ONAN MDKAL Voltage Regulator Potting Resin Melting

[nigel.platt27]

Not limited to MDKAL it would seem, I have a MDKAB in I would suggest is a well enough ventilated installation ( albeit this is in Australia ). Its a crappy problem to deal with ( I kept resting my arm on it.. GRRRRR!!!! )

I scraped the bulk of the goo off and the remainder removed with an organic cleaning spray – relatively easy.

Generator is not used regularly ( has been in the past ), so immediate heat in the vicinity may not have been the issue ( chemical breakdown more likely – age relevant perhaps – these are old units ). Installing cooling mechanism after encountering the problem would seem like closing the gate after the horse has bolted..

It starts, it runs, IT STAYS!!!  

[Ron Carter]

I am having this same problem with my MDKAL, as are several others in my Tiara Owners Forum. Suddenly this extremely sticky substance started dripping out of my control box and running down the side of the sound box. The conformal coating on the control boartd/voltage regulator has failed after 20 years and is dripping down. No chemical has been found that will dissolve it. Those that have removed it have used a heat gun and a plastic scraper, making a big mess. After clean up all who have experienced this say that the generator continues to run normally. My Cummins dealer says that the Onan part # 305-0896 is available for $1203.42 and there are 25 of them in their Memphis, TN warehouse. The cost is probably the reason the owners are not rushing to replace the board. Plus, there is no return on electronic parts.

I have been trying to track down the conformal coating’s chemical composition to find a solvent with no luck so far.

[Clark Leighs]

Don’t know your machine but after reading Tony’s mention of better venting maybe some Muffin fans would help cool the enclosure down. 

Lots of models that use 120VAC.   Get ball bearing models.   Available from electronics companies like 

Newark,   Mouser,  Digikey.    Many others also.          I would suggest the 120mm x 120mm as a starting point.

THey all offer the specs for power use, air movement and so on.     You might even rig on to blow directly at the board with the others venting the enclosure.

 

Also find and install a thermometer , battery operated, with a remote sensor that can be placed inside the enclosure  with the main readout near to hand for you to monitor. 

[Tony Athens]

I do not have a good answer for you–ONAN  sets have unbelievably overly complex systems to accomplish  “simple things”, and have very poor aftersales support once out of warranty ( MDKAL= 12 yrs +?–   

As to your exact issue–yes it could very well be the temperature “things” are operating at, especially if you have a sound enclosure… Maybe figure out a way to supply cooler “dry cabin air” to the unit at 100++ CFM while running? ?

[Michael Loy]

I have ONAN MDKAL 3386107specB s/n L990032228. It is 12v DC-supplied.

It runs fine….. but,

The voltage regulator potting resin is melting and leaking from the control box.

1. Other than the mess, because it still runs OK, can I just continue as it is?

My ONAN parts manual makes a distinction between the spec A and spec B voltage regulators. The spec A is “SRA” whereas the spec B is “AVR” but each has the same part number = 305-0896. My voltage regulator is marked “305-0896 – – – – A$ – 0094269L02”.

The ONAN Parts store lists 305-0896 as ‘out of stock’, but makes no mention of any SRA or AVR distinction.

1. Will either version work for me?

The control box is mounted directly over the AC generator portion of the machine. The AC output is rock solid. There are no odors or any color change indication of overheating.

1. Could it be that the generator AC end is overheating and thereby causing the resin melting problem?

The regulator is an EXPENSIVE part besides the problematic availability. I’d hate to have to be out of commission for some extended period.

[Author]

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