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Swarfing
24-06-2012, 07:54 PM
Guys

Does anybody have an M542 open sat on there bench? i have one here i picked up that has a blown component that sits right behind the +- power connections on the board. I can not make out if it is a protection diode or what value it is? can anybody help please?

Thanks

Paul

Robin Hewitt
24-06-2012, 10:23 PM
You mean the SMT stuff?

Swarfing
24-06-2012, 10:37 PM
I do Robin

Swarfing
24-06-2012, 10:38 PM
The model unit i have is the M542-G and the component is larger than the SMT's you have in that pic

Jonathan
24-06-2012, 10:55 PM
Wont be back home until Friday so can't check, but here's a photo I took earlier of an M542:

6188

Swarfing
24-06-2012, 11:10 PM
Thanks Jonathan but that is a completely different to mine. Interestingly though you have a large through fuse roughly where my smt one is. If only i could get a rating might give me clue. I'm trying to get a photo up of it now.

Swarfing
24-06-2012, 11:47 PM
Here is the one i have

6189

Notice the nicely blown component up the top to the right.

Jonathan
25-06-2012, 12:01 AM
Hmm, that's a bit different to others I've seen. What's the number adjacent to the blown component, 'V?5'? There looks to be a stripe on it, which would imply a diode or a transient voltage suppression diode. Is it in series or parallel with the power input, or something more imaginative?
Do you know what caused the fatality?

Swarfing
25-06-2012, 12:12 AM
Yes it could be a protection diode? problem is it is too chard to be sure about position and the number is V55. looking at the other components the ones labeled 'V' would suggest diodes? problem is 'V' can also mean 'variable component', those outside of being a resistor or cap. My guess is that he put the supply wires around the wrong way. I want to replace this first before i can apply any power to it.

I also scored a 2M88ON that has problems too, Tant has been replaced on that one already so will need to do some scope work to find the issue.

Jonathan
25-06-2012, 12:31 AM
If you can find what the component is connected to that should make it fairly obvious...


My guess is that he put the supply wires around the wrong way. I want to replace this first before i can apply any power to it.

That's easily done as different drivers put them different ways round - if I recall correctly the 2M880n is the other way round. I've got some pictures of inside a 2m880N, but unfortunately they're mostly out of focus or too dark to see anything useful:

619061916192619361946195

Just out of interest which mosfets does the 2m542 you have use? The one I looked at has IRF9Z34N

Lee Roberts
25-06-2012, 10:15 AM
I'll grab some pics for you shortly, i'v got 3 of these drivers not doing anything. I like taking photo's as well so they should come out nice !

Lee Roberts
25-06-2012, 11:13 AM
Ok mine are the original MSD542ís from Motion Control Products; they did another version after this one as well but Iíve not got any of those.

I took these quickly for you, so donít know if they help. Click twice on each for the full size image.

.Me

Swarfing
25-06-2012, 11:32 AM
Thanks for trying Lee, i will lift the dead component and clean it up so that i can see the tracks and have buzz round. Looking at the reverse side of the board it is labeled as a Leadshine M542 V2.0 dated 2008-10-09. Do we have any Leadshine stockists?

Jonathan the Fets i have on here are IRFZ44N

Swarfing
25-06-2012, 12:11 PM
I've just sent Leadshine a mail to there support people to see if they can help? see what happens?????

Lee Roberts
25-06-2012, 12:17 PM
No problem!

This one is a Leadshine v1.1 so it looks like yours is the one after, Gary @ Zapp maybe able to help or one of the guys at MCP. Dont know if they did/do a v3.0 but it would be handy if you could get another v2 to have a look at, have you not got the others...i guess not or you would of looked at one of those.

John S is likely to have a v2 and any others i would have thought?, maybe worth a try.

.Me

Swarfing
25-06-2012, 04:27 PM
Yes all my other ones i have on my machines are all different, typical???

Note to self.......Always take pictures of circuits for future blow ups.

Gary
25-06-2012, 08:11 PM
We have V3 and may have some old failed V2.
The leadshine 542 is quite a robust driver, so if you are popping them, you may need to look further than the driver.
The problem is that there are a lot of copies out there that make out to be leadshine but are in fact cheap knockoffs.

Swarfing
25-06-2012, 09:05 PM
Hi Gary

I wish it was me that made it go pop, at least i would have known what happened to it? I'm just putting together some more bits for my mill build and a friend of mine had these laying around so i hoovered them up. I spoke with him today and he said he bought these from you way back. The interesting thing is he said that he did reverse the polarity in haste to get them into his machine by following the wiring of the first one he put in (this was a different make). Do they have a protection diode on the V3?

John S
26-06-2012, 01:13 AM
Sorry not got any 542's at the moment, I never keep dead ones anyway, just bin them.
If I'd have know people want them to play with them I'd save them but to be honest it's very rare they go wrong.
I know I have a couple of dead 880's kicking about but these will be well fried.
Customer lives right next door to a main sub station and every couple of years everyone down his road get all the electrics fried but they claim it off the lecky board.

Swarfing
26-06-2012, 10:38 AM
Good news!

Leadshine replied and it is just a protection diode, the circuit is such that it will work without it. So i will clean it up and try it out :-)

Lee Roberts
26-06-2012, 03:58 PM
Result!

Nice one let us know how you get on...

.Me

mocha
27-06-2012, 08:27 PM
LOL, that looks like my 2280n!

Let me know if you need any pics of it...



If you can find what the component is connected to that should make it fairly obvious...



That's easily done as different drivers put them different ways round - if I recall correctly the 2M880n is the other way round. I've got some pictures of inside a 2m880N, but unfortunately they're mostly out of focus or too dark to see anything useful:

619061916192619361946195

Just out of interest which mosfets does the 2m542 you have use? The one I looked at has IRF9Z34N

Swarfing
27-06-2012, 10:43 PM
Right then have new components arrive today, the circuit will not power up without it and problem now is which way round should it go?

if i was to just bridge it it would be closed circuit. I'm now thinking the diode is part of clamping circuit maybe? if this was the case then the negative side of the diode would need to go to the negative side of circuit?

It does not make sense to just have a diode across the power lines as a protection circuit right? am i missing something here? wish i had a circuit diagram. The board won't clean up enough for me to see the tracks either:sorrow:

Jonathan
27-06-2012, 11:30 PM
The board won't clean up enough for me to see the tracks either:sorrow:

Presumably you've tried continuity testing, or using an ohm-meter to check where the tracks connect? Or have the tracks have acted as the fuse?

Swarfing
28-06-2012, 12:12 AM
Yes tracks are fine, it is only the mask discolored but i would not want to scrape that away

Robin Hewitt
28-06-2012, 10:37 AM
It does not make sense to just have a diode across the power lines as a protection circuit right?

Diodes have anodes and cathodes, the cathode is usually marked by a stripe, volts will flow anode to cathode but not vice versa.

A protection diode usually has it's cathode connected to the positice supply and it's anode connected above where you will break the circuit.

When the circuit breaks the supply to a coil the coil impedance wants to keep the current flowing. If it has nowhere to go the Volts go through the roof, probably exceeding the breakdown point of the transistors.

The diode carries the excess current back to the top of the coil so it can go round and round until the coil resistance eats it up.

Expect the cathode, stripe, to be at the positive supply end of the circuit.

Swarfing
28-06-2012, 10:47 AM
Robin your correct, last night i thought what the hell, spend hours pondering and testing or just solder it in. The worse that could happen is it goes pop, well it did so i put another one in the other way round it works a treat :-)


The part number is SMAJ48A-TR from RS for all those lurkers waiting for it

Jonathan
28-06-2012, 07:28 PM
Glad you fixed it - one day I'll get round to fixing the two broken M752's I have. Not had chance to look at them but I suspect some of the MOSFETs would need replacing.

Bit off topic but...
They're cutting it fine with the MOSFET ratings - both of our M542s use MOSFETs only rated for 55V absolute maximum. Considering they're driving an inductive load and the manual states they can be used on up to 50V (http://www.zappautomation.co.uk/pdf/manuals/PM542%20Manual.pdf) I'm surprised the voltage spikes on switching do not exceed 55V. The M752 (75V) and 2m880N (70V) have a much more realistic safety margin as they both use IRF540 MOSFETs which are rated for 100V. I therefore run my M752 drivers on the rated 75V having also checked with oscilloscope that the voltage spikes do not exceed 100V.


The part number is SMAJ48A-TR from RS for all those lurkers waiting for it

Ahh so it was a transient voltage suppression diode...I don't see why you would need to consider scraping the mask away to test.


When the circuit breaks the supply to a coil the coil impedance wants to keep the current flowing. If it has nowhere to go the Volts go through the roof, probably exceeding the breakdown point of the transistors.

The diode carries the excess current back to the top of the coil so it can go round and round until the coil resistance eats it up.

Yep, except the diode in question is across the supply not the individual MOSFETs in the H-bridges, however the principle is the same. I think the difference here is all the energy is immediately dumped into the junction of the diode, not necessarily going round and round. That diode should protect it against unplugging the power when running, but please don't try it!

Swarfing
28-06-2012, 10:12 PM
Thanks for the info Jonathan. Scarping the mask back was only to make it easier to see the tracks underneath. The tracks are all fine.