Posts: 1,477
Threads: 71
Joined: Jan 2005
Quote:
but as i said all the printing is lighter also.
I don't know why this changed but there's and easy and documented fix for this in the service manual.
Quote:
2-31. The remaining comparators in U4, along with the
resistor network in U5, produce the variable duty-cycle
signal STB, which is nominally 10 kHz. The STD signal
will change its duty-cycle to keep its rms value constant and
thus print intensity constant. By changing the value of R8,
the nominal duty-cycle of STD can be changed to adjust
print intensity.
There's no way to tell what the current value of R8 is without looking. Each HP-97 was shipped from the factory with a selected value, they list values from 34.8K to 196K in the service manual, but they've all 1% resistors.
-Katie