SONY DCR-HC22E c:21:00 DEW Sensor - Page 1
Forum section: electronics / repair

author: dimis7
author_rank: Newbie
timestamp: August 23, 2018, 06:52:15 am
content: Hi,I need some help in order to bypass the humidity - DEW sensor of a SONY DCR-HC22E camcorder.Sony P/N is: 1-677-049-11 FP-228 FLEXIBLE BOARD (DEW SENSOR)The sensor is damaged and camera is throwing c:21:00 error and not accept any tape.Anyone knows how this sensor is working? I assume the sensor change its resistance according to humidity, so i can replace it with a resistor, but i have no idea what the value should be.I already tried with: open circuit (sensor removed),10k,20k,30k,40k,1m and short circuit the pins of the sensor, but still the same error...Attached can find the schematics from service manual.Thank you.

author: wraper
author_rank: Unknown
timestamp: August 23, 2018, 07:07:42 am
content: You did not attach part of the schematic that really matters (PCB with the sensor itself). Also did you check the resistance of the sensor? It might be not faulty at all.

author: dimis7
author_rank: Newbie
timestamp: August 23, 2018, 07:32:38 am
content: Hi wraper,Nothing really useful there, but here it is...The sensor is for sure faulty... The owner tried to clean it, and he remove the black conductive material from the sensor.

author: wraper
author_rank: Unknown
timestamp: August 23, 2018, 07:53:42 am
content: Then attach potentiometer and try to adjust resistance until it works.

author: dimis7
author_rank: Newbie
timestamp: August 23, 2018, 07:58:10 am
content: Yes i can try that... but what value you think i must use? 1k, 5k, 10k, 100k, 1m???

author: wraper
author_rank: Unknown
timestamp: August 23, 2018, 08:03:16 am
content: Who knows but I don't think it goes over 100k in normal ambient conditions, so 100k pot would be fine for starters.

author: dimis7
author_rank: Newbie
timestamp: August 23, 2018, 08:14:06 am
content: Thanks wraper.I will try to find a 100k pot in my junk boxes and see if i can fool the microcontroller!

author: coromonadalix
author_rank: Super Contributor
timestamp: August 23, 2018, 11:02:01 am
content: If you have the service manual look for the part number, and you may find the specs / brand ...

author: dimis7
author_rank: Newbie
timestamp: August 23, 2018, 11:27:21 am
content: Hi coromonadalix,I have the s/m and the sensor p/n (it's in my 1st post).Unfortunately, it's a SONY part and can't find the sensor specs...

author: Mario87
author_rank: Frequent Contributor
timestamp: August 23, 2018, 12:18:16 pm
content: You can see in the last image you posted that FP-228 is just a resistor which connects to pins 7 & 8 on FP-468, no doubt the resistance changes with humidity / dew and can be used to adjust the voltage going to the FP-468 on pins 5 & 6 (also shown in your 2nd image). This voltage will then continue over to pin 119 on the first image where the controller will react to these different voltages. Basically, it appears to be just a simple variable resistor to adjust the voltage going to pin 119.So....first thing to check is, do you actually have a voltage appearing on these pins? Adding variable pots and the likes won't do anything if there is no signal to begin with.

author: dimis7
author_rank: Newbie
timestamp: August 23, 2018, 01:13:45 pm
content: Hi Mario,Yes i already checked this. There is about 0.6v on the sensors terminals, with the sensor disconnected. I don't know if its normal or not...What i didn't checked though, is if that voltage is actually going to pin 119 of the controller.I will try to check that also when i will go back in home

author: Mario87
author_rank: Frequent Contributor
timestamp: August 23, 2018, 02:53:08 pm
content: I would have thought 0.6v would be an "off" signal and should be closer to Vcc to indicate an "on" signal. There is not a lot of info on the MB9115LGL-G-120-ERE1 online unfortunately, so difficult to tell what it is expecting to see.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 23, 2018, 10:32:36 pm
content: yeah no dew sensors infos either, it is used in many cameras mechanism, and sold on Ebay for 20$ without the shipping ...Maybe you have an pull up resistor in the circuit, and the sensor is pulling it down ?? since one side is groundedI think the dew sensor value should go down with humidity ??

author: dimis7
author_rank: Newbie
timestamp: August 24, 2018, 07:56:50 am
content: Hi everyone,I made a simplified schematic (with MS Paint)If i understand correctly, the 0,6v I'm getting without the sensor connected is correct because of the resistors R8633 & R8634...So the controller should read something between 0v - 0,6v...Tried yesterday for hours with a 220k potentiometer but still didn't find the sweet spot...Only 1 time the tape loaded with about 0,1v to the pin 119 of the controller, but then the camera throw a different error... c:31:30 and c:32:30S/M says: "FG fault when starting capstan"Correction: "Load the tape again, and perform operations from the beginning." and "Remove the battery or power cable, connect, and performoperations from the beginning."No idea what this means. of course i already tried to load the tape again and remove power 100 times

author: Mario87
author_rank: Frequent Contributor
timestamp: August 24, 2018, 08:19:25 am
content: Looking at the circuit you do appear to be correct. The voltage divider created by the resistors will output 0.6v to pin 119. My mistake for not looking properly at the first images you posted!You say you have managed to get the tape to load with the voltage adjusted to approx 0.1v, and it cleared error C:21:00, but you are then presented with C:31:30 and C:32:30.Quick google reveals the following....Sony Error Code: C:31:30 and C:32:30These error codes will display when there is a problem with the capstan motor. Just because this error code comes up that does not mean that the capstan motor is defective. It simply means that the motor is not able to perform properly. This might be due to a bad capstan motor or something in the tape path interfering with the capstan motor’s ability to run properly. It can also be an electronic problem with the system servo circuit.So it looks like setting the voltage to 0.1v on pin 119 has cleared your DEW sensor issue, but has revealed more faults with the camcorder. At this point I would leave the voltage to pin 119 at 0.1v and start to troubleshoot other parts of the circuit relating to the capstan motor.However...as per the KISS principle (Keep It Simple Stupid), have you tried different tapes? Does it bring up the C:31:30 and C:32:30 with all tapes you have tried?

author: dimis7
author_rank: Newbie
timestamp: August 24, 2018, 08:59:34 am
content: Hi Mario,No i did't try other tapes because i don't have any...And the one i have is a cleaning tape...What is wired to me is why the capstan motor trying to operate? The error is displayed as soon as i close the door without the loading being completed. The tape never going inside the mechanism and loaded to the drum and capstan motor.Your suggestion to try other tape seems correct to me, so i will try to find another tape first.If still not working i'm thinking that maybe its something related with the rotary encoder that is sending to the controller the current position of the mechanism.Its a common problem with many SONY DAT machines and i saw the same problem with a different miniDV camera in the past.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 24, 2018, 10:57:41 am
content: Dont forget some mechanism use tape detection with infrared leds from the sides to the middle / center of the cassette tape casing , you should try to find an cassette to do tests, not an lapping /cleaning tape.You may have found the right voltageTry to do an loading without light on top of the loading mechanism