Need help with Snap-On YA-205 MIG

[redhighrider]

I've searched the web and can't seem to find much information on this MIG, it's a Snap-On YA-205. Snap-On shows it on their website but information the information they have on it is a 1-page exploded view that doesn't even identify the parts. I bought the unit used a couple years ago and it worked great the first couple times I used it. I tried to fire it up this weekend but no dice. The power light comes on but when I pull the trigger, no gas or wire feed.

I tore off the top cover to expose the guts inside and found a large mouse nest on top of the circuit board. Some of the wiring had the insulation eaten off. I replaced all the damaged wiring and cleaned off the board the best I could but still, the light comes on but no gas/wire feed. There are no solenoids or relays clicking, nothing.

There is a relay inside the case, is it likely this could be the culprit or is it more likely a circuit board issue? A transformer maybe? Any help would be greatly appreciated.

[awright]

It would help a lot if you could post several high-quality, sharp, close-up photos of the circuit board and any information you may have on the unit.

Do you have a VOM/Digital Multimeter and enough knowlege to make requested measurements on the board? Can you recognize resistors, capacitors, transistors, integrated circuits? Are you confident that you can make measurements inside an energized welder safely? There are lethal voltages inside an energized welder and it only takes one careless move to kill yourself.

It's fun, but often frustrating to try to troubleshoot circuit board problems by remote control, but remember that there are welder repair shops out there that can probably find and repair your problem much quicker than we might over the internet.

Good luck.

awright

[Sandy]

I tore off the top cover to expose the guts inside and found a large mouse nest on top of the circuit board. Some of the wiring had the insulation eaten off. I replaced all the damaged wiring and cleaned off the board the best I could but still, the light comes on but no gas/wire feed. There are no solenoids or relays clicking, nothing.

Not to forecast doom and gloom, but there isn't anything much more shagnasty than mouse/rat pee on precious metals. When I say precious metals I mean the components and traces----all the conducting metals.

Hopefully not, but this could be like pepsi on a keyboard. A one time shot.

Keep looking tho. Could be more chewed stuff than is easy to spot right away.

Take a look at that "relay", it's probably the gas solenoid or the slave relay that pulls to shoot the juice to the solenoid. See if you can read the voltage required on either one.

[redhighrider]

Do you have a VOM/Digital Multimeter and enough knowlege to make requested measurements on the board? Can you recognize resistors, capacitors, transistors, integrated circuits? Are you confident that you can make measurements inside an energized welder safely? There are lethal voltages inside an energized welder and it only takes one careless move to kill yourself.awright

I'm no stranger to a VOM and can navigate my way around a circuit board. This unit is from the early `80's and the circuit board is pretty basic compared to today's stuff. I'll borrow a VOM from work as my brother still has my Fluke and he's out of town. No problem recognizing various electrical components - I'm a Mechanical Engineer but do have some electrical background.

As for taking measurements inside an energized welder, it's only 220, right? ;) I'm jesting there, I'll be careful...

Anyhow, here's some pics of the guts. The following images are after repairing the wiring.

http://i49.photobucket.com/albums/f299/obkb2006/IM001933.jpg
http://i49.photobucket.com/albums/f299/obkb2006/IM001942.jpg
http://i49.photobucket.com/albums/f299/obkb2006/IM001941.jpg
http://i49.photobucket.com/albums/f299/obkb2006/IM001940.jpg
http://i49.photobucket.com/albums/f299/obkb2006/IM001939.jpg
http://i49.photobucket.com/albums/f299/obkb2006/IM001934.jpg

The welder is sitting as you see it in the above pictures. I can tear it apart and take additional and better close-ups as you desire. The back side of the circuit board looked clean when I had it out to clean it off this past weekend. There were no burn marks, discoloration, bubbling or broken circuit traces that I noticed.

[awright]

Nice photos. Ugh! Hope you took no offense at my questions. Just getting a little info about what resources are available at the other end of the link.

Have you e-mailed AND phoned Snap-On service with your model and serial number and an explanation of the situation with a request for a schematic and request for a quote on the cost of a replacement circuit board? That's the first resource to exhaust before trying to trouble-shoot the board blindly.

The second thing to do is to remove the board from the machine and give it a thorough bath and scrubbing with a strong cleaning agent and tooth brush or scrub brush followed by thorough blowing off with air from an oil-less air compressor or, less effectively, a vacuum cleaner blower and final drying under an infrared lamp a couple of feet away or a low-temperature ELECTRIC oven. Give it a couple of days to thoroughly dry out.

The oscilloscope manufacturer, Tektronix recommended a bath for it's old products as a first step in restoration back in the late tube days. Most components today are pretty tolerant of water with the exception of relays, fan motors, coils and transformers, and components with empty cavities like potentiometers. Even they are tolerant if you are careful to thoroughly rinse and dry them internally. It is a very good idea to do a final rinse with a gallon of distilled water from the market after a thorough tap water rinse. This assures that there is minimal potentially conductive residue left on the board from hard water. You are likely to lose paper labels in this process, so make good notes. Put a drop of oil on any moving parts like potentiometer shafts after the bath.

Coils and transformers are problematical in that the paper insulating the windings can become saturated and it may be very difficult to get all detergent residue rinsed out and the moisture dried out. It's a good idea to remove any coils and transformers from a board to be washed, being sure to make careful notations of lead orientation.

The purpose of washing the board is to stop any continuing corrosion and eliminate surface leakage due to pee. Might help, and also makes it easier to inspect the board.

Inspect each joint and trace with a magnifying glass under good light. Look for corrosion or any sign of absence of a clean fillet of solder between traces and component leads. Doesn't hurt to resolder each solder junction, being sure to observe that the lead is wetted by the solder as indicated by a clean fillet of solder between the trace and the component lead. It can be helpful to use a high quality ELECTRONIC GRADE, ACTIVATED ROSIN solder flux from, for example, Kester on each joint as you reheat it. Check with your electronics supplier.

While you have the board out of the machine, check all components that can readily be tested without damaging the board. Unskilled component removal can be damaging to the board in itself if traces are overheated and loosened while you try to work a component lead out of the hole. It is often better for the board to cut a lead to a component, test the component and reconnect the tested or replaced component by soldering to the old lead sticking up from the board. Use a short link of tinned bus wire if necessary.

Electrolytic capacitors can be roughly tested with the ohmmeter function of your VOM. Short the capacitor with a clip lead and remove the clip lead. Apply the ohmmeter test leads to the capacitor, positive lead to the positive end. The meter should dip toward zero ohms and climb back to a very high reading as the ohmmeter battery charges the capacitor. Use a middle high range of the ohmmeter. An open capacitor causes no reaction on the meter. A shorted capacitor causes the meter to go to zero and stay there.

Continuity through connectors can be a major problem when corrosive agents have been present. Test each lead through its connector with an ohmmeter with clip leads. Wiggle the connector as you test each lead to see of you get any intermittancy. If you do, it might be a good idea to simply replace the connector.

Since you comment that there is no gas OR wire feed, the problem could be an absence of accessory power or it could be some interlock that is not engaging. Check for any indication of whether the gas solenoid operates on DC or AC. The wire drive motor undoubtedly is DC driven. Trace back from the wire drive motor or a DC operated gas valve to the controller and from there to the DC power supply. Measure for the presence of DC power on the storage capacitor of the power supply. If not present, look for the rectifier bridge (four diodes) feeding the storage capacitor and see if AC is present at the bridge input. If AC is present but there is no DC on the storage capacitor, one or more of the bridge rectifiers is probably blown. Check for any relays or contactors between the rectifier bridge and the transformer feeding the bridge and check for closing.

I see what looks like a 240 volt, 40 amp SSR (Solid State Relay) in your photos. That would appear to be your main "contactor" supplying power to the transformer. Is it supplying power when requested? If not, is it getting a drive signal? Is your gun trigger contacting when you pull the trigger? Is the relay or transistor it controls closing? Is there control voltage (probably 24 VDC) across the trigger contacts before pulling the trigger?

The absence of relay clicking (assuming there are electromechanical relays present) tends to indicate that the accessory power supply is absent or the gun trigger circuit is not contacting. This will have to be traced out.

That ought to keep you busy for a while. I think the board wash is a very good measure even if you solve the problem first, since corrosion is a primary cause of failure over time.

Have fun, and be careful.

awright

[redhighrider]

WOW! Thank you very much. My brother that has my Fluke is out of town so I'll have to borrow one from work. I am going to trace this out this weekend; I don't like starting on a project like this and giving it 45 minutes here and a half hour there. I'll wait until Saturday when I can give it some prolonged attention.

No offense taken to your post, sorry if I came across a little brash. I forgot to mention in my previous posts that I can get the wire feed to work using the "FEED" button on the front of the unit. There is also a "PURGE" button to get air out of the gas line but that doesn't make gas flow when pushed...

Under normal circumstances, I don't think the wire feed trips a relay when the FEED button is pressed. I know the PURGE button trips a relay that opens the gas valve - that's why I am thinking (and hoping) it is the relay that is the culprit. Where can I get a SSR like this? Are they standard fare at most welding shops (there's several shops near where I work), should I check Radio Shack or other?

I have not contacted Snap On about this issue, but I have checked their website and searched the web for information on the YA-205. It appears the only service part Snap On offers currently for the YA-205 is a "drive transformer" http://buy1.snapon.com/catalog/parts/pro_det.asp?Item_id=44020&group_id=10878.

Once again, thank you VERY MUCH for your input and I will post an update after I tear into this project this Saturday. If anything else pops into mind that I should evaluate, please let me know.

[awright]

I reiterate: Calling Snap-On Service is your absolute first and best resource to tap. I don't have any Snap-On products, but they have one of the best reputations for standing behind their products and you may be surprised at what they can and are willing to do to help you. If it is a dead end, you haven't lost anything except a little time on the phone. If they can provide a schematic, parts, or advice, you are WAY ahead of where you sit now.

I wouldn't rush out to replace the SSR until you have proven that it is defective by testing it. If it needs replacement, I would not buy it from Snap-on or a welding supply. These are common items on the surplus market and can be had for, maybe $15 or $20. Let me know if it tests bad or, if you have any electronic surplus stores in your area, check them out. You must be sure that the voltage (240VAC), the current (40 amps), AND THE ACTUATION VOLTAGE AND CURRENT match the original. Often the actuation voltage is shown on the label near the control terminals. It can be anywhere from 5 VDC to 115 VAC.

Does your machine provide post-flow? If so, there is probably a "time delay on opening" timing relay that controls the gas valve present somewhere. These can also be expensive, new, but are sometimes available on the surplus market.

The fact that you can jog your wire feed motor indicates that it is OK and its power supply is OK. In the absence of a schematic or your tracing it out, we don't know if the wire feed motor power supply is the same as the gas valve power supply. Ability to jog the motor shifts suspicion to the gun trigger circuit. Check if the gun trigger closes its contacts at the gun interface with the welder. You could try activating the wire feed and gas valve by shorting the pins to and from the trigger switch on the gun. This would isolate the problem to the gun or to the welder.

Here again, the fact that your purge button doesn't activate the gas valve can easily be traced (conceptually, at least - possibly not physically).First check if AC or DC voltage is present across the purge button switch while it is not pushed. If so, does it fall to zero when the putton is pushed? If so, the switch is OK and you have to look downstream for the problem. If not, the switch is defective and must be replaced.

How about posting the specs on your welder? It would help to know something about its input and output voltage and current range and the type of technology utilized.

I look forward to hearing about the results of your tests.

All for now.

awright