GHD's giving me problems

twnb
Posts: 3
Joined: 11 Sep 2012, 18:08

GHD's giving me problems

Postby twnb » 11 Sep 2012, 18:15

I have a pair of 4.0b GHD's that I am repairing, they are completely dead.

I tested the R8 which was OL so I have replaced it, but the straighteners still remain dead.

Plates are reading 35 Ohms, replacement R8 is fine and the fuse in the plug is good. Thermal fuse also appears to be good as it reads 0.4 Ohms.

What am I missing? And why do they remain dead?

gary
Site Admin
Posts: 1032
Joined: 26 Jan 2008, 00:44

Re: GHD's giving me problems

Postby gary » 13 Sep 2012, 00:09

Do you have continuity down the cable from the 13A plug pins to the PCB?

If it's not that then the PIC may have failed as well as the R8 resistor. The only fix for that is a new PCB.

Gary

twnb
Posts: 3
Joined: 11 Sep 2012, 18:08

Re: GHD's giving me problems

Postby twnb » 13 Sep 2012, 10:25

Checked that as well there is power coming straight to the R8, originally thought it was the cable. There is also enough power going to the chip as well.

Webinfusion
Posts: 134
Joined: 20 Jan 2012, 02:13

Re: GHD's giving me problems

Postby Webinfusion » 13 Sep 2012, 17:19

Hi,
Sounds like the PIC has gone, very strange but i have had 5 GHD's with blown pic's this month so far wonder if its a trend.

cheers
Kevin

gary
Site Admin
Posts: 1032
Joined: 26 Jan 2008, 00:44

Re: GHD's giving me problems

Postby gary » 15 Sep 2012, 10:15

There will always be a weak link.... With uprated resistors the weak link must now be the pic.

Gary

twnb
Posts: 3
Joined: 11 Sep 2012, 18:08

Re: GHD's giving me problems

Postby twnb » 17 Sep 2012, 19:37

On closer inspection the PIC has a small chip in the plastic at pin 6, could this be caused by to much power going through it? Looks like the innards are exposed

gary
Site Admin
Posts: 1032
Joined: 26 Jan 2008, 00:44

Re: GHD's giving me problems

Postby gary » 18 Sep 2012, 08:43

My guess would be that an electrical surge occured which over volted the pin and caused the insides to pop outwards. Hence the chip.

A new pcb should solve it!

Gary


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