Imperial Impinger 1301 pizza oven

[clmdmia]

I have been working on a 1301 pizza oven that won't fire the contactor for the
heating elements. With the wires to the contactor removed I get the 208 volts that it needs to fire the contactor but as soon as I connect the wires to the coil the voltage drops to 8 volts. If I check the voltages to ground I have 120 on each termanal. I have bypassed the two high limits, the air proving switch, checked the temp control pot, replaced the contactor, the temp control bd. and the relay. I even replaced the power switch! The fans and convayor are working fine. Has anyone seen this problem before? Im ready to pull my hair out. Chad

[iceetech]

maybe the coil on the new contactor is shorted out?!?!?!?!!? sounds like that coil is the only thing that could be dropping voltage.

[clmdmia]

Thanks ice, I thought of that and jumped power right from the outlet and got the contactor to close. Chad

[markt]

Check your temp board for voltage at the terminals on the left side of the board, one terminal should be marked as N/L2 the other three will be 120, 208 or 240 (L1)
Always read voltage from potential to potential (L1 to L2) reading to ground can give you a false reading.
If you have the correct voltage reading from the terminal marked L2 to the other terminal 208 or 240 you now know the board has power.
Next leave one meter lead on the terminal for L1 (the 208 or 240 terminal) and move the other lead to terminal 7 on the other side of the board.
Terminal 7 is the "input" side of the relay.
You should have 208 or 240 volt at this point, next move to terminal 8, this is the output of the relay.
On a call for heat the relay closes supplying power to this terminal.
If you have power here move the meter lead to both sides of the high limit then the air switch, you should read 208 or 240 through this "safety chain" then at the contactor coil.
If your voltage drops out at any point through the chain that is your faulty component.
If the relay does not close, it could be the board, temp probe or potentiometor.
Let me know if you need to know how to test those components.

[clmdmia]

Thanks markt. The temp pot seems to be good, it runs 1025 ohms at the lowest temp setting to 0 ohms at the highest setting. I don't know how to test the temp probe. Do you? Chad

[markt]

Test the probe with the power turned on and the probe attached to the board.
You are checking for dc millivolts.
At 72° you should read @ 1.1 millivolts.
200° is @ 3.4 millivolts.
This is of course assuming the board has power.

[markt]

The phone # for Lincoln tech support is 800-678-9511 if you need it.

[clmdmia]

I'll try that. It's the only thing I haven't checked. Thank you markt

[clmdmia]

Thanks for the # markt

[clmdmia]

It was the temp probe. Thanks for the help!

[markt]

Glad to help.