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Small DC TIG welder remote switch needed

Clambake

Mar 8, 2016
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BTW have you ever caught the fan NOT running, I would sort of expect it to run at all times that the unit is plugged in.

Edd

Another time the fan stops running is during a stuck electrode condition. Could it be the blue relay's coil is taking power away from the fan?
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
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Edd

Another time the fan stops running is during a stuck electrode condition. Could it be the blue relay's coil is taking power away from the fan?
EEK! :eek: That's the absolute worst time I can imagine for it to shut down! That alone would be a damn good reason to replace that thing with a 120V box fan. This way it can be wired to the power cord. Then you'd be good to go with your switch wired in series with the Pot's switch. They're not expensive.

Here's another option. Since that little fan's power demand is quite minimal you could power it from a very small wall wart. Especially small if it a SM model. You may be able to stuff it inside the case. They can also be Dremel'd open and guts removed for even smaller footprint.

Chris
 

73's de Edd

Aug 21, 2015
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Sir Clambake. . . . . . .


Since you now can find the relay coil connections with my info, do that tack soldering and remoting out two wires to be able to monitor
the relays voltage in different conditions and thereby, be able to associate "cause and effect".
That resultant end info will let us see what needs to be done to involve the relay.

Fill me in on the two front panel LEDS
I am sure that the top LED is power indication and will be on any time the AC plug is plugged into power.
And that it is being fed by a minor "stand by" power supply.

BUT . . .as for that "YELLOW" LED under it, at what times does it come on ?

ASIDE:
Sir Ceeeeeedrive:
The "onliest " thing that I remember about Get Smart and Agent Maxwell Smart was his "shoe phone" and that lilliputian sized
foreign sports car that he crammed himself into.



73's de Edd

.
 

Clambake

Mar 8, 2016
39
Joined
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Messages
39
.



Sir Clambake. . . . . . .


Since you now can find the relay coil connections with my info, do that tack soldering and remoting out two wires to be able to monitor
the relays voltage in different conditions and thereby, be able to associate "cause and effect".
That resultant end info will let us see what needs to be done to involve the relay.

Fill me in on the two front panel LEDS
I am sure that the top LED is power indication and will be on any time the AC plug is plugged into power.
And that it is being fed by a minor "stand by" power supply.

BUT . . .as for that "YELLOW" LED under it, at what times does it come on ?

ASIDE:
Sir Ceeeeeedrive:
The "onliest " thing that I remember about Get Smart and Agent Maxwell Smart was his "shoe phone" and that lilliputian sized
foreign sports car that he crammed himself into.



73's de Edd

.

Edd-

I'll run that coil test during lunch today.

The green led is only on when the unit is switched "on" using the control pot. The yellow led is supposed to come on during an overheat condition, but I've never overheated it to see it happen -I'll be sure to observe if it comes on in a "stuck electrode" condition. I'm guessing it'll "pulse" along with the torch current -we'll see.


Thanks again Edd for your help!
 

Clambake

Mar 8, 2016
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Since you now can find the relay coil connections with my info, do that tack soldering and remoting out two wires to be able to monitor

Ok I did that test Edd

I got 25VDC as soon as the unit was plugged in -and I can hear the relay trip when plugged in. When the control pot is turned on, the fan and grern led come on and the reading goes down slightly to ~24.6VDC. I tried simulating a "stuck electrode" and the reading remained the same.

By the way -turns out the relay is oriented horizontally. "A1" and "A2" marked on the photo on page 3 are actually the coil pins. "C1" and "C2" are a small cap
 
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73's de Edd

Aug 21, 2015
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Sir Clambake. . . . . . .

" By the way -turns out the relay is oriented horizontally. "A1" and "A2" marked on the photo on page 3 are actually the coil pins. "C1" and "C2" are a small cap. "


Go ye now and VEWY-VEWY-VEWY carefully inspect that relay again,. both referencing to the PCB and the actual engineering drawings and photos of the
most honnable Song Le unit, that is being used in your unit.
By the terminal layout of 6 contacts , some can be clipped to have the three connections of a SPDT relay available on EITHER side of the case, as an option.
In your case, they chose to use the terminals that I have circled in PINK. and not be using the YELLOW X marked terminals.
Also in referencing to the GREEN squares, they bring up AND USE ROUND wires for the two coil connections, whereas the active relay contacts are mini rectangular terminals.

Song Le relay:

NKN7PSi.png










As was mentioned earlier:

There is a fixed foil path from the C1 coil land up to the A1 (normally closed) relay contact foils land.
Also, there is zig zag fixed foil path from the C2 coil up to the A2 (normally open) relay contacts foil land .
Assuredly those paths are making you think differently as to the actual coil connections .
Soooooooo . . . if you can confirm that C1 is being negative polarity while C2 is being the + 24 polariy, it just looks that the common AC contact is just getting a ground, when normally inactivated,
While it receives a +24 when the relay coil is activated.

Can you identify my nearby mystery FUCHSIA ? part yet ?

Look at the blue relay case and I have YELLOW highlighted the "TV-5" and that is what I usually call this relay . . .it has s been EXTENSIVELY used . . . . . for at least 30+ years


Post #57 Photo Referencing:

eFZupjY.jpg










" the coil pins. "C1" and "C2" are a small cap. "


Look at the YELLOW line that I used to connect the relay photo to its YELLOW rectangular case profile on the PCB, now just above that interconnecting line there is a 100 ohm SM resistor, and that
electrolytic cap at the SIDE OF THE RELAY, looks to be connecting across it at that point.


73's de Edd

.
 
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Clambake

Mar 8, 2016
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Hi Edd

So I've mapped out the area in question. I mirrored the pcb backside photo horizontally to make it easier to compare to the components on the frontside. You'll notice I color coded the componants with dots reflecting the colored regions they occupy on the backside. I also added a photo of that component you highlighted in Fuchsia earlier (says M7), and how it's oriented with the relay on the other side.

Oh and that green toroid (turquise) has two wires wrapped around it, each going half way around it
 

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