Hey guys, my NTE semiconductor cross reference(12ed.) gives NTE5466 as the cross for IS68, and lists it as "SCR-600VRM,10A"
It says the pins are KAG from left to right when looking at the markings. It indicates that the case/tab is connected to the anode "A", so that the insulating hardware supplied with the part must be used if subbing in the NTE5466.
Cool Brino, thanks that's good to know. I was hoping they were iso-tab like on the KB unit I have.
The main hangup now is figuring out where the 115v neutral goes on the terminal block. Possibly #1, not sure.
I can tell Phil how to test the semiconductors and replace but he'll smoke 'em unless we know how to hook it up correctly.
Phil: The key to unlocking this puzzle is tracing out the connections to the primary of that little transformer. I see the secondary goes to a bridge rectifier made of separate diodes which powers the low voltage circuits.
I also see one side of the transformer goes to pin 1 of the terminal block. So then does the other side make it's way back to 115 hot/ pin 4 somehow? If so then 1 is neutral, 4 is 115v hot, and the motor would go to 2 and 3. But trace it first to verify. I can't see it that well from the pics.
I know it's tempting but buying electronics without any documentation can be risky. We're getting closer now. It would be helpful if you could shoot a couple more close ups of the bottom of the board. Half the board with one shot and half with the other so I can overlap 'em and get the whole picture so to speak. Do a couple more of the top side too.
Thanks for jumping in here guys! Great notes. Have we taken an ohm meter to the big rectifying diodes yet. As an old EET from the linear days, I cannot tell ya how many of these I replaced. Symptom. Immediate fuse pop upon ac power up. I think I saw a half wave in one of the pics. Looked fuzzy. On a phone now . Willl check later too.
Testing the semiconductors comes later, our first task is to determine without a doubt how the unit should be connected. I'm sure we will find some bad parts too later on.
Waiting on Phil to post some more pictures so we can see the configuration of the SCR bridge.
I know this one needs parts..this is the one I put 115v on terminals 1 &3..melted the solder on loose part..green tint is from foam pad between board and circuit breaker..have 4 more 115v..1 220v and extra 220 board..if these pictures are not what you need let me know..thanks Phil..
Phil: I am fairly certain that 1 is indeed the neutral and 4 is the 115v hot. I'm going to check again tomorrow with my coffee (my best time for thinking).
See if there are any numbers on the orange part between the terminal block and the transformer- not sure what that part is
Ok I see it's a cap, orange white yellow = 394= 0.39 uf
Pick out any Fincor units you have that you think might still be good, check that the SCRs are all "IS68" and if they have insulating mica washers. If they do, you could try hooking one up.
Terminal 2 and 3 are definitely motor wires, Terminal 1 is neutral and 4 is 115v hot I'm certain now.
I see where the field would connect but it's a factory option, not connected on yours.
If you don't see any mica washers at all then those parts may be iso-tabs after all. We can check that with a meter, unsolder one and check for continuity between the tab and the center pin. No continuity means iso, no washer needed
Couple are insulated from ground..the pot case on insulated ones no continuity to ground..non insulated scr pot case is grounded..the scr that fell off board (haha) center pin to outside 2 no continuity .the non insulated scr has continuIty to ground
If the SCRs are damaged the continuity test may be meaningless. Do you want to unsolder and test them all? Or just see if any of the controllers work straight away and fix the broken ones later? Up to you.
Here's what you need to test the SCRs and diodes: You need a 9 to 12 volt dc wall wart or a car battery and a small 12v bulb. Briefly connect the gate to the anode with a wire and the lamp should turn on and stay on until you remove the power.
Use the same jig to test diodes, connect diode to A and C, lamp should light. Turn diode around lamp should not light.
Let me know what you find
Plugged one up.4 hot..1 neutral..turned breaker on..ok...turned switch on. Blew breaker ...gonna try another one..thanks for your time and info..maybe one will power up..then I'll try to test per your posts
Well I tested one scr.wired up a 220v unit to 115..hit breaker on unit..ok..hit run toggle switch..ok..had 55-56 v.putting meter leads on 2 and 3..didn't change with pot..then pow..tripped house breaker.have never Tripped unit breaker..bad scr or was it dumb to hook up to 115..
They may have all been dead before you got them.
Also you should have a motor connected when you power them
Did you say that the SCRs showed continuity from tab to center pin or no continuity?
ps I recommend unsoldering all 5 devices (3 big diodes, 2 scrs) and test them. Do it for all the units you have. You might have enough good parts to make one good controller.
No continuity to center but two outside pins have continuity..the 3 diodes with lines to them let voltage go one direction but not other..will get out the last one and test it per your info..thanks Phil
Incorrect hookup would kill it. Or motor wires coming loose while running. With the unusual terminal numbers I wouldn't be surprised if they got fried before you got them.
Diodes sound ok. The SCRs have to be removed from the board to do a proper test on them using the jig with the power supply and light bulb. Sounds like they are iso-tab types which is good, much easier to install than the non-isolated ones.
The ones that KB uses are iso too, I can get you some part numbers if you need to buy any.
ps make sure the board mounting brackets are not causing a short somewhere
pss the SCRs can fail shorted or open, usually shorted: bulb on (or off) all the time; gate having no effect.
In the process of cleaning out my reloading room so can lay this stuff out and do a proper diagnosis with your help..found a new rolling block stripped action (made in Italy I'm guessing.serial number only) I've been looking for..going to unsolder couple scr and check..Thanks
Have 4 scr off..no tab to center wire contact..on 2 light is same brightness on outside wires when switching power around..on 2 when putting power to 2 outside wires light is dimmer when switching power(positive to negative)
The only control marked with a bad tag works..last one to try..pot doesn't change speed of Baldor gear motor but what the hell..one step at a time..now ready to actually fix one or two or three..whooo hoooo