very old Engel blowing fuses?

Submitted: Sunday, Jul 14, 2019 at 10:54
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G'day all, my very old Engel has started blowing fuses for the first time, any ideas why? thanks
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Reply By: IvanTheTerrible - Sunday, Jul 14, 2019 at 11:07

Sunday, Jul 14, 2019 at 11:07
Which fuse? Is it the one in the plug?
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Reply By: RMD - Sunday, Jul 14, 2019 at 13:01

Sunday, Jul 14, 2019 at 13:01
Norm.
A few possibles:
the cable has fractured somewhere, squashed etc, and the +&- of the cable is joined, short circuited.
The power to the lead is back to front connection and wrong polarity.
The inverter section has become faulty and it is not switching properly causing a large power draw or a direct short within it’s switching transistors.
Perhaps check the power lead has it’s conductors separate, by testing with a multi meter, and not joined , plus polarity is correct.
Don’t know what your feed power supply is, but is it possible it is too high in voltage?
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Reply By: Member - Boobook - Sunday, Jul 14, 2019 at 16:08

Sunday, Jul 14, 2019 at 16:08
Based on all the information you have given, it can be narrowed down to an electrical problem.
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Follow Up By: RMD - Sunday, Jul 14, 2019 at 16:28

Sunday, Jul 14, 2019 at 16:28
I ruled out the wheel bearings too!
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Reply By: Norm F - Sunday, Jul 14, 2019 at 17:00

Sunday, Jul 14, 2019 at 17:00

this is the fuse that blows, has been working normally for a long time
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Follow Up By: RMD - Sunday, Jul 14, 2019 at 19:01

Sunday, Jul 14, 2019 at 19:01
Norm
What have checked or not checked so far, we know what it is but not knowing what investigation you have done/ been able to do, means everything can be possible. For example,
Is there correct polarity at the plug?
Is there damaged, frayed shorted wires inside the cabinet. Does the fuse blow immediately with a “crack” or is it a slow melt.
Does the compressor ever begin to run before the fuse blows.
The circuit breaker button appears to be OUT, is that the normal position?

Well! I presumed you were running it on 12v, my 12v lead for a newer model looks similar and the reason for the polarity question You didn't mention the fuse size being blown. Not being a 12v lead which we have now realized a 0.5amp fuse is a 240 fuse. That circuit should be able to be probed after removing the lead from the fridge and seeing it is blowing the fuse the resistance read by a multimeter will be very low or short circuited. If that is the case then the transformer probably is defunct. The transformer doesn't run the compressor directly, frequency too high. They don't have a motor, just a piston attached to a solenoid driven by alternating DC at about 22v, effectively being ac as it is changed at a low frequency. If it runs on 12v then it is the AC transformer because it supplies rectified AC, ie, DC to the solenoid driver.t
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Reply By: allblack55 - Sunday, Jul 14, 2019 at 19:27

Sunday, Jul 14, 2019 at 19:27
Hi Norm,

The fuse you indicate is inline with the mains winding of the power/invertor transformer, if it blows there is likely a fault within the transformer or the swing motor (or associated wiring). I wonder if it works on DC?. Depending on your ability or gameness, disconnect the wiring to the swing motor (keep the motor leads separated) and try another 0.5A fuse, if it fails then the problem is either the transformer or cabling to it, if it holds then the swing motor is probably the culprit. A multi-meter will show if it is shorted internally or to frame, the winding resistance in a serviceable one of that vintage is around 2.7 Ohms, and either terminal to frame should be in the order of M/Ohms.

Assuming we are discussing a MRFT-530 I could send you a circuit diagram of the power supply if that would assist.

Hope this helps.

Leigh.
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Follow Up By: Norm F - Sunday, Jul 14, 2019 at 19:34

Sunday, Jul 14, 2019 at 19:34
Leigh, thanks for an informative reply, the wiring diagram would be a great help, thanks I will try all of your suggestions...
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Follow Up By: allblack55 - Monday, Jul 15, 2019 at 18:33

Monday, Jul 15, 2019 at 18:33
Norm,

How would you suggest I forward the cct diag. to you.

Leigh.
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Follow Up By: Frank P (NSW) - Monday, Jul 15, 2019 at 20:02

Monday, Jul 15, 2019 at 20:02
Take a photo with your phone and post it as a picture in a follow-up here.
Cheers
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Follow Up By: allblack55 - Thursday, Jul 18, 2019 at 10:42

Thursday, Jul 18, 2019 at 10:42
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Follow Up By: Zippo - Thursday, Jul 18, 2019 at 19:59

Thursday, Jul 18, 2019 at 19:59
Leigh, would that same diagram apply to the MRFT-514?
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Follow Up By: allblack55 - Friday, Jul 19, 2019 at 18:55

Friday, Jul 19, 2019 at 18:55
Hi Zippo,

I`m not familiar with the internals of the 514, I suspect the basic wiring may be the same, there will certainly be a transformer, invertor transistors and the swing motor. An eyeball comparison the only way to be sure.


Leigh.
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Reply By: ian.g - Monday, Jul 15, 2019 at 10:50

Monday, Jul 15, 2019 at 10:50
Hi Norm, long time since I had one that model but I think that fuse should be a slow burn fuse, just can't remember for sure but if you use a ordinary fuse they will just blow as soon as the motor kicks in,
AnswerID: 626737

Reply By: Batt's - Monday, Jul 15, 2019 at 16:28

Monday, Jul 15, 2019 at 16:28
Considering it's age you could find a local Engel service agent and get it checked over they may even recommend replacing the wiring and power lead for years of trouble free use in the future. I had my 15 yr old Evakool done a few yrs back for piece of mind because it lives in the canopy out of my sight.
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