PT 100 not quite working

[chutney]

I put together a rig for cooking sous vide. I have a JLD-612, PT-100 probe and SSR Control bought from our host. I am using the seatlefoodgeek guide and modified it with tips from here. 1st mod--pre-testing would not keep a temp and I grounded(or shorted) back one of the blue probe leads to the sheath of the probe. Other mods are with components putting it together and electrical fittings. I went through the programing on the 0089 code. I have set inty=P10.0;Outy=2;HY=000.3;psb=0;rd=0;corf=1. Last night I ran AT. Last night I set SV=130 and the PV matched my thermopen with a +-.03 f degrees. This was for about 10 mins when it the PV dropped to 78 and turned the heaters on and started raising the temp of the water bath.
Tonight I again set SV=150; it closely matched my thermopen and then after 10-15 minutes and after bringing the temp to 150 the PV dropped down to 76. After the unit was off about a hour the PV was reading to the "correct" temp again, but I didn't run it see if it would cut out again.
I would like to fix this problem, but don't know where to start looking. I want to add a jack to PT-100 probe. If I put a jack on it could I use the probe from my thermo-works oven thermometers probe? If I put a jack on PT-100 probe and trim the cord can I re set the temperature calibration?
Is the probe the bad? Please help.
I tested third time and got to 45 minutes and temperature read okay. I am going to SV eggs in morning and see if I can run for hour or longer. Thanks

[chutney]

Eggs this morning didn't work. The PV dropped down to 78 with water temp at 128. I adjusted PSB to correct the reading. Came back to check temp. SV=148 PV=153 machine still heating. I tried to reset PSB and the PV reset reading was 76. Water temp is 153+ so now the correction setting has changed. I think the Probe is bad.

[richiem]

Definitely try another probe. I don't know what they cost from lightobject, but they are quite cheap on eBay -- and it's good to have a spare. You can only use a Pt100 probe with a Pt100 or Pt10.0 setting of the 612 -- other probe types need different settings, so you have to know the type of sensor in whatever probe you connect. I'm betting that your other thermometer probe does not use a Pt100 sensor, and you may not be able to find out what it actually is.

Using a connector for the Pt100 probe is fine -- assuming that the Pt100 probe has three wires (typical type), there are several possibilities:
1) 1/4 inch "phone" plug and jack with Tip-Ring-Sleeve (TRS) three-terminal connections -- these are used for stereo audio headphone connectors. Easy to get at Radio Shack
2) 1/8 inch "mini-phone" jack and plug -- used for the same purposes as 1) above; same source.
3) XLR type microphone connectors -- bulkier than either above, but very secure, low-noise connections.

[Tech_Marco]

Hello

I just reported the problem to the manufacturer and they said that the problem could be caused by the bad contact between the blue and red. Usually, it won't caue the problem till my request of making the shield 100% isolated. To make the shield isolat4ed from the probe, they have to install two pieces of ceramic ring and the task is not easy and easy to get tangled up if the rings cracked. I was trying to get better probe, it seems that it make it worst... my apology.

So, from now on, I asked them to send me regular pt-100 instead of shield isolated.

Sorry folks, if you think that you may have bad pt-100, please send it back for exchange.


Marco
(still in China)