Temperature variation Heller 1707 EXL

Is this a new issue? You could run a wide piece of masking or duct tape along the oven seal on the outside just to see what happens. What is the heating plate configuration. Are they solid from front to back or split. My thought here is if there is a front row of plates they could have a separate power source which is not turning on. Just some thoughts.

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Most of this you have probably covered, but these are what have caused heating issues for us in our 1707 EXL.

First, you would probably notice, but check that all blowers are turning by looking at there cooling fans in the top and bottom, Our 1707 has only 2 remaining original blowers out of 10 on the top, the other 8 all failed sense we bought the oven.

Heller is very good about getting you blowers for there very good warranty. 2 we replaced because they had severe vibration, and the shafts ended up having 1/16 inch of play when we pulled em. (The old blowers are black silicon power, New blowers are silver pot metal)

Pull the belt off, and open the zones on both ends, Odds are there is a lot of flux build up in there. Also sweep out the components once a month(Don't need to take the belt off for this).

There are 3 non heat blowers in the 1707, 2 for fume extraction to the chimney, 1 for cool down, All 3 of these attract a lot more flux and dust than any other blower, we clean them every other year.

Make sure your draft inducer is running well.

The cool zone intake has a baffle on it, make sure the baffle is in place and on ours covers 1/2 the intake.

There are baffles behind that rail on each end to block air coming in behind it, Make sure these are in place.

There are no rail heaters on our 1707, we run most of our boards on the belt, but the outside rail dose indeed have heating issues, 5C to never more than 10C is normal on that far edge. Our 1809 III dose not have this as much.

I am rather certain you can move this rail in several inches, if you do not need the full width, there are 2 collars holding it in place on each end.

Hope something in there helps

ead

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Generally the heller exl range has issues in cross profile, some machines more than others. I have see as bad as 15 deg c and as low as 5 deg c ranging from entire length to a few zones. They never match the specification in reality.

The markiii is better in this area as they changed the blower recirculation technique which helps balance out thermal transfer vs old exl series

The fix i have seen is customers do is move the fixed rail into the oven more and then have each zone ballanced by tweaking air flow diffusers that are in each zone that are used to try and ballance air flow across the zone. As each machine is slightly different a one size fits all ie factory set may not fit all machines.

At end day exl was not very good in terms of cross profile machine to machine from my exoerience. Mark iii is better, but still not 100%

They are low cost ovens so at end day..... will solder most pcb but always last 5 10% of more difficult pcbs thermally challanging etc cross profile of 5 to 10 deg not good....for getting correct profile balance.

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