Siemens Oven - light not working but oven ok otherwise??

[molinero]

Hi, I have a Siemens Single Oven HB75AB550B. When I turned it on last night, there was a flash/pop inside, and the 20A mcb fuse tripped in the mains box. I assumed it must be the bulb (yes it was blown), so replaced it with a new one, reset the fuse, and reset the oven clock.

All seemed ok, the oven appears to work fine, but the light doesn't come on. I tried a second bulb (both are good) with no luck. What could be the problem?

Note that the fan works, the fan element, bottom element, and grill elements all work. When I switch to light only, there is a relay 'click' but no light. I've pulled out the bulb socket unit and checked the wires - all 3 (2 + Earth) are attached, and clean. Socket is also clean.

Is there a fuse inside just for the light? Or is there something else which would stop the light coming on? I'd be grateful for any help.

 

[Diyisfun]

It may have blown the terminals on the bulb holder or even the light switch itself.
There could be a fuse for light, but I very much doubt it

 

[lordy3009]

Hi
Did you get this resolved as I have exactly the same problem!

 

[molinero]

No, unfortunately I've not managed to fix it.

We just do without it.

 

[Burnerman]

Its usually the 'pip' at the bottom of the bulb socket that burns away with faults like these.
John

 

[molinero]

Thanks for the advice John!. I think I checked that but it was such a long time ago, I can't remember!

I'll take another look tomorrow.

Rik

 

[Burnerman]

Use a multimeter (carefully) to check for 250v across the two bulb terminals.....if there's a result, its a holder fault. If no voltage is found, its either a connection or a burnt cable.
John

 

[foxhole]

Often as simple as not screwing the bulb all the way in.

 

[Graham Piddington]

Siemens oven HB75GB.50B my experience of the fault where the lamp filament short circuited and tripped the circuit breaker' was that a new bulb did not come on. I increased the height of the central bulb terminal as suggested above, but to no avail. I also tried to measure for volts on the bulb socket, no volts detected. Making this measurement is tricky. Connect one lead of the meter to the lamp socket thread using a crocodile clip and a probe with an insulated shaft. Listen for a relay click when turning the oven on. Now the the bad news, the relay is mounted on a printed circuit board (PCB), if you tests above are negative this board has suffered damage and needs to be replaced. My oven is in a stack and I did not want to get that far involved in dismantling it, so I called the local supplier's technician. Call out fee £49.99, new PCB £308.40 or new oven £799.99. I forget the cost of the bulb. I'll probably live without the light.
Graham 29.12.18

 

[oaktrentotto]

Dear All, I had the same issue with my Siemens oven HG36AB550J /10.
The bulbs didn't work but all other function were ok. My issue happened after the failure of a single bulb, the one on the side of 25W.
After the issue there were no power in may flat, this is a sing of 'short circuit'.
OK, there had been a short circuit but where?
Since the oven was working (excpet the light) I supposed there was a problem on an internal part of the oven, may be a fuse, or a relay.

I looked at the spare parts diagrams (available on the siemens site) and I wasn't able to find any fuse. Then I thougt the broken component could be the 'control board' with code: 00657052 because it is the only component with relays. The price of the board is high and now it also quite difficult to find.
To get inspired about how to disassemble the oven I found this video:

Then I decided to open the oven to see what went wrong. I wasn't completely sure the problem was about a single relay (the one the command the bulbs) because when I opened the door of the oven I was able to ear the 'click' of a relay but, of course, no light. Then I thought the commanding relay was working and the problem should be somewhere else.

Then, on the top of the oven I found a board with many relays ( the command board) and I found 2 problems. There are two burned jumpers (implemented as 0 Ohm resistor). See the picture below - yellow arrows

I replaced that resistors with two wires and now the oven work again. The bulbs make light.

The resistor I replaced were two '0 ohm' resistor. They are a sort of wire the manufactured used to save money in the production process.
But they acted as a fuse that saved the commanding relay. Then I thought I'll must replace at least one wire with a fuse.
As soon as possible I'll replace one of the wire with a fly mount fuse of 1Ampere (250 VAC)

I hope my experience helps.