Back to the future vuk transistor shorting out

[Tmach...@aol.com]

I am working on a bttf. The power supply and cpu are new from rottendog and the display and ppb are new from x-pin. The vuk was fine when first powered on but one triggered it shut off like it should then 5 seconds latter the transistor that fires it shorted and the coil locked on. I replaced the ppb and replaced the vuk diode is wired correct. Same thing happened the transistor was fine until it fired once then five seconds latter it shorts out.

[John Robertson]

On 2022/06/06 7:18 p.m., Tmach...@aol.com wrote:
> I am working on a bttf. The power supply and cpu are new from rottendog and the display and ppb are new from x-pin. The vuk was fine when first powered on but one triggered it shut off like it should then 5 seconds latter the transistor that fires it shorted and the coil locked on. I replaced the ppb and replaced the vuk diode is wired correct. Same thing happened the transistor was fine until it fired once then five seconds latter it shorts out.

Replace the coil diode - don't bother testing it - it is either open or
fails under load. That would account for the driver transistor failing
as described.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
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"Old pinballers never die, they just flip out."

[Tmach...@aol.com]

The new board failed with the old coil when I replaced the new board with another new board I also replaced the coil with diode, that doesnt mean the new diode is bad also but a little unlikely.

[Kerry Imming]

On 6/7/2022 6:02 AM, Tmach...@aol.com wrote:
> The new board failed with the old coil when I replaced the new board with another new board I also replaced the coil with diode, that doesnt mean the new diode is bad also but a little unlikely.

Could you clarify as to which transistor is blowing out? I assume it's
Q5 on the PPB board?

Looking at the manual on page 27, Q42 on the CPU board controls both Q5
and a set of flash lamps. Have you checked those flash lamps for shorts?

- Kerry

[Tmach...@aol.com]

> - KerryQ5
Thanks Kerry but while the line from the cpu controls the coil and the flash lamps it is Q5 that is shorting out and that only controls the coil.

[Tmach...@aol.com]

So i just got back to the game and I tried the ppb in a known working simpsons and the knocker coil trans shorted. Then took the original ppb from the simpsons and placed it in the bttf and its fine. So the problem is with the transistors on the xpin for the 50 v has anyone else had a problem with the xpin replacement ppb or did I just get a bad board. Does anyone have an idea for a fix for this. Maybe a replacement for the transistor. Thanks Ted

[John Robertson]

On 2022/08/12 6:20 a.m., Tmach...@aol.com wrote:
> So i just got back to the game and I tried the ppb in a known working simpsons and the knocker coil trans shorted. Then took the original ppb from the simpsons and placed it in the bttf and its fine. So the problem is with the transistors on the xpin for the 50 v has anyone else had a problem with the xpin replacement ppb or did I just get a bad board. Does anyone have an idea for a fix for this. Maybe a replacement for the transistor. Thanks Ted

Hi Ted,

It is best to quote all relevant previous information in your replies so
we don't have to hop from message to message to get the 'thread'. Not
too that I am 'bottom posting' to your previous post - the idea is to do
this in the same way as we read - top to bottom. Top with the problem,
middle with suggestions and tests, and finally the bottom with
(hopefully) a solution.

Anyway, enough of the Usenet etiquette lesson!

It sounds to me like you shorted the driver transistor on the Xpin PPP
board during the first stages of this email thread.

"The vuk was fine when first powered on but one triggered it shut off
like it should then 5 seconds latter the transistor that fires it
shorted and the coil locked on. I replaced the ppb and replaced the vuk
diode is wired correct. Same thing happened the transistor was fine
until it fired once then five seconds latter it shorts out."

At this point you have a Xpin PPP board with a shorted transistor.

Did you replace the transistor? If not, then do that before going
anywhere else. You say the game now works with a PPP board from another
game, so the VUK is now wired in correctly and has a good diode. However
the previous setup blew the Xpin PPP transistor...

Replace the transistor and get back to us!

[Tmach...@aol.com]

I had tried the new board and it shorted the transistor I then received another new board and also replaced the coil and it shorted the new board as well. I then replaced the transistor by swapping it with one of the other unused transistor from the board only two of the five are used. The vuk and the knocker coil. I then placed the new board into a known working simpsons and it shorted another transistor, So the board itself is the problem. I then took the board from the Simpsons and put it in bttf with the same vuk coil and it ran fine in there so its not the coil. But this is the second board that this has happend with plus a swap of the bad transistor. I also confirmed wires on coil were correct I never swapped wires. Maybe just a bad batch of transistors on the new board but it was also happened on both new board. I am actually a little surprised by the size of the transistors on the xpin board they are very small surface mounts and dont look like they can take the amperage from the coil compared to the size of the ones on the original board that are quite large they just dont seem like they would be able to handle the current but no one else has said they have had a problem with the xpin board yet.

[John Robertson]

> I had tried the new board and it shorted the transistor I then received another new board and also replaced the coil and it shorted the new board as well. I then replaced the transistor by swapping it with one of the other unused transistor from the board only two of the five are used. The vuk and the knocker coil. I then placed the new board into a known working simpsons and it shorted another transistor, So the board itself is the problem. I then took the board from the Simpsons and put it in bttf with the same vuk coil and it ran fine in there so its not the coil. But this is the second board that this has happend with plus a swap of the bad transistor. I also confirmed wires on coil were correct I never swapped wires. Maybe just a bad batch of transistors on the new board but it was also happened on both new board. I am actually a little surprised by the size of the transistors on the xpin board they are very small surface mounts and dont look like they can take the amperage from the coil compared to the size of the ones on the original board that are quite large they just dont seem like they would be able to handle the current but no one else has said they have had a problem with the xpin board yet.

Were both boards that suffered the shorted transistors Xpin? I highly
recommend that you go to Xpin website and email Brett about the problem
you are having.

https://xpinpinball.com/contact/

He designed and manufactured the board and should have an answer for you
soon!

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com

"Old pinballers never die, they just flip out."