urgent help 50pk550-so desperate here

[Hamie]

Re: urgent help 50pk550-so desperate here

OK so your z-sus appears to be working.

We will concentrate on the y-sus.
As both allister and nick have said you need to check and see if vs is shorting to ground.

To do this look at where the wire plugs into the y-sustain.
You'll see a table showing what pins are vs and ground.

Put your meter in OHM and put red probe on any VS pin and black probe on any of the ground pins.

If you have a low OHM reading the VS input is shorting to ground.

[ramirachamim]

Re: urgent help 50pk550-so desperate here

nick, just made short examination as you said (dmm on ohms).
got "O.L" on z brd
got 0.4Mega ohms on y brd which does not connected to the buffer boards at the moment.
what do you think it means?

[ramirachamim]

Re: urgent help 50pk550-so desperate here

1 sec i will double check the y-sus..

[ramirachamim]

Re: urgent help 50pk550-so desperate here

ok update,
double checked the y-sus resistance.
get "open loop" between ground and VS line on the power connector to y-sus.

[Alastair E]

Re: urgent help 50pk550-so desperate here

Check All IGBT's on Y-SUS.

[rami]

Re: urgent help 50pk550-so desperate here

hi all,
as alastair recommanded, i've decided to completely remove all heatsinks with it's screw attached igbt and mosfet transistors.
will make some googling/youtubing to figure out exactly how to examine each component.
do you guys think that removing all heatsinks is too crazy? or it is a common operation?
anyhow, updates/results will be given upon completion.
have a nice day!

[ReeceyBurger123]

Re: urgent help 50pk550-so desperate here

You dont need to remove them out the board until you have found ones that have a short across them.

[ramirachamim]

Re: urgent help 50pk550-so desperate here

You dont need to remove them out the board until you have found ones that have a short across them.

Yea it was and still is a pain in the *** however, ive read that leaving it on the board do not always allow accurate reading.
Btw guys, after removing and checking about 70% of igbt's more than 50% are faulty..
Alastair you basterd😉

[ramirachamim]

Re: urgent help 50pk550-so desperate here

alwright guys, i owe you some answers...
as mentioned after checking all of the components upon heat sinks the results are:
1)all fast reaction diodes (rs 2001 something) appears fine.
2)from 6 igbt's (30f124) 4 were bad.
3)from 4 mosfets (fdff51n25) 4 were bad.
4)from 2 mosfets (k3667) 2 were bad.
some clarifications:
a.none of the components were shorted, when i write bad i mean that when neg probing the right lag (source) with the middle (drain) i get "OL", when momentary touch red probe on first lag (gate) and return to drain i still recieve "OL" , if i understand correctly it meand that the transistors will not turn on.
b.the igbt's were tested exactly the same method (only for other names) e c and one more
so about the igbt's i am pretty sure the results are correct since 2 appeared ok and 4 not.
about the mosfets, well, not sure results are correct.
any insights guys?
btw,photo attached, white dots near the heat sink screw symbols "failed" components.

[Nick's Tvs]

Re: urgent help 50pk550-so desperate here

If you get O.L that is because your meter can't read that high of resistance. That is good and it means your transistor is ok. What you don't want is a low reading in the K ohms range.
If you are testing an IGBT out of circuit and it is showing you for example 400K ohms then you have a bad IGBT. Really anything below 1M ohm is probably bad. If it shows OL then you are good however the middle leg to the right leg should show you around 6Mohm to 12Mohm but I forget if you need your black lead on the middle leg or on the outer leg. Outer leg to outer leg should show OL and same with middle leg to left leg.
Also if your transistor is still hot from desoldering then it will show less resistance. The more heat you apply to the transistor, the lower the resistance. So you should wait for it to cool off just a bit to get a good reading.

[Alastair E]

Re: urgent help 50pk550-so desperate here

Err........

Why am I the basterd??--I told you what to test--and you found the fault!

[ReeceyBurger123]

Re: urgent help 50pk550-so desperate here

[ramirachamim]

Re: urgent help 50pk550-so desperate here

Alastair,if you wouldnt direct me there i'd probably throw a punch in the middle of the screen at some point you applied hope for the darn set..thumbs up!
Now as long as the components are out i would really appreciate if you guys can pin point exatly how to test them.
As mentioned at previous post there is a lots of chips from various kinds out there and my intuition tells me i made a mistake with the reading analysis..
Please refer in your answers to each chip so i can understanding better.
Thank a lot again guys!

[vinceroger69]

Re: urgent help 50pk550-so desperate here

https://www.youtube.com/watch?v=_Ygmbfw-9XE
how to test igbt

[ramirachamim]

Re: urgent help 50pk550-so desperate here

hi everyone.
i am so pissed off right now!!
after busting my *** removing all igbt's and mosfets with it heat sinks out
i've just realize that all the parts which appeared to be bad will cost me 7.5$ a piece!
(in my country)
i have about 10 bad components which will be about 75$ which is more expansive than a complete y brd..
now the thing is:
1.as told few posts before, i am not sure that i am correct with all of my measurements. i want to clarify that while testing the components NONE was shorted.
i tested 4 out of 6 igbt's which according to the test instruction movie on utube DID NOT POWER ON , for detailed clarification lets call the 3 legs L M R
when -probe on R and + probe on M the dmm says O.L
when briefly moving the + probe to L and back to M the DMM showed:
O.L on 4 igbt's (*which appears to be bad-not turning on).
some volts on 2 igbt's until i O.L when shorted out the L and M with my finger(appears to be OK)
2.i also measured all heatsinks transistors with same method(as also showen on another utube movie)-**was i supposed to measure them too?
if so- is the test method ok? i am asking because it does not look likely that 6 out of 6 are bad...
as i see it, the following are my next options:
a. i order a complete y brd from ebay (50$)-month to wait.
b. i order all "bad" components from ebay(12.5) and month to wait-no guerentee problem will be solved...
which would you pick?

please guys,
*-is correct?
**-was i supposed to measure mosfets? if so, test method ok?

thanks very much in advanced,
it got personal between me and the damn set-and i am like a pitbull

[vinceroger69]

Re: urgent help 50pk550-so desperate here

other people may test these igbt s diffrently or may have a easier test you can do i would hang on before you order any parts untill you see if other have better or can confirm the video is the correct/best way too check them.

[ramirachamim]

Re: urgent help 50pk550-so desperate here

well..
you are right.
i will wait to see what hamie/alasteir/nick have to say about it..

[Nick's Tvs]

Re: urgent help 50pk550-so desperate here

Assuming you have a digital multimeter in auto ranging ohm mode

Place black lead on middle pin and red lead on right pin of transistors.

[ramirachamim]

Re: urgent help 50pk550-so desperate here

ok.
and?

[Nick's Tvs]

Re: urgent help 50pk550-so desperate here

You should be getting around 6 to 12 Mega ohms dependent on the transistor. Most often you will get 8-10 Mohms
If you get OL then clean the leads with alcohol and make sure you are making proper contact.