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The above oven which uses electronics rather than conventional thermostats has a fault where the grill is only producing low heat.
The resistance of the elements test OK but there is a 12MΩ insulation fault.
The voltage supplying both the grill elements is about 110V. If I disconnect the element the voltage goes to the expected 240V at the connectors.
Would the insulation fault cause this or could something else cause this?that sounds like the elements are in series not parrallel
can you select a single and double grill setting ? if yes will it work on both ?
was thinking they may put elements in series when used as a top oven
dave
electrofix wrote:that sounds like the elements are in series not parrallel
can you select a single and double grill setting ? if yes will it work on both ?
was thinking they may put elements in series when used as a top oven
daveThis was definitely on the grill settings.
Single and double grill both supplied about 110v to relevent terminalss.
I had wondered about the elements being in parallel, is the power switched via the selector switch or the relays on the PCB?well if your only getting 110 on the grill elements something else is swallowing the other 110. test both other elements to see if either is powered 110 as well. very likely the fan element as the lower element is too low power wise to give an equal split
Dave
electrofix wrote:well if your only getting 110 on the grill elements something else is swallowing the other 110. test both other elements to see if either is powered 110 as well. very likely the fan element as the lower element is too low power wise to give an equal split
DaveI have returned to investigate further.
Tests show resistance and insultation OK on the fan oven circular element and base element. When I set the control to fan oven I get 240v at the fan element.
If I disconect the base element (1 terminal) I still get about 110v at the element which suggests it’s not in series with the grill.
There are 2 identical ovens at this address, the ovens are plugged in to 13amp plug sockets so I’ve swapped sockets to make sure it isn’t a supply problem, I’ve also checked connections in plug and mains connector block.
I have switched the grill elements then the selectors followed by the PCB’s, none of which made any differance.
I am at a loss as to what could be causing this.“Tests show resistance and insultation OK on the fan oven circular element and base element.”
did not expect that to be the problem
“When I set the control to fan oven I get 240v at the fan element.” well at least that rules out any supply problems
“If I disconect the base element (1 terminal) I still get about 110v at the element”
which element the base element, the wires that came off the base element or the grill element?
“There are 2 identical ovens at this address, the ovens are plugged in to 13amp plug sockets so I’ve swapped sockets to make sure it isn’t a supply problem, I’ve also checked connections in plug and mains connector block.
I have switched the grill elements then the selectors followed by the PCB’s, none of which made any differance.
I am at a loss as to what could be causing this.”its not an element problem. if it was they would either not work or have an earth fault and i am assuming they have an RCD which would have tripped
you need to approach this using ohms law. we know if we put 2 identical resistors in series an a 220v supply we would get 100v at the centre tap. you need to figure out where the other 110v is going and then you may be able to understand the fault
when you go back disconnect 1 wire on both the lower and fan elements then see if you get 110 across the grill element. if no re introduce the fan element and see if it returns. I think the fan element is favourite as its about the same wattage as the grill and it has to be a similar resistance to get an equal split
this could end up being a bad terminal on a wire as it seems you have eliminated everything else
Dave
I went back again today and following further tests I eventually found the problem.
When the grill was on I was also getting 110v at the fan element. Apparently sometime in the past (the customer can’t remember when), they think an electrician might have replaced the fan element! When doing this he’d managed to switch two of the three wires.
Surprisingly the main oven still worked OK. It wasn’t until the customer had the oven professionally cleaned they were told the grill doesn’t get hot enough.
The wires connected to the element were fairly discoloured and in all honesty, I’ve never had to take much notice of them in the past.
Unfortunately, I was trying to find a fault that had developed on the oven, not for a fault created by someone else (lesson learned)!
As you suggest Dave, the fan oven element must have been in series with the grill.
Thanks again for the help.
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