Ceronix 1492 lots of values not lining up...?

[charlesge]

Hey everyone,

I'm new to all of this but I recently got ahold of an IGT Draw Poker machine that has a Ceronix 1492. After fiddling with it for a bit I was able to get it running, although it has the exact same screen flicker / vertical size issues as the recent poster here. Took out the board and checked the 10uF surface mount capacitor on the PRA - H board and sure enough, it's burned out, so I'll try and replace that soon. While I was at it though, I decided to follow the advice in this Ceronix repair guide, and my multimeter was telling me I had a couple other capacitors burned out / not working as well.

I figured maybe I'm doing something wrong and not using my multimeter correctly (although a couple capacitors did check out at their expected capacitances), so I probed a bunch of random resistors from the 1492 repair guide and checked them with the listed values in the table. A bunch of my resistor values are way off, but a few are basically right on the dot (+/- 1-5% usually), so not even sure if I'm probing things correctly. Even weirder, one resistor I checked (002) wasn't lining up with the expected value of 75 ohms and reading 991 ohms, but I read off the resistor value from the code on the resistor itself and it was a 1k ohm resistor! However, all my other mismatches were true mismatches with the resistor code and table values lining up but not the measured resistances. So now I'm also wondering if there's an alternate parts list somewhere for the 1492 that would explain why I have a 1k ohm resistor in 002 instead of the 75 ohm one.

Anyhow, I haven't really done any formal electronics repair before so I'm wondering if I really have this many broken parts and/or how many of them are critical to getting a smooth image on the screen? Right now I can still play the game (with some flickering and everything shifted halfway down the screen). Read somewhere that only a couple of the capacitors on the board are critical enough to cause a screen blackout if they're dead, so are all the resistors that aren't checking out actually degraded but I can get the screen looking nice without touching any of them?

Would love some advice, thanks!

[shortrackskater]

I'm not sure of any alternate parts list for that monitor, but I can tell you that you won't always (and often not at all) get the expected resistance due to the influence of other circuitry in parallel with that particular resistor. The only true way is clip or de-solder one side ... and you don't want to be doing that unless you have narrowed the problem down to that certain section.

[Chris-socal]

Hey charlesge
Congrats on acquiring another machine. There are a few of us here that work on 1492s all the time.

1. You can only check caps in a board if your meter is rated for reading while in circuit, and it is usually only the ESR rating that will be accurate in circuit.
2. Before we get into other components and possible causes you absolutely must install a capacitor kit. 1492s have about 6 caps that are vital…sounds like you caught one of them.
3.  If the capacitor on the PRA board was bad, it is highly likely most other capacitors on that board are bad and likely the cause of your problem. Again until you do a Cap kit, there’s no use in troubleshooting anything else. I sell cap kits and other vital components on eBay. Don’t pay a lot of money for a cap kit or  brand name caps, there aren’t that many caps on a 1492.

I work 1492s almost daily and capacitors are 90% of the problem. That is not to say I don’t replace other components or have other problems but a cap kit is vital. The other thing that can cause some of these issues is soldered joints, and traces. When you look at the board with the naked eye, you will probably say “this board looks good. I don’t see anything wrong with it” however if you get a Magnifier and look at the solder joints at the legs of the 3 PRAB boards you might find soldered joints are loose, wiggling, dry.  Also you need to look closely at the joints on the nine transistors… three for each color. If one color has an issue it messes with all of them because XRC5346 is trying to accommodate.

Thats enough babble for now. Don’t hesitate to post an update here. If you want to send your board to me I am happy to look at it. I don’t charge a ton to cap and test. Shipping is around $15 each way depending on where you are located. Im in Southern California. Alan at KLar is a master with these also. I have a YouTube video covering the basics of a 1492 also.

Chris

[Badbaud]

On a related issue I was working on a 1492 and it had no power at all. I started suspecting the 2 wire AC power from the plug to the AC input on the board. That checked fine.
Finally I did something different, I turned the board over and measured the DC voltage across both of the main input capacitors. I read 140 volts on one capacitor and 60 volts on the other.
That didn't seem right, they should both read about the same high DC voltage.
I replaced both caps with new ones and *presto* the board came up and worked fine.

[Chris-socal]

Hey Alan
About 2 months ago I had to change the filter caps too. Talk about rare!

For the general audience, we almost never replace the 3 big filter caps, they rarely get out of spec. We only replace if there is visual signs of bulging or like Alan said, weird issues with the PS.