Guess where the short was!

[squonk 41,020]

I had some fun on a snow day yesterday on Facebook. Just an example of some of the darndest things that can happen. @Sparky, @Lane Ranger, @19richie66 cannot play because they saw the answer to this puzzler.

 

Last Wednesday I was called to a school because their Hobart dishwasher quit running. The small 1.5Amp control fuse had blown. Take some wild guesses on what happened and I will post the answer later. I was surprised my friends on FB came closer than the "Pros" on there did. Have fun and sarcastic answers are encouraged! 

 

[rmaynard 15,427]

Short of being able to physically inspect the board, my first guess would be this red wire (yellow arrow) which appears to be going nowhere and in close proximity to ground.

 

[Racinbob 11,040]

I had the urge to blurt out the answer but I saw it on Facebook too so I'll go out of character and be nice. 

[rmaynard 15,427]

By the way, that must be one heck of a dishwasher. 

[The Tuul Crib 7,336]

Hobart has been around for years. Mostly 

commercial. I installed alot of wolf and sub zero. I didn't get into the technical part of these although I'm still looking!

[ebinmaine 67,266]

Near this bug...

 

 

 

[squonk 41,020]

So far Robert has the right color wire involved but not the right answer. Eric is semi on the right track in visual only. 

[squonk 41,020]

20 minutes ago, rmaynard said:

By the way, that must be one heck of a dishwasher. 

We have about 20 schools with multiple kitchens and these are pretty standard. Almost all of the kitchens have these. This is one of the better maintained units. There is only 1 other guy besides myself working on this stuff so we are usually pretty buried! 

Edited February 8, 2020 by squonk

[Stormin 9,981]

 To many wires in there for me. Eric's fly answer is shocking.

[clueless 2,975]

As a rule, on these Hobart washers, when the kanifling bearing starts to go it will pop that fuse .

 

[c-series don 8,663]

Obviously, it’s a bad flux capacitor reducer diode that won’t allow the Framis valve to open thereby inhibiting water flow. Problem solved.

[19richie66 17,500]

5 minutes ago, clueless said:

As a rule, on these Hobart washers, when the kanifling bearing starts to go it will pop that fuse .

 

Hobarts don't use kanifiling bearings. This model uses Flanzilation bushings instead. It was a design upgrade back in 2007.

[Racinbob 11,040]

Clearly proof again of the diversified knowledge base we have here and everybody's willingness to help.

[troutbum70 857]

So you found a fried fly that caused the short.

[squonk 41,020]

Here is a hint. none of the components or wires pictured were the cause of the short. But the problem occurred in the pictured control box area

[squonk 41,020]

2 minutes ago, troutbum63 said:

So you found a fried fly that caused the short.

The fly/bug was not the issue Although when I first noticed the problem, I thought one was.

Edited February 8, 2020 by squonk

[clueless 2,975]

22 minutes ago, 19richie66 said:

Hobarts don't use kanifiling bearings. This model uses Flanzilation bushings instead. It was a design upgrade back in 2007.

My bad Rich, I haven't worked on one since '05 .

[Lane Ranger 10,945]

 

 

After you get the answer you will know why Squonk has a job for life at  his school district employer !!

 

 

[troutbum70 857]

I see an orange wire in the back of the relay second from the left that looks black on the end, but may be heat shrink protecting end of wire from shorting out.

[squonk 41,020]

4 minutes ago, troutbum63 said:

I see an orange wire in the back of the relay second from the left that looks black on the end, but may be heat shrink protecting end of wire from shorting out.

Good observation but actually that orange wire is going behind the relay. The black you see is a black wire connected to the relay and looping down behind the Dayton fan. But so far you are the closest guess as the problem occurred at that relay location! 

[Cvans 1,009]

Knowing that contactors can be an issue especially in damp locations my first thought was one of those. Seeing as how it was only a 1.5 amp fuse it's in the control circuits somewhere. Without knowing what there is for safety or limit switches I'm going to guess at least one of those was involved as they are usually exposed to the elements to some degree. 

Edited February 8, 2020 by Cvans

[troutbum70 857]

If it's like many newer circuits if that fan fails the whole system fails. 

[squonk 41,020]

7 minutes ago, troutbum63 said:

If it's like many newer circuits if that fan fails the whole system fails. 

All that crappy fan does is blow a tiny bit of air around. It has nothing to do with the operation of the unit. I had one of those at one school start making a noise like  a hoot owl. Scared the crap out of the lunch ladies when they turned the machine on.  Answer coming shortly! 

Edited February 8, 2020 by squonk

[WHX?? 48,763]

Boy sure don't take much to entertain you guys!

[squonk 41,020]

Ok here is the answer. Bear in mind my eyesight isn't the greatest anymore. I'm 6'1" and need a stool or ladder to look inside this control box: 

 

This machine blew the fuse as a tray would trip the final rinse circuit. So obviously the issue was somewhere in that circuit. Disconnected the reed switch and tested it for a short showed nothing along with the wires to it. The chemical coumpany  soap dispenser unit is tied into the circuit also so that was disconnected. Ran the machine and a couple of trays went thru with no issues so I figured it was the dispenser motor but the third tray tripped the fuse so that wasn't the issue. Now I am out of fuses so I send for some more.

          

               I chat with the food service director whilst waiting and turn to look at the machine.At eye level I see some sort of  thingy laying on top of the relay @troutbum63 mentioned. A few days earlier I worked on another machine and a stink bug flew out of the cabinet so at first I thought it was a bug @ebinmaine. I got on top of the stool and with a magnifying glass and a flashlight I found not a bug but a piece of wire insulation and a single strand of wire laying across the red wire and black wire on the front terminals of the relay. This machine had been worked on by someone else at some time and there were wire flicks all over the cabinet The red wire is tied into the rinse circuit. I removed this with a tiny pair of needle nose pliers.

 

 

Persistence and luck pay off some time!