It's true that the realtime clock will not maintain the correct time without batteries.

Yes. On the vast majority of games it's a perfect solution. On a few like TZ, Funhouse, JM, etc. with a midnight madness mode it affects that mode only.

TZ has midnight madness?
Thought the only disadvantage on a TZ is the clock on the playfield an incorrect time, when idle and syncing to display the actual time.

You are correct, no midnight madness in TZ but it does need proper timekeeping for accurate clock function.

Why does Funhouse need the clock setting saved?

One thing to add - I've seen plenty of WPCs where the RTC doesn't hold time even with batteries installed.

So, even with batteries, often the clocks aren't accurate.

JWJ - doesn't the crystal need changed in that case?
big-daddy enterprises sells them for 35 cents. I've had a few games where they gets months off with the internal clock with perfectly working batteries.
If the crystal is out of spec, that would cause a fast or slow moving clock when the game is turned off.
Or am I all wet?

Yup. Me too. I like the idea of TZ showing ToD during attract mode, but it was never right so I gave up caring about it.

Funhouse? I don't think it needs/uses ToD.

I don't think that will help. I don't know why the RTC loses time, but if the crystal was "off", which they never are, the MPU wouldn't run right.
--
Chris Hibler - CARGPB #31
http://chrishiblerpinball.com/contact/
http://webpages.charter.net/chibler/Pinball/index.htm
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LOL I found this out today after installing it in my TZ. A lot of my WPC games experience date setting problems but never time. For instance, my TZ before I installed the nvram would always keep the correct time but always would be a month or 2 off on the date. What causes this behaviour? I have a few games that do this.

Yeah, I ordered 50 crystals late last year, because the 6 I got 10 years ago was about to run out. Don't replace a lot of them.

I like the ones Andrew (barakandl) uses, because they are low profile and are unlikely to get broken off. When my pack of 50 runs out, I'm switching to the ones he uses

Since putting NVRAM in my Getaway and WH2O, both of them reset the time to 01:00 after being turned off and also do funny things like advancing the month or year by 1. The actual date itself seems to stay correct.

Unfortunately I don't know if this was caused by the NVRAM as I didn't ever check the clocks prior to putting in the NVRAM. All other settings and scores are stored correctly.

Can anyone confirm for certain that this is a normal behaviour even with the batteries installed, or that it is a problem with the crystals, or just a design flaw in general, etc?

Different crystal. There are two on WPC CPUs, one for the clock which is linked to the ASIC, and one for the MPU. However, the one for the clock likely isn't bad or off, it's just the nature of the beast on WPC CPUs.

--
Rob Anthony
Pinball Classics
http://LockWhenLit.com
Quality Board Work - In Home Service
borygard at gmail dot com

I wonder if the inability to keep time/date is similar between a WPC-089 MPU and a WPC-95 MPU. I've never tracked time/date with my WPC-95 games. Same ASIC. Probably the same crystal.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

No,its purpose is to get those batteries off the board.

Since we are talking crystals....

the ones that suck are the old ones in a big can found on clock circuits from late 70s and early 80s. The can is glued shut around the base. The glue breaks after 30 years(usually after washing the clean PCB in my cases) and causes a dead crystal, out of time, or intermittent operation. The other problem with them is they are large and protrude off the board. I often see the can of them damaged or squished. I bought 100 pack of new modern crystals a while back for like 5 cents each, they are probably 15% the size of the old ones. I replace every 3.58MHz with a modern new one now after some problems. Then i know i just don't have to deal with it, worth the 5 cents while the iron is hot since i always end up replacing CPU sockets on these old boards.

Will ANY crystal the same frequency work? Or are there other factors to think about? (Voltage, current, draw, etc?)

Not all Crystals are made alike. There are differences in some and how they are used. Often, it boils down to the value of capacitor they are designed to work with.