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Samurai Appliance Repair Man

Member Since 21 Mar 2005
Offline Last Active Yesterday, 11:29 PM

#314187 Kitchenaid Built-In Refrigerator Wont Start: KSSO48FMX00

Posted by Samurai Appliance Repair Man on 26 February 2015 - 09:20 AM

Here's a blog post that steps you through troubleshooting these BLDC inverter compressors and explains how they differ from the Old Skool split phase compressors: http://appliantology...-refrigerators/


#313862 Electrolux Range M# EW30ES65GSE

Posted by Samurai Appliance Repair Man on 21 February 2015 - 10:19 AM

Also, check the 8.5 vdc power supply on P7-4&5, of the ESEC UIB. The tolerance is +/-2.5vdc. This comes from the power supply board. 

 

Also check the 16vdc +/-5vdc at P6-3 of the ESEC UIB. This comes from the relay board. 

 

The P5 connector of the ESEC UIB is the output for the hot surface sense. It's a Pulse Width Modulated (PWM) square wave but I can't find any specs on it to compare it with. But you could use the frequency function on your meter to see if you have a frequency present. As a DC voltage, it will measure as a range but again I don't have the spec on that. 




#313825 Thermador Freezer T24IF70NSP/18 FD 8809 - bosch made Making whistle sound...

Posted by Samurai Appliance Repair Man on 20 February 2015 - 11:55 AM

Go ye forth and conquer!




#313815 Thermador Freezer T24IF70NSP/18 FD 8809 - bosch made Making whistle sound...

Posted by Samurai Appliance Repair Man on 20 February 2015 - 09:41 AM

See if this video helps you: 

 




#313795 Roper RED4440VQ1 Dryer

Posted by Samurai Appliance Repair Man on 19 February 2015 - 09:56 PM

Heating element Part number: AP3094254

Part number: AP3094254

 

Thermal fuse Part number: AP3132867

Part number: AP3132867




#313782 bosch SHY66C02UC/14 - diagnostic challenge - is it the control board?

Posted by Samurai Appliance Repair Man on 19 February 2015 - 06:02 PM

Sounds like the classic water heating problem with Bosch dishwashers. See this post for details: http://appliantology...in-the-display/

 

It's usually the control board, can try replacing it and if that doesn't fix it, return it for a refund Part number: 00219640

Part number: 00219640




#313781 Thermadore gas cooktop model: Sgs30w Igniters will not shut off after lighting

Posted by Samurai Appliance Repair Man on 19 February 2015 - 05:59 PM

I read this hastily and confused this problem with the "continually sparking when not in use" problem. Different problem, different cause. 

 

I've had this happen when I accidentally switched one of the spark ignitor wires between two burners. Drove me crazy until I re-checked my work and found the switch. 




#313757 Kenmore Front Load Washer 11045087400 Problems

Posted by Samurai Appliance Repair Man on 19 February 2015 - 12:36 PM

Could also have loose or oxidized connections at the MCU end of the wire harness.




#313654 Samsung DMT800RHS - LE code

Posted by Samurai Appliance Repair Man on 18 February 2015 - 10:12 AM

Great find! Thanks for posting the pics, too! 




#313570 Frigidare Wall Oven M#: PLEB30S9DCA - No Heat / Fried Diode

Posted by Samurai Appliance Repair Man on 17 February 2015 - 09:04 AM

Let's run through this...

 

1. There are lots of different types of diodes out there all with unique characteristics and with unique schematic symbols. The schematic for this oven shows a rectifying diode. That same symbol is also used on schematics for HF, or detector, diodes but in reality these two types are very different. HF diodes are used for very low currents, in circuits like the modulated signal detector in radio receivers, voltage limiters, etc. Clearly not the case in this AC power circuit so we know we're dealing with a conventional rectifying (also called a regulating) diode. 

 

Other types of diodes, all with uniquely different functions and schematic symbols, are  LED, Zener, photo, tunnel, Schottky, and the current limiting diode (CLD). 

 

A Current Limiting Diode, also known as a “Current Regulating Diode” or a “Constant Current Diode”, performs a unique function. Similar to a zener diode, which regulates voltage at a particular current, the CLD limits or regulates current over a wide voltage range. The standard symbols used for CLDs are shown below. The symbol on the left, with the circle and the "a" and "c", is the standard, universally-recognized symbol for a CLD used on schematic diagrams.  The symbol on the right is a functional depiction of a CLD (Not a schematic symbol!) showing the n-channel JFET-transistor with the gate shorted to the source, which functions like a two-terminal current limiter or current source. This is the functional composition of a CLD. 

 

 

Current_limiting_diode_schematic.png

 

 

Do either of these symbols look like what's shown in the schematic for the wall oven? The obvious answer is NO. 

 

This then begs the question: On what possible basis can it be asserted that the diode shown in the wall oven schematic is a current limiting diode? Answer: uninformed speculation. 

 

I appreciate that some of these diodes and their characteristics can get a bit esoteric and, in reality, we as appliance techs don't need to know all that stuff. What we DO need to know is that there is stuff out there that we DO NOT know (but which is knowable). In other words, we need to know what we don't know and not just assume that, because we know a little or hear some buzz words, we know it all. 

 

2.  The second part of clman's post, however, has to do with basic electrical circuits that EVERY appliance tech should know (but about 80% do not). This has to do with the characteristics of simple series and parallel circuits. The term "simple" here is a technical one, meaning non-reactive (no inductors or capacitors, only resistive components). 

 

clman asserts that if the fan were to fail (presumably open), that the current in the element circuit would increase. Does this make sense? Let's explore this with a question:

 

What drives current in a simple electric circuit? Answer: voltage. 

 

True/false question: the voltage in parallel circuits is the same in each branch.

Answer: true. 

 

True/false question: current in parallel circuits in the same in each branch.

Answer: false. Current in each branch of parallel circuits will vary according to the resistance of the load in the branch.

 

Since the voltage is the same in each branch shown in the schematic, how is it possible for the current to increase in the element branch if the fan motor were to fail open?  For this to happen, you would have to erroneously assume that the current would increase in the element branch, defying the laws of physics. Where does the increased voltage come from to drive the additional current?  Does the source voltage suddenly increase? Obviously not. 

 

The only other way that the current in each branch can increase is if the load resistance decreased. Does that happen in this case? No. 

 

This is simple Ohm's Law stuff, guys: E=I*R or I=E/R. This brings up another good point: in a simple AC parallel circuit like this one for the wall oven, a valid example of a current limiting device would be a resistor. See again the Ohm's Law equation. As resistance increases, current decreases. Grade school algebra and if you want to keep electricity and circuits straight in your head, you have to rely on the math. No getting around it.

 

A common analogy: what happens to the ignitor resistance in a gas oven as it ages? It increases. What happens to the current flow through the ignitor as its resistance increases? It decreases. What happens with the resistance of the ignitor increases enough to drop the current below 3.2 amps (square type ignitor)? The gas valve won't open. What's the current limiting device in this simple AC circuit? The ignitor resistance. 

 

Another analogy: a string of Christmas tree lights, the good kind where all the lights are in parallel with each other. Several of the lights get crushed by little Tommy playing with his new toy hammer. Bad Tommy! But does this cause the other lights to suddenly get brighter from the extra current flow, maybe even burning out?  No, of course not. The other lights don't even notice because the voltage in parallel circuits is the same. And since the voltage remains constant, and the load resistances remain constant, then the current remains constant. 




#313474 DCS cooktop explodes

Posted by Samurai Appliance Repair Man on 15 February 2015 - 06:54 PM

There's either a loose brass compression fitting on one of the burner gas supply tubes or one of the aluminum tubes is partially split, allowing gas to escape, fill the plenum, and then igniting when it build up to the LEL of the gas you're using. You'll have to remove the cooktop top assembly so you can test/inspect/tighten the gas burner components  underneath.  




#313342 Frigidare Wall Oven M#: PLEB30S9DCA - No Heat / Fried Diode

Posted by Samurai Appliance Repair Man on 13 February 2015 - 05:41 PM

btw....the diode issue brings this question to mind even though it may not make a difference with this AC circuit , but is there generally some indication on a schematic whether coventional or electron current flow is being used? Are we to assume coventional current flow. If so, are any of you aware of manufacturers that use electron flow?

 

It doesn't matter as long as you're consistent. No indications of actual vs. conventional are ever needed or used. 

 

I learned electricity and electronics in the Navy. We were taught actual (electron) current flow- negative to positive. Most technicians are taught actual current flow. I was troubleshooting expensive avionics radar equipment to the bad component on the circuit board using electron current flow. These radars were designed by and the schematics were drawn by engineers who used conventional current flow (positive to negative).

 

It didn't matter.

 

Either way works as long as you are consistent. For this reason, conventional vs. actual is never indicated on a schematic because it wouldn't make any sense to indicate that. The circuits function and troubleshoot the same way. You can assume either one and the analysis and function of the circuit will be exactly the same as long as you are consistent. 




#313320 Samsung WF419AAW Debris issue with drum

Posted by Samurai Appliance Repair Man on 13 February 2015 - 12:37 PM

Sounds like you have a corroding/deteriorated basket spider. Another common indication of this is white metallic stuff in the pump trap. This is commonly caused by using Eco-soaps. All soaps contain lye, which is corrosive and destroys the spider and bearing seals. Detergents are engineered chemicals, pH balanced, metal-safe and contain no lye.


#313271 Frigidare Wall Oven M#: PLEB30S9DCA - No Heat / Fried Diode

Posted by Samurai Appliance Repair Man on 12 February 2015 - 08:15 PM

 

It's not receiving half the voltage or it would be a 60 VAC element correct.  But in reality it's receiving voltage only half of the time.  Every second there would be current flow 30 times instead of 60 times.

Correct me if I'm wrong, won't bother me a bit. 

 

It's still half, just looked at differently.

 

You are correct, Brother Spanner. That is a more accurate explanation. 

 

The end result is that the element is only getting half as hot as it would without the diode. For some reason, the engineers wanted to limit the temperature of the element. 




#313260 Frigidare Wall Oven M#: PLEB30S9DCA - No Heat / Fried Diode

Posted by Samurai Appliance Repair Man on 12 February 2015 - 07:21 PM

Current out of the element is only one way with a DIODE.......Flip the diode around , now it it called a RECTIFIER.....current cannot  flow......

 

Since it's AC power, the voltage is switching from positive and negative 60 times a second in a sine wave. The diode is forward biased (conducting) when the element is receiving the positive portions of the AC sine wave, completing the path to neutral and letting current flow through the element.

 

When the sine wave goes negative, the diode is reverse biased (not conducting) and current cannot flow through the element. 

 

The purpose of the diode is to cut the effective voltage supplied the element in half.

 

It has no effect on the motor.

 

If you flipped the diode around, it would have the exact same effect but it would only allow current flow through the element when the AC sine wave went negative and block current flow when the AC sine wave went positive. The net effect on the element would be exactly the same. Again, no effect whatsoever on the motor.  







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