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One for the boffins

Yes mate that's right. The FET bridge is how the GI OCD and Afterglow create power from the 6.3VAC (J115), and it appears as though when the ground generated from this process is combined with the pinballs GND, it creates in imbalance that results in the chase board showing reversed LEDs dimmer than they should be.

Sick of me yet?! 😆

So I can't alter these boards, or that FET bridge, or how the GND from that bridge is combined with pinball GND. The only option I'm thinking of now is to bypass that bridge, and power those boards some other way. The don't need the AC lines after all.
 
Wheres the chase circuit from ?

Yep its the joining of the two gnds.
By joining them your shorting out the fancy OTT bridge circuit I think and its not liking it.
 
Vimtoman said:
...
Nothing to do with the other bridge rectifiers.

.....

Your complicated Fet bridge rectifier circuit is OTT and obviuosly causing issues on how your using it.
Click to expand...
It is the combination that causes the problem.

David
 
stumblor said:
Yes mate that's right. The FET bridge is how the GI OCD and Afterglow create power from the 6.3VAC (J115), and it appears as though when the ground generated from this process is combined with the pinballs GND, it creates in imbalance that results in the chase board showing reversed LEDs dimmer than they should be.

Sick of me yet?! 😆

So I can't alter these boards, or that FET bridge, or how the GND from that bridge is combined with pinball GND. The only option I'm thinking of now is to bypass that bridge, and power those boards some other way. The don't need the AC lines after all.
Click to expand...
Talk to the designer - others will be having the same problem and ultimately it is a design fault on the OCD/Afterglow board.

David
 
Had a look at the chase circuit and looks OK.

I think its the new FET bridge rectifer being shorted.

I can only think of one possible way round it which may work for the Afterglow.

Youll need to remove the FET bridge and use half bridge rectification. Thats one diode and loads and loads of caps.
Then run the afterglow on 3v.

5v signales from Pinball may be ok but if not then level changers on the signals.
 
Vimtoman said:
Had a look at the chase circuit and looks OK.

I think its the new FET bridge rectifer being shorted.

I can only think of one possible way round it which may work for the Afterglow.

Youll need to remove the FET bridge and use half bridge rectification. Thats one diode and loads and loads of caps.
Then run the afterglow on 3v.

5v signales from Pinball may be ok but if not then level changers on the signals.
Click to expand...
There may be a very good reason for the 'ideal' bridge. Without seeing the full circuit I can't say anything other than "talk to the designer"

David
 
The 6.3vac transformer winding is joined to the pinballs ground. Its called Gnd ref.
Half bridge means that this connection is phsycally connected.

The new FET fullwave bridge has a FET and its circuit inline.
I suspect its pulling when joined elsewhere.

The only way to prove it is to wire up and test.
 
DAFlippers said:
There may be a very good reason for the 'ideal' bridge. Without seeing the full circuit I can't say anything other than "talk to the designer"

David
Click to expand...
Yep they need fullwave for 5V and probably down to size of bridge needed for the GI so FET style was smaller and more efficient
 
No the way to prove it is to not guess and hack but to look at the full circuit of the OCD/Afterglow and then decide the best approach or better still speak to the designer as it is their problem. Hacking a board makes no sense and using a halfwave rectifier instead of a full wave also makes no sense.

David
 
If you want something to prove the cause then ground the OCD/Afterglow via a diode and not direct. No hacking.

David
 
DAFlippers said:
If you want something to prove the cause then ground the OCD/Afterglow via a diode and not direct. No hacking.

David
Click to expand...
Heres what I think may be happening. Like any bridge rectifier shorting the ac line with a + or - line will make it go up in flames :)
The same with this FET device.

Your effectively shorting part of it .

Half bridge you would not as it would be physically connected at that point. Shorted anyway
 

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Vimtoman said:
@stumblor your not connecting the chase board to the afterglow or GIOCD outputs?
Click to expand...

No nothing like that - the only thing connecting them is that they're both sharing the 6.3VAC GI.

DAFlippers said:
No the way to prove it is to not guess and hack but to look at the full circuit of the OCD/Afterglow and then decide the best approach or better still speak to the designer as it is their problem. Hacking a board makes no sense and using a halfwave rectifier instead of a full wave also makes no sense.

David
Click to expand...

Here's a full schematic of the Afterglow. GI OCD uses a different diode bridge just investigating that now.

https://oshwlab.com/stumblor/afterglow-gi-1-3

The datasheet you just referenced @Vimtoman, this one

https://www.mouser.co.uk/new/analog-devices/adi-lt4320-controllers/

Mentions that it supports DC voltage rectification. Does that mean we could substitute the 6.3VAC inputs of the Afterglow with 12V DC?
 
stumblor said:
No nothing like that - the only thing connecting them is that they're both sharing the 6.3VAC GI.



Here's a full schematic of the Afterglow. GI OCD uses a different diode bridge just investigating that now.

https://oshwlab.com/stumblor/afterglow-gi-1-3

The datasheet you just referenced @Vimtoman, this one

https://www.mouser.co.uk/new/analog-devices/adi-lt4320-controllers/

Mentions that it supports DC voltage rectification. Does that mean we could substitute the 6.3VAC inputs of the Afterglow with 12V DC?
Click to expand...

Yes you can power from 12VDC. supply

Yes thats the device thats being used.
If you look at my example it should give you an idea if what I thinks happening.
Basically shorting out the bridge on one section when the gnds are joined.
 
Yeah the Afterglow was the easy one as I could always just power it via that connector but the GI OCD - there was no obvious way to power it other than the diode bridge. Luckily, it still supports DC! :cool:
 
Vimtoman said:
Heres what I think may be happening. Like any bridge rectifier shorting the ac line with a + or - line will make it go up in flames :)
The same with this FET device.

Your effectively shorting part of it .

Half bridge you would not as it would be physically connected at that point. Shorted anyway
Click to expand...
If that was what was happening there would be a bang and the magic smoke genie would be released.

David
 
DAFlippers said:
View attachment 134463
@Vimtoman You have drawn the Triac switching directly to ground - it doesn't do that otherwise it would go bang!

David
Click to expand...

They power from J120 the GI output @stumblor noted.
If you look at page 3 of the WPC schematic manual youll see what Ive shown above.
J115 etc and its connection to the transformer winding.
The triac is the switching GI control.
 
Vimtoman said:
They power from J120 the GI output @stumblor noted.
If you look at page 3 of the WPC schematic manual youll see what Ive shown above.
J115 etc and its connection to the transformer winding.
The triac is the switching GI control.
Click to expand...
But you missed out the GI lamps...
 
Afterglow and GIOCD are systems that drive LED's and powers from the GI "bulb" switched supply. J120

There are no GI bulbs in these new led systems.

There are in the Chase circuit which is part of the reason @stumblor is having problems.
The chase circuit having its own triac circuit.

I'm going to give this a break as @stumblor is happy with running off 12VDC but have a good look at the drawings .
It's spread about so lok at pg 3 and 4 which is the drive board.
 
I have had a look through the GIOCD and I can see how it works. I can understand why the designer used the 'ideal' bridge because they were using the 6.3v tap but they didn't consider the diode voltage drop difference between their ground and Game ground. Any game powered via the 'ideal' bridge will have the same problem if the GIOCD and Game grounds touch.

David
 
I wonder if it was even realised or known, and if it was, was discounted due to the idea that the 6.3vac wasn't being used for anything anyway.

I wonder how many games would still require that ac line? BOP comes to mind (the lights in the robot head)
 
Good to see both of you got it. :thumbs:

I guess most designers for mods find issues later with their circuits as there is so many variations of pins and they probably only own one is a few.
 
Vimtoman said:
Good to see both of you got it. :thumbs:

I guess most designers for mods find issues later with their circuits as there is so many variations of pins and they probably only own one is a few.
Click to expand...
I got it yesterday but your drawing of Triac switching AC to ground is completely wrong. One side of the Triac is referenced to ground but the other side normally has the GI string as the load.

David
 
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