I've recently gotten hold of a Tektronix 7633 oscilloscope but can't seem t o get a trace or any kind of waveform on the crt. Was wondering if I'm do ing something wrong , not doing something right , or is the scope in need o f repair? Is the repair complex ( I know my way around a soldering iron ) or should I just sell it for parts. It came with three plug-ins : Dual trace amplifier , curve tracer , and d ual time base. Tried two different function generators and the output from my 4-watt tra nsceiver. No joy. Any help would be greatly appreciated. Thank you.
Are you familiar with scopes at all? Any useful answer will need to be based on your degree of experience with them. Have you owned CRT-based scopes before?
--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.
I'm not an expert with scopes but , as I'm wishing to get back into homebre wing radio gear , I think one would be a very useful instrument to have on the bench. Looking at my original post , I suppose it's obvious that I've got a lot to learn , but this is something that I want to pursue in retirem ent ( I'm 64 ). About 15 years ago I owned a Sencore scope but sold it when I moved to a new house. Never really learned how to use it. But as I said , just trying to get at least a horizontal line on the crt. Then I can figure it out from there. Thanks.
On most Teks with plugins if you unplug the vertical ones you should get a line across the screen. Just leave the horizontal in. Put it o auto. If tha t doesn't work switch it to external input. If that doesn't work remove the horizontal as well, which on some will result in a spot in the center of t he screen.
Also good test points are the deflection plates, which are usually on the s ides of the neck of the CRT. You can tell the vertical ad horizontal pairs. The voltages should be close on each element of a pair but not necessarily pair to pair.
Schematics are available on the net, if the voltages match but are all off from what the print says look to the power supply. Of course if removing an y plugin restores the trace or spot, look at that first.
It is a bit rough to measure the high voltage directly but there are tellin g test points, usually the focus control. Good luck with it. If it does tur n out to be one of the plugins, they are available. They are not scrap pric es yet so I guess there is a significant number of these old beasts that wo rk.
I'm not an expert with scopes but , as I'm wishing to get back into homebrewing radio gear , I think one would be a very useful instrument to have on the bench. Looking at my original post , I suppose it's obvious that I've got a lot to learn , but this is something that I want to pursue in retirement ( I'm 64 ). About 15 years ago I owned a Sencore scope but sold it when I moved to a new house. Never really learned how to use it. But as I said , just trying to get at least a horizontal line on the crt. Then I can figure it out from there. Thanks.
a line across the screen. Just leave the horizontal in. Put it o auto. If t hat doesn't work switch it to external input. If that doesn't work remove t he horizontal as well, which on some will result in a spot in the center of the screen.
sides of the neck of the CRT. You can tell the vertical ad horizontal pair s. The voltages should be close on each element of a pair but not necessari ly pair to pair.
f from what the print says look to the power supply. Of course if removing any plugin restores the trace or spot, look at that first.
ing test points, usually the focus control. Good luck with it. If it does t urn out to be one of the plugins, they are available. They are not scrap pr ices yet so I guess there is a significant number of these old beasts that work.
a line across the screen. Just leave the horizontal in. Put it o auto. If t hat doesn't work switch it to external input. If that doesn't work remove t he horizontal as well, which on some will result in a spot in the center of the screen.
sides of the neck of the CRT. You can tell the vertical ad horizontal pair s. The voltages should be close on each element of a pair but not necessari ly pair to pair.
f from what the print says look to the power supply. Of course if removing any plugin restores the trace or spot, look at that first.
ing test points, usually the focus control. Good luck with it. If it does t urn out to be one of the plugins, they are available. They are not scrap pr ices yet so I guess there is a significant number of these old beasts that work.
Things to check (being extremely careful to not touch any cathode circuits until/unless you've verified that cathode voltage is discharged - it's probably around -2kV and enough current capacity to kill!):
make sure filament voltage is present. can you see any glow? is filament open?
verify that Z-axis isn't too negative relative to cathode (will extinguish any beam). This potential is used to blank between sweeps so may be hard to measure. If your 'scope has an X-Y mode that might turn it on for a long time and allow use of a DMM.
is cathode voltage as negative as manual indicates?
verify that V,H deflection plates aren't wildly off. You could disconnect all 4 plate pins, connect to ground - do you get a dot mid-screen?
My memory has faded. Is this the variable persistence model? That would complicate matters.
a line across the screen. Just leave the horizontal in. Put it o auto. If t hat doesn't work switch it to external input. If that doesn't work remove t he horizontal as well, which on some will result in a spot in the center of the screen.
sides of the neck of the CRT. You can tell the vertical ad horizontal pair s. The voltages should be close on each element of a pair but not necessari ly pair to pair.
f from what the print says look to the power supply. Of course if removing any plugin restores the trace or spot, look at that first.
ing test points, usually the focus control. Good luck with it. If it does t urn out to be one of the plugins, they are available. They are not scrap pr ices yet so I guess there is a significant number of these old beasts that work.
There are three plug-ins on this unit ( none of which are just horizontal o r vertical ): curve tracer , dual trace amplifier supplying the channel 1 a nd channel 2 inputs , and a dual time base. I pulled the curve tracer. No dice. I swapped the dual trace amp with the dual time base. No good. I cle aned all of the terminals on the back of each plug in. I even pulled out al l of the plug-ins. No luck. There are no inputs on the main oscilloscope itself so I have to rely on the dual trace amp plug-in to input a signal. I've downloaded a copy of the user and service manuals so I'm going to lo ok it over. Thank you all for your time. ( PS ) I also have a BK Precision scope that works well but it's only 10 MHz bandwidth. I really need the 100 MHz for rf work.
et a line across the screen. Just leave the horizontal in. Put it o auto. I f that doesn't work switch it to external input. If that doesn't work remov e the horizontal as well, which on some will result in a spot in the center of the screen.
the sides of the neck of the CRT. You can tell the vertical ad horizontal p airs. The voltages should be close on each element of a pair but not necess arily pair to pair.
off from what the print says look to the power supply. Of course if removi ng any plugin restores the trace or spot, look at that first.
elling test points, usually the focus control. Good luck with it. If it doe s turn out to be one of the plugins, they are available. They are not scrap prices yet so I guess there is a significant number of these old beasts th at work.
al or vertical ): curve tracer , dual trace amplifier supplying the channel 1 and channel 2 inputs , and a dual time base. I pulled the curve tracer. No dice. I swapped the dual trace amp with the dual time base. No good. I cleaned all of the terminals on the back of each plug in. I even pulled ou t all of the plug-ins. No luck.
y on the dual trace amp plug-in to input a signal.
to look it over. Thank you all for your time.
y 10 MHz bandwidth. I really need the 100 MHz for rf work.
et a line across the screen. Just leave the horizontal in. Put it o auto. I f that doesn't work switch it to external input. If that doesn't work remov e the horizontal as well, which on some will result in a spot in the center of the screen.
the sides of the neck of the CRT. You can tell the vertical ad horizontal p airs. The voltages should be close on each element of a pair but not necess arily pair to pair.
off from what the print says look to the power supply. Of course if removi ng any plugin restores the trace or spot, look at that first.
elling test points, usually the focus control. Good luck with it. If it doe s turn out to be one of the plugins, they are available. They are not scrap prices yet so I guess there is a significant number of these old beasts th at work.
al or vertical ): curve tracer , dual trace amplifier supplying the channel 1 and channel 2 inputs , and a dual time base. I pulled the curve tracer. No dice. I swapped the dual trace amp with the dual time base. No good. I cleaned all of the terminals on the back of each plug in. I even pulled ou t all of the plug-ins. No luck.
y on the dual trace amp plug-in to input a signal.
to look it over. Thank you all for your time.
y 10 MHz bandwidth. I really need the 100 MHz for rf work.
Ok group. Worked on the 7633 and replaced a fuse on the first board you se e when you remove the back cover. This fixed a few things. I now can get a trace , the CRT is nice and clear , and the flash that occurred every 8-9 seconds has stopped. One problem left. The trace is vertical instead of horizontal. Still get a waveform from the function generator , but verti cal. Why is that? Thanks for all your previous help.
Try fiddling with the timebase controls. Some scopes (notably Philips) have exceptionally complicated timebase options. Can't recall what yours is off-hand, sorry.
--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.
u see when you remove the back cover. This fixed a few things. I now can get a trace , the CRT is nice and clear , and the flash that occurred every 8-9 seconds has stopped. One problem left. The trace is vertical instea d of horizontal. Still get a waveform from the function generator , but v ertical. Why is that? Thanks for all your previous help.
No Mike , I don't think the plug-ins are in those particular slots. I'll c heck and make the appropriate swaps. Does it matter if , in the two left s lots , where the dual trace amplifier or the curve tracer go? Thanks
The vertical amplifiers can go in either the left slot or the center slot. The horizontal amplifier has to go in the right slot, so if you have a curve tracer it has to go into the *right* two slots (it controls the horizontal and it controls the vertical ;-).
If you have two vertical amplifiers, you can put them in the center and right slots and do X-Y. I believe a timebase will work in the center or left slot but it doesn't make much sense (the trace will be vertical).
you see when you remove the back cover. This fixed a few things. I now c an get a trace , the CRT is nice and clear , and the flash that occurred ev ery 8-9 seconds has stopped. One problem left. The trace is vertical ins tead of horizontal. Still get a waveform from the function generator , bu t vertical. Why is that? Thanks for all your previous help.
l check and make the appropriate swaps. Does it matter if , in the two lef t slots , where the dual trace amplifier or the curve tracer go? Thanks
Ok gentlemen , all is well at the AB8CQ workbench. The 7633 is percolatin g nicely after I put all the plug-ins in the right place. I'd like to than k all of you for your input and advice. I'll make sure to come back to thi s group in case I have any other issues. Thanks again.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.