Thermador Model GPS366 Gas Stove
The photo above is the restored Thermador model GPS366 S/00 gas stove. Prior to the restoration, the two left burners were no longer lighting. Those two left burners are controlled electronically to turn the gas on and off at different intervals for low heating and simmering levels. It seemed obvious the electronic control circuitry had been impaled by power surges during thunderstorms just prior to those two burners quitting. Once the repair was well underway, I realized I should be taking more video and stills for this URL, but I got another chance. Now in May of 2020, almost two years after the original repair shown here, the day I was done with this repair segment and getting organized to upload it to the Wiggle My Legs URL, the front of the two left two burners went out. Unbelievable coincidence, but an opportunity to get more photos and video. After it was repaired in 2018 we protected it with a surge protector. We also treated it with a Black & Decker belt sander, some 3M scratch pads, some Dico polish on the spill trays, and some black appliance paint for sunken logo and burner indicators and the stove gained a brand new life. As of this writing in May of 2020 with the front left burner out, I will include some video of the disassembly and assembly of the burners and thoughts on the new repair process at the end.
After lifting off the burner caps, the front three venturi tubes (see blow up diamgram below) were very difficult to remove. This was due to years of using mostly the front burners, which causes the venturi brass to fuse with the aluminum burner orifice holder. Also, the height of the hex fitting of the venturi is such a low profile it is hard to get a grip without destroying the aluminum burner. I tried using a socket wrench, but the socket lip has a rounded edge preventing the opening of the socket from gripping the shallow hex head when a little torque is applied. As you see in the photo below, this problem made me get the grinder out and grind my socket opening down by a little less than a quarter inch. This removed the slightly rounded lip at the opening of the socket, allowing six corners of the socket to make completely flush contact with all six corners of the shallow hex head for a snug fit. The back three venturis were fairly easy to remove. Of the three front venturis that were stuck, one was freed with this socket and a whole bunch of torque. Another one would not let go of the burner orifice beneath the spill tray, so I turned with the socket until I twisted off the gas supply pipe underneath and it broke off. After that lesson, the third stuck venturi still wasn't listening and I decided to grind the venturi hex fitting off the top which releases the aluminum burner to be lifted off the spill tray, which leaves us free to remove the spill tray. Of course, when the spill tray is then removed I had a burner orifice holder with the remains of the venuturi fused into it, which was uncoupled from the gas supply and replaced. Fortunately, appliance repair companies such as our local Mastertech, and of course RepairClinic.com are always there for me during these rough moments and for this project Repair Clinic is only a short drive away to pick up parts that seem to always be in stock.
Here is the 20mm socket that I ground off to make flush contact with the shallow hex fitting.
While removing the spill trays it was a little difficult to keep the rubber sealing strips under the spill trays intact due to it's binding with years of cooked spilled food making it rip in some locations. Here below is a quick video showing the remnants of the rubber seals with two of the three spill trays removed. I used it to show the application to rubber vendors.
The photo below is the thermocouple I used to test the temperature under the rims of the spill trays at the location of the rubber seals. It is a meat thermometer with the metal sheath probe removed to expose the thermocouple wiring, shown here leaning on my laptop. I could then insert the thermocouple under the spill tray edge where the rubber seals are located to measure the temperature, and it would hang below to display the temperature. If I recall, I could get temperatures as high as 380 degrees F after 30 minutes.
Although the next photo is out of sequence and from final assembly, it shows how Rubbercal in California came through with some food grade (FDA approved for use around food) rubber sheeting rated at 450 degrees F. I had to buy a great deal of it so if anyone wants some I'd be glad to sell. This photo is after PCB repairs were complete and during stove reassembly showing a black metal straight edge clamped onto the new rubber sheet to slice off the new half inch wide strips. One of the new strips is strewn across the black straight edge over to the yard stick. I contacted RubberCal April 15, 2020 while composing this text and they still have the item number in their system, but their supplier quit making it so none is available.
The next step was to remove the two blue plastic boxes called the Simmer Control Module and the Reignition Spark Module and open them for visual inspection. The two pictures below are before removing the two blue plastic modules in order to document the wiring for reassembly.
After removing the Simmer Control Module and opening it to inspect the printed circuit board (PCB), it is easy to see the scorch marks near the big resistor R2 and the large capacitor C2. There was also heat evidence at some of the terminal pins. In the first photo R2 and C2 are highlighted on the left end of the PCB and the second photo the PCB is flipped so the scorch marks are on the right. At the time of the repair in June of 2018, the Simmer Control Module was no longer available as a spare part from Thermador and was hundreds of dollars on the Net. I removed R2 and C2 and realized I needed to write down the circuit and check related components and test. I hoped to do a complete proven schematic, but eventually when the stove started to function, time management intervened and I stopped short of complete and proven documentation. Yet if someone were doing this repair the schematic would be helpful.
The new PCB replacement components were purchased from DigiKey.com out of Minnesota. They were incredibly patient and helpful. The lead time was a few weeks for a more closely matched R2 resistor, so we opted for the closest resistor in stock. Other companies also were helpful such as Jameco, Summit Electronics, and Component Source, while Eaton was absolutely awesome when researching resistor R2. The replacement for C2 had great electrical specifications but it's leads were too short for this application which caused me to mechanically crimp on some extensions as you see in the pictures below. The ACE Hardware copper sheet metal was from an old project and I used shears to slice off the new leads you see crimped onto C2. The coil of 3M copper foil tape purchased from ULINE can also be seen on the right.
The repaired PCB is shown here below. Since I had it all open, I decided to replace more components than technically required. If I recall I needed about 3-4 parts, such as R2 and C2, but since I ordered more I put in a total of about 12 new components such as capacitors, diodes, and the relay and optoisolator. At R2 and C2, the original traces had lifted off the solder side and were replaced with 3M copper foil tape which had to be glued to the board to prevent the foil tape from being peeled off the PCB by the physical shock of applied current to the relatively large mass components soldered to the tape. I used PCFix high heat epoxy. On the component side you can see the newly crimped on leads for C2 will fit well enough to allow the unit back into the blue plastic box easily.
As mentioned in the opening, a few days ago in May of 2020, I was cleaning up some files to upload this repair segment to wigglemylegs.com and the left front burner went out that day. I finally remembered the camera and recorded some diagnosis and reassemnbly. Here is a quick video of me trying to to left hand the camera and right hand the diagnosis and reassembly. A busy schedule means I will try to purchase ahead of time, all the diodes and such for the rectifier circuit that controls the gas solenoid. Once the components arrive, then I plan to remove the Simmer Control Module and replace many parts on the PCB. I guess the solenoid could have frozen and overloaded the PCB, but it could just be more old parts on the PCB. However, the solenoid in question does sound worse than the other and gets so much more use. A very experienced Thermador tech told me years ago when replacing the Simmer Control Module it is a good idea to replace the solenoids. Of course we did neither. We replaced enough PCB components to get it working and a few more with educated guesses and now two years later this new burner failure is how I get scolded for trying to put this cheaper repair on the Net like I'm trying to brag about it..
Here below are the circuit traced diagram of the Simmer Control Module PCB, the photos of individual PCB components, and also supplemental PDF documents for certain PCB components. There is also an Excel spreadsheet that was going to be a complete Bill of Materials for the entire PCB with photos of individual components in comments for each components cell. Once the spreadsheet is open, there are red markers in the cells which have photos and hovering over the cell should bring up the photo.
Original Component Photos
Component PCBSideA Component PCBSideB Component PCBAfterSideA Component PCBAfterSideB Component C1 Component C2 Component C3 Component C4 Component C5 Component C6 Component C7 Component C8 Component C9 Component C10&C11 Component C12 Component C13 Component C14 Component C15 Component C16 Component C19 Component C20 Component D1 Component D2 Component D3 Component D4 Component D5 Component D6 Component D7 Component D8 Component D9 Component D10 Component D11 Component D12 Component D12Up Component D13 Component D14 Component D15 Component D16 Component D17 Component D18 Component D19 Component D20 Component IC1 Component IC3 Component R1 Component R2 Component R3 Components R4&R5 Components R6&R7&R8&R9 Component R10 Components R11&R12 Component R13 Component R14&R15 Component R16 Component R17 Component R18 Component R19 Components R20&R21 Component R22 Component R23 Component R27 Component R32 Component Relay Component RES1 Component SCR1 Component T1 Component T2 Component TR1 Component TR2&TR3 Component TR4 Component TR5 Component TR8 Component TR9 Component V1SideA Component V1SideB Component ZD1 Component ZD1Up Component ZD2 Component ZD2Up Component ZD3 Component ZD3Up Component ZD4 Component ZD4Up Component ZD5 Component ZD5Up Component ZD6 Component ZD6Up
Click here,to download the spreadsheet of the above components with the above pictures embedded in the cell's comments, and specifications for some components.
Documents below are related to the parts shown above.
IC3 by Motorola PDF. Click the little blue text link when you arrive at alldatasheet.com
RubberCal Rubber sheeting specifications PDF.
The new C2 capacitor by EPCOS PDF.
IC1 "ST62T20B6-HWD" by ST PDF.
Relay JS1 by Matsushita PDF.
Thermador Models GPS366S, GPS364GDS, GPS364GLS, GPS484GGS, GPS366GDS, GPS366GLS, GP24WKS Parts List