EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: djuma89 on February 09, 2022, 09:37:37 pm
-
Greetings from Serbia,
I came into possession of the Australian oscilloscope BWD from 1987, serial number: 41649. The oscilloscope was faulty but I partially enabled it. My first step was to replace all the electrolytic capacitors. Then I fixed the faulty intensity potentiometer after which I got the picture actually a trace. I adjusted all positions according to the instructions for the first start. I got a pale and flickering dot on the screen.
https://manual-hub.com/manuals/bwd-539d-01-pdf-manual/
Then turned on the X-Y button and brought the X wire to the input with my finger😊 In the attached picture you can see that the oscilloscope reacted which means that the X amplifier is good.
[attachimg=1]
Then I inspected the TB / X-Y switch and it seems ok to me. Focus changes sharpness also. Switch s201 works ok as far as I could measure.
I reviewed the Q253 Q255 bi- stabile trigger, Q257 miller saw generator and Q256. The component test says they are good after I took them off the PCB.
[attachimg=2]
I would ask you if anyone has any advice? Thanks.
Djuma
-
Welcome to the forum.
Connect a channel to the Cal output which although not a precise signal source serves just fine for rudimentary tests.
-
When I connect to the CAL only the point rises a little up. I don't see a horizontal line, just a dimly lit point, although the focus is set and the intensity is almost full turn. This is on both channels same. What do I check next?
-
When I connect to the CAL only the point rises a little up. I don't see a horizontal line, just a dimly lit point, although the focus is set and the intensity is almost full turn. This is on both channels same. What do I check next?
It might be the Cal output is not working. Check its output with a DMM in ACV.
-
2.14 VAC measurements Sanwa DCL1200R
-
If you have a signal or function generator you can put the Same signal into both channels. In X/Y mode it should be a line at about 45 degrees.
This will check both your channel amps.
Maybe you have no Time Base (Horizontal) in your scope.
If you are applying a small DC voltage to the inputs. Put the scope in DC mode. DC will not make it through the input if the scope is in AC mode as in your nice picture.