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PST/PGT/PSC Star Sandwich Grill Troubleshooting for Technicians
The following PST/PGT/PSC Star Sandwich Grill troubleshooting directions are courtesy of our friends at Star Manufacturing. The units are common at Tim Hortons and Taco Bell. These directions are intended for authorized service technicians.
A majority of service calls for PST/PGT/PSC units are regarding no heating on the top/bottom or that they're taking a long time to reach temp. The display will show:
- Constant flashing of “.17” or any other time
- Pro 1 (terminals E1 & E2 on board) OR Pro 2 (E11&E12) OR Pro3 (E13&E14)
Labels & Descriptions for Terminals on the Board:
- E1 and E2 – Upper left temperature probe input
- E3 and E4 – 10V AC power input to control board
- E5 and E6 – Upper left relay output
- E5 and E7 – Upper right relay output
- E5 and E8 – Lower relay output
- E9 – Unused
- E11 and E12 – Upper right temperature probe input
- E13 and E14 – Lower temperature probe input
- E23 and E24 – Unused
Star estimates that about 80% of the time, the problem is with a probe.
ALWAYS VERIFY PROBE RESISTANCE AND CONNECTION FIRST WHEN TROUBLESHOOTING!
These are 2K probes, so at about room temperature they should be about 2100 ohms. All probes in the unit should read the same resistance. If any of them is reading far off from the other, it's usually the culprit.
The reason the board will flash “RELY” is because the way this board is set up. If the boards senses a fault in any probe (i.e. resistance is off, bad connection, broken wire), then it cuts off power to all of the relays, hence the “RELY” error. Change probe(s) if resistance is off or any other fault in probe.**
**NOTE: THERE ARE 2 DIFFERENT TYPES OF RELAYS.
AROUND 08/2019 THEY CHANGED TO #2EZ22595 (SMALLER BLACK ONE)
PARTS LIST SHOWS #2E-Z3335 (GREY)**
Now, check the unit. Is it heating up to temperature now? If probes are fine and the board is working, check the relays next.
Are they receiving between 9-12V DC to the relay coils? And 120 or 240V out to the elements? If so, check the elements. Are they open? Pulling correct amps?
If everything is checking out fine, the only other thing Star notices is that the transformers are putting out over 13V DC to the board and making the board act odd. So confirm what you are getting out of the secondary side of the transformer.
The boards on these units are usually the last to fail, always question when a tech requests a new board for a warranty unit. If they insist without confirming everything else, just advise them that they will be charged for the board if it is returned to Star and no fault is found in the board.
(Remember, Star requests they return the defective board when they submit their claims!)
Download the PDF version of these instructions here.