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 Post subject: Hickok 533a meter swinging backwards?
PostPosted: Jun Tue 18, 2019 5:38 pm 
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Joined: Jun Tue 18, 2019 5:07 pm
Posts: 5
Hi,

I recently replaced the 6V 50mfd polarized electrolytic capacitor across the meter terminals on my Hickok 533a tester with a 6V 50mfd aluminum electrolytic from Mouser, but after I installed the capacitor and tested the line voltage, the meter swings BACKWARDS now! Before I installed the cap, I measured its value and I double-checked my wiring, soldering and correct placement for polarity and checked the Hickok schematic to ensure I didn't make any mistakes. I also checked the meter forward/reverse switch for correct setting, but everything looks OK. Has anybody ever heard of this issue before?

Thanks!


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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Tue 18, 2019 10:17 pm 
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 652
Maybe you put the terminals back on the meter backwards. I have done even more stupid things than that.


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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Tue 18, 2019 10:28 pm 
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Bob,

I didn't remove the terminals when I soldered the cap in and I'm 100% sure the wiring is correct. I also verified that the meter normal/reverse switch is set correctly. I did notice though that the original cap measures 95mfd whereas the new part measures the correct 50mfd, so I'm wondering whether the difference in capacitance value could cause the meter to swing backwards...very strange. I'm going to reinstall the original cap to see the outcome--if it resolves the issue then I will order a part that has a value closer to the original. I also read a post on this forum that the original capacitance values in the Hickok testers were much higher than the stated value on the part.


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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Tue 18, 2019 10:36 pm 
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Location: Columbus Ohio
disconnect the cap and see how it works, (it doesn't have to be there to work, its for protection)

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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Tue 18, 2019 11:18 pm 
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Joined: Jan Tue 10, 2012 8:39 am
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The capacitor has no influence on the polarity. Something in the circuit has changed.

I once repaired a tape recorder where the level meter kept reading very wrong. Turned out it was an illuminated meter and the bulb sockets were shorting to the movement connection.

In another case, an oscilloscope had a hot chassis. That one turned out to be a short inside the Intensity pot, which also had the power switch on its rear.

Expect the unexpected. That's part of what makes this hobby so much fun.

Bob


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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Tue 18, 2019 11:51 pm 
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Location: Columbus Ohio
right, did it work correctly before you started repairs on it?

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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Wed 19, 2019 2:54 am 
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Joined: Jun Tue 18, 2019 5:07 pm
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Yes, it worked correctly before I started repairs--or actually preventative maintenance. I didn't take a photo of the area under repair before I started, and now I'm doubting myself that the wiring to the cap is correct. I briefly checked it on a schematic, but I rushed through it because I've been busy lately, so I'm going to need to take another look at the wiring going to the normal/reverse switch because it doesn't make sense that a mismatched capacitance value would cause the meter to reflect backwards. :?:


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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Thu 20, 2019 3:00 am 
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***Update--I had the wires going to the meter reversed--the unit tests good and the meter reads normal now. The moral of this story is--never say you are 100% sure unless you are 100% sure. :D


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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Thu 20, 2019 3:34 pm 
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Well at least you are relieved you don't have a bad meter.

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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Sun 23, 2019 3:12 am 
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I have heard of installing a capacitor across a tube tester's meter.

why ?

is it to stabilize it ?

steve

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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Sun 23, 2019 6:51 am 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
The checkers make the tube act as a rectifier. The meter movement integrates
the half cycles into torque. The capacitor produces a DC voltage. The meter reads
higher with a lower voltage applied to the tube.

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 Post subject: Re: Hickok 533a meter swinging backwards?
PostPosted: Jun Sun 23, 2019 2:35 pm 
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ok, makes sense.

steve

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