ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hello everyone,
This is my first post to the forum. What a wonderful community you guys have, here.
I've read through the forum on cleaning the door sensor components and adjusting the doors on this 2500. The sensors work with the clean glass and black plastic panels removed. With them installed there is no action. The tracks and mechanical mechanism are fine and the motor works when the sensors are sensing while everything is removed.
All I can deduce from this is any of the following:
1. The plastic in the black panels has changed somehow over time, not allowing the light to get through the plastic
2. The LED's are old and getting weaker/low output
3. The sensors are old and not as sensitive
4. There is some calibration issue in the circuitry
Does anyone have any fixes for this issue? What are proper replacement parts for the led's and sensors?
Thanks for your input.
Anyone have any advice on this topic? Thanks.
Pure guesswork based on my experience, I have a VERY old working 2500....
Mine worked again after a very thorough cleaning of the doors and plastic parts, but I guess you have already done that?
Try replacing the bulk caps in the area, if there is an increased ripple on the supply the sensitivity goes down.
Good idea. I'll look into the capacitors on that board. I found a few replacement parts on digikey that should work. The existing led sensor is not 880nm wavelength as stated in the schematic. It is 950nm. Here are the parts I will order with my next digikey order:
https://www.digikey.com/product-detail/en/BPW82/BPW82-ND/4071229
and
https://www.digikey.com/product-detail/en/SIR-34ST3F/511-1363-ND/638559/?itemSeq=294433238
The door system works by creating a n infra red "field" in front of the keyboard area,ie this is active continuously..There are two transmitter/receiver unit's,one either side.They balance out normally,until you put your hand towards the keyboard and this disturbs the field and activates the control system.If no further disturbance occurs,the system resets and the doors close.
The black trim plates do act as ir filters,and become dirty on the inner side,which affect's sensitivity.
Also, the ir receiver diodes (BPW) can become noisy with age affecting how the system works.
As mentioned earlier too,the supply lines can become noisy due to tired electrolytic decoupling caps.
Try to avoid replacing the door ir transmitter led's,as they are matched parts.You can test the ir beam's by using your 'phone camera,which should pick them up ,holding your 'phone about 10cm from the front of the unit.
Nick
I replaced both IR sensors. I noticed increased sensitivity from the system. It would detect my hand further away from the key bed. The system works without the glass installed, or with just one side installed. It does not detect the proximity of my hand with both pieces of glass installed.
It may be time to test the capacitors on the sensor board... I'll also look for the ripple on that board with a scope and try to quantify it.
Alright, I'm reporting back with success.
I changed all 4 IR LED's. The result was a working door sensor system. I notice the sensitivity increased even more with the new emitters. I used the parts in the links, above.
The scope showed a lot of ripple in the system. It was different on either side. I don't think it is due to bad caps. I think the noise is due to EMF in the environment or from the power supply.
I guess all the LED's and the receivers had aged and weren't doing their job. Of course a thorough cleaning helped a lot, too.
Thanks for all of your input. I hope this helps others whom need to know what parts to use to refresh their door sensors.