Discussion Category: CO2 Incubator
Door Heater Output Not Correct?
Hi LabWrench,
I have a 3110 that has condensation forming on the internal glass door. I swapped out the door with a known working one and the problem persists. Digging in to it a little further, the electrical connector that feeds the heater on the door has 3 points of contact: ~4.5vDC, Ground, ~4.5vDC on a known working unit. My broken unit is ~4.5vDC, Ground, ~0.3vDC.
Unfortunately this is on the lower incubator of a double stacked unit. Is it possible to get to the control board while these units are still stacked (and full of water)?
Thanks!
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OK, I figured out how to get the tray open. The fuses all test normal. I tested the continuity between the plug on the door and the internal white plug in the circuit tray and it passed. That's as far as I got as the room is now occupied with researchers and I can't be in there. I'll probably have to come back on the weekend to dig in to it further.
Question: Is the door heater on its own separate board or is it shared? I have a bonus incubator I've been borrowing parts off of as needed to troubleshoot but realistically I'd like both incubators to work correctly.
It's not the door. I swapped out the main circuit board from a slightly newer model and it resoved the condensation issue. I found a used board on eBay for $65 shipped! I don't see any obvious visual issues with the old board; no burnt marks, expanded caps, blown fuses, etc. There are 2 transistors that show slight discoloration possibly from getting too hot, which are U19 and U33. The transistor at U15 looks normal.
Hopefully this thread will help someone in the future.
Still having door fogging issues:
I've tried a replacement main board, transformer and glass interior door. Still fogging. Blower motor is working correctly and have tried a new air filter. I'm running out of parts and ideas... DC board will be replaced next.
Have you verified voltage output at the door heater cable and continuity of the door heater element? Is the gIass door warm to the touch? Is the inside panel of the outer door warm? Is the gray glass door seal gasket in good condition all around, no breaks or tears that could exchange air?
The glass door latch incorprates a metal tab that is half of the switch that detects when the glass door is closed, the other half being the glass door frame. If you're not getting "Door Open" alarms it's probably ok, but wouldn't hurt to check that the contact is clean, the frame is clean, and there's good contact. The tab looks like what you'd typically see in a AA battery compartment.
I've checked continuity for the door heater cable all the way back to the control board. I can't check continuity inside the door as it's a sealed unit. I checked all fuses. I cannot find information on what the correct output voltage should be at the door. The glass door is warm, but the chamber is set to 37C so it will be warm regardless. The gasket looks good and I've wiped it down a few times to make sure it's making contact with the glass while dry. I did have an issue when I replaced the door where it thought the door was open when it was not. I had to adjust it a bit using the 2 mounting screws at the top left (or right if it opened the other direction). I replaced the AC to DC board but that made no change.
Could it be an interior airflow issue? I verified the blower motor working and is moving air. My next step is to remove the interior shelving and see what it does for the condensation. http://i.imgur.com/O3vKmiB.jpg
The glass door isn't warm because of the 37C in the chamber, it's warm because there's a heater built into the frame. When you disconnect the heater cable you can measure continuity on the frame connector. Better yet, check the heater and cable together at the board connector, J3 pins 2 and 6. At the top of this page, under your question, is a link to the product details page. Go there, click on the Documents tab, then open the third document (user manual). You'll find schematics in Section 9. There's 24VAC going to the door heaters, but it's applied on a programmed cycle so you'll have to wait to see it switch. It used to be settable through the configurations menu (section 3) but I'm not sure anymore. Thermo tech support can tell you. If you go to kb.unitylabservices.com and surf to the 3110 under Incubators you'll find some troubleshooting documents, one specifically for troubleshooting the door heaters.
You didn't mention if you checked the battery tab contact at the glass door latch. That tab is the switch shown on page 9-1 of the user manual schematic. Find # 15 and 16 in the column on the left and go across till you see a box labelled 190730.
If the chamber fan is stalling you'll usually see random fluctuations in displayed temperature and CO2 readings, with alarms. If that's not happening your fan is probably ok. If you look at the turbine while turning the machine on/off you should see it start and stop consistently, and it should feel smooth turning by hand. If you have an optical tach you should be able to clock it at about 3000rpm.
There seems to be some trouble on the knowledge base site at the moment, so I'll copy the door troubleshooting sheet here:
3110 Door Troubleshooting
1) Look and make sure the small metal tab is attached to the latch strike mount. This is located near door handle. If this tab is broken, the door ajar light will be on all the time and none of the other functions will work (temp & CO2). This will also happen if the tab is not touching the outer door frame.
2) The next check will require the electronic control panel to be pulled out. Locate the door cord (which will enter through the bottom of the drawer at the left side of micro board). Turn your meter to the ohm scale and put one lead of the meter on the brown wire and place the other lead on the black wire which is located to the left of the micro board and is fasted as part of the chassis ground. You should read short if the door switch is working. Open and close the door and you will see the meter change from reading ohms to reading open as you open and close the door. The indicated the door switch circuit is working properly.
3) Check the door heating element, place one lead of the meter on the blue wire from the door cord and the other lead on the black wire at the chassis ground. Your meter should read 9 to 10 ohms. If you do not have a reading you need to proceed to the glass door.
4) Pull the three pin connector off the top of the glass door. Put one lead of your meter on the outside frame and the other lead you need to step through and touch each pin. When you read short this will be your door switch pin. Place one lead of your meter on one of the remaining pins and the other lead of the meter on the other remaining pin. This will be your door heating circuit. If you have resistance replace the door cable (Part# 190566). If you have no resistance replace the door and the door cable (Part# 190756 and 190566).
5) Another way to check the door heating circuit is with an amp probe. Place an amp probe on the blue wire, where it exits the micro board. The heating circuit will draw approximately 2.5 amps. With the amp probe attached, you will receive a pulsating reading (you will receive a reading of 2.5 amps and then there will be no reading). This means the door heating circuit is working properly.
6) To check the micro board for proper operation, place a volt meter on pin connector terminal J-3 and the other lead on the ground terminal (blue wire). You should receive 24 ac volts, if no voltage reading is obtained, check the fuse, located in the fuse holder.
The wiring for the door plug goes as follows:
#1 black wire ----------power to the 5 watt heater (continuous power)
#2 white wire ----------neutral
#3 green wire-----------ground
#4 red wire -------------power to 120 watt heater (cycles from the main heater)
The 2 parts that are needed are:
950016 -----------------door cable with male plug
370075 -----------------recp. for the door cord
Following is the details of the test mode available from the panel of the series 2 3110's. This is where they put the door heat cycle (I knew it was somewhere)
Trouble Shooting Guide
3100 Series II Test Mode
3100 Series II
Revision Date: May 17, 2014
3100 Series II Test Mode
2 of 3 www.thermoscientific.com/contactus
There is also a special test/service mode built into the incubator control panel. This mode is to be used as a production tool during testing and a service tool for installing and/or troubleshooting problems with the incubator. When in test mode, all incubator control is disabled. To get into test mode the <- and -> arrow keys should be pressed simultaneously and held. The incubator's microprocessor only checks for this key sequence every 5 seconds, so the keys should be held until the display reads Test Mode -> . Listed below are the options available in test mode. To exit test mode, press the mode key and the system will resume normal operation.
MAX LOAD ON/OFF Manually turns ON/OFF all heaters, and valves so that the unit is under full load.
MAIN HT ON/OFF Manually turns ON/OFF the main chamber heater.
DOOR HT ON/OFF Manually turns ON/OFF the glass door heater.
DR HEAT XX% The incubator has a heater built into the inner glass door of the unit. This setpoint which ranges from 0 to 100% is the amount of time that heat will be applied to the glass door in relation to the main heater. System default is 50%.
GG VALVE ON/OFF Manually toggles the Gas Guard Valve. ( Gas Guard option only )
CO2 VALVE ON/OFF Manually toggles the CO2 Valve.
CO2 SPAN Used when a span adjustment of the T/C CO2 sensor is necessary.
O2 VLVE ON/OFF Manually turns ON/OFF the O2 valve. (O2 option only )
ALM CNTS ON/OFF Manually toggles the remote alarm contacts.
PULSE 485 Sends a 2 second long data stream out the 485 connecter.
OT CAL XX.X C Used to calibrate the over temperature probe.
TMPOFF XX.X C Displays the offset amount that the air temperature has been changed during calibration.
O2OFF Displays the offset amount that the O2 has been changed during calibration. (O2 option only)
RHOFF XX % Displays the offset amount that the RH has been changed during calibration. ( RH option only )
O2 XX.X MV Used to display the O2 cell millivolt reading for a given O2 level. ( O2 option only )
3100 Series II Test Mode
3 of 3 www.thermoscientific.com/contactus
RESETS XX Displays the number of times the units has been powered up. This can be cleared by pressing the up arrow and can be used to troubleshoot possible power problems. ( ie brownouts, resets)
C100 ON/OFF Used to turn the Class 100 display ON/OFF.
DFLT MAIN EE Pressing < ENTER > reloads the entire contents of the Main Micro Processors non-volatile memory to defaults. When < ENTER > is pressed the message ARE YOU SURE will appear, press < ENTER > to perform the default, otherwise press any other key to cancel. Caution: This should only be used if problems indicate that the memory has been corrupted or erased. Defaults the entire contents of the micro board non-volatile memory.
DFLT SETP Pressing < ENTER > reloads all system setpoints in non-volatile memory to defaults.
Caution: Defaults all previous setpoints that have been programmed into the unit.
DFLT CALIB Pressing < ENTER > reloads all system software calibration in non-volatile memory to defaults. Caution: Defaults all previous software calibration.
MN VERS XX Displays the main board s software version number.
Note: When in test mode, the processor will check if the analog board option exists. If it does, the processor will write out the following information to the analog board during any test mode menu: 20.0 degrees C, 20.0 %CO2, 20% rH, and 20.0% O2.
Note: When in run mode with SYSTEM OK or CLASS 100 showing in the display, pressing the down arrow will cause the over temp temperature to be displayed in the lower 7 segment display.
That 3110 Door Troubleshooting guide is awesome!
So after replacing just about everything it turns out it was the door heater wire this whole time. My glass is completely clear this morning!
It was a fun project to learn on, thanks for the support Medphysteo!
Glad you got it going, and to be able to help.
I'm currently looking for these same parts to replace for a Forma 3546 incubator (pre-thermo). The receptacle is in Unity, but the cable w/plug is not. Any ideas where I could score one?
Thanks!
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