ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
You will never guess
by grich - 02/24/21 07:18 PM
Lock-down Thread
by Bill Addiss - 02/24/21 04:40 PM
New tool
by SMOKEYBOB - 02/15/21 04:59 PM
Split Bus Breaker Panel
by gfretwell - 02/15/21 02:30 PM
Sierraplex recpts
by gfretwell - 02/15/21 02:27 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 20 guests, and 17 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 2 of 3 1 2 3
Re: Need help identifying diode [Re: Trumpy] #216534 12/28/15 03:26 AM
Joined: Feb 2013
Posts: 264
Potseal Offline OP
Member
Originally Posted by Trumpy
Can we please get a wider view of the PCB to see where this fits into the whole thing?


I will definitely post that image tomorrow. Calling it a night right now.


A malfunction at the junction
--------------------------------------
Dwayne
Work Gear for Electricians and the Trades
Re: Need help identifying diode [Re: Potseal] #216535 12/28/15 06:11 AM
Joined: Dec 2002
Posts: 204
G
geoff in UK Offline
Member
The chances are high that it's a 6.8volt zener.
Can you deduce anything from the associated circuit components? For instance it looks as though the three cathodes are connected together; is that point ground? Do the working ones have ~6.8v across them? Or are they perhaps across signal input lines as transient suppression?
Finally, (though should be firstly), have you tried calling the manufacturer? I've sometimes found specialist manufacturers quite helpful with technical queries.

Re: Need help identifying diode [Re: Potseal] #216540 12/28/15 12:14 PM
Joined: Feb 2013
Posts: 264
Potseal Offline OP
Member
Here is a more complete view of the board I'm working on:

[Linked Image from i63.tinypic.com]


A malfunction at the junction
--------------------------------------
Dwayne
Re: Need help identifying diode [Re: Potseal] #216541 12/28/15 12:34 PM
Joined: Feb 2013
Posts: 264
Potseal Offline OP
Member
Here is the identical sacrificial board that I attached to a piece of MDF and made more accessible for testing AFTER I replaced a diode that I believed was causing the malfunction:

[Linked Image from i67.tinypic.com]

This unit appears to be working fine. I have removed the touchpad and replaced it with various wires attached to a terminal strip. I can short the wires together which will cause the appropriate indicator light to come "on". Then I can cancel those same lights. Before I replaced the diode one of the "call" lights was always "on" and could not be cancelled.


A malfunction at the junction
--------------------------------------
Dwayne
Re: Need help identifying diode [Re: geoff in UK] #216542 12/28/15 12:42 PM
Joined: Feb 2013
Posts: 264
Potseal Offline OP
Member
Originally Posted by geoff in UK
The chances are high that it's a 6.8volt zener.
Can you deduce anything from the associated circuit components? For instance it looks as though the three cathodes are connected together; is that point ground? Do the working ones have ~6.8v across them? Or are they perhaps across signal input lines as transient suppression?
Finally, (though should be firstly), have you tried calling the manufacturer? I've sometimes found specialist manufacturers quite helpful with technical queries.


When I power the board that appears working properly and measure the voltage with positive lead on the anode and negative lead on the cathode I get -3.8V on CR3 and CR2 but 0 V on CR1.

Contacting the manufacturer is definitely a good idea but without being a 100% positive I believe Dukane is no longer a supplier of this equipment. Most Google searches seem to result at a company called Crest. Their website shows older Dukane nurse call equipment but it doesn't look anything like the equipment I'm working on. This equipment is quite old. Still, it may be worth sending an email.


A malfunction at the junction
--------------------------------------
Dwayne
Re: Need help identifying diode [Re: Potseal] #216543 12/28/15 12:46 PM
Joined: Feb 2013
Posts: 264
Potseal Offline OP
Member
Oops. I guess I forgot to mention... The voltage drop measured across the diodes on the board that is not functioning properly is 0.17 V.


A malfunction at the junction
--------------------------------------
Dwayne
Re: Need help identifying diode [Re: Potseal] #216544 12/28/15 01:08 PM
Joined: Feb 2013
Posts: 264
Potseal Offline OP
Member
^^^ correction - that previous measurement should be "0 V".


A malfunction at the junction
--------------------------------------
Dwayne
Re: Need help identifying diode [Re: Potseal] #216547 12/28/15 04:24 PM
Joined: Feb 2003
Posts: 361
M
mbhydro Offline
Member
If its any help, Dukane sold off the nurse call station division to this company in 2002 according to the Dukane web site

http://www.ascom.us/us-en/index-us/systems-division/ascom-telligence.htm#overview

Re: Need help identifying diode [Re: Potseal] #216555 12/28/15 07:46 PM
Joined: Nov 2002
Posts: 790
W
wa2ise Offline
Member
"CR" means "crystal rectifier". An old name for a solid state diode, made from a piece of silicon or geranium. So it is a diode.

Re: Need help identifying diode [Re: Potseal] #216556 12/28/15 08:27 PM
Joined: Jul 2004
Posts: 9,568
G
gfretwell Offline
Member
CR tends to indicate a diode and you seem to have proved it.


Greg Fretwell
Page 2 of 3 1 2 3

Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
RH1
RH1
California
Posts: 22
Joined: August 2009
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
275,348 Are you busy
209,215 Re: Forum
196,518 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3