Breadmaker woes

[Scott]

Hi, I have just taken an introductory electronics repair course but I am
having trouble diagnosing a Toastmaster breadmaker (model TBR15).
The problem is:
The machine appears to work fine until it gets to the baking part of the
cycle. It heats up and continues heating until the lid begins to melt
and then one of the relays begins clicking every second or so which
results in the time display flashing on and off (but still keeping time
- except that time is slowed down presumably because it doesn't keep
counting while the display is "off"). While this is going on, the
heating coil doesn't seem to be working.
I have moved the temperature sensors (what are these called?) away from
the baking chamber and the problem disappears except that the unit
continues to heat indefinitly. When I move either sensor near the hot
baking chamber, the problem reappears.
Could someone please tell me how to test these temperature sensors with
a multimeter and also give me a hint at to the cause of the problem. Is
it the sensors or the relay or something else entirely????

Thanks very much for any help you can give!

 

[NSM]

Hi, I have just taken an introductory electronics repair course but I am
having trouble diagnosing a Toastmaster breadmaker (model TBR15).
The problem is:
The machine appears to work fine until it gets to the baking part of the
cycle. It heats up and continues heating until the lid begins to melt
and then one of the relays begins clicking every second or so which
results in the time display flashing on and off (but still keeping time
- except that time is slowed down presumably because it doesn't keep
counting while the display is "off"). While this is going on, the
heating coil doesn't seem to be working.
I have moved the temperature sensors (what are these called?) away from
the baking chamber and the problem disappears except that the unit
continues to heat indefinitly. When I move either sensor near the hot
baking chamber, the problem reappears.
Could someone please tell me how to test these temperature sensors with
a multimeter and also give me a hint at to the cause of the problem. Is
it the sensors or the relay or something else entirely????

Thanks very much for any help you can give!

Have you run it with a thermometer in the baking chamber? Clearly the
problem is with the temperature control system.

N

 

[James Sweet]

Hi, I have just taken an introductory electronics repair course but I am
having trouble diagnosing a Toastmaster breadmaker (model TBR15).
The problem is:
The machine appears to work fine until it gets to the baking part of the
cycle. It heats up and continues heating until the lid begins to melt
and then one of the relays begins clicking every second or so which
results in the time display flashing on and off (but still keeping time
- except that time is slowed down presumably because it doesn't keep
counting while the display is "off"). While this is going on, the
heating coil doesn't seem to be working.
I have moved the temperature sensors (what are these called?) away from
the baking chamber and the problem disappears except that the unit
continues to heat indefinitly. When I move either sensor near the hot
baking chamber, the problem reappears.
Could someone please tell me how to test these temperature sensors with
a multimeter and also give me a hint at to the cause of the problem. Is
it the sensors or the relay or something else entirely????

Thanks very much for any help you can give!

So relocating the temperature sensor causes the behavior to change? Most of
these are just thermistors, the resistance value should change more or less
linearly with temperature.