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  #231  
Old 03-06-2009, 09:21 AM
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terry lingle terry lingle is offline
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No it is not great news it means that the information Gwiz wants will not be had this way .
Given that the drive sections did not run the voltage differences are not important.
The question is why did they not run.
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  #232  
Old 03-06-2009, 08:35 PM
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I am actually taking this reading on either side of the 2 watt resistor...correct?
You would be measuring the voltage across the 2 watt resistor. then Yes.
I was expecting too see the voltage in the hundreds.

That's so far off it does not seem possible. more like you got the wrong connections.
___

This test should verify that you got the right AC wires from the transformer to the bread board..

Its best too measure for a voltage before measuring resistance across anything.
Do not power up the welder.
This part is just a precaution. take your meter and check for a DC voltage across the AC wires going to the bridges SR2 and SR3 on the bread board.

Assuming there's no voltage.
Check the resistance across each AC set of wires that go to SR2 and then SR3 on the bread board.
In your post 179, you said the resistance of the transformer was 0.1 ohm.
I expect you will get the same reading, also reverse your leads and check it again.
You should get a solid reading. if it takes a while like a capacitor charging let me know.

Also check the diodes. maybe e-Bay has a bad run on them.

Let me know what resistance reading you get.
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  #233  
Old 03-07-2009, 07:28 PM
VW cat VW cat is offline
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GWIZ/Terry,
I checked for DC voltage across the AC wires going to SR2 and SR3. No voltage indicated. I checked the resistance across the AC wires at SR2 and SR3. Resistance is .2 ohms dropping to .0 ohms after 10 seconds or so. Reversing the leads, resistance starts at .3 ohms and drops to .1 ohms after 10 seconds. Both SR2 and SR3 have the same resistance readings. I was trying to be detailed here in case there was any relevance, my meter sometimes hops back and forth between 2 consecutive numbers.

All 8 diodes check out okay with the reading around .427.

I checked the wiring, specifically where my black AC leads from the 'breadboard' are going. They connect to the 2 pairs of unmarked wires, that originally were connected opposite lead #101 and #24 on SR3; and #92 and #93 on SR2.

Tracing leads #101 and #24 each connect to copper bars, which in turn connect a bank of capacitors on the right(passenger) side of the machine. Leads #92 and #93 each connect to copper bars, which in turn connect a bank of capacitors on the left(drivers) side of the machine. Although #92 & #93 weren't visibly traced, they are numbered at each end. Leads #101 and #92 originally connected to the beveled corner terminal of SR2 and SR3 respectively.

The last bridge rectifier failure left a gouge on the heat sink behind it. Metal must of vaporized. Phil
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  #234  
Old 03-07-2009, 09:36 PM
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Originally Posted by VW cat View Post
GWIZ/Terry,
I checked for DC voltage across the AC wires going to SR2 and SR3. No voltage indicated. I checked the resistance across the AC wires at SR2 and SR3. Resistance is .2 ohms dropping to .0 ohms after 10 seconds or so. Reversing the leads, resistance starts at .3 ohms and drops to .1 ohms after 10 seconds. Both SR2 and SR3 have the same resistance readings. I was trying to be detailed here in case there was any relevance, my meter sometimes hops back and forth between 2 consecutive numbers.

All 8 diodes check out okay with the reading around .427.

I checked the wiring, specifically where my black AC leads from the 'breadboard' are going. They connect to the 2 pairs of unmarked wires, that originally were connected opposite lead #101 and #24 on SR3; and #92 and #93 on SR2.

Tracing leads #101 and #24 each connect to copper bars, which in turn connect a bank of capacitors on the right(passenger) side of the machine. Leads #92 and #93 each connect to copper bars, which in turn connect a bank of capacitors on the left(drivers) side of the machine. Although #92 & #93 weren't visibly traced, they are numbered at each end. Leads #101 and #92 originally connected to the beveled corner terminal of SR2 and SR3 respectively.

The last bridge rectifier failure left a gouge on the heat sink behind it. Metal must of vaporized. Phil
It is a welder it is supossed to vaporize metal

Be very careful around those leads from the caps. Those caps are loaded by the input line.
Your ohms tests indicate that you have it wired correctly.

Gwiz can you see any way that control board can detect that the bridges are not connected except by the load on the transformer ?
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  #235  
Old 03-09-2009, 03:15 AM
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Originally Posted by terry lingle View Post
Gwiz can you see any way that control board can detect that the bridges are not connected except by the load on the transformer ?
No.
But there's some wires from the capacitors that feed back through some resistors then to the main board.
the main board may be sampling the 330 vdc.
We know if the fuse for the 330 vdc is open the fans will not power up. maybe auto shut down if the 330 is not present.

___

VW,
Lets try this.
Back to post # 226.
Do test 1d and 2d.
Also measure the output voltage at the welding lugs. (that was about 70 volts DC).

Just a note. you may still blow the breaker after 10 minutes.

Maybe the added load will bring up the DC output voltages on the bridges.
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  #236  
Old 03-09-2009, 05:42 PM
VW cat VW cat is offline
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GWIZ/Terry,
Test 1d: same results.

Test 2D: Connecting the 200 watt resistor, powering the machine back up and turning the contactor switch to 'on', I noticed a high pitched whine somewhere in the machine. I got a reading of 129VDC across the 2 watt resistor(SR2) and a check of the clamp meter showed 2.8 amps AC. Voltage across SR3 was 1.5 VDC, then smoke started coming up from either the diodes or the resistor on SR3, wasn't sure so as I reached for the off switch I heard a 'big bang'. I shut the machine off and noticed smoke from under the main control board, and a burnt smell. After turning the main breaker off I let the machine rest for a few hours(myself included). After checking for voltage on the upper capacitor bank(2), I used welding gloves to lift the control board up a few inches at the back and take a look. Pic attached.Phil
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  #237  
Old 03-09-2009, 06:35 PM
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Whitetrash Whitetrash is offline
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I've been following this thread for quite awhile and I am truly impressed with all of you for your persistence, patience, and methodical effort to troubleshoot this machine. i figured out early on GWIZ is short for "Genuine Wizard" the same goes for Terry to be able to devise test after test to remotely troubleshoot this machine. Even if you don't succeed in the end you can't say it's for lack of trying. VW I think you could make a Pitbull give up.
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  #238  
Old 03-09-2009, 09:25 PM
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Originally Posted by VW cat View Post
GWIZ/Terry,
Test 1d: same results.

Test 2D: Connecting the 200 watt resistor, powering the machine back up and turning the contactor switch to 'on', I noticed a high pitched whine somewhere in the machine. I got a reading of 129VDC across the 2 watt resistor(SR2) and a check of the clamp meter showed 2.8 amps AC. Voltage across SR3 was 1.5 VDC, then smoke started coming up from either the diodes or the resistor on SR3, wasn't sure so as I reached for the off switch I heard a 'big bang'. I shut the machine off and noticed smoke from under the main control board, and a burnt smell. After turning the main breaker off I let the machine rest for a few hours(myself included). After checking for voltage on the upper capacitor bank(2), I used welding gloves to lift the control board up a few inches at the back and take a look. Pic attached.Phil
Ouch Phil that is not good it put us back at about post 1
With no understanding of when or why that IGBT blew ( we know when it became visible ).

This probably means 4 more IGBT's with no assurance we will not get a repeat.

For what it is worth check the diodes in SR3 I suspect you will find one or more bad . If not then the side driving SR3 was not running . If it is the side driven by the blown IGBT it was bad from the start of this test.
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  #239  
Old 03-10-2009, 06:13 PM
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Originally Posted by Whitetrash View Post
I've been following this thread for quite awhile and I am truly impressed with all of you for your persistence, patience, and methodical effort to troubleshoot this machine. i figured out early on GWIZ is short for "Genuine Wizard" the same goes for Terry to be able to devise test after test to remotely troubleshoot this machine. Even if you don't succeed in the end you can't say it's for lack of trying. VW I think you could make a Pitbull give up.
Thank you. sometimes the road trip is more entertaining and educational then the destination.
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  #240  
Old 03-10-2009, 06:16 PM
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Originally Posted by terry lingle View Post
Ouch Phil that is not good it put us back at about post 1
With no understanding of when or why that IGBT blew ( we know when it became visible ).

This probably means 4 more IGBT's with no assurance we will not get a repeat.

For what it is worth check the diodes in SR3 I suspect you will find one or more bad . If not then the side driving SR3 was not running . If it is the side driven by the blown IGBT it was bad from the start of this test.

It's pretty much game over.

I'm still thinking.
as Terry asked check the diodes SR2, SR3 and the 2 watt resistors.

let me know how they check.
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