Just aquired an 465B Scope.
I have no sweep, just a wide dot when I press the beamfinder.
When I lower the timesetting I can see one single square wave, same on both channels, It seems not to be affected by the settings on the Hor- sensivity and the input selector is set to gnd.
Anyone that knows where to start.
Could be a switch setting problem. Try this:
Hook a wire from ch1 input to the calibrator loop. Ch1 input selector to "AC", 0.1V/cm, var knob all the way clockwise until it clicks. vert mode press ch1 only DOWN, all other buttons in this column OUT.
Set the two Position knobs staright up.
Sweep speed: 5 ms/cm var knob all the way clockwise until it clicks.
"x10" button OUT Intensity 3/4 of the way up.
Press sweep mode: Auto Sweep source: "A"
Press trigger source: Ch1, internal Trigger mode: normal, AC
Turn the trigger A knob to pointing straight up. The "trig" light should go on, if it doesnt, turn the knob until it does. You won't be able to see ANYTHING until you can get the TRIG light to light up. Work on this first.
Press the beam finder. You should see a bright but small square wave. Now use the horiz and vertical position knobs to center the square wave on the screen. release the beam-finder button and you should see about five cycles of a square wave. You might have to adjust the intensity and focus knobs for best appearance.
"ktl" wrote in news: snipped-for-privacy@g44g2000cwa.googlegroups.com:
I suggest you buy a service manual,and read the circuit description,it is very detailed and VERY helpful.
another scope will be very useful in troubleshooting the sweep generators and unblanking circuits where your problem could lie. It may only be a CRT bias adjustment.
-- Jim Yanik jyanik at kua.net
Finally solved it, 5 V supply was dead, due to a faulty filter cap. Now it is working, but I guess that I need to do a complete check, what I've seen is that the sweep starts one division below, then ramps up very quickly, like within 1 to 2 subdivisions, and that there is some sort of signal, even visible when inputs set for gnd.
Looks like there are even more of the voltages in the LV power supply out of tolrance. Probably at least one more dry capacitor, or even worse faults.
I'd recommend you download a complete service manual 8bama.sbc.edu or bama.edebris.com) - you nee the Lizardtech browser to open the files, but both (manual and browser are free of charge).
Then start to check the LV pwr supply carefully.
Looks like when you are through this, chances are good you have a nice working scope.
hth, Andreas
Got the manual, getting hold of another scope and a function-generator and do a complete checkout.
The Lizardtech browserthing was a terrible experience, had to save each schematic page (as well as other pages) as as bmp-file in order to print it properly. No-one got it in pdf?
Well, since I had no problmes to view and print the document with the Lizardtech browser - looks there is something unhappy with your pc or it's setup.
Well, you might check the other free download sites
Or buy a .pdf manual file from one of the sellers in the web.
It's of your choice ;-)
I hope your tek scope is doing fine now.
hth, Andreas
Well the problem with the Lizardtech browser is that there is no functions to do tiled printouts of the large pages, to get proper printouts I'd finally had to export them to bitmap, and import them into a photoeditor and then do a tiled printout.
I have been digging into my scope for some time, but there is one thing I cant find, because the fault dissapears when the casing is removed, seems to be heat related.
WHen the scope is powered up, both channels set for gnd, I can se a stright fine line for each of the channels, but after som 5 minutes or so the sweep is distorded, it sort of look like this: _____________________________ I \
The difference between the start of the sweep and the horizontal line is about one div, if I try to write the sweep in XY coordinates it looks something like this Start 0.5,-1 start+1 0,-0.5 start+2 0,0 start+3 1,0 Then it is a straight line This at 20ms At 10 ms It looks like this _______________________________ I I
And then the faster the sweep goes, the straighter line.
Now if anyone had any ideas where to start to look, so I could try to heat up components carefully, to see which component that is failing. I woild be grateful.
Best regards Tomas.
Mind to the big condensators in power supply. They are often dry. I had to change both in my 3 scopes 465.
-- -- Marcel Beysselance marcel.beysselance@hi-tek.fr www.hi-tek.fr
Marcel Beysselance wrote in news:43482b6a$0$455$ snipped-for-privacy@news.club-internet.fr:
PS filter Capacitors,electrolytics.
They also can leak corrosive electrolyte onto the PCB,eating away copper traces.
Power supplies should always be the first thing checked;voltage,ripple,AND line regulation(VARIAC needed).
-- Jim Yanik jyanik at kua.net
As it transpired, it was the Fan-motor assembly that caused the problems. After some 5 mins, the fan stalled and was pulling near 400mA from the +15 supply, not enough to shut it down, but enugh to disturb other systems. After changing the DIL14 quad transistor array, to normal BC557's discrete (plugged into the DIL-socket) it seems to work like a charm. Previously I did change all the filter-caps int pwr-sup, since they were dead. But I think that at the moment it seems to be ok, I will leave it on now for a day or so, to see if the fix lasts.
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