ceronix 1492 no pic

mike11

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here is where ia am and what has been done so far ... this mon is being a real SOB......
has neck glow and has HI v just no pic..... to eliminate a bad board its hooked up on bench with TPG .....
what has been changed or tested so far

Full recap was done to start
All components in auto bright and bias section tested good

following have been swapped

C5184
C5346
CA3224
zener @ 295
146 amp

123 has 10v on pin 22 and around 2 on the 13 pin.... didnt wanna poke any further than that with it running and short something

all 3 guns have 118vdc at neck

G1 .10 vdc
G2 54 vdc

M gain pot has no effect on pic and is tested good.....

have tested or changed all components in all test logs and manuals i could come across

im beginning to feel this is narrowed down to the fly, if i am or have missed something let me know

Thanks
 
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Finally got it running but looks like colors are inverted
 

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Oh wow...that looks crazy! I'm about ready to start on a dead 1492 this weekend. I don't even have neck glow so I'm way behind you. What finally got you up and running?

Also, is this on your test bench with the TPG? I'll have to go back and find it, but I thought I saw some information somewhere that said the video inputs were a different signal frequency than what we normally deal with on the arcade monitors. Could be full of it...vague memory.

Scratch that. Looking at the picture I see it's back in your machine.
 
Oh wow...that looks crazy! I'm about ready to start on a dead 1492 this weekend. I don't even have neck glow so I'm way behind you. What finally got you up and running?

Also, is this on your test bench with the TPG? I'll have to go back and find it, but I thought I saw some information somewhere that said the video inputs were a different signal frequency than what we normally deal with on the arcade monitors. Could be full of it...vague memory.

Scratch that. Looking at the picture I see it's back in your machine.


vert IC was bad.as well as a little ceramic daughter board..... that chassis has been a pita ....this is acting like a nintendo mon on a reg game i wonder if the mon was changed at some point and rgb lines are messed up .... sure looks like it.
 
I'm fighting a Ceronix 1492 with very similar symptoms as mike11 was.

mike11, you still active here? Which vertical IC did you replace? And which ceramic daughter board (there a half-a-dozen of them).

ShaunDBirch, you ever do much Ceronix 1492 work?

Anyone else familiar enough with these monitors to help me narrow down my issue? I've got plenty of test equipment, and know how to use it (DMM, scope, HV probe, test pattern generator)...

Just stumped on this monitor; EHT present, filiment glowing, sounds OK powering on, B+ is spot-on, 12V and 27VDC are good. -V (-200V is also OK). Just a black screen, no retrace, no matter how I adjust the gain or FBT knobs. All electrolytics and the LA7830 have been replaced... :banghead:
 
I'm fighting a Ceronix 1492 with very similar symptoms as mike11 was.

mike11, you still active here? Which vertical IC did you replace? And which ceramic daughter board (there a half-a-dozen of them).

ShaunDBirch, you ever do much Ceronix 1492 work?

Anyone else familiar enough with these monitors to help me narrow down my issue? I've got plenty of test equipment, and know how to use it (DMM, scope, HV probe, test pattern generator)...

Just stumped on this monitor; EHT present, filiment glowing, sounds OK powering on, B+ is spot-on, 12V and 27VDC are good. -V (-200V is also OK). Just a black screen, no retrace, no matter how I adjust the gain or FBT knobs. All electrolytics and the LA7830 have been replaced... :banghead:
Do you have the Ceronix manual? I just downloaded it and I have to say that is one of the most detailed service manuals that I have seen. It has a very unusual component numbering system, but otherwise it seems to be great.

A quick search (on the word "screen") leads me to think that the screen control on the flyback is almost a secondary control. The auto bias seems to be primary. I didn't study the manual, but I wonder if there is a way to defeat that circuit and see if you can get screen brightness, if not video.
There was also something that I recall seeing in passing about a disconnected video cable causing the screen be dark.

What an interesting piece of engineering and manual writing. I recall others of similar complexity from other computer monitor manufacturers during the 80s and 90s when I was a warranty servicer for several brands. If I were closer to Jax, I'd enjoy taking a stab at that problem.

Best of luck - and be sure to post your success with this problem.
 
Do you have the Ceronix manual? I just downloaded it and I have to say that is one of the most detailed service manuals that I have seen. It has a very unusual component numbering system, but otherwise it seems to be great.

A quick search (on the word "screen") leads me to think that the screen control on the flyback is almost a secondary control. The auto bias seems to be primary. I didn't study the manual, but I wonder if there is a way to defeat that circuit and see if you can get screen brightness, if not video.
There was also something that I recall seeing in passing about a disconnected video cable causing the screen be dark.

What an interesting piece of engineering and manual writing. I recall others of similar complexity from other computer monitor manufacturers during the 80s and 90s when I was a warranty servicer for several brands. If I were closer to Jax, I'd enjoy taking a stab at that problem.

Best of luck - and be sure to post your success with this problem.
Thanks for reading and chiming in, Richard.

I downloaded the manual. I suppose it is fairly complete. Perhaps too complete, as it's a bit daunting.
I've been skimming through it. It has a lot about theory of (normal) operation, but not really aimed directly at repair/troubleshooting flow.

I looked at the auto-bias/auto-bright and blanking circuits. It does seem like something (like one or more of those circuits) is likely preventing any display. I couldn't find any (documented) way to defeat/bypass the blanking.

So I powered up the scope and started carefully probing. (Monitors make be a little nervous. There's 127V everydamnwhere on the chassis, and 1000V over near the HOT... and lots of obstacles like big caps, heat sinks, etc ... and the board is difficult to move around due to all of the wiring and connectors going to the CRT, yoke, etc. I much prefer working with 5V digital TTL/CMOS stuff, or 12V audio circuits... less stressful.)

I'm becoming convinced that the reason the bias/bright/blanking is shutting it down is a lack of vertical deflection. There's certainly horizontal deflection; I can measure like 60+VAC on the horiz yoke lines, and nearly and amp of current in them (via clamp meter). However, the vertical deflection appears dead.

I've replaced vertical deflection amp (the LA7830), and all of the electolytic caps in the vertical deflection (entire chassis for that matter). I dont' really understand everything going on in the vertical deflection system... so time for another wildass guess: the LA7851 IC! It generates a lot of the deflection signals, both horizontal and vertical. The horizontal system seems to work, so that IC can't be totally fried; but I suppose it could have an issue with only the vertical side? (Honestly, hell-if-I-know... but I'm getting desperate here).
 
Thanks for reading and chiming in, Richard.

I downloaded the manual. I suppose it is fairly complete. Perhaps too complete, as it's a bit daunting.
I've been skimming through it. It has a lot about theory of (normal) operation, but not really aimed directly at repair/troubleshooting flow.

I looked at the auto-bias/auto-bright and blanking circuits. It does seem like something (like one or more of those circuits) is likely preventing any display. I couldn't find any (documented) way to defeat/bypass the blanking.

So I powered up the scope and started carefully probing. (Monitors make be a little nervous. There's 127V everydamnwhere on the chassis, and 1000V over near the HOT... and lots of obstacles like big caps, heat sinks, etc ... and the board is difficult to move around due to all of the wiring and connectors going to the CRT, yoke, etc. I much prefer working with 5V digital TTL/CMOS stuff, or 12V audio circuits... less stressful.)

I'm becoming convinced that the reason the bias/bright/blanking is shutting it down is a lack of vertical deflection. There's certainly horizontal deflection; I can measure like 60+VAC on the horiz yoke lines, and nearly and amp of current in them (via clamp meter). However, the vertical deflection appears dead.

I've replaced vertical deflection amp (the LA7830), and all of the electolytic caps in the vertical deflection (entire chassis for that matter). I dont' really understand everything going on in the vertical deflection system... so time for another wildass guess: the LA7851 IC! It generates a lot of the deflection signals, both horizontal and vertical. The horizontal system seems to work, so that IC can't be totally fried; but I suppose it could have an issue with only the vertical side? (Honestly, hell-if-I-know... but I'm getting desperate here).
It looks like the horizontal pulses on the yoke should be from 150Vp-p to 300Vp-p, depending on width. You mentioned that you measured 60+VAC. Was that with the scope (p-p) or rms with a voltmeter?

Before you jump on the LA7851, scope for the vertical waveform out of pin 15. If there, scope the vertical output on pin 2 of the LA7830.

I know it can be tough to get to some of these test points, but try to find the end of a convenient component to attach your probe to. For example, maybe you can connect to resistor H10 or H11 to check the vertical output. Do it with power off, check to make sure the probe tip isn't touching anything else, then reapply power.

Yes, digital circuits, especially the TTL/CMOS stuff can be easier. However, the last stuff in the past few decades, where 100+pin ICs became the norm, made me realize that my eyes and hands are well-past their expiration date when it comes to removal and replacement.
 
It looks like the horizontal pulses on the yoke should be from 150Vp-p to 300Vp-p, depending on width. You mentioned that you measured 60+VAC. Was that with the scope (p-p) or rms with a voltmeter?

Before you jump on the LA7851, scope for the vertical waveform out of pin 15. If there, scope the vertical output on pin 2 of the LA7830.

I know it can be tough to get to some of these test points, but try to find the end of a convenient component to attach your probe to. For example, maybe you can connect to resistor H10 or H11 to check the vertical output. Do it with power off, check to make sure the probe tip isn't touching anything else, then reapply power.

Yes, digital circuits, especially the TTL/CMOS stuff can be easier. However, the last stuff in the past few decades, where 100+pin ICs became the norm, made me realize that my eyes and hands are well-past their expiration date when it comes to removal and replacement.

The ~60VAC was measured with DMM, between the two legs of the yoke coil, not relative to chassis GND. I was just looking for some clear evidence of deflection, not trying to measure it carefully.

Now using scope, grounded to chassis GND (ground leg of a comparitor near the edge of the PCB):

- Pin 15 of the LA7851: Sits a little over 2V, with sharp downward pulses, spread out a little over 15ms apart (so, about 60 per second). The spacing changes with it turn the signal generator on or off, showing that it is syncing with the signal.

- Pin 2 of the LA7830: Steady 25 or so volts, with a little bit of noise (fraction of a volt) on it. No discernible waveform or signal present.

That makes it look like the LA7851 may be working, but there's not output of the LA7830 (which I just replaced)...

Your thoughts?
 
Is it the original monitor chassis for that game? The 1492 works with a number of different games manufacturers like IGT, brunswick (for bowling touchscreen monitors), bally I believe, and others. Each one has their own way of sending the video signal to the PCB. So what I'm getting at is it looks like you may have the jumpers configured for the wrong manufacturer/video signal? I could be wrong though... If it's the original chassis for that game and it used to work correctly then I am definitely wrong.

edit: page 50-55 of the manual is what I'm talking about...
 
Is it the original monitor chassis for that game? The 1492 works with a number of different games manufacturers like IGT, brunswick (for bowling touchscreen monitors), bally I believe, and others. Each one has their own way of sending the video signal to the PCB. So what I'm getting at is it looks like you may have the jumpers configured for the wrong manufacturer/video signal? I could be wrong though... If it's the original chassis for that game and it used to work correctly then I am definitely wrong.

edit: page 50-55 of the manual is what I'm talking about...

Sorry, I think there's some confusion with the original poster (mike11) and my current problem. The OP (in post #1) described a 1492 with all the power checking out OK, yet no picture. He (mike11) later got it working, but with inverted colors. I was responding (in post #5) to mike11's post #1. I have a 1492 with much the same original symptoms to mike11, so I was asking for more detail about how he got it working (even with inverted colors, which can easily be fixed with jumpers in the video interface).

I'm not testing my monitor in a game of any sort. It's on a workbench with a signal generator.
 
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The ~60VAC was measured with DMM, between the two legs of the yoke coil, not relative to chassis GND. I was just looking for some clear evidence of deflection, not trying to measure it carefully.

Now using scope, grounded to chassis GND (ground leg of a comparitor near the edge of the PCB):

- Pin 15 of the LA7851: Sits a little over 2V, with sharp downward pulses, spread out a little over 15ms apart (so, about 60 per second). The spacing changes with it turn the signal generator on or off, showing that it is syncing with the signal.

- Pin 2 of the LA7830: Steady 25 or so volts, with a little bit of noise (fraction of a volt) on it. No discernible waveform or signal present.

That makes it look like the LA7851 may be working, but there's not output of the LA7830 (which I just replaced)...

Your thoughts?
It is good to know that you have the vertical output from the LA7851.

Have you checked the other pins of the LA7830? DC voltages and waveforms are given on the schematic.

Also, make sure you were scoping pin 2 and not 6. Same relative position from the end, so easy mistake to make, especially if not marked and you are working from the bottom of the board (voice of experience).

You are definitely making progress with this problem.
 
Hello
I work on Ceronix 1492s on a regular basis. Until recently I have never come across a 1492 with this issue of having HV and everything seems to be working normal…except you don't get a picture. This is often referred to as "no cartoons".
However, about 3 weeks ago I got a board in with this exact system. Jumpers match the brand, although I'm using a TPG so it shouldn't matter. All the jumpers do is groom the amplifier, invert color and such.
After receiving that one board I have now accrued 3 more boards doing the same thing.
I now suspect there is one obscure component like a little ceramic cap or something.
I was just curious if this was ever resolved, the conversation just stopped.
Thanks for any insight learned.

Chris
 
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