TWO Wells 9200s not keeping color

[RichSorr]

One of my locations has Bromley's "live action ping pong" I hate it. But anyway, two cabinets that share a computer and each has a 9200 in it. Colors are  heavy on the red and dull. Make changes using the remotes and all is well (except the one of the left is a bit dull and faded). turn them off..turn them back on. back to the way they were. what could be causing this? static? bad eprom? ugh, between two screwy monitors and the paddles to these things breaking every day I'm ready to trash them

[MonMotha]

Sounds like possibly a bad EEPROM or something.  Try adjusting the settings in the "factory" (aka "service") mode.  I believe the code to enter service mode on that is down and mode at the same time.  Be careful as there's no "recall old settings" in this mode as all that normally does is reset the user controls to the factory settings (which you're adjusting). 

If it holds in this mode, then something is funny.  If it still loses things, it's probably losing its mind every time power is cycled and coming up with some untuned defaults.

I find it odd that you'd have two monitors failing in the same way.

[RichSorr]

I find it odd that you'd have two monitors failing in the same way.

thats why I was thinking static. or it really could be the 9200s living up their reputation

[Kevin Mullins]

I've read many a times about the EEPROMS going bad in these.
(hadn't dealt with one myself)

IC101 or IC103 or something ?

[MonMotha]

I can't find a schematic for a D9200, just D9400 and D9300.  It's probably an I2C EEPROM part - 24xCnn type.  Readily available.  Be aware that after you swap it, you'll definitely have to go through all the factory mode adjustments.

What type did they use, and what are the operating conditions?  There are several families available (C, LC, AC, etc.) and they have slightly different electrical characteristics.  May be possible to improve reliability by substituting another family type.

Also check the WP pin on the chip.  In many cases, you can leave it floating to enable writes, but noise may cause the part to latch up in the "write protected" state, which would cause something like this.  May be possible to pull the pin to the unprotected state and fix things.

[RichSorr]

I think there are actually two ICs that relate to this issue. I forget which ones though. these machines are on from 6am-probably 11 or 12 at night. Got them in october of 07. I had one of the cabinets opened up before I left work today and ALLLL the caps are swollen. looks like I'll be doing a couple cap kits when I pull them out.

[Kevin Mullins]

Some tid bits..... http://slot-tech.com/interesting_stuff/wells-gardner/9200/

Page 5 is a schematic.

[MonMotha]

Thanks for the link, Kevin.

Yes, if you have caps with visible evidence of distress, obviously replace.  That monitor is from the era of "bad caps", so not suprising.

Could just be that 5V is bad.  If you want, check with a meter or, preferably, a scope to see that it's good, clean DC.  Looks like the 5V supply is derived from an 8V supply with a plain old linear regulator, and the 8V supply is the feedback for the off-line supply, so unless the caps are really dead, I'd suspect 5V is probably OK.

Replacing the caps might help with some of your color issues anyway, though, and best to replace obviously dead caps before things break.

Some suggestions if replacing caps doesn't help:

IC103 pin 7 is floating.  This is the write-protect pin.  You can leave it floating and the nominal state is supposed to be unprotected, but I've had problems with noise on this pin in some designs resulting in flaky write operation.  Pull it to ground via a 100-330ohm resistor.

IC103 pins 5 and 6 are the I2C bus.  They have 100 ohm series resistors coming off the ROM.  These seem a bit large to me with 4.7k pull-ups on the line.  Drop them to 10-47 ohms and see what happens (or just replace them with wires if you're feeling adventurous).

Edit: Hum, actually on the "C" series, the floating state of the WP pin is vendor specific.  Some default to write-enabled, but some actually just float and do whatever they want.  That's probably an error on WG's part.  Definitely try pulling that pin low.  Maybe your units used a different vendor for the ROM (there are tons), and WG didn't do enough testing to determine that there was a problem.

[2600]

Some suggestions if replacing caps doesn't help:

IC103 pin 7 is floating.  This is the write-protect pin.  You can leave it floating and the nominal state is supposed to be unprotected, but I've had problems with noise on this pin in some designs resulting in flaky write operation.  Pull it to ground via a 100-330ohm resistor.

IC103 pins 5 and 6 are the I2C bus.  They have 100 ohm series resistors coming off the ROM.  These seem a bit large to me with 4.7k pull-ups on the line.  Drop them to 10-47 ohms and see what happens (or just replace them with wires if you're feeling adventurous).

Edit: Hum, actually on the "C" series, the floating state of the WP pin is vendor specific.  Some default to write-enabled, but some actually just float and do whatever they want.  That's probably an error on WG's part.  Definitely try pulling that pin low.  Maybe your units used a different vendor for the ROM (there are tons), and WG didn't do enough testing to determine that there was a problem.

May want to put a switch on the WP pin.  The OP will need to set his settings for the monitor and all resolutions the monitor is used at before WPing it.  Otherwise the settings won't be stored.

[MonMotha]

My suggestion to pull the WP pin low will permanently enable writing (disable the write protection) which is the original intended behavior.  No need for a switch unless you want the opposite behavior (write protected except when writes explicitly enabled).