hi David,
thx for the tip! i will check this as soon as possible (couple days out of town). i check tp444 before with ext. trigger and that was very small compared to the input signal. don't know the exact amplitude but much lower.
probably back on saturday. tjeenz.
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--- In TekScopes@..., David <davidwhess@...> wrote:
I would start by looking at TP444 (middle of schematic 4) which should
be a duplicate of the trigger input signal as selected by the source
and coupling controls. At the very least, there should be a 60Hz sine
wave at that point when the trigger source is set to line.
Then I would check pin 2 of U460B which should be a duplicate of the
tri.gger level voltage as set by the trigger level control. In Auto
mode this voltage will be between the peak levels of the trigger
signal but in normal mode, it should be between +0.65V and -0.65V.
It would be nice to have a nicer scan of the service manual. I
extracted and cleaned up schematic 4 from the one available online:
On Tue, 18 Sep 2012 11:00:41 -0000, "tjeenz" <tjeenz@...> wrote:
Hi,
Have a trigger problem with a 2213 tektronix.
In auto and line trigger i have a baseline. In norm not. Also ext. trigger fails (signal from function generator 4v pp and ch1 on 1v/div)
cannot get still image to see frequency, amplitude is ok. with signal on one of the channels, trig in auto i can almost get still image if freq is low enough with var hold-off. trig-level does nothing. Also the trigger led never blinks.
Checked all p.s. voltages. Are ok (no ripples), but according to service manual there should be some specific resistance on the voltages. These are way too low in my scope:
8.6v 114 ohm at tp500= 58 ohm
+8.6v 95 ohm at W975 = 16 ohm
+5v 330 ohm at W985 = 16 ohm
+30v 905 ohm at W965 = 16 ohm
+100v 12.5 kohm at W966 = 16 ohm
so i guess something is wrong somewhere. checked the big capacitors in the p.s, for 30V and +8.6V, both were in spec.
Are these resistance values in the manual a good reference for finding the faulty area?
regards, tjeenz
