Hi,
Yet another scope in trouble ...
HP 1222A. Has always been working fine, but recently (after a longer pause) it suddenly has developed a "sawtooth" baseline.
- periodicity ~9 ms, int'y ~1 graticule
- both channels are equally concerned
- A/B gain setting or grounding does not change amplitude
- both channels can be moved up/down w/o problems
- input signal overlays the "sawtooth"
- sawtooth reacts on trigger (or vice versa ;-)
- sawtooth becomes "steeper" if moved beam is moved to the lower part of the CRT
Power supplies:
+95 V adjusted, OK +210 V reads +219.5 V +12 V reads +14.20 V, -12 V reads -14.25 V (at least symmetrical ;-)I suspect that the input channels are OK and that the problem is probably related to the vertical deflection (or sweep?).
Before diving into the circuit ... does that ring a bell ... anybody?
Please feel free to contact me either via the newsgroup, or per direct mail.
Thanks in advance for any help, and greetings from Lausanne!
- Joerg
[ xpost to s.e.equipment & s.e.repair, f'up to s.e.e. ]