2 Mar
2015
2 Mar
'15
12:58 p.m.
On 2015-Mar-02, at 7:50 AM, tony duell wrote:
Lazzerini wrote:
The 1620 min Vcc2 was 8.5V, so with the max 9.5V of the 9142, it looks like the zener is
supposed to be 9V (9.1V).
One concern is that if the zener is incorrect and too high a V, and the short in the 1620
was pulling that V down, the shorted 1620 may have been saving the other semiconductors.
Powering it up with the 1620 now removed might apply high V to the other semis, so it
would be an idea to isolate them for testing the zener voltage, or remove the zener for
out-of-circuit checking (apply a voltage to it though a series R).
I'm just going by your writing in one of the photos that it's a 15V zener - how
did you know that or come to write it?
> +24vdc to R112 and the D102 Zener that is saved so
from here to pins: 19, 2
> and 12 of the LB1620 then it continue to pin 16 of the TC9142P.
The D102-zener-regulated supply, in addition to supplying the 1620 & 9142, appears to
supply that other 8-pin chip, and the hall-effect sensors.
The datasheet
of this last one say that the power voltage would be between
5Vdc and 9,5Vdc. So would this say that the zenere has to be from
5 to 9 vdc? Have i to measure the exact voltage on pin 16 of the TC9142P
without the LB1620 and how have i to expect?
Yes. Connect up the 24V supply now and measure the voltage across the zener D102. It
should be, I guess ,between 5V and 9.5V. The LB1620 is
smoked. What other components must be tested to ensure
that the new LB1620 can not be broken just fitted?
Check that zener voltage. If that's OK, it is very likely nothing will damage the new
IC.