Unit that you already own, and it died?
Or, unit you bought used and it is dead??
Download the manual and schematic.
Check the voltages at key points...
Does the pilot light come on?
The "screen illumination" knob make light on the scope grid??
If not, then somehow there is no voltage getting to the power supply, I would expect.
Fan come on??
_-_-bear
Or, unit you bought used and it is dead??
Download the manual and schematic.
Check the voltages at key points...
Does the pilot light come on?
The "screen illumination" knob make light on the scope grid??
If not, then somehow there is no voltage getting to the power supply, I would expect.
Fan come on??
_-_-bear
Tektronix 475 Service Manual available (via the US military) at the following URL:
Nice scope; good luck!
Nice scope; good luck!
Thanks I think I might have it figured out blue diode now just have to figure out its value in diode check on my multimter its showing .0007 almost a dead short but you would think fuses would blow but looks like it is causing everything to short one side of the diode says +15 other side is ground I am guessing that's a good place to start I payed 40 for the broken scope it is mint condition lol besides it won't power up what kind of diode is a blue one not sure I work on car amps and have really never messed with ac could be a cap to I am guessing
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TekScopes · All about classic Tektronix CRT o'scopes
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diode between the AC mains from the wall??
and 5ohms is not necessarily too low looking at the resistance between the two hot wires on an ac power cord...
again, a jpeg might tell more of the story since your description is not entirely clear at this point.
Also the Tek scopes usually have a switch on the back that sets the voltage for 120ac or 240ac nominal.
_-_-bear
and 5ohms is not necessarily too low looking at the resistance between the two hot wires on an ac power cord...
again, a jpeg might tell more of the story since your description is not entirely clear at this point.
Also the Tek scopes usually have a switch on the back that sets the voltage for 120ac or 240ac nominal.
_-_-bear
Ok I have power disconnected all the leads off the transformer I had screen lit up for a couple min then that went away screen will flash when turning power switch on and off the reason I unsoldered the wires off the transformer is because manual said to. I think it needs a new transformer power supply I am not sure if the screen partly run off the transformer or not I am having problems getting pics up thanks bear for helping me out with such little info. Do you have any ideas or could I send the scope to you
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I have repaired two Tektronix 275 oscilloscopes, so if you can better describe your problem, I'll probably be able to help. One of the biggest issues with these is that they become encrusted with gunk and corrosion over time, even between gold surfaces (contaminants accumulate on their surfaces) so most vintage oscilloscopes and other test equipment need an exhaustive cleaning of switches and contacts with denatured alcohol or (preferably) CAIG DeOxit, which has mineral spirits to lubricate switches as well as contains a far better cleaning compound.
Question is, what is actually going on?
You say that there was "5 ohms between the two wires" -- if that is "neutral" and "hot", you should see infinite resistance with the power switch off, and some value equivalent to the resistance of the transformer...there is not supposed to be a diode, as that would short out every halfcycle...? Is this a fuseholder?
Question is, what is actually going on?
You say that there was "5 ohms between the two wires" -- if that is "neutral" and "hot", you should see infinite resistance with the power switch off, and some value equivalent to the resistance of the transformer...there is not supposed to be a diode, as that would short out every halfcycle...? Is this a fuseholder?
I think at your knowledge level you'd be better off NOT messing around inside of it. They can be repaired by qualified techs but can be seriously damaged by inexperience not to mention there are lethal Voltages in there. Quit while you're ahead.
G²
No, sorry you can not send the scope to me except as a donation...
I don't know where I have read in a Tek manual where it says to unsolder the wires from the transformer. I think you need to do some basic things first... what jtl said needs to be clarified by you.
When you post what you find, it is important to be specific about what you are testing, how you tested it, and what you are finding...
the bottom line is that it is unlikely that you will be able to troubleshoot a Tek scope unless your grasp of schematic reading and basic measurements is clear and sound.
I'd buy a working scope... they are fairly inexpensive on ebay now, of course the cheaper ones are being sold as "parts or repair" because the sellers don't want any hassles or returns. But if you look carefully and ask questions you can likely get a good one pretty darn cheap. Even another 275, then you have a parts unit already, if you need it.
_-_-bear
I don't know where I have read in a Tek manual where it says to unsolder the wires from the transformer. I think you need to do some basic things first... what jtl said needs to be clarified by you.
When you post what you find, it is important to be specific about what you are testing, how you tested it, and what you are finding...
the bottom line is that it is unlikely that you will be able to troubleshoot a Tek scope unless your grasp of schematic reading and basic measurements is clear and sound.
I'd buy a working scope... they are fairly inexpensive on ebay now, of course the cheaper ones are being sold as "parts or repair" because the sellers don't want any hassles or returns. But if you look carefully and ask questions you can likely get a good one pretty darn cheap. Even another 275, then you have a parts unit already, if you need it.
_-_-bear
just to be certain, you have checked the line fuse and any fuses on the power supply board with an ohmeter (should read like a short - ie. the leads from your meter touched together)? There is a chance that all that is wrong is that you need to put a properly sized fuse in either the AC fuse position or else on the power supply board.
Unplugged, power off for this test.
Beyond that, best to get another scope imo...
Unplugged, power off for this test.
Beyond that, best to get another scope imo...
A good point -- if the words "flyback" or "voltage multiplier" don't ring any bells, step away from the scope. There's a -2500v supply floating all over the place on one of the boards, which then gets yonked out to +15kV for accelerating the electron beam. These are all lethal, but there are a multiplicity of other issues at hand, so it may be a project to indeed shelf or to pass on to someone else. I'd be willing to take a look -- if you are willing to ship it to Cleveland (and I might have to give you a quote to fix it.)
Depending on where it came from, the wall plug was possibly cut off because the scope was deemed to be electrically unsafe to power up.
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