Mk3 (GHD3, 3.1B, SS2 etc)
Mk3 PCBs virtually never fail. The only real issue we've come across is dodgy switches which can be fixed with a bit of switch cleaner.
Mk4 (GHD 4.0B, 4.1B, 4.2B, SS4.0 etc) & Mk5 (GHD 5.0, MS5, SS5 and SC5)
Mk4 & Mk5 PCBs normally fail with R8 or R11 resistor failures. If your irons are dead, then it could well be one of these resistors is open circuit. See the R8/R11 page for more information.
The other resistors on the PCB are very high resistance (>1Meg Ohm) so you may not be able to measure them in circuit. This does not mean they are faulty - the only resistors that ever fail are R8 and R11.
If your board does not have an R8/R11 resistor problem and you are sure it's the board (i.e. heaters measure correctly, thermal fuse and cable are ok etc) then here are some problems that have been reported:
- C5 faulty - replace with T491B107M006AT CAPACITOR, TANTALUM, 6V, 100UF
- C1 and D9 dead
- Main PIC processor failed. We stock all four types of replacement preprogrammed PICs on the shop - Mk4 round buzzer, Mk5 round buzzer, MK4 Square buzzer. Mk5 square buzzer.
Another infrequent PCB caused fault can be low operating temperature.
Check R1, it must be measured out of circuit and should be 1 Meg ohm. Replace it if reads any higher than 1 Meg Ohm.
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