Questions about ZERO CROSS

[copytech22]

What does ZERO CROSS represent? I would assume it has to do with electrical, but is it AC, DC, AC@Main Power supply? I need clarification. I have a NEED TO KNOW. LOL

I am Detecated to learning these machines.

http://www.copytechnet.com/forums/ricoh-savin-gestetner/9660-question-about-pms-4.html

[schooltech]

You don't really see this too much anymore, as it has been more formally changed to phase control.

When you have weird electrical issues, or 'noise' from the outlet, and this affects the copier, usually analog machines, the zero cross happens twice within a cycle of the AC sinewave when it crosses zero.

Imagine zero being the 'line' of the horizon and the sinewave, like a rainbow, crossing this line and then making the same path arc and then passes this line again. This is an analog sinewave, as opposed to a digital 0 and 1 signal, which is not a sinewave but rather 'blocks' of ups and downs.

When the sinewave of an AC signal passes this horizon 'line' it, for a very slight instance, a point in where no voltage is present. Copiers have this to turn it on and off if it detects awkward power coming in from the wall and it should make the copier less sensitive to these very slight voltage losses.

This is about all I know of this process, as it is never explained well in the manuals or in school.

I don't remember too much from electronic classes as I don't perform any board level repair anymore. I only did very basic repair, caps, resistors, transistors, and am not skilled enough to handle the complex microcircuitry of today's boards.

There are a lot more detailed, technical aspects of sine waves and voltages that are over my head, as the math involved is pretty complex.

[Shadow1]

Basically the machines try to switch the heat lamps on when the ac voltage is at zero in the cycle to reduce the amount of electrical noise the machine generates.

[schooltech]

I wonder if inductance coils have the same effect as the lamps in still creating noise?

There is noise generated from both the lamps and the 'dirty' power coming in, and changing the setting will try to find a happy medium for both conditions. Now, we just have digital artifacts, rather than just sinewave noise, on our newer machines.

[KopyKat]

Attached is Ricoh's simple explanation of Zero Cross as it functions in their equipment....

[unisys12]

Funny this subject comes up, because in the last three weeks our shop has had two Savin 9021's, one 7025 and one older 4018 with this code. All were popped PS Units. And when I say popped, I mean almost burned through the board!!

I don't remember exactly the component that burned out on each board, but they were all in about the same location on the boards. All machines, except one, was hooked to a 15amp Panamax Surge Surpresser (MIP-15a-EX to be exact, this is what we use on all out 15amp machines).

[neocozhu]

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[schooltech]

Even Ricoh's explanation of it is a bit vague. That is that "purposeful obfuscation" that we sometimes use with our customers as well, right? Intentional ambiguity you could say.

It gives an explanation, but not exactly what it is, only that it starts timing on the trail end of the pulse cycle. This is that tech speak we're all familiar with.

It's just like when the customer wants to know, but doesn't REALLY want to know, what happened to the machine. Fine, if they REALLY want to know, we'll tell them until they get that glazed look in their eyes.

[KopyKat]

Even Ricoh's explanation of it is a bit vague. That is that "purposeful obfuscation" that we sometimes use with our customers as well, right? Intentional ambiguity you could say.

It gives an explanation, but not exactly what it is, only that it starts timing on the trail end of the pulse cycle. This is that tech speak we're all familiar with.

It's just like when the customer wants to know, but doesn't REALLY want to know, what happened to the machine. Fine, if they REALLY want to know, we'll tell them until they get that glazed look in their eyes.

LOL!! I love to give the inquisitive customers the glazed look in their eyes.

You are correct, Ricoh gives a very ambiguous explanation...but the bottom line is the SC codes will generally lead you to the board(s) that need replacing. Thank the lord we no longer have to do board repair. Now that was a pain!!

[banginbishop]

I recently had a sc547 on an MP m/c.

started off with an sc545, cleaned the thermistors and reset.

sc547 on power up, mmmmm power supply with the lamps staying on from previous error code....

nope not that......

dopey prat - i trapped the rear thermistor over the front side thermistor wire and caused the problem.

I was lucky as i had 2 m/c's next to each other so i swapped power supplys and fusers over.