SST 01 Rev 1

[peranders]

heaveno Folks very new to this forum


After two years of uninterrupted service, Relay K2 fails to latch.
When power is applied the points continuously bounce, is there a fix.

[peranders]

November 21, 2024, 06:36:30 PM
First of all (if possible) use a 24 V source with current limitation. It's much safer not having live voltage.


Connect 24 V across the DZ1 zener or similar point. Start with T3 and go backwards. What is the base-emitter voltage on T3? Should be 650 mV and the collector-emitter voltage less than 200 mV.

[peranders]

November 29, 2024, 11:26:43 AM
Please accept my apologies for the delay in answering (I am waiting the return of my bench power supply)

[peranders]

December 02, 2024, 09:09:24 AM
No worries. Take your time.

[peranders]

Last Edit: Yesterday at 06:06:23 PM by Esprit
heaveno, I have two of the SST01 rev.1, one each in mono Pass F5t.
Following application of 24v across DZ1, the following results were obtained.


PCB No1
T3, B/E= 0v.    C/E= 22v
T2, B/E= 23v.   C/E= 23.1v
T1, B/E= 143mv. C/E= 40mv


PCB No2
T3, B/E= .94v.  C/E= 60mv
T2, B/E= .4v.   C/E= 22.2v
T1, B/E=.623v.  C/E= 1mv

[peranders]

T2 is suspect since you can't have more than 1 V across base-emitter.