Microwave Oven and Computer - Good as New

 "Whenever anyone criticizes or wrongs you, remember that they are only doing or saying what they think is true.  They cannot be guided by your views, only their own so if their views are wrong, they are the ones who suffer insofar as they are misguided." - Epictetus

 

 I went a couple more rounds with the old microwave, and it was beginning to look like it was going to get the better of me.  I mentioned in the earlier microwave oven repair post that I believed that the control relay was not making a consistent connection, which was why the microwave didn't seem to be heating very well.

I ordered a full new set of door switches as well as two new control relays, and got to work replacing that stuff.  The controller board, which serves as the brains of the appliance, had to come out to get access to the relays.  I took a picture to ensure that I got all the connectors back in the right place afterwards.  The red and white plastic connectors are attached to the relays in the image below.

 The front of the oven is certainly not as pretty with the digital display and keypad missing.

Below:  The back side of the display and keyboard panel.  The circuit board is still attached to the front panel.  The circuit board must be removed from the panel to replace the relays.  The two relays are the black cubes in the center.

Below: Underneath the circuit board, where the components are soldered on to connect them electrically.  The trickiest part of this job was figuring out which solder joints had to be removed in order to pull each relay.

Below:  I circled the solder joints that were holding in the relays.  In this image I had melted and vacuumed the solder from the pins for both relays.  After a little wiggling with needle-nose pliers, the residual solder popped, and out came the relays.

I compared to ensure that the replacement relays were the same as the ones I had just removed.  The old ones are on the left.  The specs are identical: G5G-1A 24VDC coil with contacts rated at 16 amps, 250 Volts AC.  Also the pin placement is the same, so they will fit in the holes on the circuit board.  The rest of the info is manufacturer stuff that I don't care about. 

 

 

 Below:  The new control relays are soldered in.  It's a decent solder job, but I probably could have used a wee bit more temperature - maybe 375C instead of the default 350C. Below that is a view of the top side of the circuit board after the solder cooled.

Out of curiosity, I cut both of the old relays open so that I could inspect the surface of the contacts.  I suspected that they were not in good shape - and that was correct.  Below is what the inside of a relay looks like when the side has been removed.  However you can't see the surface of the contracts (bottom left) very well without bending the contact arms away from each other.

 Below:  Each relay with the contact arms bent away, so the contact surfaces can be better seen.  The bottom one is really smoked and covered in carbon.

While I was inside the oven, I replaced all three door switches - they were cheap.  I triple-verified that the contacts opened and closed the same on each switch (old and new) before swapping them out. 

Below:  The door switch assembly has been re-installed after replacing the three individual door switches.  Time to give it a whirl. 

As a test, I filled a glass half full (or was it really half empty?) with cold water and ran the microwave for a full minute.  When it was finished, the water was still cold... like WTF?  What could still be wrong???  I'd done everything I could think of...  Everything tested OK electrically, it still wasn't heating!

At my wits end, I decided to remove the magnetron and inspect it physically.  Sure as hell, one of the ring magnets was cracked in two places - a crack on either side of the magnet. 

 

I was also forced to buy a new magnetron, to the tune of $200.  Once the new magnetron was installed, the oven finally worked again!  The oven also has new control contacts and door switches, so it should be trouble-free for a long time.

The new computer storage problem:

I built the new PC back in early June, and later loaded Windows 10, finally getting it up and running in late July.  What I didn't know at the time is that Windows 10 defaults to a maximum hard drive partition size of 2 Terabytes.  The hard drive I installed in the machine has a capacity of 4 Terabytes, so I lost the use of half the hard drive by letting Windows decide how to build the partition.  

After I got the new PC up and running, I began poking around and testing it out.  That was when I discovered that the main storage hard drive capacity was only 2 TB.  There was another 2 TB of unallocated space.  I had no idea why this was the case, and nothing I did would correct it.  I'm semi-knowledgeable about PCs, but this was outside of my experience, because it was the first hard drive I've ever owned that was this large. 

Below:  See the box at the bottom right that says "Unallocated"?  I had 2000 GB that was not usable.

Here is an article explaining how Windows requires the hard drive to be initialized a certain way in order to create more than 2 TB size.  I need the entire capacity of the disk, because I've already used up the 2 TB available.  I'm pretty cautious about data loss, so I took the PC into town and had a reputable repair shop fix my screw-up.  

First of all, they had to make a backup image of the (now full) 2 Terabyte portion.  Next, they had to delete the data I had put there.  After that, they had to re-initialize the hard drive with the GPT standard.  The GPT standard allows Windows 10 to recognize the entire 4 TB of hard drive space.  Lastly, they had to re-install the back-up image on the 4 TB drive.

But wait!  I screwed up in another way, so this task wasn't quite so simple - as the guy at the shop explained to me afterwards.   There was yet another thing I wasn't aware of:  If you install Windows with two different hard drives connected, it will install Windows on whichever one you specify.  BUT - without telling you, it will install the boot sector onto the second drive.  

I had installed Windows on the smaller and faster SSD drive.  Unbeknown to me, Windows installed the boot sector onto my main storage drive - the hard drive that I needed to have nuked and redone.  This caused the guy some extra hassle, but he moved the boot sector over to the SSD where it belonged.  

It's a damn good thing I didn't try that at home, because we would be without a home PC right now.  It cost me a $75 repair bill, a $20 gratitude tip, and a couple of trips into town.  Money well spent, because otherwise I'd be looking at a brick that needed to have all its software re-installed.  I keep backups, but that's a level of hassle and panic that nobody needs to deal with over the holidays.