Guest TheButcher69 Posted February 21, 2015 Report Share Posted February 21, 2015 I have a Dayton 5amp Speed Control that the Rectifier shorted between the cathode & anode. The part # is: 66497 RCA Date code C-7613. I've called & searched everywhere & no one has any info. I've tried to replace it with: "S8040R-ND" & "S4010LS2-ND" but on variable speed the motor just hums. Any help would be appreciate! Here are some pictures. Quote Link to comment Share on other sites More sharing options...
Guest TheButcher69 Posted February 21, 2015 Report Share Posted February 21, 2015 Here's another picture Quote Link to comment Share on other sites More sharing options...
Hero999 Posted February 21, 2015 Report Share Posted February 21, 2015 Are you sure it isn't just the TRIAC? Perhaps the motor has failed? Quote Link to comment Share on other sites More sharing options...
Guest TheButcher69 Posted February 21, 2015 Report Share Posted February 21, 2015 No I'm not sure at all. I was just going by a Digikey rep. & Dayton/Grainger rep said about it not being a triac but I'm having second thoughts that these guys are wrong because on another forum someone said the same thing as you & I tried 2 SCR's both did the same thing. The other person on the other forum suggested doubling the voltage & going off of the motor draw & try a random triac & will be using this on different motors such as a bench grinder dremmel ect. I'm in the USA so voltage would be 110v & the circuit is rated for 5amp so I was thinking anything at 240v to 400v & atleast 10amps in a triac. Would my thoughts be correct? Quote Link to comment Share on other sites More sharing options...
Hero999 Posted February 21, 2015 Report Share Posted February 21, 2015 Sorry I meant SCR not TRIAC.It's difficult to know without a schematic.How is this implemented? Is it a universal motor run off rectified mains? Quote Link to comment Share on other sites More sharing options...
Guest TheButcher69 Posted February 22, 2015 Report Share Posted February 22, 2015 The unit plugs into a 110 outlet & then any 110 device plugs into it. There is a rocker switch "Off" in the middle" right "Full" speed left "Variable" On the inside there is a 1k 1/2 watt resistor attach to the switch which runs to the "cathode" & attaches to the "Gate" a "Diode" then connect to the "Gate" & runs to the "Wiper" on the pot. The right end of the pot connects other "Diode" & runs to the top pots "Wiper" & finally the top pots right end connects the "Neutral" AC wires that run from the cord of the unit & runs to the receptacle of the unit. The "Black" wires run to the switch & the fuse & receptacle.There is another 4k resistor that runs from the switch to the "anode" & then runs to the pots left end Here is a picture of the outside & inside of the unit. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted February 22, 2015 Report Share Posted February 22, 2015 Are you sure it isn't a TRIAC?Have you traced the whole schematic and drawn it? Quote Link to comment Share on other sites More sharing options...
Guest TheButcher69 Posted February 22, 2015 Report Share Posted February 22, 2015 I'm really not sure it's not a triac. I'm only going by digi-key rep & a guy on youtube. They said the K A G represent an SCR. I have limited knowledge. I know a triac is basically 2 SCR's put together that allow current to flow each way. But I don't know how to test for a bad one. I know I had resistances between the cathode & gate & a short between the cathode & anode & I think there was resistance between the anode & gate but I can't say for sure I'd had to retest it. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted February 22, 2015 Report Share Posted February 22, 2015 Yes K, A G does normally mean SCR.But the socket seems to indicate it uses the whole waveform and there are only two diodes, rather than the four expected in a full wave rectifier.You really should try to draw the schematic, even if you're not sure of the components. Just draw the TRIAC/SCR as a box with the pins numbered from left to right (front view).Another thing you could do is consider stripping out the original circuit and replacing it entirely with a standard phase controller circuit. Quote Link to comment Share on other sites More sharing options...
Guest TheButcher69 Posted February 23, 2015 Report Share Posted February 23, 2015 I REALLY appreciate your help! But when it comes to schematics I'm really lost. I'm a machinist by trade & have no troubles reading them but electrical is a bit beyond me. I'll have to do research on the standard phase controller circuit too. Quote Link to comment Share on other sites More sharing options...
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