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Re: John Lewis JLBIDO906 main oven stays on & then over heat
I assume the thermal regulation is operating the elements individual relay, so agree that is unlikely to be sticking in the more it’s discussed.
How is the best way to measure the earth leakage on the element?thanks
Re: John Lewis JLBIDO906 main oven stays on & then over heat
Hi Dave
Thanks so much for the reply with everything I asked for and so speedy!
I must admit to being distracted yesterday and not noticing I had 3 pages of wiring, and only looked at the first one, my bad, sorry.
Also an extra fact that might be relevant; the only heater element getting hot is the fan ring one, and possibly because we really only use it as a fan oven, so might affect others too … nope just cycled it through fan to non fan and other elements/settings and the grill comes on, the main fan stops … but after only being on for 5 seconds the fan ring will then stay on and be cherry red in less than 20 seconds … so it needed not to have got hot, and the fan switches off. It is also intermittent, which is why I think it’s a relay switch, but just a hunch.So this brings on a few more questions, as I’m not sure if we have 2 issues here or just 1, as once the fan element has stuck live, surely a TCO should come to play? so let me ask these with my logic:
1. If the controller had failed (latching relay on the heater element) surely the MO thermal cut out would inhibit the heat element? As from the wiring page1 it shows a TCO inline with the controller main live supply?
From LH of page3 of wiring it shows 2 off no 7 aka “Thermal Cut off MO Fan Duct” (lists qty as 1 oddly!) and also lists in the notes a no9 MO TCO but does not place it on the diagram or any components inline with the supply wires from the mains terminal to the control panel.
On Page 3 the right hand diagram shows 2 inline TCO (180 &110) on the panel supply, and a TCO on the heater supply from the panel to the elements …From this I read, in theory at least, there should be at least 2 separate devices able to cut the power: one inline with all the elements; the other (1 or 2) inline with the control board supply?
So are both of these failing to trigger (the first time oven got blisteringly hot, past 250c and some)? Or does it need to reach near thermal meld down to trigger these?!2.from the parts pictures:
a. on the control panel page, there is an oven temperature sensor (no 6 & no 6a) on the Control Panel page, but on the basis of correct temperature control when it works, this would appear to be fine.
b. on the side back panel page; There are above the main oven a TCO and TCI but not sure if these are for the main or upper oven?
c. On the Main Oven Cavity page a TCO, assume this is the fan duct one
d. no external relays or control elements that are between the Control PCB and the element. However each element being neutral switched with a single common live (switched at K205 {inside Controller} and F2 TCO {external}) the chance of an earth fault on it’s own and intermittent nature keeping the element on seems low?So while the TCO’s appear to be reluctant to cut out the power, the fault is with the continued supply (or possible ground, or both) which would mean at least ONE part of the controller is faulty (ground short still needs K205 to be latched on the supply side)?
On a practical front, I have an insulation tester, to test the elements for leakage, should I disconnect the Controller first (obviously the mains issolated!)?
Would a DMM or low ohms tester suffice (have both)? I’m living in a 5/12/24v DC world … or 600-1000v …. so don’t want to make a snaffu 🙂Sorry for the lengthy reply, but having someone to sound off of and check the logic of clearly a product class I’m unfamiliar with is exceptionally useful !
thanks in advance
Richard
PS emailed QER, otherwise I might have to see if the relays are a common generic component and try replacing them myself, rather not, way too many other things to do …
