HK Citation V Grounding Help Needed

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Re: HK Citation V Grounding Help Needed

Postby DeathRex » Tue Dec 29, 2015 10:08 am

It would have a small display and you have to build it, but it might work. Don't need more than a few megahertz, of course you don't need more than a few Hz to chase hum.

There's also software oscopes, but you need some sorta hardware for the probe connection.
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Re: HK Citation V Grounding Help Needed

Postby dannyr » Tue Dec 29, 2015 12:11 pm

I'll have to look more into this. Maybe it's better to get a full sized scope. Once I have one do you have any tips on how to use it to trace the source of hum?
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Re: HK Citation V Grounding Help Needed

Postby DeathRex » Tue Dec 29, 2015 1:50 pm

The hum will appear on the signal, probably best to half split, or work your way backwards from the output with the volume all the way down. Connect oscope's ground to the chassis and follow the hum.
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Re: HK Citation V Grounding Help Needed

Postby dannyr » Tue Dec 29, 2015 11:37 pm

Okay great. Now I have to figure out what's a good/cheap scope to get. I have so much older stuff that I'm sure it will come in handy once I learn how to use it.
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Re: HK Citation V Grounding Help Needed

Postby cdmawolf » Wed Dec 30, 2015 10:40 am

For chasing a hum problem, any decent USB scope setup should work.
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Re: HK Citation V Grounding Help Needed

Postby dannyr » Wed Dec 30, 2015 1:00 pm

Okay great. I'd need a x100 probe though right? I'm still trying to educate myself on all of this seeing if it's better to just get a used full sized scope or not etc.
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Re: HK Citation V Grounding Help Needed

Postby DeathRex » Wed Dec 30, 2015 3:26 pm

dannyr wrote:Okay great. I'd need a x100 probe though right? I'm still trying to educate myself on all of this seeing if it's better to just get a used full sized scope or not etc.

I've never heard of a x100 probe, I have 3 10X probes (I melted the 4th), it just means that the probe will divide the voltage by 10, where a 100X probe will divide the voltage by 100. My scope will take up to 10 volts per division with 8 divisions (the outlined boxes inside the screen). You'll see on the cheapo scope from ebay has 8 vertical boxes and 10 horizontal boxes. The ebay scope goes from 10mv to 5v per division, so you can see a signal as small as about 2mv up to 40 volts full screen or 8 vertical boxes X 5 volts per box. With a 10X probe you can go up to 400 volts. With a 100X probe you'll be able to go up to 4000 volts. You don't need on to check for hum. Only time you would need one is checking the voltage on the primary side of output transformers, or secondary side of power transformers, I use a multimeter for that.
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Re: HK Citation V Grounding Help Needed

Postby DeathRex » Wed Dec 30, 2015 3:35 pm

Wow they do have 100X probes on ebay, and kinda cheap too, $14.

If you have a lot of cash, and are going to be building or fixing old amps or radios, I would get a nice Tektronix oscilloscope, you can spend from a few hundred to a few thousand. I like them because we used them in the Navy. I have a Tektronix 2215 60MHz, that does everything I want except store.

If you don't know if you're going to be doing a lot of fixing, I would get the cheap one from ebay and put it together, it will require a lot of soldering, and troubleshooting if things go wrong.
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Re: HK Citation V Grounding Help Needed

Postby dannyr » Wed Dec 30, 2015 3:47 pm

Thanks for the advice Death. I'm a newbie when it comes to this stuff. I'm going to check craigslist and if there's nothing interesting I'll just go the cheapo route. I'll then be able to make a better choice when I need something better.
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Re: HK Citation V Grounding Help Needed

Postby dannyr » Wed Dec 30, 2015 3:56 pm

On Craigslist there are a few by me that are priced well at $40 each. It looks like I have a choice between a Tektronix 2214 or a 2235. Which would be the better one to grab if both are still available? Thanks.
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Re: HK Citation V Grounding Help Needed

Postby DeathRex » Wed Dec 30, 2015 4:51 pm

2214 is a 4 channel, that one would be expensive new.
2235 looks like mine except newer.
At $40 each if they work, I would get both. At $80 each I would get both.
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Re: HK Citation V Grounding Help Needed

Postby DeathRex » Wed Dec 30, 2015 4:56 pm

He doesn't say if they work. If they do work they should be worth about $300 or so.
Last edited by DeathRex on Wed Dec 30, 2015 4:57 pm, edited 1 time in total.
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Re: HK Citation V Grounding Help Needed

Postby dannyr » Wed Dec 30, 2015 4:57 pm

I emailed him and am waiting for a response on if they are functional. I hope to get at least one of em.
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Re: HK Citation V Grounding Help Needed

Postby DeathRex » Wed Dec 30, 2015 5:02 pm

I searched all of Colorado and New Mexico came up with 1. You seem to be in an excellent place for good used test equipment.
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Re: HK Citation V Grounding Help Needed

Postby dannyr » Wed Dec 30, 2015 9:39 pm

The four channel one was sold. I got told to call after the new year for the other. I hope to get it but who knows. You never know with Craigslist.
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