Question about Samsung SMH7178STD Microwave Oven

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Samsung smh7178std won't heat, replaced fuses, connections, tested transformer, tested capasitor,

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Probably the magnetron could also be the diode on the capaciter. they have a 7 year warranty on the magnetron.

Posted on May 06, 2010


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How do you replace the spring attachment on a samsung microwave smh7178std

I'm not sure that the switch was your problem in the first place. But changing it couldn't hurt. But if your unit runs,but has no heat, it is probably the large diode that is connected to the heating unit. As for the light, the bulb may just need to be replaced.
On the other hand, one of the internal fuses may have burnt out, which could have affected both the light, and the heat circuit. In any event, you must first remove the unit's cover to access any of these parts. Good luck.

May 11, 2014 | Samsung Microwave Ovens

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Samsung microwave runs when door is closed

1.check fuse

2.check relay (microwave oven magnetron)

3, check switches of the doors 9874b22f-4bc0-46cb-bde4-3d17a6af0499.jpg

May 11, 2014 | Samsung SMH7178STD Microwave Oven

1 Answer

Microwave won't heat

Get your magnetron changed if the fuse between magnetron and HV transformer is OK.

Oct 09, 2013 | Samsung SMH7178STD Microwave Oven

1 Answer

I have a Samsung SMH7177STE/BE I accidently hit the start button in stead of the timer for 30 min. When I went back into the kitchen the microwave was turned off. Thought maybe my outside curcit blew. I...

It may have tripped a high limit switch and less likely but possible it blew the fuse. A fuse blows due to an increase in amperage or a short. There is the possibility it melted components such as the door switches or a wire due to heating the cavity. Door switches pop fuses when shorted or the door doesn't engage them properly.
As most microwaves other than Panasonics contain capacitors you must be very cautious even when unplugged to avoid shock. 2100-4000 volt capacitor on the high side.
So where to begin is unplug the unit. Attach a wire to something grounded to bare metal on the machine. Open it. Look for burnt wires or components without touching anything. Discharge the capacitor using an insulated screw driver or tool (short the leads). Test the fuse using ohms Check the high limits (black disks the size of a penny) by testing across them using ohms. If the fuse is blown check out the door switches, some are closed with the door shut and others are the opposite. So test each switch in both door positions. Test the light wires to ground. Should read open. Test ohms on the whipper motor and fan and to ground as well. Reads measurable over the motor leads and open to ground. Test the capacitor using uF and compare to rating on the capacitor (be sure its discharged). Disconnect the magnetron. Test each lead to ground. It should be open. Its highly unlikely its the transformer or a computer board so i wont go into detail about testing those components.

Jan 20, 2011 | Samsung SMH7178STD Microwave Oven

1 Answer

Microwave not heating does is need a new microne

It sounds like the magnetron may have either failed or is not being supplied with the extremely high voltage required to run it.
Make sure the !!!!capacitor is discharged!!!!! before attempting any sort of repair.
Check the door interlock switches first then the high voltage diode with either an AVO model 8 on high resistance range for short circuit, the feed fuse on the primary of the high voltage transformer and then finally, the magnetron is best checked by substitution.
Hope that helps.

Dec 15, 2010 | Samsung SMH7178STD Microwave Oven

1 Answer

No power and I replaced fuses in microwave.

Have you checked to make sure that you have power coming in to the unit? Check the fuse to the outlet that the unit is connected to before we go any further.

Nov 26, 2010 | Samsung SMH7178STD Microwave Oven

1 Answer

I have a Samsung microwave model SMH7177STE/BE. Will only heat a few minutes before and shut off, now there is no heat. I am a licensed elect. but no experience with microwaves and having difficulty...

Its tripping a high limit most likely. Be careful there is 2100 to 4000 volt high side with a capacitor if its not an inverter. The standard components consist of noise board, fuse, touch panel and power controller, high limits, door switches, whipper motor, fan, transformer, capacitor, transformer, magnetron, diode, plate rotator.
Discharge cap (for safety and further testing).. Test fuse; if fuse tests blown test door switches first. Test limits. Check amp draw with slow blow fuse; open door to stop unit and again discharge capacitor. Test resistance to ground on whipper, fan, magnetron, light. Test resistance lead to lead (measurable on motors/coils/magnetron). Test capacitor in ferrads, compare to spec on print. Check diode forward and reverse. Test output voltage from power control board to transformer. Test transformer coils.
Best of luck and play safe; dont test voltage output from the transformer, voltage at capacitor or magnetron.

Aug 03, 2010 | Samsung Microwave Ovens

1 Answer

My samsung SMH7178std microwave doesn't heat anything up. it makes a buzzing sound after i set timer and press start.

Here is a tip that will help you to figure out what is wrong with yourMicrowave Oven....

Microwave Oven Basic Troubleshooting Tips


Feb 10, 2010 | Samsung SMH7178STD Microwave Oven

1 Answer

Samsung MW SMH7178STD Not Heating

I would think it may be a failure of the cook relay on the board, since the noise is quieter.

Here are some links you or someone you know can use for test help, but read their safety warnings first:

Sorry i can't help more. This will need troubleshooting.

Aug 05, 2008 | Samsung SMH7178STD Microwave Oven

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