Blown PID?

[jasonandres]

I think I might have blown my PID (TET-612). As I was starting up my oven for the first time, one of the wires to the fan slipped off and touched the oven, it popped the 5 amp fuse I have in the control box. I replaced the fuse and now the PID doesn't work right, it over shoots the target temp by about 100 degrees and unless the target temp is way over the inside oven temp the 'out' light just pulses on every couple seconds. Has anyone else had this problem? Thanks for any replies.

[ed_denu]

If you saved your prior parameter settings you might check to see if everything is the same. If not, try running auto tune again to see if that helps.

[jasonandres]

Thanks for the reply Ed, I checked the parameters and they didn't change. I haven't run the auto tune yet, I was doing the initial burn off of the oven to get rid of the smoking.

[CarWiz]

Do you have a way to verify the temperature indicated in the PV display? It's normal for the indicator light to pulse. The problem could be the parameters set in the PID. The parameters at address 0089 should be checked. You'll need to check to make sure Input Type (INTY) is set correctly for the thermal coupler you're using. Verifying the other parameters wouldn't hurt either but you might try using Auto as Ed states. The PID will adjust the parameters at address 0001 as it "learns" time/heat differentials.

One other thing- Make sure your TC is connected directly to the PID with no other intervening wire or terminals.

[jasonandres]

I checked the temp with an infrared gun, it's about 4 degrees higher than what the PID says. I ran the auto function, it still pulses, I can hear the elements going on and off with the pulse. If I have the target temp around let's say 100 degrees above what the oven actually is then it will pulse for about a minute then stay on steady, but if it's lower then around that 100 degree difference then it pulses. Also, the PID overshoots the target temp by about 15 degrees and begins pulsing again. I checked the other parameters and they seem OK, and the TC is wired directly into the PID. Man this is confusing, does anyone have a clue what's wrong?

Thanks

[CarWiz]

There's not a whole lot wrong. As already stated, the pulsing is normal. The PID must "learn" the effectiveness of your heating coils over a period of time. I wouldn't get concerned over the pulsing. The overshoot can be adjusted as well as the temp differential. Try these settings and note the change.

Addr: 0036
I = 90
SoF = .3

Addr:0089
PSb = 4