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Master Samurai Tech Radio, Episode 9

Samurai Appliance Repair Man

Entry posted by Samurai Appliance Repair Man

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- Samurai and Son of Samurai are off to Dacor training.
- Manufacturers focusing on producing higher-profit upscale major appliances and what this means for your service bidness.
- Sub-Zero doing a huge expansion in Wisconsin to crank out upscale dishwashers and ranges. What are these manufacturers seeing that you should also be seeing as an appliance repair company?
- A recent Samsung warranty debacle shows how there’s a huge need for skilled appliance technicians but the trade is still ate-up with parts changing monkeys.
- Voltage sag re-visited.
- 120/240 VAC, three-wire, single-phase electric service vs. 120/208 VAC, four-wire, three-phase electric service. Samurai explains the difference between these two common types of electric service and gives some examples of how some appliances are equipped and labelled to work with either service. Link to a Samurai video that explains 120/240 VAC split-phase household service: http://appliantology.org/topic/53554-household-120240-vac-single-split-phase-electrical-power-supply-systems/
- Customer selection: Do you pick and choose your customers? Why or why not? We talk about a recent topic at the tech-only forums at Appliantology where this subject came up. [Link to forum topic, must be logged in and a tech member at Appliantology to read it: http://appliantology.org/topic/55055-general-question-for-stovetop-wiring/ ]

 

Listen here or subscribe on iTunes or Android.

 

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fixyourboard

fixyourboard

Posted

Excellent podcast! Your voltage sag discussion triggered a memory. Here's a typical voltage-sag symptom, from a post I made a while back. Basically, overheated, corroded, oxidized wire nuts add enough series resistance that the voltage drop during high current load (oven heating) is significant enough to cause the oven display to dim. Here's the link to the original post:

http://appliantology.org/topic/42157-whirlpool-oven-dim-display-and-wire-nuts/

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Smashycomman

Smashycomman

Posted

Very interesting, FYB! That's a good visual addition to add to what the Samurai was saying in the podcast. Helped solidify it in my mind.

 

Samurai- great podcast as usual! I do actually have a question this time... maybe it's something you'd like to answer in the next episode?

 

    So, in the episode, you mentioned how sometimes you need to discriminate...er... I mean... "discern" whether or not you'd be willing to do a repair for a person, depending on the situation. My question is this: How do you go about telling them essentially "You're going to be a pain in my butt. I don't want to fix your appliance."? I'm assuming you wouldn't actually use those words.

 

Is there some specific way to convey to these customers that you aren't going to work on their stuff? Is there a way you can do this without lying, yet still not causing any issues with them? What exactly do you say to them?

 

Dealing with people is probably the trickiest part of this business, or any business for that matter. Just wondering if you have any pearls of wisdom you'd be willing to share in this area. Thank you!

 

Have fun at training!

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  • Team Samurai
Samurai Appliance Repair Man

Samurai Appliance Repair Man

Posted

  • Team Samurai

Basically, overheated, corroded, oxidized wire nuts add enough series resistance that the voltage drop during high current load (oven heating) is significant enough to cause the oven display to dim. 

 

 

Yes, great point! This is a case where unwanted voltage drop can cause voltage sag. We discussed this in more detail in Episode 6 with an example of repeated failures of a Whirlpool VM washer shift actuator.

 

Your comments makes me recall a situation where Dacor was having problems with the solder joint for the DLB relay burning out. They claimed the problem was that a bad splice (high resistance, eg., copper to aluminum splice that wasn't properly treated) in the power junction box for the range was  causing the range to draw MORE current and burning out the DLB relay on the relay board. The Dacor field service trainers were actually saying this in their training.

 

I couldn't believe what I was hearing so I clarified, "Are you saying that the high resistance splice in the junction box is actually causing the relay board to draw more AMPS?"

 

They insisted this was the case. Their explanation is that as the splice resistance increases, the higher current is drawn through the DBL relay to supply the loads.

 

I asked them to how Ohm's Law explains this.

 

They couldn't answer, so I answered for them.

 

The range circuit problem reduces to a simple (meaning no reactive components, only resistive) series circuit. The high resistance connection in the junction box would be represented by a resistor of some significant resistance in series with the bake and broil elements (which are in parallel with other but can be reduced to an equivalent single resistance). 
 
Now we can use Ohm's Law to analyze the circuit. 
 
I = E / R
 
From this simple equation, we see that current, I, is directly proportional to voltage, E, and inversely proportional to R, resistance. 
 
The supply voltage for the circuit can be assumed to remain constant. So no affect on total circuit current there. 
 
But as the resistance increases-- via the high resistance power wire connection-- total circuit current will decrease. 
 
Thus it can be seen, using Ohm's Law and simple series circuit, that the manufacture's explanation that a high resistance power connection causes INCREASED current draw is entirely INCORRECT.
 
In fact, the total circuit current DECREASES causing the elements to stay in longer to satisfy the temperature control-- this is the key to the problem.
 
The ERC is monitoring temperature oven temperature via the sensors. As the splice drops more voltage, less is available for the heating element and so its effective wattage is reduced, producing less heat. The ERC detects this via the oven sensor and so keeps the DBL relay energized longer. The solder joint burns out on the DLB relay because it is passing current for a longer DURATION even though it's lower amps.
 
So the circuit isn't drawing more current because of the high resistance splice (as the manufacturer claimed). It's actually drawing LESS current because of the additional resistance in the circuit.
 
I think I'll discuss this in a future podcast episode, too. There are enough important concepts illustrated in this story that would make a good tech talk segment. 
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  • Team Samurai
Samurai Appliance Repair Man

Samurai Appliance Repair Man

Posted

  • Team Samurai

 

   So, in the episode, you mentioned how sometimes you need to discriminate...er... I mean... "discern" whether or not you'd be willing to do a repair for a person, depending on the situation. My question is this: How do you go about telling them essentially "You're going to be a pain in my butt. I don't want to fix your appliance."? I'm assuming you wouldn't actually use those words.

 

 

H Taylor, yes, this can be tricky. The approach we've developed is that we never actually say "no" to a customer. In these cases, I'll simply quote such a high fee up front that they don't schedule the service call (with us, anyway). In the rare cases where they want the service call anyway, the quote is high enough to compensate me for the PITA factor and extra risk. Price is usually a pretty good selector of customers, too. 

 

Of course, doing this requires an ability to do a reasonably accurate pre-diagnosis. 

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Smashycomman

Smashycomman

Posted

Makes sense, thank you!

Patricio

Patricio

Posted

As usual well thought out, very informative, geared to the tech that wants his/her business to profer.   Thank you both for continuing education & information.   Patricio

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