I have had my son's Millermatic 175 here for some time now. I last used
it about 3 or 4 months ago and it worked great. Today he comes over to
weld some small stuff and it don't work. Crap! Turn it on and nothing
happens. The internal fan comes on, but it is far from being up to full
speed. No gas flow and no wire feed.

I took the cover off and didn't see anything wrong. All wiring seems to
be clean and secure. I didn't mess with the capacitor at all, but
everything else was ok. No burn marks that I can see on the circuit
board and the green light comes on. Guess I'll ave to take it in for
service.

This machine is a few years old and has seen very light use. Not even a
full spool of wire has been run through it. Maybe 1/2 a spool. Not
even any scratches on the thing. :-) I am suspecting that the circuit
board has gone bad so here is the question. What should I expect when I
take it in for repair? I am assuming that it will most likely be the
circuit board since I have seen in a couple of forums that this is a
somewhat common problem with this machine, but the symptoms they list
when this happens are slightly different. Are there any other problems
that you know of that might cause this?

TIA,

Wayne

"NoOne N Particular" wrote in message
t...
I have had my son's Millermatic 175 here for some time now.
I last used it about 3 or 4 months ago and it worked great.
Today he comes over to weld some small stuff and it don't
work. Crap! Turn it on and nothing happens. The internal
fan comes on, but it is far from being up to full speed.
No gas flow and no wire feed.

I took the cover off and didn't see anything wrong. All
wiring seems to be clean and secure. I didn't mess with
the capacitor at all, but everything else was ok. No burn
marks that I can see on the circuit board and the green
light comes on. Guess I'll ave to take it in for service.

This machine is a few years old and has seen very light
use. Not even a full spool of wire has been run through
it. Maybe 1/2 a spool. Not even any scratches on the
thing. :-) I am suspecting that the circuit board has
gone bad so here is the question. What should I expect
when I take it in for repair? I am assuming that it will
most likely be the circuit board since I have seen in a
couple of forums that this is a somewhat common problem
with this machine, but the symptoms they list when this
happens are slightly different. Are there any other
problems that you know of that might cause this?

TIA,

Wayne

Really dumb question----It's wired 220 single phase,
correct? Do you have juice to
both L1 and L2?

NoOne N Particular wrote:
I have had my son's Millermatic 175 here for some time now. I last used
it about 3 or 4 months ago and it worked great. Today he comes over to
weld some small stuff and it don't work. Crap! Turn it on and nothing
happens. The internal fan comes on, but it is far from being up to full
speed. No gas flow and no wire feed.

I took the cover off and didn't see anything wrong. All wiring seems to
be clean and secure. I didn't mess with the capacitor at all, but
everything else was ok. No burn marks that I can see on the circuit
board and the green light comes on. Guess I'll ave to take it in for
service.

This machine is a few years old and has seen very light use. Not even a
full spool of wire has been run through it. Maybe 1/2 a spool. Not
even any scratches on the thing. :-) I am suspecting that the circuit
board has gone bad so here is the question. What should I expect when I
take it in for repair? I am assuming that it will most likely be the
circuit board since I have seen in a couple of forums that this is a
somewhat common problem with this machine, but the symptoms they list
when this happens are slightly different. Are there any other problems
that you know of that might cause this?
One suggestion is to vigorously flip all switches and controls through
all positions
a couple times, then back to where you want them. One of the selector
switches or pots may have gotten a dirty contact and prevented the rest
of the logic from completing.

Jon

TIA,

Wayne

Really dumb question----It's wired 220 single phase,
correct? Do you have juice to
both L1 and L2?



It may be a dumb question, but I didn't really have the time to do a
whole lot of diagnosis. The kid was ready to leave and he wanted to
take it with him. When he wants to go, he wants to go NOW. So I can
only **assume** that L1 and L2 both have juice. I will have to go over
to his place now to find out.

And you are right, it is 220v 1ph. I unplugged my dryer and used that
outlet for the welder which I have done several times before. I have a
good extension cord of about 50' of nice heavy wire which I think is
10ga. but might be 12ga. but it is heavy duty stuff and has not caused
any problems in the past.

So let me ask you this. IF either L1 or L2 does not have juice, would
that fan even come on at all???

Thanks,

Wayne

One suggestion is to vigorously flip all switches and controls through
all positions
a couple times, then back to where you want them. One of the selector
switches or pots may have gotten a dirty contact and prevented the rest
of the logic from completing.

Jon


Been there. Done that. Disconnected everything that I could easily
disconnect and reconnected too. Inside and out. But thanks for the tip
anyway.

Wayne

NoOne N Particular wrote:


One suggestion is to vigorously flip all switches and controls through
all positions
a couple times, then back to where you want them. One of the selector
switches or pots may have gotten a dirty contact and prevented the
rest of the logic from completing.

Jon


Been there. Done that. Disconnected everything that I could easily
disconnect and reconnected too. Inside and out. But thanks for the tip
anyway.

Seems to me that normal electronic debugging techniques would apply. Plug it
in, turn it on, and start checking voltages with a voltmeter. Check that the
wall voltage is indeed reaching the welder, and if so start following it
through. Most electronic failures are from power not getting where it's
supposed to go.

Grant

On Tue, 27 Nov 2007 11:30:06 -0800, NoOne N Particular
wrote:

I have had my son's Millermatic 175 here for some time now. I last used
it about 3 or 4 months ago and it worked great. Today he comes over to
weld some small stuff and it don't work. Crap! Turn it on and nothing
happens. The internal fan comes on, but it is far from being up to full
speed. No gas flow and no wire feed.
snip

Do you have the manual? If not that would be a good place to
start. Miller has good manuals and downloads for free. I
think you need either and/or one of these:

http://www.millerwelds.com/om/o1324c_mil.pdf

For "MILLERMATIC 175 M-10 Gun" (~1mb)

or

http://www.millerwelds.com/om/o1324k_mil.pdf

For "MILLERMATIC 175 W/M-10 GUN (~1.4mb)

A quick check in the first manual gives this under trouble
shooting:

No weld output; wire does not feed; fan
motor continues to run. Check:

-fan Thermostat TP1 open (overheating). Allow fan to run
with gun trigger switch off; thermostat closes when
motor continues to run. unit has cooled (see Section 2-2).

-Secure gun trigger leads (see Section 3-1).

There is a block diagram for the circuit board with
input/output leads labeled (page 29). It sounds like it
might just be a bad gun trigger switch or a problem en route
to the circuit board for same.

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

No weld output; wire does not feed; fan
motor continues to run. Check:

-fan Thermostat TP1 open (overheating). Allow fan to run
with gun trigger switch off; thermostat closes when
motor continues to run. unit has cooled (see Section 2-2).

-Secure gun trigger leads (see Section 3-1).

There is a block diagram for the circuit board with
input/output leads labeled (page 29). It sounds like it
might just be a bad gun trigger switch or a problem en route
to the circuit board for same.


I did have the online manual and I went through it AFTER the kid took
the machine home with him. But it sounds to me like the part "fan motor
continues to run" means the fan is running full speed. This fan is
probably not even running at 1/4 speed. It was running so slowly that
we could not hear it until we got our ears down to the rear of the
machine and then it was barely audible. I'm hoping that his next day
off he will bring it back and I can "play" with it more, and then most
likely take it in for service.

Thanks,

Wayne

On Wed, 28 Nov 2007 16:50:20 -0800, NoOne N Particular
wrote:



No weld output; wire does not feed; fan
motor continues to run. Check:

-fan Thermostat TP1 open (overheating). Allow fan to run
with gun trigger switch off; thermostat closes when
motor continues to run. unit has cooled (see Section 2-2).

-Secure gun trigger leads (see Section 3-1).

There is a block diagram for the circuit board with
input/output leads labeled (page 29). It sounds like it
might just be a bad gun trigger switch or a problem en route
to the circuit board for same.


I did have the online manual and I went through it AFTER the kid took
the machine home with him. But it sounds to me like the part "fan motor
continues to run" means the fan is running full speed. This fan is
probably not even running at 1/4 speed. It was running so slowly that
we could not hear it until we got our ears down to the rear of the
machine and then it was barely audible. I'm hoping that his next day
off he will bring it back and I can "play" with it more, and then most
likely take it in for service.

Thanks,

Wayne

Having never heard/seen one of these in action before I can
only make some suggestions.

The circuit board schematic is a mystery, sadly Miller
doesn't want to publish that part. It is possible that the
fan motor is designed to ramp-up speed as needed by control
on the circuit board. It may also just hook to the incoming
mains. It is listed in the parts breakdown as 230 volt, so
it may be possible that you aren't getting the full 230
volts to the circuit board. Check that area and make sure
you have 230 volts getting in to the unit (be careful, 230
volts probably won't kill a healthy person, but it ain't no
fun getting zapped) and making it to the PCB. The fan
running at only 1/4 speed kinda points to this area.

If that checks out, make sure the trigger switch on the gun
is actually getting to the PCB too. Just because you can
hear a little clicking noise when you pull it doesn't mean
that it actually makes contact.

If that checks make sure that the thermal protection sensor
coming from the transformer is hooked to the PCB.

If that checks and you want to try messing with it further,
take some GOOD pictures of the PCB and post them someplace
where I/we can look at them. From looking at the block
diagram it (PCB) really doesn't seem to be all that
complicated.

Good luck and let us know how you make out.

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

On Thu, 29 Nov 2007 17:23:20 -0800, NoOne N Particular
wrote:

snip
1. I think the fan is supposed to come on full speed at all times. It
always has before. Hit the switch and the fan comes on and stays on.
Never have heard it run at different speeds.

I tend to agree with your assessment here (fan full speed).
It may just be a bum on/off switch or something keeping the
full 230 volt from reaching the circuit board. When you get
it opened up again carefully measure the voltage and make
sure you have ~230 volts.

If that checks out take a good look at the circuit board and
follow the fan traces back towards the input source and look
for burnt traces or anything else suspicious looking.

The fan on my Millermatic 200 is thermostat controlled and
always starts up kinda pokey when called for. I figure it is
just a lube problem in the fan (worse when it is colder).
Your fan may be okay and have full voltage if you didn't try
running it for very long.

2. The trigger switch on the gun does nothing. No sound at all. No
click, no gas, no nothing. With the exceptions of the fan running at a
very slow speed and a green led on the circuit board, it is as if the
machine isn't plugged in at all.

The manual tells how to change the switch in the gun. Which
makes me a little suspicious that it does fail at times. It
looks like it just plugs in via blade connectors, should be
easy to bypass/check (short the blades together with a
screwdriver .

3. When I had the cover off, I did at least check to make sure
everything was connected. The thermal overload was connected and it was
not tripped. I disconnected all the push-on connectors and re-connected
them a few times just to see if there was some corrosion that may have
prevented one from making a good contact. Did the same for the gun
controls.

I have also read a couple of other forums and one or two people have
alluded to a problem with the circuit boards on some of the early 175's.

I noticed in the manual that they had 3 sets of numbers
referencing the board, so indeed they may well have made
some changes

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email