ISE W1706W – won’t turn on

[martin-h]

I have an ISE W1706W which has worked faultlessly for several years. Last week it wouldn’t turn on – there was no sign of life at all.

I could see that there was a blown resistor on the board – replaced it and it blew again. Following the advice on this thread: http://www.ukwhitegoods.co.uk/forumsphpbb3/post458721.html#p458721 I checked the voltage control chip – it had also blown (but harder to see the damage).

I have now replaced both components, but there is still no sign of life at all. I have confirmed that there is mains power going to the board. There’s no other damage that I can see.

Is a replacement control module the next step, or can anyone suggest something else first?

[electrofix]

Re: ISE W1706W – won’t turn on

sometimes when the power chip fails the electrical surge damages the logic chips.

the only other chip you could look at is the other regulator chip which I labelled with a yellow arrow

After that you have to be able to measure voltages on the board safely to continue other than that is a new board

Dave

[martin-h]

Re: ISE W1706W – won’t turn on

Hi Dave,

Many thanks for the speedy response.

There’s no sign of damage on that other chip. Presumably I should look for 5v or so across 2 of the pins on that chip?

Martin

[electrofix]

Re: ISE W1706W – won’t turn on

the other chip looks like a standard reg chip

so the 3 pins are
voltage in
voltage out
and the heatsink should be chassis

you measure between chassis and each of the pins in turn. A lot of these chips have numbers on the like 7812 or 7805. last 2 digits are voltage output

input voltage should be the same as the output voltage of the main 7 leg chip

one word of warning!! The 7 leg chip you changed has a voltage input of over 300 volts DC so playing with a live circuit can be dangerous and as a site we cant condone it

Dave

[martin-h]

Re: ISE W1706W – won’t turn on

Thanks again. Point taken re the high voltage!

The thing that I’d thought was a voltage regulator turns out to be a Triac – I’ve only just been able to identify the part number on it. I can’t see anything else that looks like a 3-pin regulator – images attached in case I’ve missed something blindingly obvious.

I’m thinking now that it’s got to be a new control module (£190) or a replacement machine. Do you think there’s much of a risk that the new module will not fix the problem?

Cheers,
Martin

[electrofix]

Re: ISE W1706W – won’t turn on

ah was assuming you were talking about the same boards as pictured and you fooled me. So yours may not have a reg chip

right brown cap at top of picture 1 should be high voltage. mains is rectified and you end up with over 300 volts DC
the 7 leg chip takes this voltage and lowers it to about 12 for the board. I would expect the 2 black caps to be 16v working or so. If you can safely measure the voltage on these to see what you get

one thing to mention is the 7 leg chip has a system known as fold back. this system lowers the out put if the current exceeds set limits. So if you measure the voltage and you find it going up and down then there is probably a short on one of the other main chips

Dave

[martin-h]

Re: ISE W1706W – won’t turn on

Apologies for the confusion.

I’m getting about 1.1v across one of the black capacitors (fluctuates slightly but only about 0.03v or so)

[electrofix]

Re: ISE W1706W – won’t turn on

well that’s fat too low. would expect min 5v up to poss 12 but never 1.1 v

if you can find a power supply reason then ok. if its a short causing fold back then you need a new board.

it looks like this machine has 2 boards linked by ribbon cables. try unplugging them and test again. If voltage comes up other board has fault

dave

[martin-h]

Re: ISE W1706W – won’t turn on

drops to zero with the cables unplugged

[electrofix]

Re: ISE W1706W – won’t turn on

it does sort of sound like your power supply is not functioning. Don’t know why as you can imagine but something does not ring true. since the 7 leg chip provides the power I would not expect the voltage to go down once the ribbons are removed

take it there are no components to speak of on the underside of that board

Dave

Dave

[martin-h]

Re: ISE W1706W – won’t turn on

Hi Dave,
The second board has a STM8S207 microcontroller chip plus a couple of other chips.

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