@R!f@@,

Why not share the value and wattage with the rest of us?

John

 

You can find the top in the same album.
Here is the direct link:
https://picasaweb.google.com/lh/photo/X1Pn9K79c7DigSK-L1IuXg?feat=directlink

The diode is a IN4004.
According to my multimeter is has a 0.508 V drop

 

it's a 2K ohm 0.5W....but before putting it in.
OP need to check the Power diode and the Mosfets.

The resistor is on the Motor B+ side which by default shud be at 200VDC.
If the SCR shorted, then he will get 300VDC.
OP also need to check the low wattage diode connected to resistor for a short.
If short is there, then he has a big problem

 

That certainly makes sense, based on the voltage ratings of the capacitors. The one I can see looks like it's 400 WV. So, 200 V across a 200 Ω, 0.5 W resistor would blow it in a hurry. I would just replace the diode too. They are cheap and readily available; although, it does not look damaged. With the resistor out of the circuit, EdgeHawk could simply test it too.

John

 

That certainly makes sense, based on the voltage ratings of the capacitors. The one I can see looks like it's 400 WV. So, 200 V across a 200 Ω, 0.5 W resistor would blow it in a hurry. I would just replace the diode too. They are cheap and readily available; although, it does not look damaged. With the resistor out of the circuit, EdgeHawk could simply test it too.

John

Sorry john. My mistake. it was a 2 kΩ. I double checked the board that I had.
I was editing when the forum stopped responding from my side.

What U said is true though about it blowing but take a look at the picture

.
The circuit uses the diodes anode for some purpose. Could be monitoring negative spikes.

 

Yea, but the blackened area seems near the "short". Even at 2K Ω, 200V = 0.1 A = 20W for a 0.5 W resistor. Not immediate, but it certainly won't take long.

I have not looked at any treadmills, but I have seen some SCR motor controllers. What strikes me is the absence of other damage. In the motor controllers, there was always a PCB track that got lifted or some other damage, though repairable. Here it just seems limited to the resistor. If the diode checks out OK, it seems more likely there was simply a short at the resistor end opposite V+ that caused it to fail. A puddle of dog pee between the resistor and the metal case is a possibility, in addition to simply shorting to the ground plane.

John

 

I soldered the 2 kΩ resister and a new IN4004 diode on the board. Tomorrow i take the next step. Am not sure what my next step will be actually. I need some sleep frist. cya.

 

Do check for shorts first.

 

Pardon my barging in, but how would you check for shorts? There must be several ways...right?

 

Pardon my barging in, but how would you check for shorts? There must be several ways...right?

Right u are....

It's a tech thing.

 

Right u are....

It's a tech thing.

And.........

 

I checked for shorts. Didn't find anything. Must say that i am a real dummy when it comes to electronics. I decided to give the trial and error method a try. hehe i know....
I connected all connectors one by one and kept my breath every time i pushed the ON switch. Everything seems to go fine until.... after connecting the last connector for the display everything went down. The residual-current device of the home circuit did what it suppose to do. I guess the display sends a signal to one of the relay and put current on the board. But that's a wild guess. I removed the SCR from the board and now the display lights up. RCD still on. So i think the SCR has gone to SCR heaven.

 

Since you have a meter, here is a link to how to test the SCR - http://www.allaboutcircuits.com/vol_3/chpt_7/5.html

 

Yes, i forgot to mention. Tons of useful information can be found here. I already did the test as described on this page.
G <-> K = 0.52 Ohm in both directions.
All other measurements don't show open. So it's defective. Rite?

 

With the gate open, cathode to anode, and anode to cathode should show open. There is usually an internal resistor between the gate and cathode, but that 1/2 ohm sounds low. I would find another one and replace it.

 

U know SCR testing has always been a pain in the ass to me. I will check and post something about the size of those SCR's and it's testing results.