WH20 random rebooting

[Agentbarry]

Hi guys,
recently my WH20 has started to randomaly reset its self during gameplay. sometimes it can last 10 mins and other times it will only last 1 min.
i really dont know where to begin looking, could this be a bad ROM?

Cheers

Allan

[Pintoxicated]

First thoughts would be a bad bridge rectifier BR2

[Homepin]

Connectors or rebuild the power supply section of the power driver board.

[pinsanity]

J101 and J102 connectors - far right hand side of the largest green board of the backbaox.

With the machine off, unplug them and plug them back in again a few times.

This is usually only a temporary* fix and you will probably need to do some further investigating to narrow down the actual cause.


*Based on firsthand experience, temporary being anywhere from one minute to one year. 

[Pintoxicated]

Taken from the old pinrepair guides......

Bridge rectifiers or diodes (and their corresponding filter capacitor) convert AC
voltage to smooth DC voltage. This is very important, as all the circuit boards run on
DC voltage. If a game plays fine, but randomly resets, often the bridge rectifier BR2 (or
diodes) and its filter capacitor and J101/J129 connector are over stressed and need
replacement.

[Agentbarry]

Thanks for all the info guys, I will check it out and will keep you posted

[andtan]

J101 and J102 connectors - far right hand side of the largest green board of the backbox.

With the machine off, unplug them and plug them back in again a few times.

+1 - I found with my WPC machines that this more often than not was the issue and not the bridge rectifiers. I replaced the headers and connectors and the problem was solved. I would suggest starting at the connectors first, then if its still resetting start looking at the BR's.

'Parts wise' the BR's are easier to obtain (Jaycar etc) and don't require any special tools (ie crimper's) - so perhaps this is why they tend to get done first.

Andy

[Strangeways]

Capacitors have a "useful life" of 10 years. BRs should last longer, but the history of these boards developing faults in the future has the "shotgun" approach of replacing all BRs and Capacitors done at the same time in one repair session. A faulty BR will blow a fuse. A leaky capacitor can contribute to a reset.

[Agentbarry]

Yesterday arvo i had a bit of a play around, the first thing i tryed was just reseating J101 J102. After doing that i turned it back on and it played fine.. has not reset once since.
I have ordered the replacement caps from RS and got some BR from alrtonics. Even though it is playing fine now i still think im going to go ahead and replace all the caps at least

Thanks for all the help guys!

[Pintoxicated]

It would be well worth your while replacing the header pins on J101 as well as replacing the actual connector.  if that is what was playing up, you may as well tidy it up whilst you have the board out doing the other work.  At bare minimum, reflow the solder joints, every chance they will be cracked.

[Agentbarry]

The fault came back yesterday and am waiting on the 15kuf caps to do the job
I got a good laugh though, my housemate was playing the machine and was having a great game. Completed whirlpool challenge, got to class 6 river, wet willies round 2 collected. all leading up to a nice vacation jackpot. he hit it, it does its usual thing of looking like its dead..... Reset just at the time the screen goes blank.
good old machine stoped my housemate from setting any more high scores hahaha

[Homepin]

Be very VERY careful replacing the bridges and caps as they are a tight fit in the PCB holes and the plating used in the plated through holes in those days was nowhere near as good as todays technology.

You run a very high risk of 'pulling out' the plated through hole and thus losing the connection between the top and bottom traces.

Make sure you check the finished job using a mulitimeter on continuity and use wire links if you need to to ensure all connections are sound or you run the risk of having a board with many more faults than when you started.

[Agentbarry]

Cheers for the heads up, i pulled the board out yesterday to find that someone has done this before me but only replaced 4 out of the 5 15kufd caps.
the attached photo is before i did any work and as you can see they had exactly the problem you were talking about.
Turns out i was an idiot and ordered the wrong bridge rectifiers, i did not realise they are a wire leg and not a spade leg ><

[DSB]

Looks pretty ugly!! It is possible this existing work is adding to your reset problem. Make sure to clean off all that old flux. Isopropyl alcohol or circuit board spray cleaner from Jaycar and small a brush is good for this. Also as suggested before, use a multimeter to bell out the tracks when finished. I found taking a photo of the board with the components removed is a good way to remember where the tracks go. The large caps cover the tracks and could leave you guessing what's connected to what.

[DSB]

It is also possible a previous owner had a reset issue and has replace these components which has just patched up the real problem. I would be wise to check the whole power train from transformer through the driver board to the CPU.