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3. Mk3 Debug

Repair Guide for Mk3 (3.1b / GHD3 / SS / SS2 / MS) GHDs

1) Start

• Check the label opposite the On/Off switch and ensure they are either 3.1B, GHD3, SS, SS2, MS or not marked with any model number. If they are Mk4/Mk5 GHDs, then you need this repair guide.
• Check the mains cable and plug for any damage, replace the mains cable or plug as required.
• Remove the metal cover on the mains switch, remove the contacts, clean the internal contacts and the removed contacts with a thin flat bladed screwdriver tip, gently scrap them clean. Refit the parts.
• Plug them in, turn them on and look at the red light:
  • It's on (at least some of the time).... Go to section 2.
  • It's not on at all or is very dim.... Go to section 3

2) Light comes on

• Does the light flash on and off when you move the straighteners?
  • Yes - your cable might need replacing / fixing - go to section 5.
• Do you hear a crackling noise?
  • Yes - wobble the cable and see if it gets worse
  • Yes - The mains switch contacts can cause crackling noises. Strip and clean the mains switch contacts if you didn't already.
• Do they come on, heat up and then go off?
  • Yes - your thermal fuse could be intermittent. You can check this by taking them apart (see section 4) and testing the thermal fuse (see section 6)
• Does the light go off when you close the two arms together?
  • Yes - the wires to one of the heaters may be about to break. You can check this by taking them apart (see section 4) and testing the heaters, gently tug the wires to find a break. (see section 7)
  • Yes - the thermal fuse could be intermittent. You can check this by taking them apart (see section 4) and testing the thermal fuse (see section 6)
• Hopefully you've said yes to one of those two questions, as I'm not aware of any other common problems!

3) They are dead - no light

• Look at the red light very closely... is it glowing very dimly? (a darkened room will help).
  • Yes - one (or both) of the heater elements is probably broken and needs replacing. Continue reading this section, so we can confirm this theory.
• Turn them off and disconnect them from the mains. Time to take them apart.... go to section 4 and return here once you've done it.
• Check the resistance of the following components:

  If any of those resistances don't agree, then you've probably found the fault. If they all agree, then you've got an unusual problem and you'll need to do your own investigations to try and find the problem.

  • Cable - zero ohms between each plug pin and it's wire on the PCB.
  • Thermal fuse - See section 6.
  • Heater elements - See section 7.

• Other less common faults are:

  • A wire coming loose from the small cable socket circuit board that the cable connects to. If this is the case, you can either solder the wire back onto the PCB, or replace the socket (for new sockets or genuine used sockets see the shop - 3.1b / GHD3)

  • Faulty switch. We've had a pair of 3.1B's where the switch buzzed loudly. You can either replace the switch, clean the insides of the switch or unsolder it, rotate through 180degrees and resolder.

4) Taking them apart

• Firstly turn them off and disconnect them from the mains!
• Using a small flat head screw driver, pop the caps off the hinge.
• Using two cross head screw drivers (one on each side of the hinge) undo the hinge. It may seem very tight, but this is normal - twist until you hear a "crack" and then they will come undone easily.
• Push the metal hinge pin out using a screw driver
• You can now seperate the two arms, although they will be connected with some wires.
• Remove the covers on each arm. You'll need to remove two cross head screws for each cover.

5) Testing the cable

• Check the cable for damage. If there are any bits of cable that are cut / melted / tightly kinked then you should probably replace it even if it works ok.
• Now plug the GHDs into the mains and lay them (and all the cable) on a table.
• Turn them on.
• Wobble the cable where it comes out of the 13A plug without allowing any other movement of the cable. If this causes the light to flash or you hear a buzz/fizz sound, then turn them off, disconnect them from the mains and cut the plug and a few centimeters of wire off and fit a new 13A plug (with 3 Amp fuse). That should hopefully fix them. If not then....
• Wobble the cable where it goes into the GHD's at the rotating joint. If this causes the light to flash or you hear a buzz/fizz sound then you'll need to fit a new cable. See the cable replacement page for instructions and the shop to buy the new cable.
• If the cables passes those tests, then it's probably ok, so go back to the section you came from and continue fault finding.

6) Testing the thermal fuse (GHD 3.1B and SS2 only)

The thermal fuse is the two brown wires coming out of the ceramic plate assembly on the switch side arm of the GHD's. If you put a multimeter across those two terminals (with them disconnected from the mains!), then it should be be close to zero ohms (maybe 1 ohm at worst). This means that when testing the thermal fuse you should see a similar output on your multimeter display as if you touched your meter's probes directly together. Don't get caught out by "OL" which means the thermal fuse is open circuit. If you've got an intermittent pair of GHD's, then you may want to try pulling / pushing on the wires slightly whilst measuring the resistance to see if it's the thermal fuse that is causing this.

Note that a broken thermal fuse wire is rare, another rare occurrence is intermittant failure of the thermal fuse whilst being used but reads correctly when checked with a multimeter.

Instructions for replacing the thermal fuse can be found here.

If you need to buy a thermal fuse, then we sell them via the shop.

7) Testing the heaters

There are two heaters - one in each arm. They are connected to the PCB's with white/clear wires coming out of the ceramic plate assembly. When attached to the PCB, the heaters are in parallel so should measure 80 Ohms. If this is not the case, disconnect the heaters from the PCB and measure them independently - they should be 160 Ohms each. See the heaters page for spare parts and replacment guides.

The heater wires can break and cause an intermittant connection.

To check, gently tug on each element wire in turn, a broken wire will pull off with this gentle tug.

Tug both ends of the elements wires, where they screw to the PCB and where they enter the element assembly.

Replace any element that has a damaged wire.

 

 

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