I had one where the VR3059 fired at 80 volts and caused the PS to shutdown.
You might check it on a curve tracer.
?
Tom
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Tuesday, October 23, 2012 4:53
PM
Subject: [TekScopes] Re: line voltage
7704a
?
Hi David,
VR3059 and Q3052 can cause troubles, but how would you
explain that a failure there causes the inverter to stop (fall back in tick
mode) when the line voltage is increased from too low to
normal?
Albert
--- In TekScopes@..., David
wrote:
>
> Are you equipped to make safe
primary side oscilloscope measurements?
>
> When you say you
checked the primary side zener diodes, do you mean
> all of them
including VR3059? Did you check them for leakage?
>
> Besides
measuring the voltages at the various pins of U3105 to see if
> it is
initiating the shutdown, I would check the circuit around Q3052
> and
see if it is triggering at normal AC line voltage.
>
> What
resonate frequency is the inverter operating at? Maybe there is
> a
problem with L3037 or C3037.
>
> On Tue, 23 Oct 2012 16:49:02
-0000, "hojo3008"
> wrote:
>
>
>Hi,
> >
> >I have a 7704A power supply that will not
work at normal line voltage but seems happy and regulated at 70 to 100 volts
in. Zeners and caps in the inverter have been rechecked and verified okay. 2
inverter chips(-02s) work the same. The 54V adjust is right on as is the -50V
adjust. The voltage select looks okay. Ideas?
>
