Possessed Bosch Oven Clock

[Loftus]

Ok so it’s not possessed our oven clock resets itself on it’s own.
Initially it would do it almost at random,
This then turned to being more apparent when the oven was really hot, or been on for a while,
Now it is happening at 6 minutes past 8pm everyday. (and when the oven is really hot or been on for an hour or so)
I’ve concluded that it is resetting at 20:06 as that number uses THE most led segments of the clock and the power draw from using nearly all the LED segments trips it out. Is there an obvious component at fault like a capacitor that’ll have dried up or literally been cooked over the years that can be replaced or is it a whole new clock unit?

[Loftus]

Obviously 20:08 would use THE most segments but 20:06 comes two minutes sooner so it never makes it to 20:08 and have to set the time to 20:10 or after otherwise it just resets again.

[electrofix]

do the segments seem to get dimmer the more that are turned on

What Enr number and FD number have you got ?

Dave

[tubafan]

Does sound like a power fault, where the maximum draw causes the unit to crash and reset. A failing capacitor could well cause such a fault and I’d be looking inside the clock unit to see if anything is obviously amiss.

[Loftus]

Thanks Dave and Tubafan, Took a while to reply as I thought before I posted I had some pictures to hand but couldn’t find them so have managed to look inside again and get some numbers:
E-Nr number: HBN131251NB/01
FD number: 8712 00021

The number that seems most handy I found is the number on the control module made by Diehl 9000180170
A quick google search has found a second hand one for £19.99 from https://appliancespareparts.mysimplestore.com/

If you know of a reputable supplier of new ones that’d be handy too.

I had remebered there was a large capictor on the board, a 16v 470uF capicitor to be precise but checking it with a multimeter it seems to be progressively increasing in resistance which I believe indicates it’s probably OK.
Under the “screen” module there are various surface mount components so I think something under there or in the actual module has gone wrong
Scrfeen module for reference had the number LTG 0383KR-T 732 THAILAND written on it.
The module is soldered on so am thinking easier to replace the whole board than just that bit.

Thanks

[electrofix]

on the clock provided its the same as the current one

change capacitor C1

your unit was built end 2007 so its likley the cap is out of spec

Dave

[Loftus]

Thank you. Sounds like you have a circuit schematic? Is that something I’d find online?
The board with the contacts for the buttons doesn’t have any obvious component labels etched on, so A can’t tell which is C1 and B think they’re all under the timer module that is solders on legs above it.
Unless you mean the board inside the timer module? I haven’t opened the timer module yet as it didn’t look obvious how to get in.

For reference this ebay listing shows what I’m looking at. I haven’t opened the black box, is that where C1 is or is it on that green board?
https://www.ebay.co.uk/p/24016706814

[electrofix]

have not got a circuit schematic but its common at this age of appliance to use a capacitor as a dropper to lower the voltage to power the board. As the caps age they give less power to the board till it crashes under load

must be an X2 type capacitor at whatever value it is

Dave

[Loftus]

OK, I’m with you. I’ve looked inside again and there is indeed an X2 rectangular shaped capacitor in there. I missed it last time looking only at the classic round ones. Testing it with the multimeter on Ohms setting showed no change in resistance so think it’s bad. It had quite a high resistance too just for info.
I’ve ordered a new one for £3 so will let you know how I get on once i’ve swapped them over.
Thank you for your help.

[Loftus]

Hi Dave, New X2 capacitor arrived yesterday evening. Couldn’t find the exact same brand (guess at 15 years old might not be made) – but same spec. Realised the new longer capacitors legs wouldn’t fit the PCB so used a short wire to stretch back one leg to the hole on the PCB.
Just soldered it and well… Thank you! All the digits seem brighter and the clock doesn’t crash when it hits 8pm.
Massively appreciate your help and time, not only saving some money but more importantly saving it going in the trash when such a small part was all that was needed to keep it going.

[electrofix]

no problem glad it fixed it

Dave

[Author]

Posts