Hi Guys,

I just started into working on the HH I had mentioned that was in Hamilton.  I figured it would be a few coils, soundboard PS fix, battery pull and a couple of transistors, but when I booted the game yesterday I whole new problem cropped up.  When the game is booted, the U,Q and T relays start to chatter, and then once it boots it seems to do fine in attract mode, and then slowly but surely the above relays start to vibrate, and then progress to full chatter over the course of about 1 minute.  When it happens, the sound starts to mess up so it would indicate a problem with the 24VDC line.  I replaced the Bridge and the Cap for the 38V and 24V lines and still no fix.  I've brought the boards home with me so I can pull the battery and do some touch ups, and I figure I'll sub them into my wifes game one at a time.  

I figured someone may have already solved the problem, so any genius's out there chime in.

This problem is probably related to:
- edge connector/fingers on the driver board, or harness between MPU to driver board, and/or
- ground mod needed.

Is the mandatory minimum Ground mod done ?
(power supply - MPU - doubling of +5/GND wires on MPU to driver board harness).

see here for more details:
http://www.marvin3m.com/sys80/index.htm
http://www.flippers.com/gottlieb_ground_cures.html

Good luck,
- Sylvain

Thanks sylvain,

You know I did consider that, but I got distracted and simply forgot to give it a go. The red herring I was chasing was that it was working ok util I connected the cellar playfield, and then everything went bad.  The other thing that had me scratching my head was that is seems ok at first and then gets worse as the machine is on for a minute or so.  Curious.  None of the mods have been done yet, I'll do only the most nessessary as she doesn't have a lot of money and I don't have a lot of time.  I also have a few spare pins so I'll re pin the most important connections on the MPU to driver connector and do the grounds before I chase anything else.

Thanks

p.s  

The problem remained after I disconnected the cellar again, so I had figured I'd disturbed something, but could find nothing.

No point chasing red herrings and wasting more time (and possibly burning some coils and drive transistors with the current problem).
Moving wires or simply lifting the playfield may be enough to cause more issues when mods are not done and connectors/boards checks not done.

I recommend that the mandatory ground mods be performed (power supply, MPU and doubling of +5/GND wires on MPU to driver harness), as well as connectors and pins checked (especially if there was battery corrosion at some point).
Often some of the pins are either broken or weak/corroded...

Also check for any cold solder joints under the header pins of the power supply (a pain to get to, but often this is another issue these boards have).
Finally, the +5V adjust pot on the power supply is often dirty, and may cause random game reset or lockups.... Pop-bumper mods will also need to be done.

In any case, Haunted House is a pin well worth the time and money investment now.
If the person does not have the money now, better to leave the machine unplugged and unplayed (and the original battery removed from the MPU!) until proper and quality repairs/mods can be performed.

... just my two cents

Regards & Cheers,
- Sylvain