[skyguynca]

I loaned a standby/extra driver I keep on hand for emergency repairs to a "friend" to test his cnc lathe.
Well he returned it saying that it did not work, just kept flashing the leds both red and green together.
I then went and looked at his machine, he had the pwr supply hooked up backwards, so he blew my driver.

Does anyone know what parts are damaged when this happens? I do not want to loose $90 because a jerk
who will not replace it blew it up?

I have done a visual insp of the board and components and can not find anything physically damaged or burned.

Thanks for the help

David

[john-100]

Hi Dave

with the power reversed I'd expect a large fault current to flow through the diodes inside of the 8 FET's that make up the 2 H bridges
that control the power to the stepper motor coils

the FET's may be hidden between the PCB and the heat sink

if your very lucky that's all you need to change but its possible the overload to the current sense resistors may of damaged the resistors and possibly
the circuit used to measure the motor current

can you post pictures of both sides of the PCB?

John

PS
the diagram of the A4988 IC's internal circuit shows the usual H bridge and current sense resistors
that will be built out of discrete components in your KL8056d

Attachment 262634

[jalessi]

Skyguynca,

It wouldn't surprise me if PCB copper traces were blown open due to excessive current, check the board carefully on both sides.

Jeff...

[2e0poz]

It would help to know what driver it is?

[skyguynca]

Here is the pictures of my circuit board and I will start by ordering the FET's, 10 are only $10 delivered.

What else should I be checking?

Thank you very much for the help

David

[skyguynca]

sorry KL-8056D

[2e0poz]

I obtained a Leadshine that had similar damage which turned out to be blown transistor. The thread for that is here

MYCNCUK

The chap who owned previously conected it up back to front too. It cost a few pence to fix in the end.

[skyguynca]

That is actually what is printed on the circuit board Leadshine, thanks

[john-100]

Hi Dave

what is the part number on the FET's and the four 8 pin driver IC's marked ?
so I can look for the data sheets

Attachment 262656
only half of one H bridge shown - circuit repeated 4 times




using a digital multimeter

I'd expect resistance checks the possible combinations of any two FET connections should be high resistance
except for Drain to Source, due to the internal diode

Drain to Source will be high resistance when the positive meter lead is connected to the Drain & negative to Source
and low resistance when Source is connected to the positive meter lead & Drain to the negative lead

check the two current sense resistors marked R020 are not open circuit - 0.02 ohms will be less than the test leads !

also check the resistors that connect the FET Gate connection to the driver IC

John

[2e0poz]

Glad to help ;-)

[skyguynca]

FET is irf540n
drivers IC ir2104s

Thank you so much for your help

[skyguynca]

The resistors check out from 7.8 to 8.1 ohms
some of the FET failed, low to no resistance with +drain and - source
sense resistors show .9 ohms

- - - Updated - - -

I ordered a full set of FET's for $8 should be here next week.
What else should I be checking?

You have no idea how much I really appreciate the help

[skyguynca]

That is actually what is printed on the circuit board Leadshine DM556 V1.1 #100205#

[jalessi]

That is actually what is printed on the circuit board Leadshine DM556 V1.1 #100205#

Leadshine private labels there products for many distributors including Keling.

Jeff...

[jalessi]

You may see physical damage on the FET's once the front side is exposed, sometimes the plastic case pops and it may even be burnt.

[skyguynca]

Oh and I also checked all the diodes, closed in the proper current flow direction and open in the opposite

[john-100]

Hi Dave

the diagram on page 1 of the IR2104 gives you a better idea how the half bridge is connected to the IF2104
note - the current sense resistor is not shown :-

Attachment 262666


the one thing I cant see in your photos is the current feedback pcb track from junction of the sense resistor and FET Source

John

at twenty past one I'll call it a night

[jalessi]

John100 is giving very good troubleshooting advice, I will be quiet now.

[ger21]

I merged your two separate threads into one.

[lucas]

You said some mosfets are shorted, check if these are shorted to the gate also (they alsmost certainly will be). There's a big chance that the IR chips are gone too.

I would remove all fet's and power the thing up, verify the supply voltages: 12V? on the IR and 3V3 or 5V on the logic chips.
If these are fine:
Replace the IR chips and mosfets, don't forget the big electrolytic capacitor (these don't like reversal). Use a low ESR type.

Check the big blue resistor (black, brown, black, silver...) close to the Dip switches, this looks like a fusable resistor in the + line to the mosfets.

Use a lab supply set at 24V and a current limit for testing.

Hope this helps.