Rf sampler smoked out my radio

[Captain Kilowatt]

All of this discussion about the sampler, the 'scope and the house AC service is nice, but I believe the reason the radio smoked was due to "HUMAN ERROR". When 805 repaired the burnt trace, he soldered the jumper to wrong place on the board. Here is the photo he posted.View attachment 18580

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I thought the trace was just burned but still there. Old eyes I guess. In any event I don't see how simply hooking a load to the antenna jack which is DC isolated would cause something to fry back in the DC input area. Stranger things have happened however I guess but the hot scope chassis is still an issue.

 

[222DBFL]

Maybe not. Find a shop that does calibrations on equipment such as that. It might be able to be fixed very simply. Just don't do it yourself if you don't know about AC voltage and such. That is JMHO. Don't get so discouraged yet man!! If you don't fail sometimes, you will never learn from your mistakes. And this one could have possibly saved your life in the end. If indeed anything was YOUR fault!! Which doesn't appear to be the case!!!! So keep your head high and don't let MURPHY's LAW, have its way with you!! Or look for another scope. They are around if you LOOK and ask the right people. Not me included, just saying.

 

[Captain Kilowatt]

I thought about this again. If that jumper is not in the right place and IF it is associated with the radio's ground then the scopes cgassis voltage certainly could cause grief. If the scope chassis grounded the issue may go away. Check for continuity between the ground pin of the power cord and the scope chassis. If there is none then that is half the problem and if there is then there is a problem with the way the outlet is wired because if the chassis is grounded then there won't be any voltage on it if the outlet is wired correctly.

 

[805 california]

I thought about this again. If that jumper is not in the right place and IF it is associated with the radio's ground then the scopes cgassis voltage certainly could cause grief. If the scope chassis grounded the issue may go away. Check for continuity between the ground pin of the power cord and the scope chassis. If there is none then that is half the problem and if there is then there is a problem with the way the outlet is wired because if the chassis is grounded then there won't be any voltage on it if the outlet is wired correctly.

10-4. The radio didn't have a burnt trace before I hooked it up to the scope. The first time I hooked it up to the scope the radio didn't turn on.... I looked and it burned the trace. I repaired the trace with solder, powered up the radio without the scope and it worked fine. Hooked it up to the scope and burnt the trace again. This happened three times before I finally had to jump the trace. It has to be the scope.

 

[kaos513]

10-4. The radio didn't have a burnt trace before I hooked it up to the scope. The first time I hooked it up to the scope the radio didn't turn on.... I looked and it burned the trace. I repaired the trace with solder, powered up the radio without the scope and it worked fine. Hooked it up to the scope and burnt the trace again. This happened three times before I finally had to jump the trace. It has to be the scope.

Have you tryed changing the part numbers that go those traces?Maybe just maybe you have a faulty part causing the scope act that way,just a thought.just a simple question, Are those original rectifer diodes or you added higher voltage diodes?

 

[Captain Kilowatt]

Anything done inside the radio would not affect the sco0e "and make it work that way". I still say to check for continuity in the power cord's ground pin to chassis. You could throw a clip lead from the chassis to a ground screw on a cover plate if the outlet is wired right to carry the ground. If there is a bad issue the breaker will trip and if it just a floating ground issue things will work right like I did to a piece of test gear I had just like I mentioned a couple pages ago .

 

[kaos513]

Sorry for confusion i just read where the op states when he takes it off the scope radio works fine,must be the test equipment.

 

[Tallman]

It has to be the scope.

Have tried calling Tektronics tech support? I'm willing to bet they have seen this more than once and can direct you into the proper place to look.
Check the place in back of the scope where you can select the operating line voltage. There a device in which you can select 110 Vac or 220 Vac for the power supply. Be sure it is set to 110 Vac.

 

[805 california]

I thought about this again. If that jumper is not in the right place and IF it is associated with the radio's ground then the scopes cgassis voltage certainly could cause grief. If the scope chassis grounded the issue may go away. Check for continuity between the ground pin of the power cord and the scope chassis. If there is none then that is half the problem and if there is then there is a problem with the way the outlet is wired because if the chassis is grounded then there won't be any voltage on it if the outlet is wired correctly.

Check for continuity between ground pin on scopes power cord??

 

[Captain Kilowatt]

(Sigh)........Using an ohmeter.....does the ground pin of the power cord have a good connection to the scope chassis?

 

[bob85]

I once got a small shock as i disconnected the antenna from a locals yaesu 7700 receiver,
touching the plug outer to the chassis of the radio produced a spark, measured about 60v, he had run 2 core cabe to his shack from the garrage,
replacing the cable for twin & earth fixed the issue,

 

[BBB]

A little late to the party, but this is a good related watch. About halfway thru, Mr Carlson talks about Oscilloscope electrical isolation and its relation to hot chassis mishaps.

 

[805 california]

There is continuity between ground pin and chassis. I get the same reading on the volt meter from wall ground to chassis and wall neutral to chassis reading .675 ac volts. Then if I turn on my power supply and plug in scope: I touch negative terminal on power supply and positive on chassis of scope and get 24 volts DC and 34 volts ac.

 

[Captain Kilowatt]

I'm beginning to think you should have bought some knitting needles and yarn instead of a scope. Sorry but I have offered all I can. It is a simple solution I know it and I am sure that if I was hands on there it would be solved in a few minutes with a few simple hands-on tests that I have done numerous times. There is definitely an issue with the grounds in your set up. Someone with a good knowledge of electrical principals should be able to find and solve the problem in short order be-it no ground or reversed neutral/hot leads. Time to call an electrician and let someone who knows what they are doing look at it for you. I don't want to be known as the guy that gave you info that resulted in your electrocuting yourself because you didn't know what you were doing. In the meantime I wouldn't use that scope. It's not junk it simply is incompatible with whatever you have for AC distribution in your home.

 

[222DBFL]

Then you have no ground at the chassis of the scope. You need to find some kind is service shop that can work on it. Or look for a new scope. There is obviously some type of ground and AC power issue. Could be a simple fix, could be a big issue. Hard to tell without taking the covers off the scope and checking the wiring from the power plug back to inside the scope. Tracing wiring and checking for proper grounding and wiring itself as any burnt components. You need to UNPLUG the scope, turn the power ON, and let any remaining power get discharged. Let the scope be for a couple days and research the issue you have to any other issues that other may have had that appear to be the same as yours. Then, after a couple days. Slowly remove case on scope and look at the power plug port. Check the wiring first and then trouble shoot back from there. Making sure to be very mindful that there could still be some power left over in a capacitor somewhere. Like CK said, trying to help trouble shoot AC power issues isn't easy over the forum!! Not like being your next door neighbor as stated. Just be VERY CAREFUL. No jewelry, chains, this goes for necklaces as well. And make sure you take your time. That is if you even decide to mess with any of the inside of the scope. JMHO's.