Techno Gym - TGYM ALE A - S6T12 - VSD

[shepp]

Hello People, Not been on here for a long time but I have a treadmill to get my teeth into & I'm struggling to find the problem....

So the machine runs sometimes, but then other times I get the error code 3 for Low voltage, so the low voltage could be the motor output voltage from the drive or it could mean something else, all the voltages seem stable enough, like 24V etc...

On startup from a mains power up the relay at the line input socket clicks in & out constantly which its not suppose to do, so my 1st thoughts are with this circuit somewhere.....

I have checked all diodes & optos & I am getting some dodgy readings from a couple but there is no circuit diagram so I am literally just guessing at the minute,
I have removed some diodes & checked & they are all fine, so no major issues, which is always a harder job to find the fault....

I have checked the A3120 optos, which I pressume switch to create AC for the motor & across all the diodes on pins 2 & 3, I get 0.50v each way on diode test,
I can only think, that is correct as they all read the same & they are £5 for 2..... so dont really wanna chuck £15 at it for it to be the same,
I could start taking them all out 1 by 1 to test but thought I would post here 1st to see if anyone has any suggestions for looking elsewhere or what might cause the relay to keep clicking in & out.....

The motor tested out at 2.4 Ohms each winding so that seems ok to me when the test says 1.9.

Please see pics attached.....

The Patient in question is a Techno GYM Run Now 700 with the fancy digital webview display.

p.s. I am unable to power it up to do live testing on it but i will work through any suggestions when I can.

[truclacicr]

The relay must be bypassing the inrush current limiting resistor. This would suggest that the voltage comes up to spec and the relay closes. Something then causes the voltage to drop, and the relay opens. I think you need to unload the supply and see if it stabilises.

[shepp]

So maybe power it up without everything connected to it? like the screen etc?

I can do this tomoz, I didnt even think about that before I took the board out, what a donut.....
But like I say the voltages going out from the board are all stable, 24V etc, the relay is 24VDC.

I just checked the 2x Big caps 470uF & they both measure 850uF on my meter, they are still fitted though, does this sound right?

just checked the above & they are in fact in parallel & 20% tolerance so all good 👍

[shepp]

At present I didnt get chance to take it down to power up again,
but this is the relay circuit below, area in red is the multi point transformer, Diodes at the top.... the one on the right seems to measure what it should,
The one on the left is giving me some readings that are way off the other one so this could be dodgy (wont know til the new ones come & I remove to test & replace)
The 3 pin Yellow area is a STP5NK100Z - N Channel MOSFET which appears to be ok,
& the other 3 pin similar (Left side) is a K10N60A, which again appears to read ok....




I have ordered some more diodes, the relay, the mosfet & another IGBT while I have the board out, might as well remove all these & replace with new while its out.

The K10N60A though I couldnt get that version so ordered this one..... Toshiba GT20J341 IGBT, 20 A, anyone know if this is a good sub/replacement?

I looked through both datasheets & think it will be an ok replacement but I am not 100% - if anyone with this knowledge could let me know if it will be ok or not that would be great?

I know I shouldnt really just be buying stuff to replace but I am having to remove to test properly so thought it will be worth it in the long run for the board,

I have literally been through everything else & cant find anything else, even after removing loads of stuff which on the board looked dodgy but wasnt when removed.

Hopefully a step closer to fixing it.... 🤞 😜

[truclacicr]

I would locate the circuitry that controls the relay and determine what voltage it is sensing when it decides to close the relay's contacts and bypass the inrush current limiting resistor.

[shepp]

Thanks for the advice but I thought thats exactly what I was doing?
can you be a bit more specific & point me to some devices to check, its a little bit too vague.... it would be really helpful if you could point them out on one of the pics ive uploaded?

I have refitted the board tonight & retested......

The ticking from the relay has now stopped, which I thought was a great sign, machine booted up fine.....

I pressed Start & it cut off straigtht away with the same error, code 3, before I did anything to it, it managed to actually run but then cut out when trying to speed it up too quickly, so if you were soft with the adjustment it would actually run, now it just errors instantly.

So I swopped the bits like for like, apart from the K10N60A with a Toshiba GT20J341 IGBT, 20 A, if anyone could tell me if that will work that would be great? I compared the datasheets but I wasnt 100% sure.

[shepp]

This is an extract from the manual, but the supply is solid at 240V, so this must also be something to do with the output to the motor as well