Author Topic: Heathkit oscope repair  (Read 2459 times)

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Offline Daniel_Reyes

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Heathkit oscope repair
« on: August 29, 2015, 11:23:02 pm »
Does anyone have any safety tips when it comes to probing an old heathkit oscope that uses tube amplifiers?

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Offline AF6LJ

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Re: Heathkit oscope repair
« Reply #1 on: August 29, 2015, 11:36:42 pm »
Yes;
1. get to know your circuit, know where the HV is.
2. use a meter rated for task at hand, don't attack that scope with a Cat-2 meter.
3. if you are going to measure high voltages over 1KV use a proper high voltage probe..
4. when making the measurements keep your left hand in your pocket.
If that hand is in your picket it won't be completing a a path to ground should you come in contact with even moderate voltages. The electrical path across the heart; BAD NEWS.
Sue AF6LJ
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Offline Daniel_Reyes

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Re: Heathkit oscope repair
« Reply #2 on: August 29, 2015, 11:38:10 pm »
Are those cheap free multimeters usually cat 2?

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Offline AF6LJ

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Re: Heathkit oscope repair
« Reply #3 on: August 29, 2015, 11:54:57 pm »
Are those cheap free multimeters usually cat 2?

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Yes at least the one I have here is.
I don't use it unless I have to, I a decent that was built before the CAT ratings.
One of these days I will do a teardown of it.
Sue AF6LJ
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Offline Daniel_Reyes

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Re: Heathkit oscope repair
« Reply #4 on: August 30, 2015, 12:04:40 am »
What aspect of high voltage leads makes them rated for high voltage? Insulation resistance?

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Offline AF6LJ

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Re: Heathkit oscope repair
« Reply #5 on: August 30, 2015, 12:20:28 am »
What aspect of high voltage leads makes them rated for high voltage? Insulation resistance?

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That and the way the probes are built.
http://www.trs-rentelco.com/Model/FLU_80K_40.aspx?ctcampaign=3716&ctkwd={product_id}&ctcreative={creative}&gclid=Cj0KEQjwsIWvBRCnzevvor2g4L8BEiQAAN234b-eesSeMqAuz78qpT1YuAQ6LpNzl-dRmQMrB4pisFAaAs9u8P8HAQ

Get your hands on a manual for that scope, Heath manuals are full of real good troubleshooting information.
What is wrong with the scope to begin with?
Sue AF6LJ
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Offline Daniel_Reyes

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Re: Heathkit oscope repair
« Reply #6 on: August 30, 2015, 12:23:30 am »
I'm not sure yet. A friend is giving it to me to have, I just need to fix it first. 

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Offline AF6LJ

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Re: Heathkit oscope repair
« Reply #7 on: August 30, 2015, 12:28:34 am »
I'm not sure yet. A friend is giving it to me to have, I just need to fix it first. 

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When you get it;
The first thing you want to check is to see if the transformer windings are all okay and that none of the windings are shorted to each other. This is a problem with early Heath scopes. I have a Heath Vector scope in the garage with a blown transformer.

That is your first place to start.

Heath used a lot of carbon comp resistors, many that were used in the CRT circuits were not rated to hold off the voltages they saw in real use, the resistors would go high in value.
Check all the resistors connected to the V and H position, focus and intensity controls.

When you get it post a picture.
Sue AF6LJ
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Offline Daniel_Reyes

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Re: Heathkit oscope repair
« Reply #8 on: August 30, 2015, 12:44:48 am »
Will do! Thanks!

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Offline bills

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Re: Heathkit oscope repair
« Reply #9 on: August 30, 2015, 02:43:42 am »
Tip #1 Replace all wax and filter caps before applying power!
     # 2 Get an  manual has all test points and assembly instructions.
If you post the model # I may be able to help you find one, or do a search manual pdf's are easy to find.
Never argue with idiots. They drag you down to their level and beat you with experience.
 

Offline Daniel_Reyes

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Re: Heathkit oscope repair
« Reply #10 on: August 30, 2015, 02:51:21 am »
Will do! I'll take it slow with this one. Never worked on a scope before. I should have in by next month and ill post to here.

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Offline AF6LJ

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Re: Heathkit oscope repair
« Reply #11 on: August 30, 2015, 12:24:54 pm »
Will do! I'll take it slow with this one. Never worked on a scope before. I should have in by next month and ill post to here.

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Sounds good
Sue AF6LJ
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