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DRAM (:baffled:)Hi, Can someone explain to me the definitive rules on DRAM access times in terms of suitability for a particular speed of processor? Specifically, …
... me the definitive rules on DRAM access times in terms of ... have a number of handy DRAM chips that are 60ns (compared ... -
+12v/-12v/9v and peripherals?Do any peripherals use the +12v, -12v or 9v lines exposed at the edge connector? Firstly, if they use +9v they won't work on a +3, since the +3 does…
Do any peripherals use the +12v, -12v or 9v lines exposed at ... traces down to pass the +12v/-12v through, so I'm looking ... -
DRAM without powerSomething interesting I noticed last night, after making a bad Spectranet ROM image which crashed the machine... Looking at the image on the screen,…
... for the maximum time between DRAM refresh cycles. Perhaps the values ... -
48K Speccy Repair Log.Some people may know my love for writing up my repairs of arcade PCBs on various forums so thought I would do the same for this little fella. Had th…
... a set of eight 4116 DRAM chips. These are very ... power supplies, each chip needs 12V, 5V and -5V and ... are the infamous half faulty DRAM chips, they are actually ... slightly more than the 8 DRAM chips, a 74LS00, a ... to removed the 8x16 pin DRAM chips its a bargain, ... -
12V -> 9VI found this simple dc-dc converter: [url]http://www.mcrent.com/workbench/dcdc1216/[/url] it converts 12V to 16V, can it be used to produce 9V by mod…
I found this simple dc-dc converter:
[url]http://www.mcrent.com/workbench/dcdc1216/[/url]
it converts 12V to 16V, can it be used to produce 9V by modifying R1 and R2?
is there some better solution? -
Spectrum +2 grey 12v railHello everyone, I have this grey +2 with no video from tv. After much reading and testing i realized it was the internal power supply. At the 12v ra…
... internal power supply. At the 12v rail to tea2000 and serial ... -
Understanding DRAMI think I am going slightly mad. My hardware knowledge has got more rusty than it should have done, and I am going to have to turn to the experts to…
... head around the way that DRAM, and specifically upper memory is ... -
Question about 48K DRAM refreshHi guys. Can anybody tell me how the 48K spectrum refreshes the upper ram. RAS only? CAS before RAS? I've got a bunch of 41256 DRAM that i would lik…
... got a bunch of 41256 DRAM that i would like to ... -
12v in a Spectrum +2My Speccy 128 +2 requires a 9v 2.1a PSU, all my 9v PSU's are much below 2.1 amps :( I do however have a 12v 2amp PSU, if I reverse the polarity so t…
... /> I do however have a 12v 2amp PSU, if I reverse ... -
Joytsick Interface damaged SpectrumHello All, Sob.. I am a plonker, I did the cardinal sin, I was testing a bunch of joystick interfaces that I got off ebay and one didn't have the ke…
... -5v and +12v. Does this mean the lower DRAM is now toast ... -
12V Rail - Spectrum 48kOkay - I may just be having a senior moment here, but I'm running out of ideas. I'm working on a Spectrum Issue 4S board,and have had to remove al…
... -5V are fine, but the 12V rail is at almost 25V ... , and the rail there was 12V as expected.
Has ... -
12V ripple with lower ram installedI repaired a speccy this week. Before doing anything I replaced all caps and measured the transistors in the power section. When doing this I found t…
... on and measured the voltages, 12v was giving me an extreme ... on with the ram removed. 12V line was fine with a ... the picture. Looked at the 12v line and there is a ... lower ram ic's the 12v line is ok but when ... causing the instability in the 12v line, it's ruining the ... -
Faulty DRAM chips wanted!If you have any suspect or known faulty DRAM chips, I'm after some so I can conduct some testing. I only want chips that are DIL type, either 16 p…
... any suspect or known faulty DRAM chips, I'm after some ... -
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…
... vertical lines. Turned out the 12V line is bad (along with ... (eliminating the need for -5V/-12V) according to this http://www ... cathode of D15 and feed 12V with a second PSU. However ... D15 soldered in place, the 12V line gets ~8.4V-8 ... -
12V missing on an issue 3I’ve been working on an issue 3 Spectrum +. It shows thin distorted vertical stripes on bootup. +5 and -5V are all right but the 12V line measures ro…
... are all right but the 12V line measures roughly two volts ... the other place that uses 12V is the LM1889, which is ... -
4116 4164 DRAM testersSaw this and thought it may be of interest. https://www.ebay.co.uk/itm/DRAM-TESTER-for-4116-ZX-Spectrum-48k-other-retro-computers/154054505831?_tr…
... ://www.ebay.co.uk/itm/DRAM-TESTER-for-4116-ZX-Spectrum ... ://www.ebay.co.uk/itm/DRAM-TESTER-for-4164-ZX-Spectrum ... -
zx spectrum +2A power supply missing -12v voltshey.. i'm looing at a zx spectrum +2A power supply that the -12v rail seems to be missing .. it has the 12 volts and 5 volts .. it is the version wit…
... +2A power supply that the -12v rail seems to be missing ... ok, i have changed the -12v regulator (79L12) no change then ... to the 5 volt and -12v rail ,,, confused.com
i ... realize that the -12v is not strictly required for ... -
Using a thermal camera to fix speccy's.Hi All, Thought I'd share another repair... Got a board that collapsed the bench supply straight away ( I run a bench supply and give it just enou…
... that's D15... In the 12v rail.
So I ... it in circuit. Check the 12v generating circuit... Needs a replacement ... , no problems, 5v rail stable, -12v and -5v also both present ... to identify and locate faulty DRAM chips... It does tend to ... -
I want to build a new, super spectrum ;-)only kidding Andrew :-) my brain's going at a mile a minute at the moment, so I thought I should put some of the ideas down in case one of them is w…
... datasheet says that the +12v/-5v supplies should be turned ... exactly what happens, since the +12v/-5v supply ceases).
< ... glue logic) to replace the DRAM. This would reduce power ... decreasing availability of the original DRAM rather than actively going ... -
sinclair zx spectrum issue 6a (again) - how to repairHi All, Is there someone who may explain what these jumpers can be used for. [url]http://forest.no-ip.org/repair/jumpers.gif[/url] <- this is from …
... providing the +12V and -5V supply lines to the lower DRAM. I ... state that applying 5V without 12V and -5V is a fantastic ... case) to generate -5V and +12V from the 9V supply input ... -
Spectrum 48K input voltageI have a power supply that is rated 9,5 Volts DC. With no load it outputs about 9,86 Volts. Is it safe to use it for ZX Spectrum 48K? (it can do …
... to generate the 12V and -5V supplies for the DRAM and Colour ... by underpowering them on the +12V/-5V lines. So if you ... -
connecting 3" flopy disk drive to PClooking at this image: [IMG]http://www.fileden.com/files/2006/9/12/214909/Amiga/3inchFDD_figure.png[/IMG] why are pins 2,4,6 and 14 coneccted to +5V…
you didn't forget to swap +5V and +12V, right?
otherwise it would kill most of electronics on 3" FDD.
I once did that on Amiga A590, but luckily only two DRAM chips were fried. -
Z80 ApplicationsI never realised how widely in use the humble Z80 processor was in early Arcade games (Galaga had 3 running in Parallel), Fax Machines, Photocopiers,…
... required -5v and +12v rails), and integrated DRAM refresh logic, to make ... -
4116 DRAM for 48KSomeone told me I got faulty RAM in my broken 48K. They should be 150ns, right? What would be a good place to buy them from?
... -bit register directly with a DRAM control signal, I clocked it ... generate it, could go. The +12V was still used, but only ... -
component out?I would like to connect ZX48K to plasma TV with component cable. I read somewhere that signals are on the expansion edge connector. Do I need somethi…
... use an external PSU for +12v as well as for +5v ... .uk/techwilliams4164.html"]Using 4164 DRAM with Williams Video Game CPUs ... to use 4516 or 4164 DRAM[/URL]
Any other ... -
My Spectrum has gone a bit dud since doing some Mods, HELPMy father in law and I did some modifications to my 48K rubber key Spectrum last weekend, and now it seems to be very keen to crash, especially when …
... little harder to produce +12v for the DRAM and video subsystems, as ... -
Remove +12 Volt itemsWhich items can be removed on a ZX48K issue 4b PCB if I don't need the +12 Volt? Micky
... there exist 16K x 1 DRAM's that are +5V only ... negate the need for the 12v supply circuitry can possibly cause ... input is already around 11~12V if you're using the ... -
damaged spectrum+ (blinking squares)Hi, Sorry for my poor english, but I couldn't find on family forums any remedy for my hardware problem with my first speccy in my life :) I've bought…
... 23A is not delivering -12V as the manual says, ... is therefore an unsmoothed +12V supply".
Dickens mentions ... real life somewhere around 12V,
B22,B23 ... is the generated +12V which often is a little ... or more defect 6116 DRAM. Still make a thorough ... -
damaged spectrum+ (blinking squares)Hi, Sorry for my poor english, but I couldn't find on family forums any remedy for my hardware problem with my first speccy in my life :) I've bought…
... 'm looking for transistors and DRAM to replace. I'll start ... 8 to pin 16 is +12v
voltage of pin 9 ... -
The Sadness of my Decaying Speccies.I've been avidly collecting ZX Spectrums since the late 90's and whilst at the time of the late 90's and early millennium my Spectrums and associated…
... arrives some microseconds before the +12v and -5v supplies (generated by ... momentarily shorting the -5 or +12v outputs at the edge connector ... , M1 is right next to +12v). Fortunately, the Ferranti ULA turns ... or some other type of DRAM) as the supply of 4116s ...