Mitre saw brake not usually working

[phatboy]

Hi all,

Recently my mitre saw (Hitachi C8FSE) brake has stopped working, usually, or kicks in really late.

I have:
- Replaced the brushes (unbranded)
- Sanded and sprayed with contact cleaner the armature, and cleaned out the gaps
- Cleaned out the whole tool
- Using a multimetre, checked the switch. The contacts are fine.

Not quite sure what to do next? Any advice much appreciated.

 

[GhostIntMachine]

Your saw should have a controller unit somewhere inside the housing (it is shown on the parts diagrm). Power goes through that and then to the motor. When you switch off the controller reverses polarity of power going to the motor for a short period. The rest is done by friction within the drive belt and bearings. Clean the contacts on the controller, also check (or better replace) the fuse in the plug at the end if the flex because flaky fuse might be another source of problems. AFAIK if you need to replace the controller they are in the order of £60.

But before doing any if this, do a search of YouTube to see if Dean Docherty has posted a repair video for the Hitachi or Hikoki C8FSE

 

[phatboy]

Your saw should have a controller unit somewhere inside the housing (it is shown on the parts diagrm). Power goes through that and then to the motor. When you switch off the controller reverses polarity of power going to the motor for a short period. The rest is done by friction within the drive bemt and bearings. Clean the contacts on the controller, also check (or better replace) the fuse in the plug at rhe end if the flex because earth grounding issues might be another source of problems. AFAIK if you need to replace the controller they are in the order of £60.

But before doing any if this, do a search of YouTube to see if Dean Docherty has posted a repair video for the Hitachi or Hikoki C8FSE

Thank you for this, very thorough.

No repair video for this sadly.

I had mis understood that the 3rd contact on the switch was for shorting the motor briefly to stop it, but instead there is a costly controller! I'll tear it down again and give that a look over and clean.

Are you suggesting replacing the fuse in the 13amp plug? As I cannot see an internal fuse on the diagrams. How would this help with possible grounding issues?

Many thanks
Tim

 

[foxhole]

Use to own one , had same braking problem and also found it cut 2mm out over length of rail . Just used it to chop firewood,

 

[GhostIntMachine]

Are you suggesting replacing the fuse in the 13amp plug? As I cannot see an internal fuse on the diagrams. How would this help with possible grounding issues?

Sorry about that meant to write "flaky fuse" (corrected)

I haven't done this repair on a Hikoki mitre saw, but I have done it on a couple of Makitas and a DW where it turned out to be ropey brushes on one plus a flaky fuse, and a failed controller on another and the switch being rammed full of sawsustvon all three. With saws and vacuums it's always worth cleaning out the switch and cleaning off the contacts before spending money on spares, I've gound. You might be able to see the polarity reverse on the output from the controller igg you have a multimeter

 

[phatboy]

Sorry about that meant to write "flaky fuse" (corrected)

I haven't done this repair on a Hikoki mitre saw, but I have done it on a couple of Makitas and a DW where it turned out to be ropey brushes on one plus a flaky fuse, and a failed controller on another and the switch being rammed full of sawsustvon all three. With saws and vacuums it's always worth cleaning out the switch and cleaning off the contacts before spending money on spares, I've gound. You might be able to see the polarity reverse on the output from the controller igg you have a multimeter

Thanks.

So what fuse should I replace?! I cannot see anything internal on the diagrams.

I did clean the switch with contact cleaner, but will get the meter on it again to confirm, and will clean the controller fully.

May spend a few £ on replacement brushes, as they were eBay cheapy ones, if the cleaning doesn't work and the switch looks functional.

It's not dangerous as it is (Now I've cleaned the guard and got that working again), but I'd prefer it to be as it should be