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TV is on the blink - litterally.My TV has gone on the blink. Its a Philips Matchline 32" CRT (See image below). When I turn it on the sound comes on, it makes the usual Bzzzt of th…
... the power supply (CAUTION, very high voltages can be present in ... of the PCBs especially around voltage regulators or any component that ... -
Issue 2 voltage troubleDear all, I got my hands on an old issue 2 from a friend. Price was close to zero so I did not hesitate to take it. After powering it up I was sur…
... pulsating signal this is impossible high. The voltage cannot come via Tr5 ... , I would say that the voltage over C43 equals that of ... -
BeginnerIm having a go at fixing a spectrum which has been in the loft for 20 years and would like some advice please.... I have downloaded the 'spectrum se…
... test, is the forward threshold voltage (offset) of the diode in ... good then.
The voltage that is sent out by ... -5V line, so the rather high value is no surprise then ... -
speccy sound input sensivityis there a way to increase sound input sensivity of 48K spectrums? As most of us trying to transfer tape files to spectrum via our onboard soundcard…
... to the input limiting the voltage to about 4 V peak ... /> But be aware of high (peak) voltage at the sound input of ... -
Issue 3B only sees 16k (and RAMTOP NO GOOD on loading)A ZX+ with issue 3B board that i got recently, does not see anything more than 32768 (sometimes 37267..) on "PRINT PEEK 23732 + PEEK 23733 * 256 (Ent…
... capacitors, 7805 malfunction, sudden voltage variations that cannot be regulated ... memory bank) need three voltage supplies, which must be ... /> - Computer chips exposed to high variations of temperature over years ... bank can be used (High or Low bank). Of ... -
Microdrive units with weak (not dead) ULAs...Hi everybody, I've got a Microdrive unit here. It didn't work. It does now (actually, it was the ribbon had broken and the ground had lost contact, …
... s a problem strictly with voltage (i.e. the ...
If the low voltage is just an artifact of ... current (and therefore, the voltage sagging), you can use ... any voltage gain, but it will present a high impedance ... follwer to the right voltage, and you're sorted ... -
ZX Spectrum 128k Heatsink RGB behaviourHello, this is George from Greece. I have an 128k+ (Heatsink) and i use the rgb cable i bought from ebay on a 1084st monitor. As the monitor does …
... if the voltage levels at the monitor's inputs are too high. -
Another BUG play tapes, in ALL EMULATORs when press STOP1 FOR n=1 TO 20 : PRINT IN 254 : NEXT n : PRINT AT 0,0 : GOTO 1 RUN Type this simple code, load a TZX, pres PLAY, when ear input change between 191 …
... will be - it might be "high" and it might be "low ... change, and not generate output voltage.
The only can ... -
Another BUG play tapes, in ALL EMULATORs when press STOP1 FOR n=1 TO 20 : PRINT IN 254 : NEXT n : PRINT AT 0,0 : GOTO 1 RUN Type this simple code, load a TZX, pres PLAY, when ear input change between 191 …
... generate output voltage.[/quote]
Or the line goes high: depends ... -
Modulator oddness - previous owner's mod?Hello, just bought a rubber key 48k Issue 3 I'm trying to fix up. I'm wanting to do a composite video out mod ( n00b at this) but the "spare" hole in…
... noticed the lack of that high pitched twittering noise you should ... , so I checked out the voltage regulator and it was putting ... -
Intermittent sound cutting outHello, I'm resurrecting an old rubber key spectrum. Originally it had no sound at all, diode D9 was blown, I replaced it with one from my other dead …
... diode has forward drop voltage and i doubt that ... a tester creates enough voltage for resistance measuring to ... reached the resistance is pretty high. (R=U/I, U ... real diode has some voltage drop and therefore has ... of the diode the voltage will be 4.4V ... -
How the DC-DC converter worksI've not seen this before. The DCC-DC converter inside the Speccy has always been quite a mistery for me: [url]http://www.tablix.org/~avian/blog/arch…
... extra diodes are forming a voltage doubler. That way the circuitry ... is higher. The voltage doubler
allows a high resistor at the ... . In consequence if the input voltage is initially higher than 12V ... this higher voltage will not get to the ... -
Replacing coil with other component?The purpose of the coil transformer, from what I gather in the schematics of the issue 2 spectrum, is to create 5V from about 9-10V. Would it not be …
... is not a steady DC voltage nor an AC sine wave ... superimposed on it during the high parts of the cycle at ... -
Spectrum +3 FavourCan a kind soul with a multimeter and a +3 measure the resistance on the power socket between the 5V and the ground? I have a dead +3 that only has 0…
... the base voltage is healthy either, surprised it is so high tho ... -
Internal amp and signal cleaner for tape inHello! Is there known to work INTERNAL schematic which cleans signal from tape in and amplifies it. I need such thing so i can load from my smartpho…
... which work with single rail voltage to make 5x amplification of ... /> However, maybe a low and high pass fillters at the input ... -
(Re) building a ZX Spectrum laserharpThe Cambridge show is nearing, and I want to bring my laserharp with me. Why? Because it's built around a ZX Spectrum +2: [IMG]http://benophetintern…
... voltages (comparator), amplify a voltage with a fixed amplification (non ... make a buffer when a high impedance circuit is used that ... sensitive to electro-magnetic influence (voltage follower), and much more.< ... has a built in high impedance circuit to boost ... -
(Re) building a ZX Spectrum laserharpThe Cambridge show is nearing, and I want to bring my laserharp with me. Why? Because it's built around a ZX Spectrum +2: [IMG]http://benophetintern…
...
1. The DC voltage needs to drop to zero ... TTL blanking output should be 'high'.
How to get ... have a very low voltage drop to maintain most ... (the schematic shows a voltage follower, forgot to update ... create a new DC voltage again with common ground ... -
THE VOLTAGE OF THE POWER SUPPLY UNITCould anybody who has a ZX Spectrum 128k +2 count with a voltameter the voltage which the power supply unit gives to the Spectrum and tell me the [B]…
... "internal resistance".
An unexpected high internal resistance is often caused ... testing. This load brings the voltage of a 48K brick down ... -
RECOM pin compatible DC-DC 7805 regulator replacementsFinally got myself sorted out now. If you want to purchase chips send me an email to [email]alistair@alistairsserver.no-ip.org[/email] with your payp…
... inductor (choke) to reduce the high frequency ripple.
Some ... meter) to set the output voltage correctly.
[I][B ... -
Getting an 14Mhz crystal to oscillate?I am building a circuit with an 74LS32 and a 74LS193 to work as frequency divider. Though I have hit a snag, how to I wire up a crystal to make it os…
... read that as continuous logic high. [/QUOTE]
A circuit ... be able to set the voltage you want as the mid ... -
128k +2 (grey) Ear mod - New ULA and still problemsBverstee kindly sold me a 128K ula since the one in my +2 seemed to have a broken ear in. But even with the new ULA, I still can not load games throu…
... (here), without incoming sound, the voltage at the collector should be ... there is room for the voltage to go up and down ... oscillating like mad, probably somewhere high up in the audio range ... -
Tape loading from PCSo, I found that I had been using the wrong audio jack socket on my 48k for tape loading (my spectrum is in a third party case, so there are not labe…
... ]
Hrm, what threshold voltage does the speccy need? I ... will deliver a greater voltage across a high impedance input. I was ... -
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…
... /> Let's digress from the voltage levels. The output stage 32 ... the contention periods (it appears high in the scope traces because ... -
Tape loading for realHi, Having failed to load anything from my laptop or phone into my 48k, I have sourced a data recorder. An acorn ALF03. When I received the item I …
... , so it has a relatively high power output.
If ... diode and transistor) switch on voltage.
After a bit ... -
Strange failure modeI just had a 48K machine "fail" in what seemed like an odd way. Problem: Random keypresses (not from any particular part of the key matrix) appearin…
... . A weak coupling between low-voltage parts and AC mains is ... components that serve to filter high-frequency noise leaking back into ... -
Preamp Solution for Speccys?Hi, I was wondering what people were using to amplify their sound card or line level datacorder signal to a loud signal for a speccy. Is anyone usin…
... which typically boosts the output voltage of mics to line level ... . Then adjust RV1 for a high output level.
Alas I ... -
Another cause for DivIDE problems on 48K'sThe last months some topics were opened to discuss problems with 48K ZX Spectrums and DivIDE. Sofar we found: - Bad Z80's because of poor fanout (si…
... seems to not pull ROMCS high enough, and sometimes, low pulses ... of both buffer instead of voltage at the output), the BJT ... -
Another cause for DivIDE problems on 48K'sThe last months some topics were opened to discuss problems with 48K ZX Spectrums and DivIDE. Sofar we found: - Bad Z80's because of poor fanout (si…
... seems to not pull ROMCS high enough, and sometimes, low pulses ... of both buffer instead of voltage at the output), the BJT ... -
Another cause for DivIDE problems on 48K'sThe last months some topics were opened to discuss problems with 48K ZX Spectrums and DivIDE. Sofar we found: - Bad Z80's because of poor fanout (si…
... everytime the ROMCS signal went high to low (hence the false ... 1K resistor depends on what voltage your input buffer (inside the ... -
ahh..sooo close :) Spec128k+ RGB on LCD monitor helpHello, Was trying out RGB on my 128k+ and a Samsung Syncmaster 204 lcd monitor. Tried this monitor with a Genesis/Megadrive and a SNES and works real…
... can be fussy about the voltage.
2. At the end ... to RGB when CSync goes high again. This might drive the ...
