(Topic ID: 155191)

STTNG Tieback Clarification


By mskoenen

3 years ago



Topic Stats

  • 36 posts
  • 14 Pinsiders participating
  • Latest reply 7 months ago by ArcadeDanger
  • Topic is favorited by 20 Pinsiders

You

Linked Games

Topic Gallery

There have been 5 images uploaded to this topic. (View topic image gallery).

8-drv RB mod resistor (resized).jpg
Sol_28_tie-back_(resized).jpg
RD_8-drv_tie-back_(resized).jpg
8-drivermod_top_marked_(resized).jpg
8-drivermod_back_marked_(resized).jpg

#1 3 years ago

I just got a STTNG and was reading about how one should preemptively fix the tieback situation on the drop target coil, so as to keep the 8-driver board from exploding with the heat of a thousand suns and ending all life as we know it on earth. I read one thread that said to unsolder all three wires from the coil, then solder them together with a short length of wire, heatshrink that connection, then solder the other end of the new wire to the 50v lug on the coil:

https://pinside.com/pinball/forum/topic/sttng-drop-target-tie-back-mod-help

Then in another thread about the tieback, ZaZa illustrates that you should take the tieback wire and run it directly from J4-1 to J107-1, and skip the playfiled altogether:

https://pinside.com/pinball/forum/topic/sttng-tieback

Do both of these methods achieve the same thing, or is one method better than another?

#2 3 years ago

I've seen some people also tie back a second coil down the line for redundancy if one were to come loose although I don't know if that's the best way to do it. I blew up a transistor because the 20 year old solder joint failed at the coil, and I just cut and resoldered it with a solid connection figuring in home use it won't happen again. The second method shown eliminates coil vibration as a factor though.

#3 3 years ago

More info...
http://www.pinwiki.com/wiki/index.php?title=Star_Trek:_The_Next_Generation

The two methods are equivalent, although I like Zaza's method better. Never thought of it, but next time I'm in my STTNG, I'm going to do that.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#5 3 years ago

I hesitate to call anything in pinball "the best", but it's certainly a good method. It's essentially the same as Zaza's illustrated method.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#7 3 years ago

There is a modification for the 8-driver board to guard the data lines.
This involves adding a 10K resistor array and a single 10K resistor to the clk line.
When a flat cable comes a bit lose and doen't make good contact, it could effect the transistors to activate.
Doing this mod will prevent "floating" data lines.

8-drivermod_back_marked_(resized).jpg

8-drivermod_top_marked_(resized).jpg

#8 3 years ago

I also have a preference for zaza's method : )

One important note !
The tie-back wire has to be on the same 50Volt fuse as where the 4 coils are connected to with Violet-Green.
That would be J106-1, J107-1 or J108-1 but safest would be to join the 2 wires so no mistakes can be made.

If tie-back wire is on another fuse and that group would fail, the 8-driver would be without protection.
Also, be careful using another connector other than J107, when you forget to plug it in after maintenance or so, it gives troubles for 8-driver.

#9 3 years ago

Sascha...can I use your images for this mod in the PinWiki? Thanks!
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#10 3 years ago

Sure you can, Chris.
I was thinking about an update for the picture and include J106 and J108, but if you like it as they are, you can use them.

#11 3 years ago

i just replaced mine with the Rottendog board. Did that new board take care of this problem?

#12 3 years ago

Saving for future reference.

#13 3 years ago
Quoted from sulli10:

the Rottendog board. Did that new board take care of this problem?

The rottendog 8-drv also needs this wire to protect the transistors. Diodes are on this board as well:
RD_8-drv_tie-back_(resized).jpg

#14 3 years ago

A lot of great info, thanks again everyone!

Adding this to the wiki is a good idea, Chris. When I checked there, it gave me a good idea that the problem exists, and why, but not what to specifically do about it. Spelling it out for people like me who are, at best, amateurs is never a bad idea

#15 3 years ago

Stupid questions ... if I may ... if I'm directly connecting J107-1 to J4-1 with an additional wire do I need to remove (disconnect or isolate) the actual wire that runs back from the solenoid to J4-1? Or is it simply redundant and harmless if I leave it in? Should I consider the additional wire like insurance in case the tieback diode wire actually connection actually fails under the playfield?

#16 3 years ago

DumbAss (the only time I can use a name like this and mean nothing more than your "name" )

Quoted from DumbAss:

do I need to remove (disconnect or isolate) the actual wire that runs back from the solenoid to J4-1?

Nope.

Quoted from DumbAss:

Or is it simply redundant and harmless if I leave it in? Should I consider the additional wire like insurance in case the tieback diode wire actually connection actually fails under the playfield?

Yes, and yes.

--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#17 3 years ago
Quoted from zaza:

Sure you can, Chris.
I was thinking about an update for the picture and include J106 and J108, but if you like it as they are, you can use them.

Thanks Sascha...added...
http://www.pinwiki.com/wiki/index.php?title=Star_Trek:_The_Next_Generation

Adding the other two connectors to the image might be even more helpful.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#18 3 years ago
Quoted from ChrisHibler:

Thanks Sascha...added...

Nice !
I will add the two connectors in the picture and put them on the e-mail tomorrow or day after.

edit: done !

#19 3 years ago

It may be easier to add diodes on the coils themselves. No extra wire, no connectors which may fail, just solder 4 diodes on the 4 coils.

#20 3 years ago

That's what I do.

#21 3 years ago

Would it hurt to do both?

#22 3 years ago
Quoted from mskoenen:

Would it hurt to do both?

If you mix the wires up at the coil - YES.

If a diode fails, is it the one on the coil or the one on the board ?

Fix things right, don't make more work or problems in the future.

LTG : )

#23 3 years ago
Quoted from LTG:

Fix things right, don't make more work or problems in the future.

Considering some of the "work" done on the games my group gets, I'm pretty sure what you just said is the opposite of how us amateur's are supposed to do it .

#24 3 years ago

if you put a coil diode on in reverse, you'll know it immediately! (it will short the diode and blow up the driver transistor, smoke, locked on coil, stuff like that.) It's not like it will take more than like 10 seconds to know.

so basically coil diodes are a good thing.

If you understand the history of coil diodes and how williams moved them to the boards, and then later decided that was a really bad idea, and moved them back to the coils, well, you get the point...

redundancy in this case is a good thing. when mounting the 1n4004 diode on a coil, just makes sure the power wire (thick usually doubled-up wires) get the diode band.

#25 3 years ago

Thanks, Clay! Looking forward to making the trip out your way in May!

#26 3 years ago
Quoted from cfh:

If you understand the history of coil diodes and how williams moved them to the boards, and then later decided that was a really bad idea, and moved them back to the coils, well, you get the point...

Ok, I understand. But when exactly did Bally/Williams WMS stop with diodes on-board because on CactusCanyon this technique is still used.

#27 3 years ago
Quoted from zaza:

Ok, I understand. But when exactly did Bally/Williams WMS stop with diodes on-board because on CactusCanyon this technique is still used.

Jim answers this in the wiki.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The new place for pinball repair info

#28 3 years ago

moving diodes to the boards started with system11 and the Auxiliary power board. the problem was they did it for only certain coils, and it became confusing which coils needed diodes, and which did not. With WPC basically all the coil diodes (except flipper) went to the driver board. With fliptronics wpc they put diodes on the fliptronics board. so the flipper coil diodes were actually redundant. (see williams even thought coil diode redundancy was a good idea.)

But WPC95 things started to change. And with pinball 2000 now basically all coils had diodes again. Williams basically made it confusing. So i just always use a coil diode if there's any doubt. It can never hurt, assuming you install it correctly.

#29 3 years ago

This is the eye of the beholder.

Diodes on coils are supposed to be as near as possible to the source of the voltage spike. Theoretically.
Practically the 2m. wiring is not a long distance at all, so it really doesn't matter if it is on the PCB or the coil.
When a coil is replaced and the wiring is connected wrong... results in damage.
So from that point of view it is best to put them on the driver board.

However: when this system (the 8-driver board) depends on a very thin wire which is connected to a coil, and if this wire breaks it results in burnt coils? I think that can be seen as a design flaw. Especially when connected to the playfield, with movement, vibration, solder-connections, etc. one can expect that wire breaks are possible.

And the design for the 8-driver PCB is imho also flawed on the data lines through the flatcable: it results in burnt coils or flashers burning plastics when the flatcable is old. A simple resistor array can be used for a better (very cheap) solution, but this is not the way de PCB is designed.

Again: this is in the eye of the beholder...

#30 3 years ago

Thanks for your answers guys.

Yes, there are pros and cons for both versions. I just looked into the manual of StarWars:ep1 page 3-10 and 3-11 and find that Williams decided to do it with P2K as follows:
Solenoid 1-16 - Diodes on-board and on coils
Solenoid 17-28 - Only diode on coils (when coil is used)
FlipperCoils - Diodes on-board and on coils.

Call it redundant or safe, it is good to know that some coils are equipped both ways.

Last week I had to look for a problem with the Williams 'ticket tac toe' where the flippers were very weak and the right one falling back after energize.
It happend to be that 50Vac fuse was blown and the rest of the (flipper-)coils get their supply by the flashers' 20Volt because sol#9-16 has multiple flashers and one coil in that circuit with tieback diodes on-board.
This is a great example that diodes on-board can be very tricky for your machine.

#31 3 years ago

Another question related to tieback diodes but not Star Trek (TNG) related.

I have a T2 and I see from the schematics and wiring diagram that it has the same issue. Power to the drop target is supplied by J107-2 (VIO-ORG) and there is a tieback diode wire from the coil to J122-9 (VIO-ORG). This connects to the power side (banded end of the diode) on the schematic. It seems that each pin for J122-5/6/8/9 is "optional" in that if J107-2 is used for a coil it needs an individual tieback diode wire for the appropriate driver transistor.

Is it safe to also apply the same logic and connect J107-2 to J122-9 directly as originally suggested for Star Trek (TNG)?

#32 3 years ago

Hey, that's funny, I made a picture for that one too, and must say that you do understand this matter very well.
https://pinside.com/pinball/forum/topic/please-help-this-beginner-t2-pinball-driver-board-destroyed#post-2602559

So yes, this board has 8 drives (sol.# 21 -28) with an optional diode in case a coil is used and it is even possible to drive a 20 Volt coil this way.
Here with sol.#28 in the T2, it can be done the same way as in ST:tng direct to 50V power at J107-2.
As mentioned before, the original method, this way or a diode on the coil are ways to protect the drive-transistor.
In all 3 cases a solid connection is required !

Sol_28_tie-back_(resized).jpg

1 year later
#35 2 years ago
Quoted from ChrisHibler:

Jim answers this in the wiki.

thanks for the reminder, I did search for 'Jim' and 'diode' in the wiki but never found the 'answers'.
Would appreciate if someone has a direct link to this story so I can read it.

--
and a nice close-up for this pull-resistors modification:
8-drv RB mod resistor (resized).jpg

1 year later
#36 7 months ago
Quoted from zaza:

and a nice close-up for this pull-resistors modification:
[quoted image]

I used this picture to perform the modification to my board. Thank you, was very easy to do.

Promoted items from the Pinside Marketplace
$ 999.00
Pinball Machine
Mircoplayfields

Hey there! Got a moment?

Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside