5V reset issue with IJ


Site Supporter
Jan 10, 2017
Hi All - I seem to have the 5V reset issue with williams IJ . It was resetting on Friday night when I had it on alongside a bunch of other machines for an extended period. Haven't had the problem before or since (though rarely have it on for that amount of time) but the pinsound diagnostic file confirms that its dropping to 4639mV. I'm following the pinwiki advice on problem solving this, and so far can show that I have a solid connection between Power and Driver board (only a 0.02 VDC drop). So next step was testing Bridge Rectifier and Capacitors. Caps seemed ok at 250mV AC, BUT...the Bridge Rectifier was coming in at 11V when it should've been 9V. This seems weird! If it was duff it should be showing about 7V so I don't understand why it would be higher than 9. Any thoughts? From what I could see, the positive lead of BR2 (which is what i was measuring) did seem to have a slightly rubbish looking solder connection - but would this cause an increase in voltage? And how would this in turn lead to a drop below 5V elsewhere. Next step is likely going to be taking the board out for a better look, but any advice on what I've found so far would be much appreciated.

Sgt GrizZ

Staff member
Jul 21, 2011
40 clicks North of Saigon (or Brighton beach )
Andy N, he of Pinball Mania fame and legend 😁 always used to give this advice for resets ....... see below


A problem with BR2 is a possibility, but is in fact rarely the cause

of most reset problems.

It is more likely that there is a bad power connector. You need to

carry out these checks first.

Measure against ground on a DC scale the voltage reading at TP2 on

the power board – the 5V test point. If this is below 4.9 V then you

have a problem on the power board, either with the LM323K regulator

or the J101 power input connector.

Look to the right hand side of the power board and locate connector

J101 which has red and blue wires. Remove and replace a couple of

times. If it is scorched then it needs replacing. Re-check the 5V and

see if any improvement.

If still less than 4.9V then replace LM323K rectifier.

If 4.9v or above, make a note of the reading and then take another

measurement on the CPU on the top end of the copper coil you can see

to the right hand edge of the CPU. If this is more than 0.04V less

than the recorded reading from TP2 then the power connector between

the two boards is at fault.

Locate the short grey ribbon connector that joins the CPU and power

driver board.

Now remove and replace the connector directly below this on the power

driver board. Do this several times, which basically removes

contaminants and improves connectivity.

This may well solve the problem, but it may re-emerge in the future

and the connector may need replacing long term.

If all the voltages are good, and you have more than 4.9V

consistently on the CPU then you are at liberty to replace BR2 and

its capacitor.


Site Supporter
Jan 10, 2017
Thanks guys,
Yeah this is in line with the pin wiki advice. I've done those checks and voltages are good (4.94). and the drop between the two boards is 0.02, so in theory all good. BR2 should read as 9V, but I'm getting 11V. So looks like replacing BR2 and the c5 should sort it, but I was curious why the voltage had gone up and not down. Pinwiki says your BR2 is knackered if its down at 7V.

Yes - the soldering also looks a bit dodgy from what little I can see. If I'm taking the whole board out I will change the BR and Cap and check all solders.