overheating

[jason king]

hi
i changed the thermal fuse and they came on but they then overheated, checked the thermistor and is ok. any ideas or suggestions..

jason

[astroman.no1]

Hi, I had the same problem as you seem to be having, though the ghd's i was repairing got so hot they melted?! the cure i found was to change the thermal fuse, and also change the triact, which if im not mistaken is there to regulate the current.(something like that anyway?!).

[gary]

Hi Astroman / Jason,

Sorry for the delay in replying - I've been windsurfing in Egypt for the last week

When triacs fail they have a habit of failing "short" which means that the heaters will be on all the time despite the brain trying to switch them off. Therefore replacing the triac could well solve the problem. You can test the triac by measuring resistance between the two mains pins (with power disconnected). If it has gone short, then the resistance will be very low.

Gary

[jason king]

hi gary
thanks for the advice... where can i get a triac from?, would you have a part number i could use to get one from maplins or rs components.

many thanks
jason

[gary]

Hi Jason,

I know you can get a suitable part from RS, however I don't know the exact part number as I've never had to buy any as yet. Can you read the markings on the device which should help work out what it is.

Regards,

Gary

[Guest]

hi gary
ive tested the triac and it messures 768 ohms.. the thermal fuse i ok as i replaced it the other day. the thristor olso measures 68k/ohms..
do you have any surgestions as to what is making these ghds overheat,
there doing my head in hehe.
thanks
jason

Hi Jason,

I know you can get a suitable part from RS, however I don't know the exact part number as I've never had to buy any as yet. Can you read the markings on the device which should help work out what it is.

Regards,

Gary

[gary]

Hi Jason,

I'm guessing here, however I'd say the triac should have infinite resistance when not powered... therefore that might be the problem....

Gary

[jason king]

ok thanks gary
il unsolder the triac and take it to maplins or rs and see if i can get a replcement.. if that works il give you the part numbers and tell you my results..

many thanks
jason

[gary]

If you can read the markings on the triac, it will probably be possible to work out an RS stock number.

Gary