(Topic ID: 279846)

Big problem with transistor Q16 on Space Jam

By NeedaVirus

1 year ago


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  • 11 posts
  • 5 Pinsiders participating
  • Latest reply 10 months ago by NeedaVirus
  • Topic is favorited by 1 Pinsider

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#1 1 year ago

Hello Everyone,

I try to find help here, because i cannot find any response to this problem over the internet,
So here it is :

When I played my Space Jam, the right flipper always seems too soft, specially on "hold" position.
For cause : Q16 was replaced with IRF540... We all know this is not good.

So, i've decided to re-replace it with correct STP40N10L (or 20N10L).
But,
Since i've done this, i've got big big problem and cannot play the game anymore, here's the problem :

Since I push ONE time the button for the right flipper, It still on hold position, instantly kill Q16 (GND short), and after 2-3 sec burn the associated fuse !
I've replaced 3 times Q16, and always exactly the same issue...
Yes, i'm sure of my solders and components. (tested before soldering).
The resistance of the coil is good, and i've putted new diode on it, same issue...

I cannot find the problem (and understand it by the way...)

Do you think U2 (74HCT273) could be DEAD and giving me this problem ?
Or something else ?

Everything was fine with the IRF540 before... (Just the weak flipper)

I've somebody has any idea / suggestion it would be great

Sorry for my medium english, I'm From Belgium.

Thanks a lot !

#2 1 year ago
Quoted from NeedaVirus:

i've decided to re-replace it with correct STP40N10L (or 20N10L).
But,
Since i've done this, i've got big big problem and cannot play the game anymore, here's the problem :
Since I push ONE time the button for the right flipper, It still on hold position, instantly kill Q16 (GND short), and after 2-3 sec burn the associated fuse !

I can’t find a data sheet for a STP40N10L.
Great Plains Electronics shows the IRL540N as the correct replacement.
https://www.greatplainselectronics.com/proddetail.asp?prod=IRL540N

#3 1 year ago

40N10L is 100V 40A logic level MOSFET. IRL540N is 100V 36A, so it is OK for replacement.

Is the diode at right flipper coil properly connected and working? Sounds like the inductive kick-back from coil destroys the MOSFET.

#4 1 year ago

Hello, Thanks for your response !
Yes, it's sure the diode is ok and of course soldered with cables and coil themselves

#5 1 year ago

The driver board gives a 40 ms power pulse to flipper coil when flipper button is pushed, and after that a 1ms pulse every 12 ms while holding the flipper up, and if the EOS switch is closed it will give a 40 ms pulse again.

This pulsing will cause inductive problems if the diode is not connected, but since you verified that, it should be OK! I think there are only two reasons for Q16 to instantly burn out - either the diode is open, causing inductive kickback, or then the coil is partially shorted, exceeding maximum current of the transistor.

Since the coil seemed "soft", check the coils resistance and compare to left side coil. It is strange that the IRL540N did not burn out while the 40N10L did.

Unlikely the problem is in 74HCT273, since the coil is not continuously on, but only after button push.

Edit: I see you have checked the resistance to be OK. Maybe then you could try replacing the '273 and the pull-up resistor / filter capacitor between '273 and Q16?

#6 1 year ago

The IRF540 (not IRL540) didn't burn out because it was only partially turning on (partially turning on = weak flippers). The IRF part is not TTL compatible requires a higher gate voltage to fully turn on. Since it was only partially turned on - it was self-limiting for the current which is why things weren't burning with this component.

You replaced the coil and diode so this problem sounds more like the FET is turning on and not turning off. I suspect the 74HCT273.
Do not go to the higher current STP40NF10L -- you run a higher chance of burning pc board traces. Better to burn the FET than burn the PC board traces.

#7 1 year ago

Hello,
If you talk about C255 + C247 and R16, I've changed C255 last time for trying.
Do you think should I change both the two + R16 AND a new '273 on U2 ?

Don't have '273 so I need to order one...

For the coil resistance, it's not the same coil on the left side, so not the same value, but when I've changed the diode on the right side, I've measured it and compared to coils resistance list, it was ok.

Thanks ! =)

2 months later
#8 1 year ago

Hello again,
I've received my new '273 ... (Better late than never...)
I've replaced it, and once again, a new Q16.

And, ...
No.
The problem is STILL PRESENT !
So it was NOT U2...

Unbelievable... What's wrong with this board ?!
I'm totally totally lost ...

Please, any help...

2 months later
#9 10 months ago

Hello again, Tried again another thing today, replace the 40N10L (Both Q15 and Q16) with the recommanded IRL540N and the problem is STILL PRESENT !!!
Now on both Flippers by the way !
This driver drive me crazy...

I'm definitively still looking for any help ...
Any idea, any suggestion ? This problem is very uncommon ...

#10 10 months ago

Are they both locking on after pressing the flipper button or are they both weak?

If both are weak only, how are the other high voltage coils behaving?

#11 10 months ago

No they are both locking and destroying respective transistor only when i push flipper button :-/

Hey there! Got a moment?

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