From reading previous posts the polarity of the Spectrum jack is reversed? No real confirmation though.
So + on the outside barrel/ring and - on the inside barrel/ring?
Whereas T'ZX81'000 is + tip and - ring?
Having trouble discerning polarity from traces on refurbished Spectrum 48 (thanks Bytedelight!)
PSU Polarity
PSU Polarity
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
Re: PSU Polarity
Thought I would never find it...from WOS
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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Re: PSU Polarity
ZX80, ZX81 use a 3.5mm “audio” jack plug (U.K. terminology). Tip is +9V (nominal). Ring/sleeve is 0V/GND
ZX Spectrum 16K/48K/+/128K/+2 (grey) all use a 2.1mm (I.D.) “DC” barrel power connector. Outside is +9V (nominal). Inner contact is 0V/GND.
Please note that there is, and never was a standard polarity for these barrel power connectors, manufacturers using whatever polarity they felt like at the time. In the 1980s, it was about 50/50 to 60/40 of one polarity compared to the other for gadgets used inside the home. But most gadgets designed for use in a car had the negative on the outside contact.
Mark
ZX Spectrum 16K/48K/+/128K/+2 (grey) all use a 2.1mm (I.D.) “DC” barrel power connector. Outside is +9V (nominal). Inner contact is 0V/GND.
Please note that there is, and never was a standard polarity for these barrel power connectors, manufacturers using whatever polarity they felt like at the time. In the 1980s, it was about 50/50 to 60/40 of one polarity compared to the other for gadgets used inside the home. But most gadgets designed for use in a car had the negative on the outside contact.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
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Re: PSU Polarity
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
Re: PSU Polarity
Thanks for the definitive answer.
That is how I ruined someone's laptop years ago. ...no standard...I still feel stupid. Polarity! Should have remembered to check it.Please note that there is, and never was a standard polarity for these barrel power connectors, manufacturers using whatever polarity they felt like at the time. In the 1980s, it was about 50/50 to 60/40 of one polarity compared to the other for gadgets used inside the home. But most gadgets designed for use in a car had the negative on the outside contact.
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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Re: PSU Polarity
Also, sometimes the barrel connectors are used for low voltage (4.5V to 30V) AC from external “power bricks” (just a transformer in a case). These are very good at killing devices that are expecting a DC supply. In a ZX Spectrum, such an AC supply will kill the 7805 voltage regulator, some electrolytic capacitors and the transistors that form the DC/DC converter/inverter circuit (that supplies the lower RAM and some of the video circuitry).
Mark
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.