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 Post subject: Hickok 533A meter issue
PostPosted: Mar Tue 06, 2018 9:31 am 
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Joined: Jan Mon 25, 2010 7:51 am
Posts: 2692
Location: Toledo, Ohio
I picked up a 533A from a fellow radio collector who was retiring from the hobby. He told me the tester always worked but test results did not seem accurate.

I cleaned the tester up, replaced the couple caps and de oxit controls and fired her up. Everything seemed to work but noticed an issue with the meter. Pressing line check I noticed 3 out of 5 tries the meter would only read about 80% of what it should. It did this with line check and doing any test. I found a light tapping with my fingers on the meter would cause the needle to suddenly jump to the correct spot.

All of this was done with the tester flat on a table. To expiriment I stood the tester almost upright (about a 70% angle). In this position he meter worked perfectly, I tested several tubes never had an issue one time.

So I am assuming there is an issue with a sticking needle in my meter. Is there any maintanence that can be performed on this meter or am I just looking at straight up replacement with a known good one.

Thanks

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 Post subject: Re: Hickok 533A meter issue
PostPosted: Mar Tue 06, 2018 10:58 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 17933
Location: Albuquerque, NM 87123
Either it's sticking at the meter movement or there is a static charge on the plastic cover.

A sticking movement can sometimes be corrected by loosening the very small screw above the pivot.


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 Post subject: Re: Hickok 533A meter issue
PostPosted: Mar Tue 06, 2018 4:54 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2011
Location: Oswego, NY, USA
I agree w/ johnnysan; your original Hickok meter is probably very repairable. The anti-stat treatment you could use can be as simple as wiping the meter lens/face with a soft cloth dampened with diluted dishwashing detergent such as Dawn or Joy, then letting the detergent dry & not wiping it off. If you take the meter apart, be sure to also wipe the inside surface of the lens/face with the anitistat, too. Another possibility, especially since you get different response when re-orienting the tester (from horizontal to vertical) responses, is maybe a bit of dirt or metal shaving stuck between the moving armature winding and the magnet, which can be removed (cut a sliver of masking tape & carefully drawn thru the gap; be sure to not hit the coil springs with the tape) when meter's apart. Hickok-brand meters are noted for their needles & other armature parts coming unglued, so be very careful to not bump or twist the parts when working on it. Also make sure the tip-end of the needle is adequate distance away from the number scale across its travel-arc.....because if it rubs against the scale (in any orientation), then the needle will stick at very unpredictable times.

Fred


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 Post subject: Re: Hickok 533A meter issue
PostPosted: Mar Tue 06, 2018 8:19 pm 
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Joined: Jan Mon 25, 2010 7:51 am
Posts: 2692
Location: Toledo, Ohio
Hi guys, it is definitely not static, I have other test equipment with meters and I am familar with that issue. I keep static cling sheets stuck in my cabinet next to test equipment even. Yes, I have done the static treatment to the Hickok and no change.

I am leaning towards it being mechanical as there is a definitive percentage of full it always sticks at no matter what the needle position. It is always just like 10% short of where it should be and that exact same error can be reproduced over and over again until the meter is tapped or needle just pops loose on it's own. When it does come loose the meter will read at exact where it should be.

The reason I vertically repositioned the unit is too take the horizontal pressure off the needle. I am guessing there is an obstruction that is being hit when the unit-needle is horizontally weighted but it clears it when the unit is vertical. My hypothesis was right and it works beatuifully in vertical position.

I wasn't sure if these meters had a common issue with suspension of the needle assembly or something like that I did not know about. Tips or tricks for cleaning. I think my next step is to remove the meter for the tester, open it and put eyes on the inside to see if anything is obvious. Then possible the tape clean trick.

I also found someone with a web site on line sells-rebuilds Hickok tester meters so that is a good thing.

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 Post subject: Re: Hickok 533A meter issue
PostPosted: Mar Tue 06, 2018 10:11 pm 
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Joined: Feb Thu 24, 2011 3:13 pm
Posts: 852
Location: Ironwood, MI
I am very reluctant to treat the inside of any meter case with detergent or anything else. Maybe it is because of my HP and Tektronix gear. I do not know if Hickok applied any anti-static treatment to the inside of the meter case like other companies. I have also heard that, in addition to HP and Tek, there is at least one other company's product, the RCA Voltohmyst, in which removal of the anti-static coating inside the meter cover has a deleterious effect. Somewhere here on the ARF forum there is a thread about someone doing just that and his regret for doing so. The most I will do is apply Dawn or (as you) fabric softener sheets to the outside.

Fred is absolutely correct about checking to make sure the needle is true and not bowed. One time I had a similar problem and my "fix" was to loosen the meter screws, power up the tube tester and let the meter move until it stuck. Then I simply lifted the meter away from the face and movement and the needle continued moving proving it was bowed toward its tip end and rubbing against the outer meter cover. Be judicious with pliers, though. Those needles are so fragile.


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