Microwave not heating  - Page 1
Forum section: electronics / rf-microwave

author: hpibmx
author_rank: Regular Contributor
timestamp: May 18, 2023, 04:34:05 pm
content: Hi everyone,I’m back to this lovely forum again, so I tried to heat up my food using my microwave after 8 month and realised it’s not heating up at all while it turns on, tried on all options (level of heat) no worked expect the very last I assume is 750W if I’m not mistaken. I can provide pictures next day as well,And even the very last option wasn’t supper heat at all when I set for 2 min bowl of water. Only the bowl would be heating!What I’ve done tested thermocouple, capacitor, magnetron, door switches, fuse, and the diode (replaced) they’re reading all good (on continuity) and cap value.Any idea of this?Please do let me know if future info needed or pictures, I have been away from this forum for long.Cheers.

author: coppercone2
author_rank: Super Contributor
timestamp: May 19, 2023, 12:27:00 am
content: lol I have bowls like this too, the colored ceramic ones prevent heat from going into the food, but they get hot

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2023, 05:14:00 am
content: Do you get voltage at the primary of the HV transformer when the unit is cooking? The safest way to test this is to disconnect the wire to the primary and connect it to another load like an incandescent lamp. You might also be able to hear the transformer humming when it comes on. This will tell you if the problem is on the primary or secondary side.

author: mayor
author_rank: Regular Contributor
timestamp: May 19, 2023, 09:53:49 am
content: FWIW, resistance test (if that's how you tested) on the magnetron isn't guarantee it's still good. Wasn't in my case.

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2023, 06:02:19 pm
content: Yes I've had magnetrons fail more than once such that the filament checked good and nothing was shorted but they did not oscillate. It has been relatively rare though, the most common problems are faulty door interlock switches and cracked solder joints.

author: CaptDon
author_rank: Super Contributor
timestamp: May 20, 2023, 10:01:59 pm
content: If the magnetron ever overheated one or both ceramic magnets may have cracked. In that case the magnetron is dead!! How much line current does the unit draw?

author: james_s
author_rank: Super Contributor
timestamp: May 23, 2023, 12:16:25 am
content: Quote from: CaptDon on May 20, 2023, 10:01:59 pmI don't think I've ever seen that happen but I suppose it's possible. I have several magnets from defunct magnatrons on my fridge. I paint them with a thick coat of enamel to prevent them from chipping and they make good strong general purpose magnets.

author: TERRA Operative
author_rank: Super Contributor
timestamp: May 23, 2023, 11:04:44 am
content: Check out this website, it has all the info you need to fix a microwave:https://www.repairfaq.org/sam/micfaq.htm

author: tkamiya
author_rank: Super Contributor
timestamp: May 25, 2023, 07:59:32 am
content: If the bowl containing water is heating up, obviously, rest of the system is producing RF at least. So first thing I would try is use different vessel to hold water and see how it performs. I have a set of PLASTIC bowls that act like this.

author: james_s
author_rank: Super Contributor
timestamp: May 27, 2023, 12:42:22 am
content: Oh I missed that part, yeah if the bowl is heating then the microwave is working, definitely try a different bowl.