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4116 SRAM replacement (and ULA timings).As mentioned in another thread, I have spent quite a lot of time experimenting with different circuits and components for using a static RAM IC to re…
... have sufficiently low gate threshold voltages to work, and many types ... -
128k Toastrack repair advice needed..Hey all, Just got my second toast rack in a oddball deal when i visited a local farmer for some other second hand stuff. The 128 was sitting in a p…
... because it looked suspect. Wrong voltages came from missing 5V, at ... -
Faulty +2 advice please :)Hi all , I have a faulty +2 which when powered up gives a black border and 6 black and White stripes , I'm thinking faulty ram ??? Any one have any b…
I've seen this effect a few times, when the power plug socket was loose or not fully connected/inserted all the way. Does the ram get correct voltages to power up all the way? -
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, …
... what the output waveform and voltages are looking like on the ... -
48k Speccy chucks a wobblerI've got a problem with my rubber keyed 48k speccy. When it is first switched on everything is fine but after a couple of minutes the picture on scr…
... 'd want to monitor these voltages as the Spectrum warms up ... -
TR4 is goneMy TR4 transistor is burned. Can I replace this transistor with a TIP31B or C ? My 4116 RAM ic?s are showing +0.05V, +5V and +8.49V... :) My Spectru…
Hmmmm... I don?t know much about electronics. :)
I?m only trying to learn fixing thie Speccy.
Without the TR4, it turns on normally. But the voltages of 4116 are wrong.
So if a 4116 is faulty, the TR4 can burn? -
TR4 is goneMy TR4 transistor is burned. Can I replace this transistor with a TIP31B or C ? My 4116 RAM ic?s are showing +0.05V, +5V and +8.49V... :) My Spectru…
... powered without all their supply voltages present. If I were you ... -
TR4 is goneMy TR4 transistor is burned. Can I replace this transistor with a TIP31B or C ? My 4116 RAM ic?s are showing +0.05V, +5V and +8.49V... :) My Spectru…
... smoke anymore. :)
But my voltages on IC6 are yet wrong ... and C44) and measure the voltages... argh! :cry:
PS ... -
TR4 is goneMy TR4 transistor is burned. Can I replace this transistor with a TIP31B or C ? My 4116 RAM ic?s are showing +0.05V, +5V and +8.49V... :) My Spectru…
... smoke anymore. :)
But my voltages on IC6 are yet wrong ... -
TR4 is goneMy TR4 transistor is burned. Can I replace this transistor with a TIP31B or C ? My 4116 RAM ic?s are showing +0.05V, +5V and +8.49V... :) My Spectru…
... don't know where my voltages are becoming wrong... :(
Maybe ... points can I measure the voltages to know where they are ... 4116 until I fix the voltages.
Thanks ... -
Does a spectrum +2 power supply work on a +3?tiny question, does a spectrum +2 power supply work for a +3?
... supply has all the same voltages on the same pins as ... -
No colour after changing LM1889NI replaced the faulty LM1889N in my issue 2 spectrum, since I had a very yellow picture, and soldered a socket to put the new LM1889N into, however, …
... . And the VR1 and VR2 voltages was at their correct levels ... -
Does a spectrum +2 power supply work on a +3?tiny question, does a spectrum +2 power supply work for a +3?
... ?[/QUOTE]
No. The voltages are the same, the worst ... -
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…
... numbers in brackets after the voltages.
If the -5V ... .
If all the voltages are present, then your Spectrum ... -
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…
... powered without all their supply voltages the more likely they are ... -
Dark Screen, non working 48k Spectrum (rubber key)I have an issue 1 (I think) "dead cockroach" 48k Spectrum. On power up I get a dark screen and the machine is unusable - see pics. Any ideas on the…
... fault. Are all the supply voltages present at the 4116 ICs ... -
Occasional noise over RGB on +2AHi all I have a +2A that is misbehaving at the moment. I'm using the RGB to SCART lead (which incedentally is great on my +3) The problem is, the …
I havent opened my +2s but making an RGB cable today I was finding the voltages were most certainly not what the various docs claimed they should be. Leading me to think +2s are just wrong(tm). -
48k PSU UpgradeCan anyone give the definitive word on a PSU upgrade (rather than just a replacement) for 48k machines? I'm thinking of adding at least an IDE inter…
... , he could get the additonal voltages. It is good for up ... -
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…
... then any of the 2 voltages is still not ok, I ... -
+3 PSUHiya. Having moved house 3 times since using my +3, I appear to have lost the power supply. I don't suppose anyone has a spare they would like to s…
... PSU this has all the voltages you need and is easier ... -
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 …
... .[/QUOTE]
Measuring the voltages at the coil with a ... -
Better Picture QualityToday I built a PSU and RGB-SCART monitor cable for my +3. However, I'm not too happy with the picture quality. It appears that there's like halos a…
... you are getting the correct voltages out of the scart cable ... -
48k+ CPU SocketThink I've bitten off more than I can chew... After the desoldering my z80 went without incident, no damaged pads, tracks etc. I expected the socket…
... ] suggests that TR3 and/or TR6 could have bought it and ... near TR3 and I knocked TR6 a few times whilst working ... -
48k+ CPU SocketThink I've bitten off more than I can chew... After the desoldering my z80 went without incident, no damaged pads, tracks etc. I expected the socket…
... enough for TR3, but for TR6? Hmm.... (unsolder one side of ... -
48k+ CPU SocketThink I've bitten off more than I can chew... After the desoldering my z80 went without incident, no damaged pads, tracks etc. I expected the socket…
... number of tries. The 3 voltages were OK though.
It ... -
Ear + Mic bits behaviour in relation to beeper outputHave just read [url=http://www.worldofspectrum.org/forums/showpost.php?p=348953&postcount=38]this old post of Joefish's [/url] in the development for…
... can effectively generate 4 different voltages on pin 28 (which drives ... EAR is 0, the two voltages generated (MIC=0 and MIC ... -
Ear + Mic bits behaviour in relation to beeper outputHave just read [url=http://www.worldofspectrum.org/forums/showpost.php?p=348953&postcount=38]this old post of Joefish's [/url] in the development for…
... EAR is 0, the two voltages generated (MIC=0 and MIC ... four levels, mapping the ULA voltages directly to the sample values ... -
48k+ CPU SocketThink I've bitten off more than I can chew... After the desoldering my z80 went without incident, no damaged pads, tracks etc. I expected the socket…
... I've yet to replace TR6.
Thanks Johan, but ... -
48k+ CPU SocketThink I've bitten off more than I can chew... After the desoldering my z80 went without incident, no damaged pads, tracks etc. I expected the socket…
... measure.
Check your voltages on lower memory.