Miele Induction Hob Problems 2.0

 Miele Induction Hob Problems 2.0

The Miele hob has gone wrong again. The previous fix was a relatively simple capacitor replacement. This time things are not so straightforward. The initial fault was that the hob tripped the RCB in our fuse box when an attempt was made to turn on either of the front two rings. This happened several times. 

The hob was removed to the workshop to see what could be done. Once wired up there the controls report an FE60 error whenever the hob is turned on.

I managed to find some documents online that said that FE60 was a communication error. After a few hours of going round in circles I decided to buy some replacement PCBs. After swapping all of them into the hob I continued getting the FE60 error. So still no working hob. A cheap-ish hob came up on ebay so I bought that and tried that out. Absolutely amazingly that hob came up with the exact same FE60 error. After ruling out an airborne electrical virus of some sort I finally found out what the problem was when I tried operating the hob with the lights out in the workshop. The lights I was using were interfering with the touch sensors used to control the hob. I suspect the code saw that as a communication error with the push button PCB and reported the FE60 error. 

How do you fix FE60?

Operate the hob with the dark glass cover in place. 

So, hob was replaced in the kitchen with a completely new set of PCBs. As I now have two hobs and about three sets of PCBs I have enough spares to last for a while and can completely swap electronics.

A few days later the RCB trips again. This is with completely different PCBs, so I now think that there's a dodgy piece of equipment somewhere in the house and that caused the leakage current to go up. Induction hobs are known to have high leakage and that pushed the RCB over it's trip limit.

At least I now have spares for the hob for about three decades...

Novena Laptop Fix

Novena Laptop Fix

I got a Novena laptop from Crowd Supply several years ago. 

 

 

I didn't use it too much and that probably contributed to the batteries not being charged enough to maintain good health. That lead to some magic smoke being released from the battery charger PCB. It looks OK in this photo, but it's not.

 

 

The laptop was dead at that point. Being open hardware, though, means that I have all the schematics, gerbers and firmware for the system, so it should be fixable.

I decided to change the Novena to a desktop system, so I removed the battery charger PCB and tried powering from the power socket that is on the main PCB. That seemed to work, in that it powered the main PCB, but the LCD didn't come up and there seemed to be a configuration problem. The push button at the front of the machine also didn't work.

It turns out that to run the Novena as a desktop you need a different PCB where the Senoko PCB lives. It's called the 'Senoko pass through' PCB and the Gerbers are available. I had some made and populated a couple. 

 

 

 

Once fitted in the Novena all was well and the power supply can now be turned on using the button on the front of the case.

The display still didn't work, though. After looking at the schematics I came to the conclusion that a high voltage had travelled down the I2C bus that the battery controller was on and had destroyed anything on there. That unfortunately included the LVDS to eDP video converter chip. Well, that's not too much of a problem as the chip is still available ( I bought a few) and the PCB gerbers are available as well. So I had a few of those made up and populated two of them. 

 

 

 

This PCB was much harder to populate as the BOM wasn't online (I subsequently got a copy) and so some of the components I used weren't exactly the right footprint. The packages used by these components were also in the 'nasty to handsolder' category.  I tried both PCBs and neither came up with a display on the LCD. Was it the layer stack up? Maybe as I just had the PCBs made using my usual cheap supplier and didn't pay any attention to layer stack up. Was it my soldering or the footprint problems? More likely. Either way I still had no LCD display. Did the LCD get blown up? That was possible, so I bought a second LCD panel and tried that. 

 

 

 

No output on any eDP PCB. 

 

I then noticed that you can buy cheap HDMI to eDP converter boards and got a couple of those. Attached to the HDMI port of the Novena and attached to the second LCD I had bought, we had output. The HDMI output still worked and I had verification that the LCD I had bought worked. having an HDMI cable running from the external connector into the case and through a converter PCB to the LCD was untidy though. 

Could I have damaged the mainboard somehow and the LVDS was broken? Maybe, so I bought a new mainboard as they were on sale. I tried that and the same result. No LCD output. 

 

After more searching online I found that you can buy LVDS to eDP converter PCBs that use the same chip that the Novena eDP board uses. I bought one of those and started to investigate wiring it up to the LCD and the Novena mainboard. It wasn't an easy job. Before I finished doing that (or actually, even started wiring), I remembered that I had some spare LVDS to eDP chips that I bought to populate the eDP PCBs. I could remove the chip from the eDP board I got with the Novena and put a new one on. That board wouldn't have the possible layer stack up problem or footprint/component problems of the boards I'd made from scratch. I swapped the chip and tried that. Still no luck. This wasn't looking good. I swapped the mainboards around and still no luck. 

The debug serial port spits out information about the setup as the Novena boot sand I noticed that the LVDS to eDP chip was recognised but didn't get powered up. I fiddled with the EEPROM settings but still no display. The chip seemed fine though, so my swap seemed to be OK.

I then booted into recovery mode, I can't remember why now, probably as it was another option to investigate the disabling of the LCD. I had the Novena facing me (the case opens in the opposite way to a normal laptop), so the LCD was facing away from me. As I booted I suddenly noticed that there was a reflection of the LCD on the screen of my logic analyser. the LCD had started up!

This was good news, but why was it on now? The only thing I could think of was that the disabling of the LCD was now a software problem, the hardware was functioning. Normal boot on the mainboard I had in the Novena was disabling the LCD for some reason. Which main board was I using? Well, it was the new one that I had bought, and that was part of a 'just the board' kit, so it may not have been configured for an LCD, rather to run as a server. I swapped the SD cards between mainboards and rebooted. The LCD worked fine. So maybe that theory was correct and my later problems after the chip swap were due to the SD card configuration. I've not found the setting for the LCD disable, partly due to taking a break after all the kerfuffle.

 Battery Leakage Again

A recent purchase:

It's a Casio FX502P in pretty much perfect cosmetic condition. Unfortunately the display isn't. It's not displaying anything very well at all. It's attempt at displaying Pi shows how bad the LCD is:

Once I opened it up, the problem was immediately obvious. It was battery leakage again. It's not very obvious in this photo but the batteries have leaked in the area of the battery contacts (which are remarkably clean) and the LCD. 

The LCD is fortunately connected with zebra strips on this calculator, not heat seal:

This meant that I could dismantle the display and clean it. I also cleaned the tracks that had had leakage on them. the solder resist was loose so I removed it on any affected tracks. You can see that tracks I've cleaned are missing their resist and appear gold in this photo:

Once re-assembled, the LCD is working perfectly. It's got good contrast and the filter is completely free of scratches. It's the best example of a FX502P I've got.