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Vitronics XPM1 problem

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Vitronics XPM1 problem | 11 March, 2013

So I have this issue with my 1240. During my weekly oven surveyor check I get a software alarm that says I am out of tolerance. Probe #3 which is closest to the hinge side of the oven is approx. 10 degrees hotter in zone 12 than the other 2 probes on my oven surveyor. ( I use a copper clad sheet of FR4 with 3 thermo couples as a surveyor) When I go back and look at the historical data in my software I see that this has been getting gradually worse over time.

Here is what I have done to trouble shoot: 1. Used different oven surveyor and different logger to rule out a thermo-couple or data logger issue. I got the exact same results. 2. Checked to make sure the exhaust tunnel was clear and functioning correctly. (This is an air oven) 3. Checked adjustment of entrance and exit flues. 4. Checked blower rotations. 5. Checked for obstructions in orifices on heater panels. 6. Took amperage readings off zone 12 top and bottom and compared to other zones. They are within a couple amps. 7. Replaced zone 12 bottom heater panel with a new revision heater. 8. Verified that the rubber seal is good all the way around the lid.

The only thing that made any difference what so ever was changing the heater panel. Now I am at an6- 8 degree delta instead of 10 which could be considered trivial I guess. I am at a complete loss as I do not understand how it is even possible to have a delta that large over 4 inches or so. I put probes on a circuit board and got the same results. There is definitely something going on by the hinge side of the oven in zone 12 only. If I run a board or surveyor through hugging the right side of the belt there is only a 2-3 degree delta which is what Vitronics tells me is normal.

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Vitronics XPM1 problem | 11 March, 2013

I would check/replace the neighbour zones. If your temp isd higher than what you set is probably the cooling zone not working normal(fan replacement or cleaning). The problem might be caused by zone 11 too.

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Vitronics XPM1 problem | 11 March, 2013

Maybe I misinterpreted, because different people have different names for different devices, (i.e... I believe that the device that you refer to as your "surveyor", I refer to as a "profiler"), but did you already determine that your oven thermocouples in Zone 12 are functioning correctly? Can you swap them with zone 1 and see if the problem moves with it? If one or more isn't functioning correctly, it could be driving the heater to overheat the zone.

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Vitronics XPM1 problem | 11 March, 2013

The surveyor is a a plate that I use to "survey" or verify the oven on a weekly basis. The data logger or profiler is the actual unit that follows the board through the oven to take readings.

I don't think the zone thermo couple that measures temp at the heater face is the problem. As I was saying it's only hot on the hinge side of the oven. When the heater is on it's on all the can't turn half of it on. I'm thinking I have some kind of weird air flow issue.

Evtimov: There is only a 20 degree setpoint difference between zone 11 and 12.

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Vitronics XPM1 problem | 13 March, 2013

Not knowing XPM ovens , have zones are usually top heat and bottom, you replaced one heater panel-platten thus have a another above or below, maybe one above or below also is faulty causing heat spot on one side of oven ?

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Vitronics XPM1 problem | 14 March, 2013

I don't know your oven but I have dealt with high temperature ovens/furnaces before.

These would be my thoughts.

Change in the resistivity of the heating element due to aging. Blockage of air flow in the oven by buildup of soot/ debris in either the heating chamber itself, or in the exhaust stream area. Movement in a metal baffle affecting airflow. blockage in the exhaust system.

At a previous employer we had faults in a furnace caused by a combination of a cracked fire brick falling partially into the heating zone affecting airflow leading to unpredictable airflow heating, Blockage in the exhaust which was meant to be cleaned monthly but in an economy drive didn't get done for 6 months, wearing in the chain mail that wold cause unpredictable stoppages/ trip times through the furnace.

Remember at the end of the day ovens are pretty predictable physics..

Good luck finding the problem!!


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Vitronics XPM1 problem | 14 March, 2013

The entire oven is clean there are no blockages and the heater plates are brand new. I have worked with Vitronics technical support and gone through this thing with a fine tooth comb. I have even gone as far as to compare the exhaust and intake cap configurations on the plenums to the original factory build sheet. I also compared the individual zone damper settings. Our mesh belt is approx 18" wide. The temperature is totally fine (2-3C delta) about 3/4 of the way across the belt. The 1/4 of the belt closest to the hinge side of the oven is showing a 12 degree delta. I don't even know how that's physically possible, but the profiler doesn't lie. I have used two different data loggers and different thermo couples with the exact same results each time.

I'm stumped. (See attached photo)


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