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Anyone Interested in All the Different Models of Kempston Joystick Interfaces?I've been acquiring some flat-type Kempston Joystick interfaces to adapt to K-55 (yes, spoiling our cultural heritage), but along the way I've picked…
Just got a Power Play one off eBay, out ... Kempston interface, hough with the Power Play logo embossed. Interestingly on ... doesn't mimic the Kempston circuit. It's a cheaper quality ... -
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 …
... PSU that I build supplied power via an I/O interface ... . This in turn fed a circuit board that I made that ... -
Spectrum CapacitorsLooking for some opinions here, if I may? In the 80's and 90's I used to repair Spectrums and other machines for a living so I'm reasonably famili…
... the electrolytic capacitors in the power section should always be renewed ... the power rail decoupling capacitors and the ones in the video circuit ... -
48k not startingHi team, I have 2 48k's, one works (Issue 4s), one doesn't (Issue 4a). The non-working one appears to start, but not finish the RAM test. The pape…
... testing anything other than the power pins, you will likely get ... />
A faulty TR7 open circuit TR7 will result in no ... -
PSU replacement for +2a/+3Hi, With the suitable connector does a PC power supply can be used to power a ZX+2a/+3 ? Thanks
... suitable connector does a PC power supply can be used to ... power a ZX+2a/+3 ?
< ... all three power lines simultaneously when a short circuit is detected on ... -
48K colour issuesGentlemen, A friend handed me over a number of 48K machines to service, and among these there are four of them with various flavours of colour iss…
... this circuit. They should not be damaged, as these are not power ... -
48K colour issuesGentlemen, A friend handed me over a number of 48K machines to service, and among these there are four of them with various flavours of colour iss…
... only from within the LM1889 circuit, yet the fact that the ... depends essentially from the digital circuit. How can it be?
power supply line and feed it ... clean 12Vdc from my lab power supply.
I'm ... -
Not bored with the Boards.Going through some old tapes stored rather badly I came across an unlikely item that that I must have stored away quickly with other low grade items …
... are properly fitted to a circuit board, the risk from a ... I recommend the following:-
Power everything down (including the display ... -
I recapped my 128K toastrack, installed stereo kit and detached audio from video, but...Hello fellow forumers! I'm seeking for help: I've finally decided to change all electrolytic capacitors of my 6U (with all Panasonics 105oC)... Af…
... circuit... I will also look for solder splashes. Then before even power ... ...
Then I'll power it up again to see ... -
I recapped my 128K toastrack, installed stereo kit and detached audio from video, but...Hello fellow forumers! I'm seeking for help: I've finally decided to change all electrolytic capacitors of my 6U (with all Panasonics 105oC)... Af…
... , 5v and 12v around the power area, OK... I also checked ... far as the synchronization signal circuit is concerned, do you mean ... -
48k problemsHi all Just plugged in a 48k that I bought to find that the screen is jumbled with different colour pixel blocks. I removed the casing and noticed…
... volts, assuming anormal Sinclair type power supply. Output (pin 3) should ... duff regulator or a short circuit somewhere dragging down the voltage ... -
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 …
... are carried out with the power off and with no ... large electrolytic capacitors for conventional power supply design is normally not ... electrolytic capacitor that is open circuit, or which has lost a ... problem. But getting the power supply section working is the ... -
Was there a POKE that broke the SpectrumHi Everyone I've been recalling myths and rumours from back in the day. You know "Lunar Jetmans" trailer and that sort of thing. But one rumour …
... recommended. Normally a reset, or power down/up will sort things ... low, that's a short circuit. Normally because the outputs are ... , use either an mains adaptor/power supply that outputs AC instead ... -
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 …
... 't know how the regulator circuit is wired up in a ... . And in the area of power supplies, it is best not ... sheet to prevent a short circuit to the case (which should ... -
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 …
... 't know how the regulator circuit is wired up in a ... . And in the area of power supplies, it is best not ... sheet to prevent a short circuit to the case (which should ... -
Display bandsHi all, I'm busy working on an issue 3 16k Spectrum I picked up on eBay. I've upped it to 48k and put a new membrane in. I noticed the display was…
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A dry joint/open circuit joint on C44 would more ... frequency AC signal from the power section inverter/converter to leak ... -
Switched voltage regulatorIn the past a replacement voor the (hot!) 7805 has popped up a couple of times in various threads. As far as I know, Recom Power Inc. was always ment…
... buy a modern switch mode power supply (9v, centre negative) - ... did this to my sinclair power supply:
[URL= ... DC output of the sinclair power supply with the added benefit ... some dedicated dc current filtering circuit?
Recently, I ... -
Switched voltage regulatorIn the past a replacement voor the (hot!) 7805 has popped up a couple of times in various threads. As far as I know, Recom Power Inc. was always ment…
... in the computer has less power to dissipate - so it does ... "raw" DC from a conventional power supply made up of a ... ), (which is all the Sinclair power supply unit is).
[/list ... . The pre-regulator design and circuit was much cheaper.
Power issues on a 6A 48 K SpectrumHello all! I decided to take another look at my 6A Spectrum that I broke via a bad joystick adapter, I’ve removed the bottom 16K ram and replaced…
... with resistance tests. If the circuit is built from just resistors ... do the measuring, as the circuit itself! This is because each ... fitted them.
Next, power up. Measure the voltages for ... the voltages were all okay, power down/up several times with ...Help with TV repairHi spec-chums. I'm looking for some help with a repair I'm doing on a Polaroid P40LED13 TV. It's problems are there is no picture at all, no backligh…
... the power board which appeared to have shorted when testing in circuit ... . However when testing out of circuit, I found that only one ... the new diodes back in circuit, and both tested fine and ...Kempston ConfusionSomehow, I just can't get this straight on my mind :-O I guess my neurons are playing tricks on me. ~X( Kemspton interfaces allow joysticks …
... a very strange turbo-fire circuit in it that you can ... the case and tried to bypass it, but it was quite ... current through any auto-fire circuit.Spectrum 128k +2 (grey) getting started..So, I just received a grey +2 in the mail. I don't know if it's in working condition, but that doesn't really matter. I opened it up and a small r…
... do the same RF modulator bypass hack as with a 48k ... (your choice) do the modulator bypass ('aka composite mod' per this ... />
I'll try to power up the device first and ...Modern PSU: picture improvement?I've recently seen advertised some 'replacement power supplies' for Spectrums for which the claim is made that they may make an improvement in pictur…
Switchmode power supplies (like the small 'bricks' ... methods to power a ZX Spectrum:
1) Bypass onboard regulation ... . Works fine with original ZX power supply.
For both ...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…
... that are in TR4's circuit has died, causing TR4 to ... defect and many years without power followed by being powered up ...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…
... [*]Vital connection internally goes open circuit.
[*]Produces an output when ... unplugged or plugged in while power on (maybe meaning outputs ... voltage surge on either the power supply or any external ... current, too high a power, running too hot causing ...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…
... the computer unplugged from the power supply.
Which ... is used for decoupling the power lines. Ceramic 100nF types ... to accurately differentiate between open circuit and logic one / logic ... When connected to a logic circuit, it will show green if ...Jiiira's Sparrow LITEHi All, Just for info .. :) big eprom, cheap 32KB ram and etc. i don't know specification .. :) https://youtu.be/NbI7E1aebrM modern speccy .. …
... have been removed from the circuit, I think.
* Small signal ... for the +5V supply.
* Power LED on board.
* Is ...Dead 48k and +2I have a couple of questions. My old 48k had a very wobbly power socket so bought a new one and soldered it on. It will not work at all now? Is ther…
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Electrical power (for a DC circuit) is Voltage X Current ... />
In a simple circuit, there is a resistance to ... , or with the circuit disconnected from the power supply, it can ... measure the resistance of the circuit.< ...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…
... like with an internal short-circuit. But for any that ... ZX Spectrum's voltage conversion circuit. And that -in turn- ... keep tests short, and power off immediately if you see ... use external -5/+12V power supplies for the 4116 ... I read that the power rails have to be ...Can anyone show a slight diagram of how pokes work in a jet set willy game for example?I know its kind of something to do with machine code and Memory addresses etc but would be nice to see a youtube video or some drawings etc ? .Many t…
... have way more memory and power on a basic mobile phone ... so the majority of games bypass it, except maybe for printing ...
