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ZX spectrum 128K + 2 (Grey one :)Hi all, I'm trying to revive a dead ZX 128K +2 (the grey one). The regulator was damaged and seemed to be feeding 7.8Volts onto the pcb. Yikes ! I…
... with the TR8 / TR9 power supply circuit, is to use your Oscilloscope ... -
Op-amp question for the more knowledgeable tech headI have a dual op-amp IC in a 9 pin SIL package. Pin 1 and 9 are Vcc as marked on the datasheet. The internal schematic as supplied on the datasheet…
... that this is a low power device, and the internal connections ... than one pin for a power line (Vcc / Vdd / 0V / GND ... go wrong. I have a circuit diagram and nowhere on it ... -
spectrum issue 6a oddityMorning everyone Bought a speccy (rubber key) from ebay in near mint condition - couldn't tune in on analogue particularly well so did the comp mod …
... by extreme power supply ripple; another reason why I suggested replacing all ... -
ZX Printer not workingHi All Been meaning to post about this for a while - I have a ZX Printer which doesn't work. Tried on 48K +, +2 and +3 same result LLIST / LPRINT …
[QUOTE=guesser;722338]It won't ever work on the +3 (or the +2 if it's a black one) because there is no power available for the motor.[/QUOTE]
I'm rather pleased they took power off the edge connector. Too easy to short circuit it. -
Interface 1bisHas anyone on here got a "Interface 1bis": [URL="https://sites.google.com/site/interface1bis/"]https://sites.google.com/site/interface1bis/[/URL] I …
... the problem is due to power supply fluctuations (old capacitors do ... very simple reset circuit (with no "brown-out" circuit). And part of ... , use a battery back-up power controller chip to supply the ... SRAM with power instead of using diodes. Of ... -
Interface 1bisHas anyone on here got a "Interface 1bis": [URL="https://sites.google.com/site/interface1bis/"]https://sites.google.com/site/interface1bis/[/URL] I …
... the problem is due to power supply fluctuations (old capacitors do ... very simple reset circuit (with no "brown-out" circuit). And part of ... , use a battery back-up power controller chip to supply the ... SRAM with power instead of using diodes.
DK?Tronics keyboard troubleI have a DK?Tronics keyboard here, which is causing some trouble. Physically it?s in great shape, but some keys simply do not work. The non-working k…
... the gunk off all the circuit board.
I guess ... intermittent and in need of replacing or something doing with the ...Issue 3 board with strange piggy-back boardIn case you are interested. I?ve never seen something like this before. I have an Issue 3 board here. When I opened the case and found a strange pig…
... on the chips they're replacing and would require soldering a ... ! Again, the chips they're replacing don't include anything from ... need for a more complex circuit and another dead cockroach in ...The Spectrum Resuscitation ThreadKicking off this thread as a place where people who are fixing/restoring Spectrums (or indeed any other piece of related hardware) can show off their…
... ]noisy display greeted me upon power on. Voltages checked out, apart ... had bought the farm, so replacing just this part gave me ...Issue 3 board with strange piggy-back boardIn case you are interested. I?ve never seen something like this before. I have an Issue 3 board here. When I opened the case and found a strange pig…
... my understanding the Speccy should power up as a 16K machine ... this broken wire at your circuit?
I thought I ...Official - Birmingham is in the 3rd WorldA water main has decided to have a little lie down and left a large section of Brummie town without water. I thought is was my fault at first becaus…
... had "fun" when they were replacing all the Victorian mains , maybe ... .
we all take power / water for granted, until it ... now flats. here will lose power while 2 or 1 flat ...One more grey +2 with video problemsI guess I need your help again to hopefully be able to do some proper troubleshooting myself one day. Here I have a grey +2, which could be a bottom…
... that is causing too much power to go through it.
circuit on the +12V and -12V power rails.
One more grey +2 with video problemsI guess I need your help again to hopefully be able to do some proper troubleshooting myself one day. Here I have a grey +2, which could be a bottom…
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 …
... into which an external 12V power supply may be connected. If ... .
Using an external power supply is the approach I ... be buffered through an external circuit and then all issues of ... this would require an external power source be used. The loading ...Faulty grey +2, or not?While I?m still fighting with two to three grey +2 computers, which doesn?t give a video signal, I received another grey +2, which acts very strangel…
... across them, taking into account power spikes and a safety margin ... , obviously). So, in a 5V circuit you usually get 16V rated ...Spectrum Missing -5vMy Spectrum is "almost" booting, just when you expect the (C) 1982 Sinclair Research to appear it just displays flashing squares on the screen :( I …
... a problem with the internal power supply circuitry in the Spectrum ... . Do not power it for more time than ... for issue 3B) is short circuit, or one of the 4116 ... RAM chips is short circuit.
EDIT: or if ...Downloading code to physical hardwareHi folks, Back in the day, my devkit was a TRS-80 and I had a simple connector device from the TRS-80 parallel (printer) port to the expansion bus o…
... :(. I got hold of the circuit diagram and worked out what ... , but I can follow a circuit diagram reasonably well) then I ... . Getting that chip out and replacing it was rather worrying as ...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…
... *anything* with *anything* on the power supply lines, actually means that ... also take it, the short-circuit was brief, perhaps even momentary ... the +3 with a different power supply. If it still doesn ... works, then it's the power supply that got killed, so ...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…
... *anything* with *anything* on the power supply lines, actually means that ... +3 (or any other digital circuit) working and feeding it +12V ... certainly can't produce enough power to do that by shorting ...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…
... somewhere between the power supply and the short circuit) for any ... given circuit.
... polarity reversal anywhere in that circuit by shorting +12v to ... ) upstream of the short circuit, you'd likely read something ...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…
... can't produce enough power to do that by ... even know what kind of power supply Spiv was using. ... each other. However, in a circuit being "fed" 5V through ... 12V from the same power supply that provides the 5V ... br /> If you short-circuit the computer's ground plane ...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…
... ;740307]
If you short-circuit the computer's ground plane ... the design of the +3 power supply and +3 PCB. It ... with the design of that power supply (and any "ground bounce ...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…
... equate to zero potential. The power supply voltages of +5 and ... , basically creating a brief short circuit. Additionally, they must overcome whatever ... between the cap and the power pin, and the cap and ... ground as measured at the power supply by shorting it to ...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…
... basically creating a brief short circuit. Additionally, they must overcome ... between the cap and the power pin, and the cap ... />
Similarly, a short circuit can briefly pull ground "up ... the area around the short circuit (especially given its slow ...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…
... 3, with a short circuit appearing on the PCB at ... area near where the power lead plugs in to ... voltage on the Spectrum circuit board will rise with ... PSU. But on the Spectrum circuit board, the components "down ... stream" of the short circuit will just see the loss ...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 +12V, other than the power supply
Fact c: The ... said he tried a different power supply
Question: explain ... (except perhaps components within the power supply) we can offer the ... is happening with the reset circuit).
I'd put ...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…
... some of the really fragile power supplies in the Spectrum ... general even just a shorted power supply input can cause ... inadvertently creating a switch mode power supply while creating the ... unlikely especially given the remaining circuit isn't designed to do ...128K RGB Display problem.I have just got my hand on a toast rack, but when powered and connected to the telly the picture jumps horizontally at random intervals. Could it be…
... capacitor in he PSU needs replacing.
Other known video ... electrolytic capacitors on the Spectrum circuit board having come to the ...Favourite things to do in a power cut threadApparently we have yet another power cut at home, this is after 35 hours without any leccy over Christmas Eve/Christmas Day. Suggestions for favouri…
... year in London it was power cut also... joke being some ... road are on a different circuit = half a house was lit ...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…
... it's not meant to power anything other than headphones being ... that mean? Looking at the circuit diagrams I can see no ... it anyway. Looking at the circuit diagram once more, I realise ...
