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Repair CT2940

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First post, by Peter.Mengel

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Hi my CT2940 Gameport had a short Circuit today, i checked the whole card its working just the gameport doesnt react anymore
So i found the Problem. But i cant figure out what i need to buy to replace it.
R67 is Burned its the one next left at bottom to the Gameport.
Thanks.
soundblaster_16pnp_ct2940.jpg

Reply 1 of 13, by weedeewee

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From the photo that looks to be a 1 ohm Resistor. I'm guessing, it was likely used as a fuse to protect the game port +5v from shorting out the whole computer.

You might want to verify whatever device you had hooked up to the game port before attaching it again.

the size of the smd resistor is... look for smd resistor sizes and measure the broken one, then select the closest dimensional size you can find from the list of sizes. value, 1 ohm for replacement.

Right to repair is fundamental. You own it, you're allowed to fix it.
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Reply 2 of 13, by Peter.Mengel

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weedeewee wrote on 2022-07-15, 14:39:

From the photo that looks to be a 1 ohm Resistor. I'm guessing, it was likely used as a fuse to protect the game port +5v from shorting out the whole computer.

You might want to verify whatever device you had hooked up to the game port before attaching it again.

the size of the smd resistor is... look for smd resistor sizes and measure the broken one, then select the closest dimensional size you can find from the list of sizes. value, 1 ohm for replacement.

Writen 180 on it? Does it stay for something?

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Last edited by Peter.Mengel on 2022-07-15, 16:03. Edited 1 time in total.

Reply 3 of 13, by weedeewee

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Peter.Mengel wrote on 2022-07-15, 15:57:

Writen 180 on it? Does it stay for something?

oh... 180 ? I read it as 1R0.
If it's 180 then it's likely no fuse and something else must've been going on for it to burn.

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !
https://www.vogonswiki.com/index.php/Serial_port

Reply 4 of 13, by Peter.Mengel

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weedeewee wrote on 2022-07-15, 15:59:
Peter.Mengel wrote on 2022-07-15, 15:57:

Writen 180 on it? Does it stay for something?

oh... 180 ? I read it as 1R0.
If it's 180 then it's likely no fuse and something else must've been going on for it to burn.

Hmm maybe its 1R0 i cant read it on mine anymore.
I just added the mt32 pi to the gameport, then i did plug in the jack into the wrong place and it was over...ive tried serdas chill and phill adapter for gameports and it didnt work anymore either...

Reply 5 of 13, by Peter.Mengel

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weedeewee wrote on 2022-07-15, 15:59:
Peter.Mengel wrote on 2022-07-15, 15:57:

Writen 180 on it? Does it stay for something?

oh... 180 ? I read it as 1R0.
If it's 180 then it's likely no fuse and something else must've been going on for it to burn.

Well i could say yeah its 1R0 youve right!
s-l1600.jpg

Reply 6 of 13, by weedeewee

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I guess, you could use a multimeter set to continuity/resistance and try to find out where both sides of the resistor go to.
If i(m guessing right, then it would be +5V in the isa slot and one pin on the DB15 connector... two pins... pin 1 & 9 apparently .

Then it's only hoping the mt32-pi isn't fubar or the circuitry inside the big chip that's responsible for reading the game port.

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !
https://www.vogonswiki.com/index.php/Serial_port

Reply 7 of 13, by Peter.Mengel

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weedeewee wrote on 2022-07-15, 16:20:

I guess, you could use a multimeter set to continuity/resistance and try to find out where both sides of the resistor go to.
If i(m guessing right, then it would be +5V in the isa slot and one pin on the DB15 connector... two pins... pin 1 & 9 apparently .

Then it's only hoping the mt32-pi isn't fubar or the circuitry inside the big chip that's responsible for reading the game port.

So 1ohm Resistor should work?
Lets say like this one?
1-ohm-resistor-550x550.webp

Reply 8 of 13, by weedeewee

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?

You write 10 ohm and then you show a photo of a resistor with the color code amounting to 1kilo ohm, while there is 1 ohm written next to it.
That's one way to make it confusing 😀

1R0 should be 1 ohm. you could replace it with a solder blob, or a thin wire, or a fuse for a few 100mA or a 1 ohm resistor, so, yes, I guess.

edit: woops misread 10 ohm, is 1 ohm.

Last edited by weedeewee on 2022-07-15, 21:21. Edited 1 time in total.

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !
https://www.vogonswiki.com/index.php/Serial_port

Reply 9 of 13, by mkarcher

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Peter.Mengel wrote on 2022-07-15, 16:28:
So 1ohm Resistor should work? Lets say like this one? https://www.flyrobo.in/image/cache/wp/gp/Resistor/1-ohm-resistor-550x550. […]
Show full quote
weedeewee wrote on 2022-07-15, 16:20:

I guess, you could use a multimeter set to continuity/resistance and try to find out where both sides of the resistor go to.
If i(m guessing right, then it would be +5V in the isa slot and one pin on the DB15 connector... two pins... pin 1 & 9 apparently .

Then it's only hoping the mt32-pi isn't fubar or the circuitry inside the big chip that's responsible for reading the game port.

So 1ohm Resistor should work?
Lets say like this one?
1-ohm-resistor-550x550.webp

A fuse is a better substitute than a 1 Ohm resistor (you were already called out on the picture showing a 1kOhm resistor). It is not important whether the resistor is 0.5 ohm, 1 ohm or 2 ohms. But it is important that the resistor blows if you apply a short circuit to the game port. It's primary function in the circuit is being a fuse, not being a resistor. So you should not replace it by a bigger resistor, because that bigger resistor might not blow that easy so it wouldn't protect the system as good as the small SMD resistor did.

A slow-blow fuse (around 250 - 630 mA) would be the best component at that position. A SMD 1-ohm resistor of the same form factor as the blown one would likely work as well. A big through-hole resistor is not a good substitute.

Reply 10 of 13, by Peter.Mengel

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mkarcher wrote on 2022-07-15, 21:11:
Peter.Mengel wrote on 2022-07-15, 16:28:
So 1ohm Resistor should work? Lets say like this one? https://www.flyrobo.in/image/cache/wp/gp/Resistor/1-ohm-resistor-550x550. […]
Show full quote
weedeewee wrote on 2022-07-15, 16:20:

I guess, you could use a multimeter set to continuity/resistance and try to find out where both sides of the resistor go to.
If i(m guessing right, then it would be +5V in the isa slot and one pin on the DB15 connector... two pins... pin 1 & 9 apparently .

Then it's only hoping the mt32-pi isn't fubar or the circuitry inside the big chip that's responsible for reading the game port.

So 1ohm Resistor should work?
Lets say like this one?
1-ohm-resistor-550x550.webp

A fuse is a better substitute than a 1 Ohm resistor (you were already called out on the picture showing a 1kOhm resistor). It is not important whether the resistor is 0.5 ohm, 1 ohm or 2 ohms. But it is important that the resistor blows if you apply a short circuit to the game port. It's primary function in the circuit is being a fuse, not being a resistor. So you should not replace it by a bigger resistor, because that bigger resistor might not blow that easy so it wouldn't protect the system as good as the small SMD resistor did.

A slow-blow fuse (around 250 - 630 mA) would be the best component at that position. A SMD 1-ohm resistor of the same form factor as the blown one would likely work as well. A big through-hole resistor is not a good substitute.

Ok thanks alot? Any Tipps on what exactly fuse i should get? iam somehow new to this but as the Gameport is not working anymore anyway i cant destroy it more i guess...

Reply 11 of 13, by mkarcher

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Peter.Mengel wrote on 2022-07-15, 21:13:
mkarcher wrote on 2022-07-15, 21:11:
Peter.Mengel wrote on 2022-07-15, 16:28:
So 1ohm Resistor should work? Lets say like this one? https://www.flyrobo.in/image/cache/wp/gp/Resistor/1-ohm-resistor-550x550. […]
Show full quote

So 1ohm Resistor should work?
Lets say like this one?
1-ohm-resistor-550x550.webp

A fuse is a better substitute than a 1 Ohm resistor (you were already called out on the picture showing a 1kOhm resistor). It is not important whether the resistor is 0.5 ohm, 1 ohm or 2 ohms. But it is important that the resistor blows if you apply a short circuit to the game port. It's primary function in the circuit is being a fuse, not being a resistor. So you should not replace it by a bigger resistor, because that bigger resistor might not blow that easy so it wouldn't protect the system as good as the small SMD resistor did.

A slow-blow fuse (around 250 - 630 mA) would be the best component at that position. A SMD 1-ohm resistor of the same form factor as the blown one would likely work as well. A big through-hole resistor is not a good substitute.

Ok thanks alot? Any Tipps on what exactly fuse i should get? iam somehow new to this but as the Gameport is not working anymore anyway i cant destroy it more i guess...

Looking for a small (I guessed the common size code "0603") SMD .5A slow-blow fuse, I found this product at Mouser: https://www.mouser.de/ProductDetail/Bourns/SF … ByQNqFrLA%3D%3D , which should work perfectly. I guess Creative Labs used the 1-ohm resistor, because it is a cheaper option. You can even upgrade to a self-resetting fuse (it will recover in some seconds after the short circuit is removed) like this: https://www.mouser.de/ProductDetail/Littelfus … OEyWdBD6A%3D%3D .

Reply 13 of 13, by Peter.Mengel

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keenerb wrote on 2022-07-16, 00:30:

I don't get what happened here. I have a mt32pi, i don't know how you plugged it in wrong to blow the fuse.

Well all i did was, i put the 3.5mm jack into mic, then into line out....Then i smelt some kind of burning...
and i shutdown my system...i first thought my power supply died cause its an original one from 1995
but after a restart evrything worked fine just no gameport signals anymore.

Evrything else was working well, wavetable was working so GM was ok, OPL3 Sound...evrything...
I checked the card today more closely and saw some black "burning" on the fuse and as i touched it it came half off.
Changed the SB card to another one, tried evrything the same to see if that happens again too, but no.
Maybe the fuse was just "old" and couldnt handle the power. I rly dont know.

Will solder it this week as i couldnt get any parts from local stores, so ill have to order...and wait.
So rly no clue...maybe cause ive used a wavetable board and gameport at once? I dont know.

But ive asked here in the forum and people told me it will be fine..i just need to turn the wavetable to
zero value and iam fine.