Also take into acount the Sinclair PSU supplies 9VDC at 1.4A. You might get it to power up with a universal supply as long as it can supply 9VDC at 750mA or better. It might not work reliably if not at all with anything less. The current draw will be also higher if any interfaces are connected to the Spectrum. A wise and good call to ask about polarity. Getting that wrong would lead to a fried Spectrum. :((
Completely random but the same PSU works with the Oric Atmos but the polarity is the other way around for that. Interestingly said Atmos does *not* fry immediately if you do have it wrong. You can probably guess how I know that
! 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 in Somerset later in the year :)
It didn't come with a plug-in power adaptor, but took four C-type batteries which it ate up very quickly!
I noticed the socket on the back looked exactly the same as my Spectrum, so innocently thought I could use my Sinclair PSU - knowing nothing about polarity or voltage :-O
As you can imagine, 9V into 6V doesn't go and I fried my mate's game :-S
I had to post if off to get it repaired for him, which ended up costing me weeks of pocket money... :(
Thank you. I can´t tune the picture. The best I can get is a bright grey white screen with barely readable Sinclair Research while the picture is moving. :( Keyboard works, but I got few buzzing sounds while pressing keys. :-/ Should Spectrum+ be silent when powered up? I remember my Rubber key Spectrum gave quiet buzzzzzzzzzzz when it was power on.
! 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 in Somerset later in the year :)
The TV-cable I am using is the original Spectrum TV-cable, I think. Connected to TV which has manual tuning knobs. I used the same TV with my previous Spectrum successfully.
On the PSU your using does it mention the current rating? It may be in Amps - 1.5A, or Milliamps - 500mA. If your hearing a buzz from the internal speaker of the Spectrum, that to me may indicate the PSU current rating is too low. It may be causing the poor picture too, but that could also be caused by a faulty RF cable.
Interestingly said Atmos does *not* fry immediately if you do have it wrong. You can probably guess how I know that.
There’s probably a diode that protects it from reverse polarity.
One might wonder why Sinclair didn't so that! it only costs pennies to include such a diode, and i simply don't believe there wouldn't have been room for it on the PCB :))
On the PSU there reads 300mA3.6VA(max). Same PSU was used on my earlier Spectrum. I also tried another RF cable which gives my C64 a good picture.
I'd of thought myself 300mA would not be enough to power a Spectrum although you say it worked ok with another Spectrum is quite an achievement. The Sinclair official PSU's were rated 1.4A. Convert the 1.4A to mA is equal to 1400mA.
On the PSU there reads 300mA3.6VA(max). Same PSU was used on my earlier Spectrum.
That's not enough current (and therefore power) for a normal typical ZX Spectrum. A normal 48k ZX Spectrum typically uses around 530mA to 620mA on the +9V input (with no expansions connected). Although you should use a PSU rated at 700mA minimum. As Your Spec-chum says, Sinclair supplied 1.4A PSUs with retail boxed ZX Spectrums.
Has your "earlier Spectrum" been modified? Maybe with a switching regulator in place of the heatsink and 7805?
! 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 in Somerset later in the year :)
Yes, I managed to use my earlier Spectrum with the same PSU, didn´t know it was an achievement of some sort. :) I have tried to search for suitable PSU. I think I have found suitable one, but I will need to confirm it´s ok for 48K Spectrums before buying. It is DC and it produces 1500mA and 9V, so it´s ok? Another one produces over 2200mA, is that too high and dangerous rate?
Yes, I managed to use my earlier Spectrum with the same PSU, didn´t know it was an achievement of some sort. :) I have tried to search for suitable PSU. I think I have found suitable one, but I will need to confirm it´s ok for 48K Spectrums before buying. It is DC and it produces 1500mA and 9V, so it´s ok? Another one produces over 2200mA, is that too high and dangerous rate?
From what you say, both of these may be suitable. It would be helpful if you could post more details.
For a replacement PSU, the things to look for are:
Correct polarity
Output voltage (see below)
Output current 1.4A (1400mA) or greater
The current output should be greater than 700mA (0.7A). However, 1.4A (1400mA) or greater is recommended. PSUs with greater output currents are not a problem.
The output voltage of the PSU should be a nominal 9V to 10V. The ZX Spectrum 16k/48k/plus is designed for use with an unregulated DC PSU. So if you have a multimeter and test the output of an unregulated PSU when it's not connected to a load (the computer), you may find it's output voltage is as high as 15V. This is not a fault.
When connected to a ZX Spectrum, the actual PSU output voltage should however be below 11.9V DC, as a higher voltage causes problems for ZX Spectrums with earlier PCB versions. All issue 5 and above PCBs have an improved internal PSU circuit, as do some issue 3 and issue 4 boards (but not all).
You can also use regulated or stabilized DC PSUs. The acceptable voltage range is 8V to 11V for these.
! 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 in Somerset later in the year :)
Has your "earlier Spectrum" been modified? Maybe with a switching regulator in place of the heatsink and 7805?
Mark
To be honest, I don´t know. I suppose it is not, I got it from the first owner. It had been stored in the closet since 1986 or so.
Strange. If it had not been used since 1986, then it is very unlikely to have a modern switching regulator. A modern switching regulator is much more efficient, so uses less power. So the current required from the PSU is a lot less.
! 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 in Somerset later in the year :)
I dug my closet and found AC/DC adapter, outputting 9V and 1.3A. It plugs to Spectrum. Is this closet find safe for Spectrum?
If you’re worried it might fry your Spectrum, don’t. What you should be worried is that it might not provide sufficient current for it.
Here’s an analogy of how a PSU power rating works. Imagine the water pressure in your kitchen sink pipes. If the pressure is high enough, you can regulate it with the faucet—you open it more if you need more pressure, and open it less if you don’t need as much. However, if your pipes are too small, or the water pressure is low for some other reason, no matter how much you open the faucet, you won’t get more pressure than there already is in the pipes to begin with.
Now, the power rating (the amperage) stated on a PSU is like the maximum water pressure in the pipes. Any device that you attach to the PSU will operate its own “faucet,” that is it will draw more or less current as it needs it. If your PSU is not powerful enough (i.e. doesn’t have enough “water pressure” in its “pipes”) then when a device needs more power, it simply won’t get it. It may malfunction or operate incorrectly/intermittently. But you can’t fry it with a PSU that is “too powerful.”
Voltage is a different matter, however. You want it to be close to what is required by your device—no less and definitely no more. (Well, the Spectrum will be okay if it gets a little more, as there is a special IC inside that will convert a small amount of extra voltage into heat, but that’s another story.)
Every man should plant a tree, build a house, and write a ZX Spectrum game.
! 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 in Somerset later in the year :)
Ast_A_Moore, thank you for good explanation how kitchen sink pipes and a faucetPSU works. I got it. :)
This closet find AC/DC adapter, there is no "centre negative" or "centre positive" symbol, but there is a symbol between 9V and 1,3A, which is like this: on the bottom there are three short lines and one solid line on top. Does it tell what polarity it has?
there is a symbol between 9V and 1,3A, which is like this: on the bottom there are three short lines and one solid line on top. Does it tell what polarity it has?
Like this:
That symbol just means DC (direct current) and tells you nothing about the polarity of the output connector.
Talking of connectors, the correct connector of the Spectrum's 9V DC input is a 2.1mm ID, 5.5mm OD mini power jack. Where ID means inside diameter and OD means outside diameter. The extra long version is preferred, as the shorter standard version sometimes won't fit through the hole of the case properly.
If no polarity is marked, then the only simple and quick way to find out is to either try it and risk blowing up your Spectrum (very likely, so NOT recommended). Or use a voltmeter (multimeter) or other suitable electronic test device to test the polarity.
Do you know any one who has electronics as a hobby, or is a radio ham? Or maybe you know an electrician? They should be able to test the polarity for you.
Or, as low cost multimeters have now dropped to $5 or lower in most countries, you could buy one and test it yourself.
It is also possible to make a LED polarity indicator. But you do need to be able to solder. I can give details if you are interested.
Unless of course you buy a new PSU and that has the correct polarity.
! 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 in Somerset later in the year :)
A breakthrough! :D I found another PSU, which has everything needed, amps were little low, 800mA, but as you said, it should be enough. I managed to get non-working rubber key Spectrum working! :D The problem was the previous PSU didn´t bring enough amps, as you said. I spent many hours by trying to get games to work until Jet Pac worked at the first try. :) I don´t know if there is something wrong with Spectrum+ or is it just me as I don´t have manuals for it. I noticed it has different keyboard than rubber key model. I cannot type all commands, either I cannot use it or there is something wrong with the computer. In example, on rubber key Spectrum I can instantly type LOAD "" but on Spectrum+ I can get just LOAD, nothing happens when I press SYMBOL SHIFT + P. :(
A breakthrough! :D I found another PSU, which has everything needed, amps were little low, 800mA, but as you said, it should be enough. I managed to get non-working rubber key Spectrum working! :D The problem was the previous PSU didn´t bring enough amps, as you said. I spent many hours by trying to get games to work until Jet Pac worked at the first try. :) I don´t know if there is something wrong with Spectrum+ or is it just me as I don´t have manuals for it. I noticed it has different keyboard than rubber key model. I cannot type all commands, either I cannot use it or there is something wrong with the computer. In example, on rubber key Spectrum I can instantly type LOAD "" but on Spectrum+ I can get just LOAD, nothing happens when I press SYMBOL SHIFT + P. :(
Good that you have found a PSU that has got your Spectrum+ working.
It is possible that there is a fault with the membrane. The Spectrum+ has the quote " symbol on it's own key, does that work? If no, after entering REM (on the ### key), try all the keys and note down which don't work.
Under the 'hood', apart from the wires for the reset switch (button), the Spectrum+ PCB is no different from the PCBs in later 48k rubber key Spectrums.
! 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 in Somerset later in the year :)
It is also possible to make a LED polarity indicator. But you do need to be able to solder.
Well, technically no. You could just hold an LED and a resistor with your fingers and then touch the PSU output plug. Dodgy, but will work in a pinch.
Yes. However, I was thinking about if the design included an in-line mini DC power socket... or maybe a chassis mount socket in a small plastic project box...
! 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 in Somerset later in the year :)
It is also possible to make a LED polarity indicator. But you do need to be able to solder.
Well, technically no. You could just hold an LED and a resistor with your fingers and then touch the PSU output plug. Dodgy, but will work in a pinch.
Yes. However, I was thinking about if the design included an in-line mini DC power socket... or maybe a chassis mount socket in a small plastic project box...
Ah, well, that’s nifty, but—like you said—it’s probably cheaper to get a “disposable” multimeter. ;)
Every man should plant a tree, build a house, and write a ZX Spectrum game.
Comments
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.
A few Spectrum game fixes.
Mind you they cook in other ways :(
B)
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.
A few Spectrum game fixes.
https://en.wikipedia.org/wiki/Astro_Wars
It didn't come with a plug-in power adaptor, but took four C-type batteries which it ate up very quickly!
I noticed the socket on the back looked exactly the same as my Spectrum, so innocently thought I could use my Sinclair PSU - knowing nothing about polarity or voltage :-O
As you can imagine, 9V into 6V doesn't go and I fried my mate's game :-S
I had to post if off to get it repaired for him, which ended up costing me weeks of pocket money... :(
Are you using the RF UHF TV output?
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
One might wonder why Sinclair didn't so that! it only costs pennies to include such a diode, and i simply don't believe there wouldn't have been room for it on the PCB :))
Feel free to help yourself to the Sinclair ZX Spectrum +3 Manual.pdf
Feel free to help yourself to the Sinclair ZX Spectrum +3 Manual.pdf
I'd of thought myself 300mA would not be enough to power a Spectrum although you say it worked ok with another Spectrum is quite an achievement. The Sinclair official PSU's were rated 1.4A. Convert the 1.4A to mA is equal to 1400mA.
Has your "earlier Spectrum" been modified? Maybe with a switching regulator in place of the heatsink and 7805?
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
For a replacement PSU, the things to look for are:
The current output should be greater than 700mA (0.7A). However, 1.4A (1400mA) or greater is recommended. PSUs with greater output currents are not a problem.
The output voltage of the PSU should be a nominal 9V to 10V. The ZX Spectrum 16k/48k/plus is designed for use with an unregulated DC PSU. So if you have a multimeter and test the output of an unregulated PSU when it's not connected to a load (the computer), you may find it's output voltage is as high as 15V. This is not a fault.
When connected to a ZX Spectrum, the actual PSU output voltage should however be below 11.9V DC, as a higher voltage causes problems for ZX Spectrums with earlier PCB versions. All issue 5 and above PCBs have an improved internal PSU circuit, as do some issue 3 and issue 4 boards (but not all).
You can also use regulated or stabilized DC PSUs. The acceptable voltage range is 8V to 11V for these.
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
I dug my closet and found AC/DC adapter, outputting 9V and 1.3A. It plugs to Spectrum. Is this closet find safe for Spectrum?
If you’re worried it might fry your Spectrum, don’t. What you should be worried is that it might not provide sufficient current for it.
Here’s an analogy of how a PSU power rating works. Imagine the water pressure in your kitchen sink pipes. If the pressure is high enough, you can regulate it with the faucet—you open it more if you need more pressure, and open it less if you don’t need as much. However, if your pipes are too small, or the water pressure is low for some other reason, no matter how much you open the faucet, you won’t get more pressure than there already is in the pipes to begin with.
Now, the power rating (the amperage) stated on a PSU is like the maximum water pressure in the pipes. Any device that you attach to the PSU will operate its own “faucet,” that is it will draw more or less current as it needs it. If your PSU is not powerful enough (i.e. doesn’t have enough “water pressure” in its “pipes”) then when a device needs more power, it simply won’t get it. It may malfunction or operate incorrectly/intermittently. But you can’t fry it with a PSU that is “too powerful.”
Voltage is a different matter, however. You want it to be close to what is required by your device—no less and definitely no more. (Well, the Spectrum will be okay if it gets a little more, as there is a special IC inside that will convert a small amount of extra voltage into heat, but that’s another story.)
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.
A few Spectrum game fixes.
Can you post up or link to a photo of it (include a shot of the rating plate/label/markings).
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
kitchen sink pipes and a faucetPSU works. I got it. :)This closet find AC/DC adapter, there is no "centre negative" or "centre positive" symbol, but there is a symbol between 9V and 1,3A, which is like this: on the bottom there are three short lines and one solid line on top. Does it tell what polarity it has?
That symbol just means DC (direct current) and tells you nothing about the polarity of the output connector.
Talking of connectors, the correct connector of the Spectrum's 9V DC input is a 2.1mm ID, 5.5mm OD mini power jack. Where ID means inside diameter and OD means outside diameter. The extra long version is preferred, as the shorter standard version sometimes won't fit through the hole of the case properly.
If no polarity is marked, then the only simple and quick way to find out is to either try it and risk blowing up your Spectrum (very likely, so NOT recommended). Or use a voltmeter (multimeter) or other suitable electronic test device to test the polarity.
Do you know any one who has electronics as a hobby, or is a radio ham? Or maybe you know an electrician? They should be able to test the polarity for you.
Or, as low cost multimeters have now dropped to $5 or lower in most countries, you could buy one and test it yourself.
It is also possible to make a LED polarity indicator. But you do need to be able to solder. I can give details if you are interested.
Unless of course you buy a new PSU and that has the correct polarity.
BTW, where in the world are you?
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.
A few Spectrum game fixes.
It is possible that there is a fault with the membrane. The Spectrum+ has the quote " symbol on it's own key, does that work? If no, after entering REM (on the ### key), try all the keys and note down which don't work.
Under the 'hood', apart from the wires for the reset switch (button), the Spectrum+ PCB is no different from the PCBs in later 48k rubber key Spectrums.
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
Yes. However, I was thinking about if the design included an in-line mini DC power socket... or maybe a chassis mount socket in a small plastic project box...
Mark
Repair Guides. Spanish Hardware site.
WoS - can't download? Info here...
former Meulie Spectrum Archive but no longer available :-(
Spectranet: the TNFS directory thread
! 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 in Somerset later in the year :)
Ah, well, that’s nifty, but—like you said—it’s probably cheaper to get a “disposable” multimeter. ;)
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Member of the team that discovered, analyzed, and detailed the floating bus behavior on the ZX Spectrum +2A/+3.
A few Spectrum game fixes.