# Problem with my KEMMPI 1500 Mastertig

#### IOANOS

##### New Member
Hi,all members this forum.
In last weekends I bought in the ,,FLEAT MARKET,,one Keamppi 1500 master. The seller said ,,IT is faulty but sure can be repaired,,
I disassemble all ,,KEMMPI ,, for to clean.
The first time i saw that pcb Z001 -FILTER POWER -it is faulty.
The resistors RZ101 and RZ102 burned all because(in my opinion) primary power > 230V /50Hz sure ,,Diesel electrical generator,, was defective.
Now not understand -RZ 103 why burned ?
ok RZ 103 -through the voltage 220 V ac -to diodes bridge- to optocupleor type CNY 65 -
I rebuilt the circuit add RZ 103 --35KΩ ????? I removed CNY 65 and chek voltage in point diodes optocupleor --3,5 V dc. I mounted the diode I check current and i see 1,5 mA dc .
I energized electrical 12Vdc the circuit MC 14093PBC point 7 gnd 14 + and check signal in point 1 -conector .
Here not exist signal .
Where i wrong or who is cause ?
This my pictures with problem.
The first pictures tilling location filter.

The second pictures tilling all filtter disassemble.

the final pictures tilling home made schematic ,,trigge smith,, circuit .

Without the trigger smith machine does not work all ?
BEST REGARDES
IOAN

#### Rotarymaker

##### New Member
Hi Ioanas,

I can see so far you've done most of the hard work.

First of all, all of the named "RZ" components are not resistors,
they are varistors ..... these will burn up exactly as shown once their rated voltage value has been exceeded .....ie. they act as open circuit (high impedance) when a voltage below their rated value is present, BUT, when this rated voltage is exceeded, they immediately switch to a very low impedance (basically a short circuit) therefore causing the inline protection fuse to blow. Hopefully you still have
the faulty items (or bits and pieces from them) as you will then be able to identify the proper replacement value from them.

Onto the circuit operation..........you can setup and test this board outside of the machine.

I would suggest you get an oscilloscope for checking these waveforms
(BUT MAKE SURE that you use a mains power isolation transformer on the oscilloscope mains power input) before performing tests on mains side of the this circuit. ......VERY, VERY IMPORTANT!!!!!!!!! ..... otherwise you WILL destroy the oscilloscope due to its input side being connected to earth AND possibly electrocute yourself in the process!!!!!!!!!!!!!!

From 220V 50Hz line in, this is full wave rectified, so you should have 100Hz pulses onto the anode of your diode side of the optocoupler. IF not replace the bridge rectifier .... all 4 diodes, as
they have sustained a heavy hit from the overvoltage input.

With 12v setup as you have shown in your circuit, you should see these pulses appear at the collector pin of the optocoupler and also at pin 8 and 9 of the schmitt trigger ic..... if not, replace the
optocoupler, or check that the capacitor across the optocoupler is not short circuit, or that the feed resistor from 12volt to pin 8 and 9 of the schmitt trigger ic is not open circuit, or that the input pins 8 and 9 of the schmitt trigger ic are not short circuit.

The schmitt ic is used to convert a jagged input waveform on pins 8 and 9 into a nice squarewave on pin 10.
Pin 4 of output plug A I notice, (when you have your circuit board out of the machine), has been left floating..... you should place a temporary 10k resistor between pin 4 of plug A and ground so as to load the output and be able to to see this square waveform. You are not getting an output because either the schmitt ic is faulty, or because its output is not loaded .... also check that the resistor from pin 10 is not open circuit, or the capacitor after this resistor is not short circuit.
All (on this pcb!) should work after this......hopefully.

hope this helps,
let me know how it goes,
Rotarymaker

#### IOANOS

##### New Member
HI
Thank you for advice,i check all circuit steep by steep and will inform.
Not understand very good:The tigger Smith function when my ,,kEMPPI ,, have voltage 220V/50Hz.
So the my KEMPPI need the squarewave non stop for good function in mode MMA and TIG.
BEST REGRDES
IOAN

#### Rotarymaker

##### New Member
HI
Thank you for advice,i check all circuit steep by steep and will inform.
Not understand very good:The tigger Smith function when my ,,kEMPPI ,, have voltage 220V/50Hz.
So the my KEMPPI need the squarewave non stop for good function in mode MMA and TIG.
BEST REGRDES
IOAN
Yes Ioanos,

That is how this circuit works.
It is there to show inverter microprocessor on main pcb board that it has a constant good stable power input to welder.... also, it is for checking if line voltage goes bad ......example, brownout (supply voltage dropping low) or wrong frequency of power input, etc.
I would also check where mains power goes on through this pcb to possibly one or two large bridge rectifiers on heatsinks.....make sure there is no short circuit across these bridge rectifiers .......also check for short circuits across any mosfets on heatsinks, BEFORE you fit this pcb and apply mains power.

hope you get it going,
Rotarymaker

#### dr pepper

##### Well-Known Member
I have a similar weld set by kemppi, they are reasonably good sets.
The board you pictured does 2 jobs, one is to filter electrical noise out to prevent it from getting onto the power lines, and the opto and logi chip look like zero crossing detectors, on one of the pins you'll probably get a 50hz squarewave in sync with the mains.
The burned out components on the board unfortunately are probably indicications that something else is wrong, like the main power switching board, maybe the switching devices and or the transformer have failed.
Is there signs of anyone opening up the machine?, if so maybe its been to a repair shop and they found its totalled.

#### IOANOS

##### New Member
Hi ,i can use in my kemmpi mastertig 1500 IGTB MG 75 Q 2YS40 BRAND TOSHIBA ?
because original IGBT --MG75J2YS40 it is faulty .
The difference it is ,,J,, and Q
I see in the catalog and not understand 2 pcs zener diodes .
BEST REGARDES
IOAN

#### Rotarymaker

##### New Member
Hi ,i can use in my kemmpi mastertig 1500 IGTB MG 75 Q 2YS40 BRAND TOSHIBA ?
because original IGBT --MG75J2YS40 it is faulty .
The difference it is ,,J,, and Q
I see in the catalog and not understand 2 pcs zener diodes .
BEST REGARDES
IOAN
Hi again Ioanos,
New IGBT part MG75Q2YS40, which you bought should be 100% OK .....main difference between old J part and new Q part is... old J part is 600 volt 390 watt rating and new Q part is better 1200volt 560 watt rating.....according to datasheet.
As you have said, also different between J and Q parts is the two "back to back" zeners are not shown on datasheet for old J part. This is not a problem. You may find that these zener parts are on printed circuit board beside old J part
These two zeners are fitted to limit the gate to emitter drive voltage to safe limits ... no more than + or - 20 volts
Unfortunately I cannot say what damage may have happened when you wired new component not correctly......it may have caused lots of failure in driver circuit.....or maybe not. You will now have to check all IGBT components and driver circuit for more faults and it maybe best to replace these parts again...sorry
do not give up,
keep testing, and you may get Kempi to work,
best regards,
Rotarymaker

#### bryan

##### Member
Hi Ioanas,

(BUT MAKE SURE that you use a mains power isolation transformer on the oscilloscope mains power input) before performing tests on mains side of the this circuit. ......VERY, VERY IMPORTANT!!!!!!!!! ..... otherwise you WILL destroy the oscilloscope due to its input side being connected to earth AND possibly electrocute yourself in the process!!!!!!!!!!!!!!
Shouldn't the amp be on the isolation transformer, not the scope. Always thought it was bad to float a scope.

#### Rotarymaker

##### New Member
Shouldn't the amp be on the isolation transformer, not the scope. Always thought it was bad to float a scope.
Sorry Bryan / Ioanas,

You are absolutely correct.....my mistake......it should be the equipment tested that should be on the isolation transformer
.......theoretically speaking

.....although from practical point of view (from working within crt tv repair trade past 30 years) some tv switch mode power supplies under test refused to power up correctly while testing using an isolation transformer (eg Philips G11 chassis which had inside chassis at half mains potential)......in this case most tv shops I worked or visited used no isolation transformer, but illegally disconnected the earth from the plug, therefore "floating the scope" to allow tests on power supplies of this nature with absolute no harm coming to the scope......
I know. I know, this should NOT be done under any circumstance
, but this was what was done in days gone by (......now awaiting a toroid of abuse from Health & Safety officials)

#### Rotarymaker

##### New Member
Here also is Tektronixs Health and Safety view on this......

Safety Engineering Principles

Tektronix has adopted many safety principles in the design of their products. Of particular concern to making electrical and electronic measurements are these principles:

When the instrument is used properly, accessible parts shall not become hazardously live, even in the event of the single worst-case fault.

Electronic devices (those devices employing conduction in a vacuum, gas, or semiconductor) shall not be relied upon for providing operator protection from electric shock.

Products should not develop insidious hazards during proper operation (an insidious hazard is a hazard which can develop in a way as to be well established before becoming apparent).

The operator shall not need to defeat a protective system to make the measurement.

Safety - A Shared Responsibility

The operator and employer share in the responsibility of meeting these principles - through proper operation and measurement techniques.

WARNING

Never attempt to defeat the protective grounding system of your oscilloscope by using an isolation transformer (top) or disconnecting the ground connector on the power plug (bottom). Failure to follow safety warnings can result in serious injury or loss of life.
__________________
WARNING! All suggestions are informative only. It is the prerogative of the user to implement under his sole responsibility. This commentator will not be liable for any damages or injuries incurred.

#### bryan

##### Member

I know. I know, this should NOT be done under any circumstance
, but this was what was done in days gone by (......now awaiting a toroid of abuse from Health & Safety officials)

Just wear rubber boots and gloves.

#### Rotarymaker

##### New Member
hi
in this moment my inverter start in good function .http://i.eto-static.com/images/smilies/redface.png
thank for all instruction
and thank you all users that helped me.
not necessary use osciloscop because
I mistake conection in PCB correct gate igbt .http://i.eto-static.com/images/smilies/frown.png
again thank you ,and when there are problems I ask with trust.
IOAN -YO3HSX -ROMANIA
Fantastic news Ioanos ..... so glad we were able to help.
Thanks for letting us know you have welder running now.
regards,
Rotarymaker

#### IOANOS

##### New Member
hi again
i have one ,,dillema,, my keamppi good function but no starting cooler . I checked cooler independently and it is ok the cooler function.
i work 60 seconds with welding electrode 2,5mm.
not understand , the cooler start function when temperature increase by > ,,x,,degrees ?
best regardes and wait your replay
ioan

#### Rotarymaker

##### New Member
hi again
i have one ,,dillema,, my keamppi good function but no starting cooler . I checked cooler independently and it is ok the cooler function.
i work 60 seconds with welding electrode 2,5mm.
not understand , the cooler start function when temperature increase by > ,,x,,degrees ?
best regardes and wait your replay
ioan
Hi Ioanos,
I have attached owner/user manual for your welder.....it says fan (cooler?) should start as soon as you begin to weld and then should continue to run after you finish welding......so I do not think the fan is triggered to run when inside welder temperature reaches a certain value. If fan is not running as per user manual says, then you have a fault which will need to be fixed.
Is the inside fan "the cooler" you are talking about?......or are you talking about an external water cooler unit that is added for tig welding to allow cooling of the tig torch?
regards,
Rotarymaker

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#### Rotarymaker

##### New Member
Hi again Ioanos,
Check this website.....
Code:
http://issuu.com/doeboy1966/docs/sm_master_dc_mastertig_dc_v1.0en?viewMode=magazine
....click on the manual picture and you can read online some of the service manual
I have copied/pasted fan info from this to an attached Word document for you (please open with Microsoft Word (not Wordpad!)...... it says fan should operate 30 seconds after you start welding, no matter what settings on welder you set...... and fan should continue running up to 5 minutes after you stop welding.
I'm sorry, I don't have schematic circuit diagram for this welder but above block diagram info shows its controlled via the SG3526 chip circuit and its buffers. Have a look at this area within welder.
hope this helps a little,
Rotarymaker

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#### Rotarymaker

##### New Member
Hi Ioanos,

Searched again and found for you above service manual in full pdf format..... see attachment

cheers,
Rotarymaker

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#### IOANOS

##### New Member
ok
yes the cooler intern .
tnx for bibliography
Out pcb A001 and check with atentions all solder
I try location jumper power cooler and check ,,cold solder joint,,
In this moment , until I hear function cooler ,can not operate as because high risk .
Best regardes IOAN

#### inkilas

##### New Member
Hi,
maybe someone known, what diode type is on big aluminum radiator near the fun?

#### IOANOS

##### New Member
hello all
NOW my KEMMPPI it is very good function in MMA mode the cooler starting.
In TIG I not checked,but sure function.
I buy via EBAY one ,,torch,, and next year I buy gas tank with ARGON.
Best regardes IOAN