pete10uk Posted July 10, 2014 Share Posted July 10, 2014 Evening all I have a jem / Martin magnum hazer about 4 years old, it is used 6-7 times a year for a day or so each outing but cleaned through for storage. since new the unit has failed to heat on 3 occasions in the first 3 years while the unit was under store warranty, each time it was returned it was sent back working, I then tested it and all seemed to work fine, the repairs were not detailed. The unit has just failed again, this time it is out of warranty so I stripped it down and found the thermal fuse had failed, I bypassed this and the unit functions again. I'm a bit annoyed as the unit is well overkill on performance and cost for what I needed but I purchased it for the name and the fact I see many gigged units out there working without issue even though they are dinted, battered and rusty. I wasn’t expecting issues for many years. Has any one come across this issue before? or is it in fact a tendency of these units, the replacement part is about £15 and easy to swap so not a massive cost issue but a pain never the less. It appears to me that the fault could actually be with another part and the symptom of the fault is the thermal fuse blowing. Any suggestions as to why it is so infrequent. Cheers Link to comment Share on other sites More sharing options...
timsabre Posted July 10, 2014 Share Posted July 10, 2014 I have experienced resettable thermal trips going if the machine is put away hot into a flight case. I suppose this could happen to a thermal fuse. If the heater switch triac was to fail "on" this would run the heater at max till the fuse went but I have never heard of this happening. It's an important part because the block heater is software controlled, if the software were to crash or the switching triac were to fail, the block could turn into a puddle of molten aluminium - so don't run the machine with it bridged out except for testing. The heater should run on full until the block approaches the operating temperature but will then cycle on and off. Link to comment Share on other sites More sharing options...
pete10uk Posted July 10, 2014 Author Share Posted July 10, 2014 I have experienced resettable thermal trips going if the machine is put away hot into a flight case. I suppose this could happen to a thermal fuse. If the heater switch triac was to fail "on" this would run the heater at max till the fuse went but I have never heard of this happening. It's an important part because the block heater is software controlled, if the software were to crash or the switching triac were to fail, the block could turn into a puddle of molten aluminium - so don't run the machine with it bridged out except for testing. The heater should run on full until the block approaches the operating temperature but will then cycle on and off. The flight case thing makes sense, I'd never really thought about that before, but in this case the unit has come out working and just stopped after a short while. I would certainly never run the unit without the cutout, except for testing but thanks for the advise, certainly well worth the mention. I'll have a look at the triac that could be the issue, do you know what temperature the unit should work at? the cut out is 182c but I could measure the temp manual and see if the block heats to temperature and then cut-out. Thanks for the response. Link to comment Share on other sites More sharing options...
timsabre Posted July 10, 2014 Share Posted July 10, 2014 I can't remember the operating temp offhand, I think it is about 220C, but that's the inside of the block. Where is the thermal fuse located on that unit?The heater is burst fired (PWM) when it approaches temp, it's not a straight on/off so you might not see it on a meter. I would check with Jem service what the fuse is supposed to be, could be the wrong one has been fitted at some point. Link to comment Share on other sites More sharing options...
pete10uk Posted July 10, 2014 Author Share Posted July 10, 2014 I can't remember the operating temp offhand, I think it is about 220C, but that's the inside of the block. Where is the thermal fuse located on that unit?The heater is burst fired (PWM) when it approaches temp, it's not a straight on/off so you might not see it on a meter. I would check with Jem service what the fuse is supposed to be, could be the wrong one has been fitted at some point. Thanks The fuse is quite far down a metal arm off the block, so I would expect the temp to be a fair bit cooler than the block its self. I'll get on to jem. Thanks again Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.