Jump to content
Electronics-Lab.com Community

SCR Rectifier Dayton Speed Control Need cross reference No one can find


Guest TheButcher69
 Share

Recommended Posts

Guest TheButcher69

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.

post-117575-142791449404_thumb.jpg

Link to comment
Share on other sites

Guest TheButcher69

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?

Link to comment
Share on other sites

Guest TheButcher69

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.

post-117575-1427914494073_thumb.jpg

post-117575-14279144941024_thumb.jpg

post-117575-14279144941344_thumb.jpg

Link to comment
Share on other sites

Guest TheButcher69

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

Guest TheButcher69

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.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...