20 Most Recent Samsung SMH7178STD Microwave Oven - Page 4 Questions & Answers

you probably have a problem with the magnatron, I change out a lot of these, but when you change it make sure you order the capacitor and the diode (rectifier)

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.

"SE" means you have a shorted membrane keypad.

Actually the best overall solution to this problem is usually to order a new controller assembly (control box) and install it yourself. It's pretty simple.

We have a similar service manual and have uploaded it to our site here to help you.

Your part numbers may be different, so you can find helpful exploded views by entering your actual full model number at the Sears Parts Direct Web site here.

At our Web site , we have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.

Some connectors on the relays may have a lock:


We're happy to give you with help and appreciate your thoughtful rating of our answer.

The -SE-error is a shorted keypad / membrane switch.

Disconnect power for about 20 min and then reconnect if it resets just put it down to one of those things, if it doesn't reset you need to replace the keypad.

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.

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.

E42 is a High voltage transformer (HVT-II) error. This can be caused by a bad HV transformer, a bad high voltage diode, a broken wire / burned terminal or a bad capacitor. The only way to confirm which one has failed is to read the circuitry with a meter and do a Visual inspection.

Kelly

look for access panel on back or bottom of unit ,should show location in manual

there is a web site,search-samsung microwave ovens

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

Microwave Oven Basic Troubleshooting Tips

heatman101
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Hi,
Here is a tip that will help you to figure out what is wrong with yourMicrowave Oven....

Microwave Oven Basic Troubleshooting Tips

heatman101

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Well it runs so the fuse is good, That means it could be the: Magnetron ( the most likely part to die) Diode (2nd most likely thing to fail) Capacitor (3rd most likely thing to fail) The magnetron has 2 leads going in from the transformer If those are open (no continuity) then that is your problem Also mounted on the mag is a limit switch. If open then their would be no heat. If it was shorted to ground it would also be bad but it is not shorted because the fuse ain't blown. The diode can fail in 2 different ways. open or shorted. Obviously is ain't shorted because the oven still works but it could be open and that would stop the capacitor from operating. The capacitor holds a great deal of stored energy. The transformer (which is not likely to fail by the way) steps up the power and sends it to the mag via the diode and capacitor. The diodes job is to agitate the signal to the mag and cause friction between molecules in the food. If you need further help, reach me via phone at https://www.6ya.com/expert/dan_73bbd84fe1d95b61

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

Hello :

SE error means you have a shorted keypad . If you couldn't find parts , then It will be cheaper to replace the unit or have new one .

good luck .

please rate !

yes, you also need to know what output the generator is producing at least 10 amps

Don't know that they had anything to do with the problem. When you say it doesn't start working I assume you mean lights come on, time counts down, fan runs but no heating occurs. If that is the case something has failed in the power circuit. Microwaves have a HV diode to rectify the AC to DC for the magnatron. 99% of the time this is what fails. When microwaves were expensive I used to fix a dozen a week with this problem. It usually blows because someone ran the unit with nothing in it. If there is no load for the heat it will build up in the magnatron and eventully the diode will blow. It could be something else but this is the most common problem and not an expensive fix.It probably is more than the average owner would want to tackle but a reputable appliance repair shop should be able to fix it quick and cheap.

hardrocko