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Induction brass annealer redux

hello guys

i,m building and inductor base on you design with a slit difference power supply is 24 volts 20 amps , i,m not and eletronic guru can not find varistor 130 vac from jameco it not avalable any more , my question can i replace 34462 varistor 130 vac by v 130 la20ap LA serie from littlefuse mouser or and other varistor would be more appropriate for this build . thank you
Yes....Only if your your house hold voltage is 110/120 VAC. If 220 VAC you will need a higher voltage varistor
Gina
 
Been reading and watching this post for the last week or so......this is an awesome thread! Ordering my supplies withing the next couple of weeks. Gonna build mine in an ventilated electronic project box or reuse an old computer tower. I'll build it first, tweak and change things I want and then make a feeder system controlled by an Ardiuno. :)

Jthor, your not the first. A couple of guys, already did that with Ardiuno. Check back a couple of pages on this thread. PM them, I'm sure they could give you a couple of pointers.
Gina
 
Hi Folks,

I recently finished the build and everything worked great the first time trying. I was elated and after a few months my unit suddenly stopped working. I was running the unit at around 43 volts. Now, if I try to run the unit, the current reads around 6V and the current draw around 30 amps. The transistors on the induction board (with the pre-installed heat sinks) start getting hot instead of the region under the capacitors (when it was running correctly). The only thing I did was replace the voltage/current meter because the old one has a defective blown out digit. I pulled the connectors from back of the old meter and plugged them into the new one and now the unit won't run. I'm almost going to dis-assemble everything and re-assemble it all again. I previously checked and re-checked all the wiring.
Any ideas?
 
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Hi Folks,

I recently finished the build and everything worked great the first time trying. I was elated and after a few months my unit suddenly stopped working. I was running the unit at around 43 volts. Now, if I try to run the unit, the current reads around 6V and the current draw around 30 amps. The transistors on the induction board (with the pre-installed heat sinks) start getting hot instead of the region under the capacitors (when it was running correctly). The only thing I did was replace the voltage/current meter because the old one has a defective blown out digit. I pulled the connectors from back of the old meter and plugged them into the new one and now the unit won't run. I'm almost going to dis-assemble everything and re-assemble it all again. I previously checked and re-checked all the wiring.
Any ideas?

Just for the heck of it, try putting the old volt/amp meter back in, see what happens. If it works you may have a defective meter. Recheck the shunt wiring. Everything was working up until that point... So what changed ?? Sure sounds like you have a short circuit some place.
Keep in touch

Gina
 
Thanks, I tried switching back to the old meter with the same result, low voltage, high current. I was guessing the shunt wiring was bad, also and rewired it and same result again. The induction board looks OK so I hope the semiconductors on them are not destroyed.
 
Thanks, I tried switching back to the old meter with the same result, low voltage, high current. I was guessing the shunt wiring was bad, also and rewired it and same result again. The induction board looks OK so I hope the semiconductors on them are not destroyed.

One quick check... Disconnect one power wire (+) from the inductor PCB. Power on, if the voltage comes up to 43 volts, then it would look like your PCB is shot.
One other thing, look maybe some parts or coils of your inductor coil are touching or shorted out.
Gina
 
@GrocMax - I decided to go w/ the RSP-750-48 power supply to implement the current control feature. Just curious - how'd you physically wire yours? Seems like it'd be dodgy to cut/splice the jumper between pins 7 & 8.
 
One quick check... Disconnect one power wire (+) from the inductor PCB. Power on, if the voltage comes up to 43 volts, then it would look like your PCB is shot.
One other thing, look maybe some parts or coils of your inductor coil are touching or shorted out.
Gina
Thanks,
Yes, I tried that also and the voltage is at the 43 volts. Only when hooked up to the induction board do things go wrong. It does seem like the board is shot. I tried a new board I ordered and the same result. High current, low volts, warm semiconductors on the induction board. Two bad boards back to back? The coils are separated by wraps of nylon thread to prevent shorts, although it ran when I did have shorts. Just no heat to brass. It did run for a couple months but I feel like I got to date a dream girl for a few months and now the good times are gone. I'm going to tear the whole machine down and re-wire it again without voltage control variation to see if it works over the next month. Any new ideas before then are welcome. Thanks for the suggestions, nevertheless.
 
@GrocMax - I decided to go w/ the RSP-750-48 power supply to implement the current control feature. Just curious - how'd you physically wire yours? Seems like it'd be dodgy to cut/splice the jumper between pins 7 & 8.

Purchased another connector body and terminals for the jumper pins. Full schematic is somewhere between pg 18 and 22 of thread.
 
Thanks,
Yes, I tried that also and the voltage is at the 43 volts. Only when hooked up to the induction board do things go wrong. It does seem like the board is shot. I tried a new board I ordered and the same result. High current, low volts, warm semiconductors on the induction board. Two bad boards back to back? The coils are separated by wraps of nylon thread to prevent shorts, although it ran when I did have shorts. Just no heat to brass. It did run for a couple months but I feel like I got to date a dream girl for a few months and now the good times are gone. I'm going to tear the whole machine down and re-wire it again without voltage control variation to see if it works over the next month. Any new ideas before then are welcome. Thanks for the suggestions, nevertheless.

Wish I could help. So your build was a "constant current" design. The one that GrocMax designed ? He might have more insight into whats going on with your annealer and some ways to trouble shoot it. Try PM'ing him for advice.
Good luck
Gina
 

Yup. A std universal B crimp tool with some smaller dies for smaller terminals (such as D-sub) works.

You could cut the loop and solder the tails or crimp splice as well.
 
Thanks,
Yes, I tried that also and the voltage is at the 43 volts. Only when hooked up to the induction board do things go wrong. It does seem like the board is shot. I tried a new board I ordered and the same result. High current, low volts, warm semiconductors on the induction board. Two bad boards back to back? The coils are separated by wraps of nylon thread to prevent shorts, although it ran when I did have shorts. Just no heat to brass. It did run for a couple months but I feel like I got to date a dream girl for a few months and now the good times are gone. I'm going to tear the whole machine down and re-wire it again without voltage control variation to see if it works over the next month. Any new ideas before then are welcome. Thanks for the suggestions, nevertheless.

It sounds like the tank circuit is not firing off and resonating. Does your PS have protections it might be tripping? Has anything changed in the way the induction board is switched on/off? (SSR, contactor or relay wiring)
 
I'm actually running the Meanwell RSP-1000-48 without current limiting. I had it handy so I used it.
I tried again tonight to disconnect the power output to the board and run it into an incandescent light bulb. The voltage is stable with little current. It all worked the first time I powered it up a two months ago. Then I exchanged volt/current meters by unplugging the connector and reconnecting it (simple) and it stopped working. I switched back volt/current meters and same result. I must have knocked something loose or shorted something out. If I disconnect the leads to the board and connect them to a voltmeter, I get 39 -44 volts (depending upon my control resistor setting) after the Packard relay trips(no load). My suspicion is the wiring going to the voltage control portion of the power supply is at fault. It is a different connection arrangement than the RSP-750. It has only 12 leads. I may need to probe all of them and see what is wrong.
I put a lot of sweat labor into preparing the induction board by bonding in heavy duty heat sinks with thermal epoxy. I may just remove the MOS FETs test them and replace them rather than buy a new board.
 
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Yup. A std universal B crimp tool with some smaller dies for smaller terminals (such as D-sub) works.

Perfect - thanks, man.

You could cut the loop and solder the tails or crimp splice as well.

Yeah, that's true - there's not much wire to work with in the loop for my fat fingers, though - and there's a lot to be said for keeping that connector as is as a troubleshooting tool in case I botch something up. But, if I couldn't get ahold of a connector and pins, or something, that'd be the way I'd have to go.
 

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