FITTING AN INKOCHNITO BRIDGE PCB TO A WILLIAMS BLACK KNIGHT

[new forest pinball]

Thought this guide maybe useful to some. My black knight has just come out of storage after a ten year sleep.....!
It's completely dead. The power supply needs a rebuild and the existing rectifiers are the originals, so past their best by now. Also this machine was tombstoned way before inkochnito had invented his bridge board. So this game had the old fashioned anti-combustion mod..which you can see in the picture below...so would be good to remove this also. (Effective , but a bit of a hack!)

Here's a picture of the pcb, with the voltages marked up.......


So here goes..first we need to remove the two existing bridge rectifiers and the large blue capacitor. (Circled).

Just cut all the wires off at the components. Also unplug the two connectors from the power supply pcb, as circled below......

Once all are removed you will be left with this, also a short black cable and a short purple cable will need removing as they previously connected to the old capacitor and one of the old bridge rectifiers. These easily just pull out of the existing cable ties. Here's what needs removing, the connector with the two black wires will be reused, so do not chuck that!

Now we need to mount the new pcb in the backbox. Easiest thing to do is to move the fuse block to the left about 40mm , then you have enough room to mount inkochnitos board, use the old screws from the old bridge rectifiers.also you need to add an additional earth connection on some early versions, ours is an early one so I made up an earth strap (circled.you could reuse the black cable you removed earlier if it's in good condition)...like this.....

Now it is time to connect up all the cables to the new pcb. All the plugs are different sizes so no chance of connecting them up incorrectly to the new pcb. First the 34v dc cables, they go on the five pin connector on the new pcb.these are the blue and orange ones connected together at one of the old bridge rectifiers, and also the larger block removed from the power pcb. Also join in the new earth here if required.........

Next we will do the 18v dc connections. This is the 4 pin connection on the inkochnito pcb. These cables are the two black ground cables from the power supply pcb and the purple cable......

Next 14vac connections. This is the 3 pin connector on the inkochnito pcb. These are the two blue wires cut from the other old rectifier from the transformer....like this.......


Finally this leaves the two red wires that are your 26vac connections......into the two pin inkochnito connector....

Now is the time to plug in all the connectors to the new inkochnito pcb. These can only fit in one place in one way so no chance of incorrect connections......then turn on the machine and you should have power and two leds lit on the new pcb. The machine is ready to test/ play...in my case test as it's not powered up for a decade!!!........

JOB DONE............WATCH THIS SPACE AS TO HOW MANY FAULTS THE GAME HAS..............

 

[DAD]

Thanks for posting that, really helpful. I'll be doing that job on two of my games in the next couple of weeks and two more afterwards. That's after fitting Weebly fuse board protection for the special solenoids following some bad experiences.

 

[Inkochnito]

What I also did is splitting the G.I. 20A fuse into 2x 5A, 1x 10 and 1x 2A.
Then you will have to split the insert board lamp string into 2 parts of 18 to 20 lamps each (2x 5A)
The playfield string is too hard to split, so that is the 10A fuse.
The cabinet string is only the coin door lamps (1x 2A).
To accommodate the 4 fuses, I moved the two 9Vac fuses (for the 5V supply) to the right, just above the transformer.
The old fuse card is no longer useable for this, so I used new fuse holders.

I don't know if you want this info to be put here, but I have images to show how it looks like.

 

[new forest pinball]

What I also did is splitting the G.I. 20A fuse into 2x 5A, 1x 10 and 1x 2A.
Then you will have to split the insert board lamp string into 2 parts of 18 to 20 lamps each (2x 5A)
The playfield string is too hard to split, so that is the 10A fuse.
The cabinet string is only the coin door lamps (1x 2A).
To accommodate the 4 fuses, I moved the two 9Vac fuses (for the 5V supply) to the right, just above the transformer.
The old fuse card is no longer useable for this, so I used new fuse holders.

I don't know if you want this info to be put here, but I have images to show how it looks like.

Yes please!...... @Inkochnito

 

[Inkochnito]

This is what I did in my Blackout, but it is very similar for Black Knight.
Only the positions of the insert lamps are different.

In the back box the G.I. fuse (20A) and the 5V supply fuses (4A) are mounted on the same card (center bottom) in the back box.
I moved the fuses for the 5V supply (gray wires) to the right to create more space for the additional fuses and the Bridge Board.

The G.I. strings are split into 4 sections.
Insted of one 20A fuse, you now have 4 fuses (5A, 5A, 10A, 2A).
There are two sets of wires going to the insert, one to the playfield and one going to the cabinet (coin door).
Put in 4 fuse holders and connect one side with a thick wire and connect the yellow wire coming from the transformer.
The other yellow wire must be connected to the yellow-white wires previously connected to the lugs on the old fuse card.
I used an old switch stack with two side lugs to create a junction point.
Notice the thick yellow wire going to the G.I. relay from the junction point.
When the yellow-white wires are long enough you can also use the relay as a junction point.

The four thinner yellow wires each goto one of the fuses.
We will sort out which is what later.
First we need to split the G.I. on the insert.
I've started at the top left of the insert and started counting 39 lamps.
(on Black Knight there are 38 lamps actualy)
Split in two would result into a 20 lamps and a 19 lamps string (or 2x 19 lamps on Black Knight).
Start counting at the top left untill 20 (20x0.25A=5A).
The wires connection to the lamps after #20 can be cut.
Now you have split the string into two parts.
String one is supplied at lamp 13 and string 2 is supplied at lamp 3.

If you put a 10A fuse in one of the new fuse holders you can see which string is lit.
If it is the playfield you can leave the fuse in there.
If it is one of the insert strings, replace the fuse with a 5A fuse.
Again for the cabinet / coin door string and put in a 2A fuse.
If you used led's you can even go lower.

Please note the images are from a Blackout game!!!

 

[Inkochnito]

This is an image from Black Knight insert frontal, but I don't have the back side.
So I cannot tell you where to split the strings untill I see the back side image.

 

[Inkochnito]

And this is Black Knight with the Bridge Board in place and the G.I. split done.

 

[Inkochnito]

And this is an image of the added Special Solenoid Saver board.
Available at https://nvram.weebly.com/repair--conversion-kits.html

 

[stumblor]

Lovely stuff @Inkochnito

Am I being thick - where are the rectifiers on your board?

Ahhh they're underneath - I just rubber ducked myself.