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Old 03 July 2020, 07:52   #21
solarmon
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@Misclegend

Yes, I have a rev 2B A1200.

I found that there is some issue with the A1200 I was initially testing with, that I need to investigate further.

It seems that on this specific A1200 machine, the 2nd Fire button signal going to Paula pin 39 and 36 doesn't go low enough. When measured with a logic probe in TTL mode, I see the signal changes from 'high' to 'floating'. If I short the pins directly to ground, the 2nd Fire button signal is activated, because it goes low.

Compared my A500, which works with 2nd Fire button, the same signals goes from 'high' to 'low'

I have another A1200 rev 2B and the 2nd Fire button works for that. So that is something specific about my first A1200 that prevents the signals from going low enough. I suspect the EMI component the signal goes through.
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Old 03 July 2020, 14:18   #22
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Quote:
Originally Posted by solarmon View Post
@Misclegend

Yes, I have a rev 2B A1200.

I found that there is some issue with the A1200 I was initially testing with, that I need to investigate further.

It seems that on this specific A1200 machine, the 2nd Fire button signal going to Paula pin 39 and 36 doesn't go low enough. When measured with a logic probe in TTL mode, I see the signal changes from 'high' to 'floating'. If I short the pins directly to ground, the 2nd Fire button signal is activated, because it goes low.

Compared my A500, which works with 2nd Fire button, the same signals goes from 'high' to 'low'

I have another A1200 rev 2B and the 2nd Fire button works for that. So that is something specific about my first A1200 that prevents the signals from going low enough. I suspect the EMI component the signal goes through.
I also had a rev 2b motherboard it have such problem which I could never fully solve and that I didn't investigate too much
now I have a rev 1D3 which have not this issue

anyways try this

connect the pin 9 to 5v through a 10k resistor, then try such button in some games
also you can try some values from 1k to 10k to check which one is more responsive/compatible with games
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Old 03 July 2020, 14:29   #23
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This second button thing is always complicated

Could you try this? http://eab.abime.net/showpost.php?p=...postcount=1520

Or simply the latest Rygar AGA version.

EDIT: just to see if it's an hardware issue or something that could be software solved (with a game or whdload patch)
Unfortunately there is not a definitive 'working for everyone' hardware solution
(well, you can make a switch from the two general hardware solutions yourself )

Last edited by ross; 03 July 2020 at 14:44.
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Old 03 July 2020, 17:48   #24
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I've done some further investigation and troubleshooting.

My suspect rev 2B A1200 didn't like my Master System Control pad, and my Quickshot Maverick in 'Sega' mode (which effectively is the two-button Master System Control Pad). It seems it just wasn't pulling down the signal to ground far enough - i.e. was getting down to about 1.2V.

Eventually, I figured out a workaround for this type of joy pads, which have carbon rubber buttons. Even though resistance of it only measured about 25 ohms, I suspect that this could be on the threshold. So I put copper tape over the carbon pads.

...and it works! For both both Master System Control Pad and Quickshot Maverick in Sega mode, the 2nd fire button now seems to work on this suspect A1200. It was now pulling down the signal to 1V, which seems to be low enough for Paula to trigger the signal.

However, my QuickShot Maverick for Sega Megagrive and my Sega Megadrive Control Pads were still not working. there are different for the Sega Master System Control Pads and have additional logic, so that was not surprising.

For my Sega Megadrive Control Pad I did try swapping pins 5 and 7 to make sure it was getting 5V from VCC rather than from Paula. But this did not seem to help.

The thread that was linked (http://eab.abime.net/showpost.php?p=...postcount=1520) talks about needing 10K pullup resistors for the buttons to work better. The Sega Megadrive Control Pad already has these pullup resistors. So I'm not sure yet on why these Sega Megadrive game pads do not work on this suspect A1200. They do work without issues on my A500 and another rev 2B A1200.

At least I seem to have found a workaround for the Sega Master System Control pads, which (*EDIT*) does require *doesn't seem to require the need for* pullup resistors, just having better contacts on the fire buttons.

EDIT: When I say working, I meant detected as the second fire button in Amiga Test Kit.

I need to take out the suspect A1200 to that I can check all the traces and components and compare against the working A1200 motherboard.

Last edited by solarmon; 03 July 2020 at 23:37.
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Old 03 July 2020, 20:58   #25
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Quote:
Originally Posted by solarmon View Post
I've done some further investigation and troubleshooting.

My suspect rev 2B A1200 didn't like my Master System Control pad, and my Quickshot Maverick in 'Sega' mode (which effectively is the two-button Master System Control Pad). It seems it just wasn't pulling down the signal to ground far enough - i.e. was getting down to about 1.2V.

Eventually, I figured out a workaround for this type of joy pads, which have carbon rubber buttons. Even though resistance of it only measured about 25 ohms, I suspect that this could be on the threshold. So I put copper tape over the carbon pads.

...and it works! For both both Master System Control Pad and Quickshot Maverick in Sega mode, the 2nd fire button now seems to work on this suspect A1200. It was now pulling down the signal to 1V, which seems to be low enough for Paula to trigger the signal.

However, my QuickShot Maverick for Sega Megagrive and my Sega Megadrive Control Pads were still not working. there are different for the Sega Master System Control Pads and have additional logic, so that was not surprising.

For my Sega Megadrive Control Pad I did try swapping pins 5 and 7 to make sure it was getting 5V from VCC rather than from Paula. But this did not seem to help.

The thread that was linked (http://eab.abime.net/showpost.php?p=...postcount=1520) talks about needing 10K pullup resistors for the buttons to work better. The Sega Megadrive Control Pad already has these pullup resistors. So I'm not sure yet on why these Sega Megadrive game pads do not work on this suspect A1200. They do work without issues on my A500 and another rev 2B A1200.

At least I seem to have found a workaround for the Sega Master System Control pads, which does require pullup resistors, just having better contacts on the fire buttons.

EDIT: When I say working, I meant detected as the second fire button in Amiga Test Kit.

I need to take out the suspect A1200 to that I can check all the traces and components and compare against the working A1200 motherboard.

in some low end gamepads the carbon is very buggy to make good contact
and yes you can add copper or aluminium paper in the back of buttons
as alternative you can replace the carbon from another better game pad button

add a 10k resistor to the sega master system pad and you will have a 100% 2nd button amiga joy

btw,

I just remembered that in the game Aladdin the 2nd button only works if there is no resistor, if there is a resistor the 2nd button will not work
this is for the origina and cracked floppy game, this was fixed in the whdload version

Last edited by Misclegend; 03 July 2020 at 21:07.
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Old 03 July 2020, 21:15   #26
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There seems to be two types of joysticks with second fire buttons. Or rather, two different ways of detecting them.

Ones that pull the signal to ground and ones like the Sega Megadl Drive controllers.

Some games support the pull to ground type - like Turrican. And some support the Mega Drive type - like BC Kid.

Unfortunately, Amiga Test Kit seems to only support detection of the pull to ground type, although there is some detection for the Mega Drive type when you put it in gamepad mode ( but several button signals are activated when you press the 2nd fire button.

For my Master System pad, it doesn't seem to need the pull up resistors to work. Actually, there is no pin 7 connection to provide pull to VCC anyways.

For the Mega Drive pad, that already has pullup resistors.

So I'm not sure when the pullup resistors are needed to be added. I assume this is for joysticks that are like the Mega Drive, but don't have pullup resistors?

Last edited by solarmon; 03 July 2020 at 21:25.
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Old 03 July 2020, 21:44   #27
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Quote:
Originally Posted by solarmon View Post
For my Master System pad, it doesn't seem to need the pull up resistors to work. Actually, there is no pin 7 connection to provide pull to VCC anyways.
of course does not need the pullup resistor but BCKID and CD32 blue button will not work
if there is no pin 7 wire to provide 5v you could change the gamepad cable for a full 9 wires one
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Old 03 July 2020, 22:03   #28
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I haven't got a CD32 (or compatible) pad to be able to test. So maybe that is a third type of joystick to be aware of.

I assume the official CD32 pad does not have pullup resistors by default/design?
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Old 03 July 2020, 22:16   #29
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2nd button works great with my A1200 but this is 1 4D mobo that is recaped.
About the 10k resistor.
Is it like this one?
https://www.ebay.com/itm/10PCS-Metal...cAAOSwi6JaqzVH

This resistor will be connected from 5v to the 2nd button pin, right?
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Old 03 July 2020, 22:17   #30
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How many ohm is 10k resistor. Can someone give the full specs?
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Old 03 July 2020, 23:06   #31
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Let's clear a few things up here.

If the signal doesn't get low enough, a pull-up resistor will only make the situation worse, not better. The Amiga shouldn't need a pull-up, Paula provides the pull-up by setting the pin to high.

The second button is exactly the same electrically as the right mouse button, and even Commodore themselves didn't include a pull-up on the switches of either mouse button. So if the machine can read the right mouse button without a pull-up, it can read a controller without a pull-up.

Controllers and devices with internal logic are a different story of course, and these may or may not need pull-ups, depending entirely on the nature of the logic used in them.

The theory about there being too high a resistance from the EMI filter makes sense - between the resistance of the (probably well worn) carbon pad and the EMI resistor, it could lead to the signal drifting too high. In this case, a pull *down* resistor might help, but it's not an ideal situation.

If games are set to use a CD32 pad, the will not read the second button. The game also needs to support standard 2-button controllers for that to work. If that's the case, the blue button will work as button 2. If a game wants to read the blue button as button 2 like a normal controller, it *must* ensure pin 5 is set high. This is usually the default, but not in every case, and if it's not done, the blue button won't be read.

The standard CD32 pad does not have pull-ups for pin 9. It's driven directly from a logic output.

As well as having additional logic, Megadrive controllers also use a different pinout, and as a result only work by coincidence when they do. They draw power through pin 5 instead of pin 7 as is the Amiga / Atari / Mastersystem standard, and as a result, will only work when the power consumption of their logic is very low, and when pin 5 is set high. As I already mentioned, this is the case most of the time, but isn't guaranteed. And if a game tries to read a CD32 pad, it's turning on and off the power to the MD controller's logic, while also applying 5V to the inputs, which can lead to unpredictable results.

Finally, a note about the 10K resistors: 10K just means 10Kohms, or 10,000 ohms. 3W is massively overkill (and very large as a result), a 1/4 or 1/8W resistor will do the job just fine.

Last edited by Daedalus; 03 July 2020 at 23:17.
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Old 03 July 2020, 23:28   #32
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Quote:
Originally Posted by Daedalus View Post
Let's clear a few things up here.

If the signal doesn't get low enough, a pull-up resistor will only make the situation worse, not better. The Amiga shouldn't need a pull-up, Paula provides the pull-up by setting the pin to high.

The second button is exactly the same electrically as the right mouse button, and even Commodore themselves didn't include a pull-up on the switches of either mouse button. So if the machine can read the right mouse button without a pull-up, it can read a controller without a pull-up.

Controllers and devices with internal logic are a different story of course, and these may or may not need pull-ups, depending entirely on the nature of the logic used in them.

The theory about there being too high a resistance from the EMI filter makes sense - between the resistance of the (probably well worn) carbon pad and the EMI resistor, it could lead to the signal drifting too high. In this case, a pull *down* resistor might help, but it's not an ideal situation.

If games are set to use a CD32 pad, the will not read the second button. The game also needs to support standard 2-button controllers for that to work. If that's the case, the blue button will work as button 2. If a game wants to read the blue button as button 2 like a normal controller, it *must* ensure pin 5 is set high. This is usually the default, but not in every case, and if it's not done, the blue button won't be read.

The standard CD32 pad does not have pull-ups for pin 9. It's driven directly from a logic output.

As well as having additional logic, Megadrive controllers also use a different pinout, and as a result only work by coincidence when they do. They draw power through pin 5 instead of pin 7 as is the Amiga / Atari / Mastersystem standard, and as a result, will only work when the power consumption of their logic is very low, and when pin 5 is set high. As I already mentioned, this is the case most of the time, but isn't guaranteed. And if a game tries to read a CD32 pad, it's turning on and off the power to the MD controller's logic, while also applying 5V to the inputs, which can lead to unpredictable results.

Finally, a note about the 10K resistors: 10K just means 10Kohms, or 10,000 ohms. 3W is massively overkill (and very large as a result), a 1/4 or 1/8W resistor will do the job just fine.
Thank you Daedalus

Some of that has certainly clarified or confirmed my understanding.

The problem I have is that I have two A1200 2B where one works and the other doesn't with the Master System pad 2nd fire button, until I put copper tape on the rubber carbon pads. I put that down as slight differences in tolerances and spec of components in each machine. Which is fine, as long as that is the correct understanding. I'm finding that the signal needs to get to 1V or below to be active.

Quote:
Originally Posted by Daedalus View Post
The theory about there being too high a resistance from the EMI filter makes sense - between the resistance of the (probably well worn) carbon pad and the EMI resistor, it could lead to the signal drifting too high. In this case, a pull *down* resistor might help, but it's not an ideal situation.e.
I'm confused about this pull *down* statement. Wouldn't that just mean/make the fire button will be active all the time, since the signal is *active low*?
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Old 03 July 2020, 23:55   #33
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Originally Posted by solarmon View Post
The problem I have is that I have two A1200 2B where one works and the other doesn't with the Master System pad 2nd fire button, until I put copper tape on the rubber carbon pads. I put that down as slight differences in tolerances and spec of components in each machine. Which is fine, as long as that is the correct understanding. I'm finding that the signal needs to get to 1V or below to be active.
Yep, I think you're correct in that the resistance of the pad combined with the particular EMI resistor in your problematic A1200 is simply not allowing the voltage to drop low enough. 0.8V or lower is the standard TTL threshold for logic 0, and while Paula isn't using TTL, it's likely aiming to approximate the same levels, so a 1V threshold is reasonable enough, and actually slightly more forgiving.

Quote:
I'm confused about this pull *down* statement. Wouldn't that just mean/make the fire button will be active all the time, since the signal is *active low*?
It will depend on the value of the resistor. The Amiga is pulling pin 9 high, and the resistance between that line and ground determines the final voltage that is read by Paula. The higher the resistance, the higher the voltage. As the resistance lowers, so will the voltage, down to 0 ohms, which would in theory give 0V. If the resistance of the copper pad isn't itself low enough to drop the level, adding a second resistor in parallel will effectively mean the pad switches between two resistances - one higher than the pad by itself (which doesn't trigger the input), and one lower than the pad by itself (which is the pad in parallel with the pull down). Too high a resistance and it will have no effect. Too low and it will trigger continuously. But if you measure the pad at 25 ohms and that isn't low enough, but, say, 15 ohms is, then a 36 ohm pull-down would probably do the trick, which would give you 36 ohms when not pressed, and around 15 ohms when it is pressed. Again, this isn't ideal, and the root cause of tired carbon pads or an excessively high EMI resistance should ideally be sorted instead.
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Old 04 July 2020, 00:18   #34
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Deadalus: Great answers. For CD32 2nd button is it not only for jump? Is so, is it not only to connect a button to joystick up and you are done?
What I would like to build is a arcade joystick that also got buttons on the side for pinball games. I know that the CD32 pad use L1, R1 for this. Could whd-load be made to use joystick, right, left for flippers? That way it would be easy to configure side buttons?
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Old 04 July 2020, 19:40   #35
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Quote:
Originally Posted by Daedalus View Post
Yep, I think you're correct in that the resistance of the pad combined with the particular EMI resistor in your problematic A1200 is simply not allowing the voltage to drop low enough. 0.8V or lower is the standard TTL threshold for logic 0, and while Paula isn't using TTL, it's likely aiming to approximate the same levels, so a 1V threshold is reasonable enough, and actually slightly more forgiving.


It will depend on the value of the resistor. The Amiga is pulling pin 9 high, and the resistance between that line and ground determines the final voltage that is read by Paula. The higher the resistance, the higher the voltage. As the resistance lowers, so will the voltage, down to 0 ohms, which would in theory give 0V. If the resistance of the copper pad isn't itself low enough to drop the level, adding a second resistor in parallel will effectively mean the pad switches between two resistances - one higher than the pad by itself (which doesn't trigger the input), and one lower than the pad by itself (which is the pad in parallel with the pull down). Too high a resistance and it will have no effect. Too low and it will trigger continuously. But if you measure the pad at 25 ohms and that isn't low enough, but, say, 15 ohms is, then a 36 ohm pull-down would probably do the trick, which would give you 36 ohms when not pressed, and around 15 ohms when it is pressed. Again, this isn't ideal, and the root cause of tired carbon pads or an excessively high EMI resistance should ideally be sorted instead.
@Daedalus

I've done some more testing so I think I understand a bit better the 2nd fire button requirements.

I won't bore everybody with my test results, but there is still a differrence between how my two A1200 behaves.

On each, if I pull the signal to ground on pin 9 of the joystick port (on the Amiga motherboard), it triggers the 2nd fire button signal.

On the Master System pad, (once I fixed the rubber pads with copper tape), it pulls the pin 9 down to ground 0V directly - so this works on both of my A1200 machines.

The main issues is when it comes to the Mega Drive pad - which uses an MC74HC157A chip to manage the signals. For fire button 1 on pin 5 (on the Mega Drive pad) I see that the chip does drive it down to effectively 0V (18.4mV) - so fire button 1 always works on both A1200's. However, for fire button 2 on pin 9 (on the Mega Drive pad) it only seems to drive it down to 0.5V, which is what is causing the potential issues.

On my working A1200, 0.4V on pin 9 seems to be enough for when it reaches Paula to trigger the signal. However, on my non working one, this does not seem to be low enough - so it won't trigger it.

I'm not sure why the MC74HC157A chip is not driving it down to 0v for both outputs, or how to change it so that it does.

So I think I understand the reason why one of my A1200 is not working, but I don't know exactly why unless I tear it down and compare component values with the working A1200.
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Old 04 July 2020, 22:28   #36
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Quote:
Originally Posted by nikosidis View Post
Deadalus: Great answers. For CD32 2nd button is it not only for jump? Is so, is it not only to connect a button to joystick up and you are done?
Connecting a button in parallel to joystick up will give you a jump functionality, regardless of controller type. There are patches for games that also map a CD32 pad button to jump using software, but as standard, the CD32 pad doesn't map anything to joypad up - it's all up to the software how it interprets the inputs.

Quote:
What I would like to build is a arcade joystick that also got buttons on the side for pinball games. I know that the CD32 pad use L1, R1 for this. Could whd-load be made to use joystick, right, left for flippers? That way it would be easy to configure side buttons?
Many WHDLoad games are already patched for CD32 pad use. The simplest way of building an arcade controller would be to connect the switches directly to the PCB from an old CD32 pad. However, the CD32 pad circuitry is pretty simple, and probably cheaper to build from scratch than a CD32 pad would cost / is worth. It's just two very cheap logic chips and a few resistors and capacitors.


Quote:
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The main issues is when it comes to the Mega Drive pad - which uses an MC74HC157A chip to manage the signals. For fire button 1 on pin 5 (on the Mega Drive pad)
I'm not sure if this is a typo or not, but pin 5 on the Megadrive pad is the power input. MD pads aren't fully Amiga compatible without an adaptor or modification, and only work in most cases by happy accident. The logic inside ends up being powered by the Paula output instead of the 5V rail, which isn't an ideal situation. Pin 6 is the fire 1 pin, just in case...

Quote:
I see that the chip does drive it down to effectively 0V (18.4mV) - so fire button 1 always works on both A1200's. However, for fire button 2 on pin 9 (on the Mega Drive pad) it only seems to drive it down to 0.5V, which is what is causing the potential issues.
Again, not sure if it was a mistake or not, but if pin 5 is being driven low, either the actions of the logic are using more power than the output can provide, or the Amiga is dropping pin 5 low because it things there's a CD32 pad attached. 0.5V is a little high, but as I describe further down, doesn't necessarily mean the pad is at fault as 0.5V is at the high end of normal output for logic 0.

Quote:
On my working A1200, 0.4V on pin 9 seems to be enough for when it reaches Paula to trigger the signal. However, on my non working one, this does not seem to be low enough - so it won't trigger it.

I'm not sure why the MC74HC157A chip is not driving it down to 0v for both outputs, or how to change it so that it does.
Well, the Megadrive pads are similar to the CD32 in that a logic output drives the Amiga's input, and 0.4V output does sound acceptable for a logic output. 0.4V is a very low target for a logic 0 to meet (the standard is 0.8V), but it's within the normal range for a TTL logic output, and you wouldn't normally expect it to drop right down to 0V.

Quote:
So I think I understand the reason why one of my A1200 is not working, but I don't know exactly why unless I tear it down and compare component values with the working A1200.
I think it might be an interesting experiment to see what the final voltage is on both machines as it enters Paula. The ADC circuitry that ultimately determines whether it's triggering the button or not isn't particularly precise, and any differences in the EMI resistance on that line will have an effect too.
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Old 04 July 2020, 22:44   #37
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@Daedalus

Many apologies, I should have mentioned that I did the pin 5 and 7 swap, so that it gets power from VCC, not from Paula. So when I said pin 5 I meant what is marked on the board on the Megadrive pad, so it is actually pin 7 on the Amiga side.

What I was trying to explain is that for fire button 1, it is driven to near enough 0V - so this is OK. But for Fire button 2 it only goes down to 0.5V, so by the time it gets to Paula, and due due to other components, it gets raised and doesn't get below 1V.

On the working A1200 it gets to Paula just below 1V and on the non working A1200 it gets to Paula just above 1V.
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Old 04 July 2020, 23:42   #38
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Ah, I see now, that makes sense. Yeah, there's probably not a lot you can do to get that signal closer to 0V. The logic is essentially working as intended. A pull-down as I described before might help, as could buffering the signal with a transistor, but it does sound like it's ultimately down to a small difference in the ancillary components. The schematics show they should be the same on all revisions, but it might be interesting to check the resistances from pin 9 to the relevant pins on Paula, and also to check the resistance from that Paula pin to ground and 5V, just in case there's something else going on.
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Old 05 July 2020, 23:15   #39
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I made the following measurements on the suspect A1200, with it NOT powered on.

Resistance of Paula pin 39 (POT1Y) to:
* Pin 9 (Joystick port): 68.9 ohms
* Ground: 2M ohm
* VCC: 2M ohms

In comparison to

Resistance of Paula pin 38 (POT1X) to:
* Pin 5 (Joystick port): 69.1 ohms
* Ground: 1.5M ohms
* VCC: 1.5M ohms

Resistance of Paula pin 36 (POT0Y) to:
* Pin 9 (Mouse port): 69.4 ohms
* Ground: 1.5M ohms
* VCC: 1.5M ohms

Resistance of Paula pin 36 (POT0X) to:
* Pin 5 (Mouse port): 69.1 ohms
* Ground: 1.5M ohms
* VCC: 1.5M ohms

So resistance to the corresponding pin via its resistor seems OK, but there seems to an increase in resistance to ground and VCC for Paula pin 39, compared to the other POT pins.

EDIT: Although, the 2nd Fire button is not detected in the mouse port, when testing in ATK.

I will need to do the same measurements in the good A1200.

Last edited by solarmon; 05 July 2020 at 23:25.
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Old 05 July 2020, 23:58   #40
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And on the working A1200:

Resistance of Paula pin 39 (POT1Y) to:
* Pin 9 (Joystick port): 69.1 ohms
* Ground: 1.6M ohm
* VCC: 1.7M ohms

Resistance of Paula pin 38 (POT1X) to:
* Pin 5 (Joystick port): 68.9 ohms
* Ground: 1.6M ohms
* VCC: 1.7M ohms

Resistance of Paula pin 36 (POT0Y) to:
* Pin 9 (Mouse port): 68.7 ohms
* Ground: 1.6M ohms
* VCC: 1.7M ohms

Resistance of Paula pin 36 (POT0X) to:
* Pin 5 (Mouse port): 69.0 ohms
* Ground: 1.6M ohms
* VCC: 1.7M ohms

So the differrence is the resistance to ground and VCC of Paula pin 39
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