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 Post subject: Need Oscilloscope Repair Shops
PostPosted: Jun Mon 03, 2019 3:58 pm 
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Joined: Jan Mon 17, 2011 2:10 am
Posts: 223
Location: Revere,Massachusetts U.S.A.
Hi Folks,

I am the proud owner of a BK 2120 scope and I would like to know if there are any repair shops in my area? I live about 3 miles north of Boston, Massachusetts. At the present moment, the scope works like a champ. It came to me in the original carton never powered up. I used a variac and brought it up to line voltage very slowly, I would have liked to replace the electrolytic caps but after taking the cover off...............Nope way above my paygrade.

I would appreciate any help that you folks could offer.
Thanks Tony

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 Post subject: Re: Need Oscilloscope Repair Shops
PostPosted: Jun Mon 03, 2019 4:52 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 11285
Location: Sunbury, Ohio 43074
The 2120 is a 20mhz dual trace scope. I’d use it till it blows up and then find something similar or better for $50. Or learn to fix it yourself.

Any shop that can work on these will have to charge you way more than the scope is worth

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 Post subject: Re: Need Oscilloscope Repair Shops
PostPosted: Jun Mon 03, 2019 11:20 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
Posts: 11141
Location: Long Island NY
This oscilloscope is actually very modern. The 2120 was introduced around 2005 and was still in production until around 2012 when it was replaced by the "B" model. The "C" version (30-MHz) is still in production and is one of the last analog CRT scopes you can buy new. While the first generation 2120 scope model is discontinued, B&K might still offer non-warranty repairs on it if needed. If not, they could probably tell you who does.

Pre-emptively replacing 7 to 15 year old electrolytics that appear to be working fine would be silly. Do you pre-emptively replace all the electrolytics in your TV set, even though there's nothing wrong with it? Do you open up your personal computer power supply and re-cap it, even though it is running properly? Do you take your car's engine control module out and change the electrolytics along with the spark plugs and fan belts? I didn't think so.

What I would suggest is that you let the scope run with the intensity turned down (to avoid burning the trace into the CRT phosphor) for about 24 hours. This will give any electrolytics which deformed in storage enough time to shape up, after which the scope should be good as new.

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 Post subject: Re: Need Oscilloscope Repair Shops
PostPosted: Jun Tue 04, 2019 2:41 am 
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Joined: Jul Mon 26, 2010 8:30 pm
Posts: 30055
Location: Annapolis, MD
My Tex scope from the 70s is still running on the original electrolytics.

But--when i get something like a 70s or 80s "popular-priced" receiver, electrolytics get replaced.

For everything that goes through here, the Tek is very much the exception--If I don't know the pedigree of an electrolytic, and it is over 30 years old---out it goes.....

My Onkyo receiver from the late 90s is still fine

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 Post subject: Re: Need Oscilloscope Repair Shops
PostPosted: Jun Fri 07, 2019 10:11 pm 
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Joined: Oct Thu 18, 2007 11:34 am
Posts: 3983
Location: Port Orchard, Wa 98366
Modern Scopes From Tektronix when idle do not burn the screen. This has been one of the selling points for many years.

Heres from a Tektronix booklet on Cathode Ray tubes.
Quote:
"Burn resistance
Any Phosphor can be burned but some are more easily than others. Phosphors may be divided into three groups when considering thier burn resistance.

Group 1 Low (easily burned) P12, P9, P26, P33
Group 2 Medium (moderate) P2, P4, P1, P7, P11
Group 3 High (hard to burn) P31, P15

Group 1 phosphers are easily burned and should be used with care. Group 2 phosphors are about 10-100 times more difficult to burn than those in Group 1, so normal care should be exercised. A P31 phosphor is quite difficult to burn. In fact, you really have to want to damage the phosphor even with a 10kV tube......."

In the manual for the 2213 Scopes it states that the phosphor used is P31.

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 Post subject: Re: Need Oscilloscope Repair Shops
PostPosted: Jun Sat 08, 2019 6:05 pm 
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 2895
Repairing an oscilloscope is no different from repairing anything else. Troubleshooting techniques are just like all other types of gear.

I just repaired my Tek 2215 that stopped working. Its problem had nothing to do with its being an oscilloscope; a failed power supply component was the culprit. (Not a capacitor)

I just repaired my old HP 6 digit voltmeter. Its problem had nothing to do with its being a voltmeter, just an intermittent circuit board connector.

I have a receiver I am going to scrap because repairing it would be too labor intensive. It has a complex gearing setup for one of the controls that has several problems and really isn't worth the time it would take to get it working. That's not even a circuit problem, although the radio has one of those as well. I will salvage the knobs and perhaps power supply components; there is an S meter as well and a small loudspeaker. Not to mention the rubber feet on the cabinet, etc. Sometimes it pays to be realistic about these things, especially in this case because the radio is from Radio Schlock and is labeled Realistic.


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