Nordictrack MC2100ELS-50W-V1 help please

Thread Starter

smdts

Joined May 13, 2022
8
My treadmill went pop.
U3 which is an STR G6352 failed spectacularly, and R74 is open, and R73 is vaporised with the pads burnt clean off the board. Everything else seems to test ok.
The problems I have are
1. What value should R73 be?
2. With the pad being burnt away completely and a small crater being left where R73 was it looks like pin 5 of u3 should connect to 1 side of R73 but does it then also go to one side of C48? I think the other side of R73 should then connect to one side of R75 and R74 is that right?
3. R74 has a weird colour code, it looks like it begins with black which I have never come across. Is there something wrong with my eyes?
Does anyone have a schematic they can share? Maxheadroom has posted some but the seem to be for a different variant, nothing seems to tie up.
I am a bit rusty, it has been 16 years since doing component level stuff.
 

Attachments

Thread Starter

smdts

Joined May 13, 2022
8
Yes r74 i cant identify the colour code, see photo above seems to start with black, r73 was exploded right off the board, your arrow is correct.
 

Thread Starter

smdts

Joined May 13, 2022
8
So the sole purpose of u3 is generating 12vdc so i go over to the secondary side of the high frequency transformer and inject 12v 5a from a decent inline psu across the smoothing cap, and thr rest of the motor drive shouldn't care?
 

MaxHeadRoom

Joined Jul 18, 2013
25,190
If you trace the input of the TFMR it should be connected to U3.
If going with a sub 12vdc, then remove the transformer. and feed into the cap connections, confirm first that the Cap/DC goes to HD1 & 2 .
 

Thread Starter

smdts

Joined May 13, 2022
8
It feels a bit like cheating, but it works well. I used an elmdene psu as I have used hundreds of them at work and they are very robust.
Thank you very much, I was kind of focusing on fixing what was there, bit this works too.
How many bloody software updates do these things need just to go for a jog, it was only broken a year.
 

Attachments

Top