New machine several weeks back. Was getting 3.2v or so on backpanel GI bulbs. Removed interconnect board and found it to be burnt up in places with solder traces and jumper wires..as expected from the pics and feedback from the forum. Attached the old photos..and also the new

Repinned J7 - did both the pins on the interconnect board and new connector with molex .156 trifurcon crimps. I haven't touched the incoming feed which plugs onto J6 ( vertical on side of board ) as that has black jumper wires a plenty linking to burned off tracks and I didn't want to play with too much first time soldering.

After re-installing i now see 4.2v at the backpanel GI bulbs which is an improvement but not quite what it should be.

Checked directly at transformer outputs and on Yellow / Yellow White wires I'm getting 5.6v AC when it should be 5.9v - not sure if that is major ?

At the other end of those wires on the IDC plug I get 5.3v so some voltage drop...

At J7 ( GI lights ) across pins 10 & 8 and 9 & 7 i also get 5.3v so the jumper wires from J6 are working.

However when i plug the new connector back in and check the voltage on the backboard wires I am seeing 4.2v across each bulb.

The lights all work but still look a bit dim in a lit room.

What should i be looking for that is causing the voltage drop between the interconnect board and the GI bulbs. Could it be resistance in the bulbs or the old bulb holders ? Anything to check next thanks.

Cheers

Ged
IC Front (resized).jpgIC J7 Burn (resized).jpg

New pins (resized).jpg

New Molex (resized).jpg

Thanks for coming back so quickly. To update. GI connectors have already been broken apart so i could check the voltages directly at the transformer - 5.6v which was straight from the connector on transformer. No yellowing and seemed to be in good nick. I have purchased a box of fuses so will swap them out. I appreciate the fuse in the picture looks blown but was removed from the board and tested when i was soldering J7 into place and passed.

I can remove the connector and put another one in. What's best way to remake the traces as they were burned off by looks of things. The back of the board for j6 is well burnt. Use jumper wires again? You can see a completely missing trace as an example between F1 fuse and J5. I've been through with a meter and all jumper wires connect to where they should as per the schematics. What would cause the voltage drop from 5.3v to 4.2v between J7 and the backboard ?

Uploaded the rear side. I've upgraded all the wires to AG18 and re-soldered the tracks and made sure no dry joints etc since this pic was taken. This is as how i found it.

So if i'm getting 5.3v at the J7 pins ( appreciating it's not the full 5.9v) and then get 4.2v at the backbox GI lights, is the issue somewhere between the J7 molex and the GI lights ? A lot of the lights and light connectors look fairly original. If i desolder the connections to the lights in the backbox and test the bare leads would that help in identifying the issue? Thanks...

IC back (resized).jpg

So. As an update.

I de-soldered one set of wires that was attached to the lamp connection loop on the backboard GI circuit.

The good news ( I think ) is they read 5.3v which exactly matches what the transformer is putting out so the jumpers, tracks and re-pinned connections appear to be working ok.

When i connect them back upto the GI light circuit they read 4.2v again so can i assume the voltage drop is due to a dodgy light fitting or bulb creating resistance in the circuit ?

If so, what's easiest way to determine the culprit(s). Or am i on the wrong path ?

Thanks

PinballManiac40 Sorry.. Don't understand what you mean ? Can you elaborate a bit please. Still somewhat new to all of this and using DMM etc.

I've de-soldered the green / white&green from one of the backboard GI circuits - circled in red. The other GI circuit from J7 - Brown / white&brown is in the top right of the picture.

These come directly from J7 on the interconnect which i replaced due to burning. I'm getting transformer output voltage at these wires until i connect them back upto the GI circuit at which point it drops.

Are you referring to wires in the interconnect or wires on the back of the backboard GI circuit etc.

Thanks

Backbox (resized).jpg

No. I think we have wires crossed sorry. Excuse the pun. Connections are correct as per schematics.

I'm getting about 5.3v at the interconnect board that feeds the GI circuits. I put that down to the transformer only giving out 5.6v instead of 5.9v ( directly at the main connections to it ) and the interconnect board being a bit burned up. I've fixed some pins on it. Those pins are now connected to the GI circuit in the backbox through some wires.

There are 2 x GI strings in the backbox. I've only desoldered one for now to test and get the following

When i measure the voltage across the two wires circled while they are ' in circuit' and the bulbs are lit I get 4.2v.
When i remove the wires from the circuit and the bulbs are taken out of the equation I get the full 5.3v across the wires.

I may well be wrong but had assumed i would also see the 5.3v while they were in circuit and bulbs were lit. I was asking if the voltage drop is due to resistance in the bulbs / wiring / holders etc and if there is a way to reduce that resistance and therefore have brighter lighting ?

Hey...Transformer plugs/ wires all look good. The yellow and yellow/white wires go from the transformer into J6 on the interconnect board. I've sent off the board today for a repair so will see what comes back and then work through things methodically again. What i can confirm

* At the GI output on the transformer I get 5.6v and not 5.9v AC...That's nothing to do with the burnt connectors on the interconnect...That's at the transformer with no load.

* That drops to 5.3v AC by the time it's made it through all the wires , through the burnt J6 Power connector and out the J7 repinned connector

* That 5.3v AC is present at the insert bulb string in the red circled picture at the end of wires the but when the those wires are connected to the backbox insert string of lights the voltage drops to 4.2v

I still don't fully understand if that voltage drop is normal / acceptable or is being affected by something else. Will wait to get the board back then will start again.