GCM 12 GDL Laser
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Other woodworking
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Hey there guys, I've just picked a used unit of the mitre saw and started overhauling it. It works pretty good,but i have a problem with the laser,  it does not work. i dont have a clue about electronics...so what and how do i check. i wouldn't like to buy the laser unit if it could be from the on/off switch or the cable. i can't figure out from the parts diagram how the cable is conected or if it is a single part.
any advice would be welcome. thanks.
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Joinery installation in the broadest sense
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Hello trink.
If it's a used saw, the first thing I would check is that the laser lense is clear/clean. The laser is in the black box at the front of the blade guard. Fine dust accumulation can have the effect of completely blocking the laserlight.
The laser unit itself has a single wire with a crimped terminal in the end (see pic below), so if you were to open up the black box on the blade guard to have a look inside, there won't be too much to befuddle in terms of wiring.
If the connection looks good, get yourself a voltage test pen, circuit test screwdriver or multimetre (i prefer the pens for simple live wire detecting as they don't require metal/terminal contact but can detect voltage through wire sheathing). Taking due care (remove the blade, mind your eyes and be aware of live wires) , turn the laser on at the switch on the handle and test for current. If there's current detected but no laser light, you likely need a new laser unit. (part no. 1609B02439 - costs about 52GBP).
If you detect no current, it could be a fault in the switch or indeed the electronics module. I know the laser switch is on the handle assembly and I'm pretty sure the electronics module is in there too. Once opened, it should be pretty obvious determining the to/from wires at the switch to test. If there's current to the switch but not from it when on then the switch needs replacing (part no. 1619P03669 - cost about 18GBP). No current to the switch points to a fault at the electronics module (part no. 1 609 B02 562 - again costing around 18GBP).
If you suspect a wire fault/break, these are best tested end-to-end with a multimetre. I'd have thought this fault unlikely as the wires aren't stressed like at power cord inlets.
It should be reasuring that even if you replaced all these parts it could be done for less than 100GBP. It can cost nearly that just for the electronics module of many cordless tools.
It's worth saying that opening up the laser housing for test/repair may mean a fair bit of time will need to be spent resetting the laser position (adjustment screw setting etc). I've never had to do it thankfully but someone did share their experience of just that on here recently. Took them a couple of days tinkering on and off by the sounds of it.
When opening up the handle assembly or anything else for that matter, do it with the power off and take care to remember the position of the trigger parts etc. Can be tricky/fiddly to reseat these.
If you're a bit daunted by having a go or you can't get it to work, Bosch do offer out of warranty repair/servicing with fixed price quotation - See Here.
Beast of a machine. Be good to have it in full working order I'm sure. Hope the above helps or at least points you to a fix.
Good luck.
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Other building trade
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Hi

Do oyu have any instructions for removing the blade guard, so I can access the black plastic cover? I'd like to check for any dust accumulation, as my laser does not work either!

Thanks.
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Joinery installation in the broadest sense
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Hello Dougie.
You only need to remove the clear plastic guard. This is easy enough on the model we have as there are a series of fixing screws on the left side of the guard. Undo these and it'll allow you to remove the main body of the cleaar plastic guard. See pic below. Once removed, this should allow you access enough for inspection and cleaning (there is another version out there that doesn't have these screws but by the looks of it, it is still fixed only on the left side but you'll have to remove the push rod to get to the retainer).
Should you need to get into the laser itself, with the plastic guard removed, undo the screw at the bottom of the black box containing the laser. I'm pretty sure it's just this one screw holding the cover on so the cover should now pop off. You'll see the laser unit inside which you'll be able to test. Be advised though if you remove the laser unit from it's seat, it could mean some possibly lengthy realignment when you re-seat it. It might go back in just fine but it's more likely it'll be slightly out of wack.