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Member postings for mark smith 20

Here is a list of all the postings mark smith 20 has made in our forums. Click on a thread name to jump to the thread.

Thread: Coronavirus
29/05/2020 15:07:43


Thread: oscillating spindle sander help?
29/05/2020 09:14:24

Dave thanks for the explanation, i couldnt picture what was meant by dry joint.smiley

Thread: Coronavirus
28/05/2020 19:49:45

Does anyone else think this lockdown relaxation is too early? I mean estimated new infections in the overall comunity (by office national statistics) of 8 - 9000 a day is not a small amount of people to me.

Edited By mark smith 20 on 28/05/2020 19:50:25

Thread: oscillating spindle sander help?
28/05/2020 17:55:27


I dont understand these bad/or dry joints though, how does it suddenly happen when it was working fine. I can understand vibration loosening things but not dry joints or whatever.

28/05/2020 16:51:32

joseph its fixed i think smiley I reflowed all the solder joints on the pcb and `vroom` it started , dont know if it was a bad solder joint or brushes badly seated , i suspect the pcb.

Thankyou for you help

Edited By mark smith 20 on 28/05/2020 16:51:58

28/05/2020 16:30:16

Between the two actual motor carbon brushes measured removed from the motor im getting no DC but 106V AC

28/05/2020 15:22:18

DID you read that i got -250v DC  when i measured between the two toroids as you suggested??

I get 0.7 V between the live and neutral plug pins.


Edited By mark smith 20 on 28/05/2020 15:26:03

Edited By mark smith 20 on 28/05/2020 15:41:18

28/05/2020 14:55:25

There is 240v ac going into the board  measured with the meter but at the other side of the board ,the points that go to the motor brushes there is no DC but 70V AC when measured between those two points ???

But when i measure between the two toroids i get  -250V DC


Edited By mark smith 20 on 28/05/2020 14:56:33

Edited By mark smith 20 on 28/05/2020 15:19:02

28/05/2020 14:38:08

Where do i put the probes to measure the brush terminals ? One probe on one terminal and one on other ?

28/05/2020 14:36:49

Sorry, no humming noise and no movement of motor spindle at all.

28/05/2020 14:23:03

Bypassed the switch and nothing!

The two toroids?? both measure 0.5 ohms.

Second half of your instruction i am lost! No idea where to put probes etc....

Edited By mark smith 20 on 28/05/2020 14:31:22

Edited By mark smith 20 on 28/05/2020 14:35:45

28/05/2020 12:32:29

The blue things are marked

JD222MY1 400v- X1 400v -Y1

The black wire in the middle of the photo going to the right is the earth (screwed to motor casing)

Tested larger inductor.

lower left to upper left 0.4 ohms, lower right to upper right 0.4 ohms (lower left to upper right etc reads OL)

Upper the blue caps it says C4 and C3.

The blue caps measure 4.52nF from the back on the solder joints but dont know if accurate as some solder joints touch others.Cant get to the caps legs from the front.

Edited By mark smith 20 on 28/05/2020 12:32:46

Edited By mark smith 20 on 28/05/2020 12:36:47

Edited By mark smith 20 on 28/05/2020 12:39:22

Edited By mark smith 20 on 28/05/2020 12:46:07

Edited By mark smith 20 on 28/05/2020 12:50:40

Edited By mark smith 20 on 28/05/2020 13:02:18

28/05/2020 12:08:13

If it helps all the diodes have tested 0.495v forward and OL in reverse.

The two rectangular black capacitors measure 0.31uF (stated on capacitor as 0.22uF),

I cant seem to get any straight stable readings on the blue ceramic disc capacitors (taken from the pins at the back of the pcb.) multimeter seems stuck on nF


Edited By mark smith 20 on 28/05/2020 12:09:48

Edited By mark smith 20 on 28/05/2020 12:12:30

28/05/2020 10:44:30

Thanks for the replies. Im terrible at electrical diagnosis. I do have a multimeter but unsure where to put the probes and on which settings. Heres a photo of some of the components. The only thing that maybe looks odd to me is behind each of those two round things with a coil going round the circumference . Messy black areas on the back of the pcb.


Thread: goerge h alexander milling machine.
27/05/2020 19:17:28

I broke mine down to the horizontal long gear in order to get it from the garden into the workshop. It was hell for two of us getting it out of a van even though it had a tail lift .

This is the gear im talking about , mine has an aluminium slide in cover to protect it. The swivelling table if presnt comes off, as does the vertical head and the section above the gear in the photo. The vertical table will come off but the vertical saddle behind it needs lifting clear of the column which isnt easy without a crane /wynch of some sort.


Edited By mark smith 20 on 27/05/2020 19:25:38

Thread: oscillating spindle sander help?
27/05/2020 19:07:10

No more thoughts, im doubtful that the switch is the problem. The board above is supposedly some crude ac/dc converter .Motor is dc brush motor rated at 450 watts.


27/05/2020 15:44:36

Thanks , but still puzzled why the working one from the bench grinder doesnt work on the sander . (It definitely works on the grinder as i just checked again.)

The only thing between the motor and switch is this board, which i havent a clue about.


Edited By mark smith 20 on 27/05/2020 15:49:39

27/05/2020 15:31:09

Are these suitable


27/05/2020 15:24:30

Could you point to suitable one of better quality as all i see is variations of the same chinese switches on google.

27/05/2020 14:47:50

HI, I was busy using the sander today and then switched it off . When i went to switch back on ,no power. From experience its usually the crappy nvr magnetic on/off switch these things are usually fitted with.

So tried another but remembered it was broke.

Decided to use one out of a cheap grinder but still will not work,the switch rumbles when pressed but will not start.

Any suggestions as i get sick of replacing these cheap chinese switches .Or is something else wrong. Brushes look fine. They are the KJD  switches or similar the one in the machine was unmarked (just 250V 6 amp)



Edited By mark smith 20 on 27/05/2020 14:49:38

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