5890 EPC issue reads 110 psi always

[MSCHemist]

I am trying to bring my 5890 SII EPC FID back online and have run into a problem. I turned it on last week and it was fine I did full inlet maintenance replaced the gold seal, liner, septa o-ring etc. Today I turned it on and the inlet pressure reads 110 psi no matter what I do.

-I took off the column
-I took off the septa
-I opened the inlet from the top
-I opened and closed the purge valve
**still reads 110 psi
I read 15 ml/min coming out of the split vent
I read ~2 ml/min coming from the septa purge **actually I am not sure anything is coming out the septa purge**

Any idea what the issue could be? Where/what reads the inlet pressure?

[MSCHemist]

I am pretty sure the 6 channel EPC board that plugs into the main board must be shot. I tried unhooking the 2 cables that go the proportioning valve and controller and on the other side the cable for A that goes into that board and nothing changes even if I turn the 5890 on and off it cannot tell the difference. It still reads 110 psi. If I pull that board off the main board it detects no EPC. Clearly there must be a short in the 6 channel EPC board.

[James_Ball]

I am pretty sure the 6 channel EPC board that plugs into the main board must be shot. I tried unhooking the 2 cables that go the proportioning valve and controller and on the other side the cable for A that goes into that board and nothing changes even if I turn the 5890 on and off it cannot tell the difference. It still reads 110 psi. If I pull that board off the main board it detects no EPC. Clearly there must be a short in the 6 channel EPC board.

Or in the pressure transducer in line before the inlet. Should be wires from that to the EPC also. The proportioning valve is a solenoid that opens and closes to adjust the back pressure read at the transducer. If it is reading 110 and set lower than that it should be holding the valve full open trying to let the excess gas escape.

[MSCHemist]

I literally unhooked the entire EPC from the controller board and the GC couldn't tell the difference. It is also reading a pressure on B (107 psi I believe) when there is no B and nothing hooked up to B.

I tried cleaning the board with IPA to no effect. No obvious dust or burns on the board but there are a bunch of large capacitors on it that may have gone bad.

[MSCHemist]

Yea that board is telling the GC there is 110 psi pressure in inlet A even when the inlet isn't hooked up to the board and at the same time telling it there is 119 psi in inlet B even though there is nothing and never has been anything hooked up to port B on that board. clearly it is shorted. I found a board on Ebay for < $100

except oddly today nothing is coming out the split/splitless vent and variable gas flow is coming out the septa purge vent.

[James_Ball]

Yea that board is telling the GC there is 110 psi pressure in inlet A even when the inlet isn't hooked up to the board and at the same time telling it there is 119 psi in inlet B even though there is nothing and never has been anything hooked up to port B on that board. clearly it is shorted. I found a board on Ebay for < $100

except oddly today nothing is coming out the split/splitless vent and variable gas flow is coming out the septa purge vent.

If the board is bad, who knows what signals or commands it is sending to the actual inlet controls.

[MSCHemist]

Yea that board is telling the GC there is 110 psi pressure in inlet A even when the inlet isn't hooked up to the board and at the same time telling it there is 119 psi in inlet B even though there is nothing and never has been anything hooked up to port B on that board. clearly it is shorted. I found a board on Ebay for < $100

except oddly today nothing is coming out the split/splitless vent and variable gas flow is coming out the septa purge vent.

If the board is bad, who knows what signals or commands it is sending to the actual inlet controls.

That is throwing me though. The septa purge regulator is just a mechanical 3 ml/min with no electronics. Not sure how I am getting higher flows out of that vent unless it is also governed by the PCV.

[James_Ball]

Yea that board is telling the GC there is 110 psi pressure in inlet A even when the inlet isn't hooked up to the board and at the same time telling it there is 119 psi in inlet B even though there is nothing and never has been anything hooked up to port B on that board. clearly it is shorted. I found a board on Ebay for < $100

except oddly today nothing is coming out the split/splitless vent and variable gas flow is coming out the septa purge vent.

If the board is bad, who knows what signals or commands it is sending to the actual inlet controls.

That is throwing me though. The septa purge regulator is just a mechanical 3 ml/min with no electronics. Not sure how I am getting higher flows out of that vent unless it is also governed by the PCV.

It is 3ml/min based on head pressure, since it is not adjustable, it will vary with head pressure. If the pressure is up, then the flow should be up some. I think also when the valve for split/splitless actuates some flow is diverted that way, but not certain since it has been quite some time since I looked at a flow diagram for those.

[MSCHemist]

I just got the board in and indeed it seems to be working correctly. I says no B inlet and pressure readings on A vary and seem reasonable. However I am still seeing high flow out the septa purge vent. I have 20ml/min coming out the split vent and 20 ml coming out the septa purge vent. I went over the entire inlet and EPC looking for leaks and plugs. The PCV seems to be working. Perhaps that regulator got fed too much flow and blew out.

I found a septa purge regulator on Ebay for $13 so I bought that though not sure how that could go bad. It is mechanical with no electronics.

[James_Ball]

I just got the board in and indeed it seems to be working correctly. I says no B inlet and pressure readings on A vary and seem reasonable. However I am still seeing high flow out the septa purge vent. I have 20ml/min coming out the split vent and 20 ml coming out the septa purge vent. I went over the entire inlet and EPC looking for leaks and plugs. The PCV seems to be working. Perhaps that regulator got fed too much flow and blew out.

I found a septa purge regulator on Ebay for $13 so I bought that though not sure how that could go bad. It is mechanical with no electronics.

If it got some dirt in the diaphragm it could be sticking open and letting it have excess flow. Most mechanical regulators are just a spring pushing the diaphragm against an orifice, if the spring or diaphragm get dirty they don't regulate as they should.

[MSCHemist]

I got it working Friday. New septum purge regulator worked. I also fixed the old one. I ripped it out and sonicated it in isopropanol, let it dry overnight then adjusted it using the hex bolt in front to adjust the regulator.

Thanks