On Sun, Oct 13, 2024 at 11:07 AM, Dave Voorhis wrote:
I have two 577s and haven't seen your problem, and changing the intensity pot itself almost certainly had nothing to do with the problem. It sounds more like there's been some reassembly blunder or an unrelated fault. Have you tried cleaning the switch and mainframe connector contacts on your 177?
Mine tend to get noisy after not being used for a while, and that might contribute to an out-of-range condition.
If not, you'll need to debug it per the service manual circuit description, etc.
On Sat, 12 Oct 2024, 22:24 Marco Lazzarato via , <lazza2012=
[email protected]> wrote:
The curve tracer was fully operational,i ran through the whole calibration/adjustment steps when i brought it home, than i realized that when I tried to set the intensity the pot was moving but in a weird way, some days passed and then i¡¯ve changed it with a new one.
Now it works ok if i set the vertical/div in the mA or upper ranges, but when i turn the knob over lower ranges the yellow light ?of the overrange turns on, and the beam goes out of range, i¡¯ve tried to test some of the resistors of the 177 and they¡¯re pretty much in spec.?
I can¡¯t figure out the cause¡
Thanks again for your reply.
?
Thanks Dave, i¡¯ve tried but i think that something inside the preamp circuit or the amp itself isn¡¯t working properly.
If you have any idea, let me know¡?
Marco
