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ZX Spectrum 48k issue 3b power problem?Hi :) I was lucky enough to find a couple of ZX Spectrums at a car boot sale yesterday. I spent the evening fiddling about with one (issue 2) and t…
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The second is an issue 3b. I am willing to fiddle ... the coil near where the power lead goes in during this ... wondering if this is a power issue? Its like it is deliberately ... cutting off its own power.
Thanks in advance ... -
48k + Issue 3B Power SocketHi All, Trying to get a Issue 3b resurrected that had a faulty power socket. The socket has come away from the board and peeled away some of the tra…
... to get a Issue 3b resurrected that had a faulty power socket. The ... -
Issue 3 /3b power rail improvements<!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:AllowPNG/> </o:OfficeDocumentSettings> </xml><![endif]--> <p class="MsoNormal">Hi F…
... odd issue 3 and 3b’s with added components
to the power circuit ... /> The changes must improve to power rails around the pcb and ... will be?I have an issue 3 I trying to get ... -
Issue 3B woesHello there, I currently have a Issue 3B for repairs around, it used to have broken upper and lower RAM, which I replaced with 41256-120 DRAMs (hac…
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I currently have a Issue 3B for repairs around,
it ... connected.
On power down the issue remains until I let ... previously verified in another computer, issue persists when swapping ULA & ... -
Issue 3B turning offI'm trying to save a Spectrum Issue 3B. I restored the power supply section, changing the 7805, TR4, and TR5, besides all electrolytic capacitors. No…
... to save a Spectrum Issue 3B. I restored the power supply section, changing ... some more failures on the power supply section but I'm ... -
Issue 3B problemHi! I have an issue 3B board that is having a strange problem: when I got it it didn't had the -5V and +12v, as usual. After replacing TR4 and TR5 t…
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I have an issue 3B board that is having a ... -
48 Issue 3b working but very hot ula and cpuSalve to everybody I bought from e*ay an Issue 3b 48k , fitted in a + case. Fixed the keyboard problem with a new keyboard membrane from good Rwap (w…
... bought from e*ay an Issue 3b 48k , fitted in a + case ... -
Issue 3B(S)?Got an Issue 3B rubber in today, all boxed up but a sticker on it that states it was made in Korea, hmm, 4S then I think, till I opened it up. Same …
Got an Issue 3B rubber in today, all boxed up but a sticker on it that states it was made in Korea, hmm, 4S then I think, till I opened it up. Same colour board as a 4S but its a 3B, first one like this ive ever come across -
Tape loading problem with Issue 3BI have an Issue 3B 48k that doesn't seem to want to load any tapes. I have an MP3 player connected to the EAR socket. When I type LOAD "" and start p…
I have an Issue 3B 48k that doesn't seem ... same setup working with my Issue 2, where the stripes appear ... -
Issue 3B no soundI just noticed that there's no sound in the Issue 3B Speccy that I've been fixing. Is it more likely that the speaker is bust or is it TR7 and D9? …
I just noticed that there's no sound in the Issue 3B Speccy that I've been fixing.
Is it more likely that the speaker is bust or is it TR7 and D9? Or both? -
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…
... /> I've been donated an issue 3b which has some nice black ... -
48K Issue 3B slowly fading over 15-20 seconds, capacitor gets hot.Hi folks, Recently my much-modified* RAM testing 48K board failed with a hot/burny smell so I turned it off quickly for looking at later. Thinking…
... /> Something's failing in the power circuit and causing a short but ... -
16pf Capcitors for C72/C73 issue 3b. Can I use 18pf?Looking at the service manual it states to use a 16pf ceramic disc capacitor in positions C72 and C73 on issue 3b boards. Is this very critical in bo…
... positions C72 and C73 on issue 3b boards. Is this very critical ... -
16pf Capcitors for C72/C73 issue 3b. Can I use 18pf?Looking at the service manual it states to use a 16pf ceramic disc capacitor in positions C72 and C73 on issue 3b boards. Is this very critical in bo…
... you intend on doing the issue 3B power mod ?
i intend on ... 5/12 volts so no power circuit .. and either a lower ram ... -
16pf Capcitors for C72/C73 issue 3b. Can I use 18pf?Looking at the service manual it states to use a 16pf ceramic disc capacitor in positions C72 and C73 on issue 3b boards. Is this very critical in bo…
... PCB socket (mounted on an issue 3 board) is not the ... you intend on doing the issue 3B power mod ?[/quote]
I do ... last Sinclair recommended version. The issue 3B PCB does not include this ... -
Issue 3 power problemHi all, I have an issue 3 board with an odd power problem, I have no -5V in fact, measuring the voltage on this line leads to a surprising result : …
... I have an issue 3 board with an odd power problem, I ... the -5V bit of the circuit, C46, C47, D11, D12 ... inductor from another (scrap) Issue 3 board, but still ... think the TR4/TR5/L3 circuit must be working as ... comparing to another (working) Issue 3, it does seem to ... -
Unconventional way of diagnosing a faultHi everyone Some time ago I got a 48k Spectrum (issue 3B board) in a pretty bad condition. I believe the power supply transistor TR4 failed, causing…
... (issue 3B board) in a pretty bad condition. I believe the power supply ... transistor TR4 failed, causing a short circuit over ... have managed to repair the power supply and from what ... just remove ULA from the circuit because it also provides CAS ... -
Is it possible to use external power supply for +-12; +-5 for ZX SpectrumRecently I acquired a damaged Sinclair ZX Spectrum, issue 3B. According to the maintenance manual I have to replace TR4 and TR5. These type of transi…
... a damaged Sinclair ZX Spectrum, issue 3B.
According to the maintenance ... can use a regular PC power supply for the Sinclair and ... discard the power supply parts. Has anyone done ... -
issue 6a faultyHi All I got issue 6a pcb from ebay with status faulty pcb had bad voltages when I power up I changed tr4 ztx650 and all voltages got back on ic6 I h…
Hi All
I got issue 6a pcb from ebay with ... had bad voltages when I power up
I changed tr4 ... chips I got from working issue 3b board
any suggestions ... -
Issue 3B suddenly goes black and whiteAnother 3B I have here had a faulty ULA, swapped that out for another and hurrah! Works! New keyboard membrane and composite mod later I load a game…
Another 3B I have here had a ... -checked the mod, tested the power supply, power socket, regulator, LM1889 (on ... -
48K keyboard issue48K issue 3b reads keys without... keyboard. Looking at recorded keys, problems seems to be with one data line - D1. It happens after a while since p…
48K issue 3b reads keys without... keyboard.
... of temperature may suggest short circuit somewhere. -
'Interesting' Issue 2 modSo I've been lurking on this forum for a while and I've got to the point where I want to see if I can repair a speccy.. so I bought me a 'broken' one…
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[LIST]
[*]The standard power socket (replaced with a square ... the ULA chip in an Issue 3b or Issue 6a board, or would ... -
48K Issue 3B ROM to EPROM methodsHi folks, While fixing up a completely dead Commodore PET I needed a way of testing the 4116 RAM chips that make up its 32K, some googling found a…
... to have such a board (3B that the previous owner had ... TANEX board and laid the circuit out on a breadboard, soldered ... -
48k Speccy died, resistors getting too hot to touchHi folks, With 2 days to go till an exhibition my trusty dual-boot 48K issue 3b that I made last year has given up the ghost and I'm not sure I ha…
... my trusty dual-boot 48K issue 3b that I made last year ... but tested out of circuit they're fine. Power is good, I ... -
ZX Spectrum Issue 2 - 12V badHey there, I'm currently attempting to fix a ZX Spectrum issue 2 that I recieved. Overall the machine was generally working when I recieved it, bu…
... to fix a ZX Spectrum issue 2 that I recieved.
power a different Spectrum - Issue 3B IIRC), using a ... -
Powering up a Speccy after long-term storage.Staying at my folks for Christmas. Feels good to be back in God's country again, even if it is -12C outside at the moment. :-o Anyway, I was plannin…
... all electrolytic caps before applying power source, but that defintely ... (12V rail) (this is for issue 3B board)
Unless ... piece of wire and short circuit the two terminals of the ... buzzz" is heared just after power on, disconnect inmediately: TR4 is ... -
Zx 48k after the ic7805 other problemHi everyone, i am Tiago from Portugal, and i am trying to repair a Zx Spectrum 48K. the machine didn't do anything, no image, no sound, nothing. The…
... limit to about 700mA) to power the Spectrum. The limit may ... active for a instant at power on while capacitors charge, but ... straight away, then turn the power off. This will usually stop ... it should; prior to the issue 3b circuit, there should be a sawtooth ... -
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 ... (D16 for issue 3, or D19 for issue 3B) is short circuit, or one ... ] says, a faulty C46 (issue 3 and issue 3B).
You may ... -
Running a Spectrum from a battery...?Here's a bizarre idea that crossed my mind the other day: is it possible to run a Spectrum from a 12V battery? You see, I've got this strange idea…
... have had the power supply upgrade modification (issue 3B upwards), then they ... earlier issue boards are known to had the "mandatory" power supply ... it's not wise to power these with any input voltage ... So a 5V switching regulator circuit would be needed to supply ...
