br />
This type of voltage regulator is not very precise. Which ... /> [quote]I have been looking at the 78XX datasheet with particular ... much of a ripple voltage on the regulator's input is ... i]. Or replace internal regulator with a low-drop type (like an ... -
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…
... you mean the 7805 5V voltage regulator?
The whining noise ... [/url].
For the low +12V:
[list][*]Test the ... +5V rail at the emitter of TR5 to ... -
Can't tune into spectrumHi - I recently discovered an old ZX Spectrum in amongst a load of junk (it's the 48K version). Not sure whether it works yet because when I try to t…
... that, whilst giving the correct voltage (9V according to the manual ... constantly clicks (very quickly). The voltage in the cable to the ... TV also oscilates (but at a very low level, my multimeter only ... -
Speccy MTBFHi, Looking at the old (issue 1-2) PCBs, they do look like someone knocked them up in an etching bath/with a soldering iron in their shed but has th…
Hi,
Looking at the old (issue 1-2) ... should imagine that the 7805 voltage regulator and [drink spill induced] keyboard ... -
Which Linux distro for low end PC?Hi, I have a low end PC knocking about which I want to turn into a fairly simple and secure granny PC for surfing, email, odd word doc etc without h…
... ,
I have a low end PC knocking about which ... seems to run reasonably well.....at least as well as Windows ... -
GUIDE: How to convert TZXs to LOSSLESS low bitrate MP3s (56, 64 and 80 kbps)I posted this to comp.sys.sinclair last year, but it didn't get a single reply. Which annoyed me a bit. Since some people here seem to be intereste…
... the version I tested with) at:
[URL="http://www.rarewares ... like this:
"start /low batch.bat *.tzx 24 56 ... the following:
"start /low batch.bat *.tzx 24 80 ... -
how to set voltage regulator to the correct setting ?On the power supply that is broken it says AC adapter INPUT : 230v 50Hz OUTPUT ; 9v 200mA Regulated On the variable voltage adapter i have the…
... />
On the variable voltage adapter i have there is ... do to set the correct voltage ? -
Spectrum +2 power supply - voltages on each pin..?My +2 suddenly stopped working yesterday. It was working fine earlier in the day and now the power light will not go on, nor will the tape drive and …
... there is no video signal at all. Having run a volt ... deck/keyboard/LED seem extremely low. Yet there does seem to ... supply indicates according to the voltage meter, but there doesn't ... -
+3 PSU PoorlyI have a +3 that just stopped working. Its the psu thats gone and opening it up discovered a blown fuse. After replacing the fuse it still doesnt wor…
... work. Theres no +5 volts at the connector and have found ... on it. Looks like a voltage regulator. Has anyone got one of ... -
Silent low power serverLooks like my server has troubles with overheating again, both due to the failing case fans and stupid CPU frequency governor problems. Instead of fi…
... for a silent (ideally fanless) low power server which I could ... connection(s) running at few Mbits, which implies at least few hundred ... -
R.I.P. spectrum 48kRecently one of my 48k rubber key (issue 4) machine bit the dust the other day when I tried to power it on. When powering it on, it gave a weird 'bee…
... a short one at power up).
Looking at the screen ... full check of voltages, new voltage regulator, new membrane... Also added a ... /website on a better voltage regulator that can be used ... possible to add an additional voltage regulator in case one fails ( ... -
So you need to double (or triple, or quadruple) the clock speed...No particular reason for posting this, other than I was looking at an eZ80 evaluation board that does this, and that jogged my memory of a project I'…
... than I was looking at an eZ80 evaluation board that ... is set to oscillate at the frequency you want, ... flip flops go high at the same time, they ... time with its output at logic 1 before the ... control input (voltage from the low pass filter). The low pass filter ... -
Oli Frey low cost prints now availableFor a while you've been able to order Oli Frey prints from [url]http://www.oliverfreyart.com/[/url] - there are now low cost prints available at ?8.9…
... /[/url] - there are now low cost prints available at ?8.95 + P ... -
Question about 7805 regulatorOne of my common practices when I service a ZX machine, is to replace the electrolytic caps as well as the 7805 regulator and some times the ztx650 t…
... machines used the same 7805 voltage regulator but totally by accident I ... uses an 78S05 regulator which is a 2A regulator. That got me ... showing a regular GL7805 (1A) regulator, and the ones on my ... service guide...
"78S05 2A regulator can be used, but hardly ... -
Spectrum 48k PSU voltageI have been running into problems with my rubber key speccy. To cut a long story short I did a voltage check of my power supply. It seems to fluctuat…
... story short I did a voltage check of my power supply ... the speccy itself it starts at about 9v and slowly drops ... -
2 48K speccys dead..Hey guys! I've got two of our rubbery friends with me that need some help. They've been like this for some time, but I would like to try and fix th…
... though it might be the voltage regulator at first but all the voltages ... -
Dead Spectrum SocietySo I'm getting back into real Sinclair computers rather than emulators. During the summer months I was lucky enough to buy a working ZX81 and was giv…
... , the heat sink on the voltage regulator gets quite warm after only ... . Numbering the pins on the voltage regulator 1,2,3 (from left ... /> Any ideas? Are there voltages at specific points on the board ... -
A 30th Anniversary ProjectHappy new year (belatedly...) So with the 30th anniversary approaching, I've decided to do a hardware project to celebrate it. Something hands-on (o…
... ) which will be good at retro events, and is ... this is so that at some point I can use ... through a low pass filter to make a voltage. The voltage changes ... 't reliable for timing, at least without making things very ... failed and the attempt at rework lifted a pad ... -
Inlay Preservation etc., Why Such Low Quality?First up, this site is very good and has brought back some classic memories. I was looking through the Inlays section and other artwork and wondered …
... the scan quality looks so low. On most of the inlays ... and it says to scan at 300dpi (that would be lovely ... work like that. Why scan at brilliant quality then resize it ... are JPG). If you look at an original inlay on the ... -
Repairing a Disciple disk interface - info for othersJust posted this [URL="www.benophetinternet.nl/hobby"]on my weblog[/URL], but I think it's also interesting to put here. This week I did some work o…
... fine, except for the 7805 voltage regulator on the Disciple, which is ... paste, and replacing the cpacitor at the 7805.
Hope that ... -
Anatomy of a bad M1No, not the motorway (although at times the tarmac M1 goes about as well as this one...) But the bad M1 problem that seems to occur most with issue …
... not the motorway (although at times the tarmac M1 goes ... voltages reached (high and low) by the M1 output ... line is active low, so it should sit at near +5V ... It shows a maximum voltage of 778mv and a minimum ... not connected to anything at all, most likely because ... -
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…
... in a "controlled environment" at my University (translated: ... resistors from address lines at the multiplexer outputs ... EUR
2.5V regulator: 0.92 EUR
... are produced my the low quality of this expired ... put too much quantity at some points. Nevertheless, ... -
Revisiting Spectrum CPU clock regenerationWarning: This post will be a bit nerdy :-) Some time ago, I experimented with phase locked loop circuits as a possible way to regenerate the Spectru…
... task? Instead of an analogue voltage controlled oscillator being used to ... the correction should be. At the next Spectrum positive clock ... be slowed. If it's low at the rising edge of the ... larger corrections could be made at the expense of possible increased ... -
Semi-Dead Spectrum - Help RequestedI have finally got my hands on my two old Spectrums - neither of which work, but ideally I hope to get both of them working again. Spectrum number o…
... />
I have replaced the Voltage Regulator and the Spectrum now "boots ... R62 has got extremely hot at some time in the machines ... life. Could I be looking at a RAM fault?
The great 128k ConversionWell, I am not sure if it is going to be great. Hopefully it will! This evening, I set about getting my Issue 6A Spectrum Plus working. I suspecte…
... the wrong polarity, back at some time in the ... had already replaced the voltage regulator back when the machine ... my knowledge of electronics at that time meant that ... soldered in, and the voltage levels tested. All ... have the correct heatsink at the moment, so a ...Issue 2 video problemHello all, Need some help with an issue 2 board that I 'm trying to restore. I've replaced all the electrolytic capacitors, changed the voltage regu…
... the electrolytic capacitors, changed the voltage regulator, tr4, and a Zener and ... accurate but brightness is really low. Any suggestion where and what ...ZX Breakout availabilityOK - after much procrastination, this board is now available! Details on the board are here: - [url]http://spectrum.alioth.net/doc/index.php/ZX_Bre…
... or XC95144XL), a 3.3v regulator and ROMCS mechanism.
voltage regulators, edge connectors etc. as ... in the bill-of-materials at the bottom of the link ... own components, make sure the regulator has the same pin-out ...Designing a Modern 'Professional' low cost ZX Spectrum ??Hi, I'm looking at designing a low cost hight performance (20MHz) ZX Spectrum... in the mould of the original, but using modern-day components. The…
... />
I'm looking at designing a low cost hight performance (20MHz ... is as follows :
Low Cost (less than ?50)
+2 (Grey) and AT/ATX PSUAny ideas on the best way to power a grey +2 board from an AT or ATX PSU? Looking at the schematic, I could do this one of two ways... 1: Bypass th…
... grey +2 board from an AT or ATX PSU?
...
Looking at the schematic, I could do ... />
1: Bypass the regulator (pins 1 and 3 of ... />
2: Remove the regulator and supply 5v to pins ... to 12v and making the regulator get nice and hot, ...
