I have a small wire welder. The machine will work with fluxcore, but does not maintain proper arc with solid/gas. I switch polarities as required for each type. The arc with solid and gas acts like gas is not reaching the weld pool. I know it is though. I'm sure connections are solid throughout the machine. It is electrically quite simple- step down center tap transformer, full wave rectifier, inductor coil to smooth the ripple, wire drive control card for drive motor. It has eight diodes(mounted in two sets of four), and they appear fine outwardly. Checked with ohmeter and found no shorts or opens. ( 7 ohms one direction, infinite the other.) They are mounted on an aluminum heatsink. Swapped for a new gas cylinder with the same results- running 75/25. When I checked all the connections I found no evidence of burns or oxidation on them. It has me dumbfounded and I don't really want to buy a new rectifier assembly, then discover it still doesn't work. It was working fine before. Also the diodes have no identification marks or numbers on them. Although the machine has never thermally shut off, it does have a low duty cycle. Perhaps I pushed it a bit too far.
Bzzzzzzz
This looks like deja-vu all over again. How far can you go and remain cost-effective?
Is this a training project? If so, reference to welding power supply design texts would be appropriate... probably through college libraries but some public systems integrate many catalogs electronically over the internet. An instructor and formal training is really the appropriate course of actiion.
You can "reverse engineer" the diodes if you know what kind of power they have to handle and provide ample excess for safety.
I have seen different type diodes fail. I have never seen them intermittant. I dont work on this kind of equipment so I would not be surprised to have my experience disputed. What you need is the appropriate TESTING PROCEDURES for the circuitry with which you are dealing.
The shortest route to swift conclusion is to spend energy on finding a repair shop that will guarantee their work and provide an estimate before repair, and let them troubleshoot to find your problem. CAVEAT EMPTOR; buyer beware, so protect yourself from the unforseen.
Good luck
d
At the risk of being too simplistic here: I'd try smaller diameter solid wire or else bite the bullet and buy a bigger machine.
My thought here is that you are probably running the same wire size for both your flux-cored and the solid. I believe the flux cored will require less power to run that solid wire will for equal diameters. The fact that your machine will run one but not the other suggests that you are at the upper limit with FCAW and will probably burn out something soon. It sounds like you are having fun and learning as you go- nothing wrong with that- but a machine suited for what you need it to do would be even more fun. (No, I'm not in the sales business, just have broken a few machines myself)
CHGuilford
Do you have the model number of the little beast? Preferably century's.
Do the devices we are referring to as diodes have one or two connections at the top?
Bill
Forum
