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Old December 29th 15, 01:46 PM posted to sci.electronics.repair
John-Del John-Del is offline
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First recorded activity by DIYBanter: Jul 2006
Posts: 263
Default Baffled by cordless tool problem

On Monday, December 28, 2015 at 10:49:03 PM UTC-5, Bob Engelhardt wrote:
On 12/28/2015 10:13 PM, Bob Engelhardt wrote:
On 12/28/2015 8:22 PM, amdx wrote:
On 12/28/2015 6:30 PM, Bob Engelhardt wrote:
On 12/28/2015 7:13 PM, wrote:
One bad winding on the motor, a bad spot on the commutator, really
worn brushes? (Assuming it's not brushless.)
...

When it's dead, even the LED does not come on. Which it normally does
even without the trigger being pulled. So it can't be commutator, etc.


Intermittent battery connection.

Mikek


I want to say that I've checked that - that there is voltage on the
connector terminals when it was dead. But I've gone around in so many
circles that I can't remember if I was even able to do that. I.e., if
it was ever dead after I opened it.

I have wiggled and stressed the battery connector without consequence.

When it dies again, that will the first thing I check.

Thanks,
Bob


Update: I put it together & it died. It took it apart & it stayed dead.
There is voltage on the connector and on the board. No poking,
prodding, twisting brings it back.

That pretty much clinches it for me: the board is bad. It is curious
how intermittent it was without reacting to anything I did.

The saw is under warranty - if I can find the receipt for it (unlikely)!

Bob


If you can't find the receipt, reflow the board (including the chip). I've seen a lot of reflow repairs where flexing or thermal cycling is inconclusive. Make sure you don't miss the crystal/resonator. Thoroughly clean the board afterwards as some unseen residues can wreak havoc with processor ICs..