Bosch tumble dryer: delay after switching on
 

It's a condenser model, about 10 years old. The fault is that when the rotating switch is turned from the off position to any of the programs ("very dry", "cupboard dry" etc.), which normally causes an LED to light up and the machine to be ready for action (pressing the "start" button should set things in motion), there is a significant delay.

If the machine has been recently in operation, then there is no delay in lighting the LED when a program is selected. However, if the machine has been turned off for a few hours or more, then the delay is around 45-60 seconds.. To be clear, it isn't an LED fault; the machine will not begin operating until the LED lights up and there is an audible click (a relay, I assume) when it does.

My first thoughts are a knackered built-in battery or a dead capacitor. Does that sound about right? If the machine still works (with a delay) in its current state, then I'm not sure what function the battery/capacitor is supposed to have. Maybe power for a memory function in the event of a mains disruption, to allow the machine to pick up where it left off?

Advice welcome.

Thanks.

Ant.

Bosch tumble dryer: delay after switching on
 

On 18/07/2019 05:36, wrote:
It's a condenser model, about 10 years old. The fault is that when the rotating switch is turned from the off position to any of the programs ("very dry", "cupboard dry" etc.), which normally causes an LED to light up and the machine to be ready for action (pressing the "start" button should set things in motion), there is a significant delay.

If the machine has been recently in operation, then there is no delay in lighting the LED when a program is selected. However, if the machine has been turned off for a few hours or more, then the delay is around 45-60 seconds. To be clear, it isn't an LED fault; the machine will not begin operating until the LED lights up and there is an audible click (a relay, I assume) when it does.

My first thoughts are a knackered built-in battery or a dead capacitor. Does that sound about right? If the machine still works (with a delay) in its current state, then I'm not sure what function the battery/capacitor is supposed to have. Maybe power for a memory function in the event of a mains disruption, to allow the machine to pick up where it left off?

Advice welcome.


A few years back, my parents had an issue with a washing machine where
it would fail to power on every time when turned off (i.e. not left in
"end of program" standby)
Randomly turn the power off then on again a few times, and you could
persuade the thing to power up correctly until the next time it got
turned off again.

Extracting and opening the control module revealed a bulging
electrolytic capacitor. Replacing the capacitor fixed the issue.
Note that this was a "normal" capacitor, not a "supercap" used to hold
settings etc.

I would do a physical inspection of any control board looking for bulged
caps. (a google image search for "bulging capacitors" will show you what
you are looking for).

Bosch tumble dryer: delay after switching on
 

Door delay sensor faulty and affected by temperature?
IE I can't do anything just yet I think my door is still open, but its not
of course.
Brian

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It's a condenser model, about 10 years old. The fault is that when the
rotating switch is turned from the off position to any of the programs
("very dry", "cupboard dry" etc.), which normally causes an LED to light up
and the machine to be ready for action (pressing the "start" button should
set things in motion), there is a significant delay.

If the machine has been recently in operation, then there is no delay in
lighting the LED when a program is selected. However, if the machine has
been turned off for a few hours or more, then the delay is around 45-60
seconds. To be clear, it isn't an LED fault; the machine will not begin
operating until the LED lights up and there is an audible click (a relay, I
assume) when it does.

My first thoughts are a knackered built-in battery or a dead capacitor. Does
that sound about right? If the machine still works (with a delay) in its
current state, then I'm not sure what function the battery/capacitor is
supposed to have. Maybe power for a memory function in the event of a mains
disruption, to allow the machine to pick up where it left off?

Advice welcome.

Thanks.

Ant.

Bosch tumble dryer: delay after switching on
 

On 18/07/2019 05:36, wrote:
It's a condenser model, about 10 years old. The fault is that when the rotating switch is turned from the off position to any of the programs ("very dry", "cupboard dry" etc.), which normally causes an LED to light up and the machine to be ready for action (pressing the "start" button should set things in motion), there is a significant delay.

If the machine has been recently in operation, then there is no delay in lighting the LED when a program is selected. However, if the machine has been turned off for a few hours or more, then the delay is around 45-60 seconds. To be clear, it isn't an LED fault; the machine will not begin operating until the LED lights up and there is an audible click (a relay, I assume) when it does.

My first thoughts are a knackered built-in battery or a dead capacitor. Does that sound about right? If the machine still works (with a delay) in its current state, then I'm not sure what function the battery/capacitor is supposed to have. Maybe power for a memory function in the event of a mains disruption, to allow the machine to pick up where it left off?

Advice welcome.

Thanks.

Ant.

My non-condensing machine switches off when it decides it is dry, but
often re-starts a few times before it finally stops.

So this could perhaps be a sensor holding it "off" until it is happy
that it is damp enough to be required to be running. Given that all
tumble driers collect fluff to some extent (even if not around the
heating elements, like Whirlpools) I think I might also be looking for
fluff in the air passageways, particularly around sensors.

Bosch tumble dryer: delay after switching on
 

Thanks for the replies.

It's not a wet sensor or door sensor. There is no electronic door lock to prevent opening and the wet sensor merely stops the machine when clothes are dry, but the machine continues to light the "on" red LED.

Regards.

Ant.

Bosch tumble dryer: delay after switching on
 

On 18/07/2019 05:36, wrote:
It's a condenser model, about 10 years old. The fault is that when the rotating switch is turned from the off position to any of the programs ("very dry", "cupboard dry" etc.), which normally causes an LED to light up and the machine to be ready for action (pressing the "start" button should set things in motion), there is a significant delay.

If the machine has been recently in operation, then there is no delay in lighting the LED when a program is selected. However, if the machine has been turned off for a few hours or more, then the delay is around 45-60 seconds. To be clear, it isn't an LED fault; the machine will not begin operating until the LED lights up and there is an audible click (a relay, I assume) when it does.

My first thoughts are a knackered built-in battery or a dead capacitor. Does that sound about right? If the machine still works (with a delay) in its current state, then I'm not sure what function the battery/capacitor is supposed to have. Maybe power for a memory function in the event of a mains disruption, to allow the machine to pick up where it left off?

Advice welcome.

Thanks.

Ant.
If it is any way similar to our 7yr old Bosch TD and it has a SMPSU*
then as the other post suggests could well be capacitor failure.
Another possibility is the startup resistor going high in value, if the
design uses one.

*The SMPSU failed on our Bosch TD (due to capacitor failure) but becuase
it was still under an extended warranty they changed the entire panel,
with the LCD display and everything.

Bosch tumble dryer: delay after switching on
 

Hmm, managed to screw up the formatting...

Our Bosch TD has a SMPSU, it suffered capacitor failure and the whole
panel was replaced. If yours is similar then suggest SMPSU trouble
shooting steps...