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 Post subject: Need to test caps. with low value
PostPosted: May Fri 18, 2012 11:40 pm 
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Joined: Apr Wed 18, 2012 2:05 am
Posts: 6
What test equipment can your recomment for testing caps. with low value, ect. a 0.02 uF caps.
The equipment must also be able to test ESR

Price range = as low as possible, but i do now you dont get these tester for free 8)


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sat 19, 2012 12:33 am 
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Location: Latham NY
Depends on what you want to test them for. Value, leakage at full voltage or both. The ESR test is only useful with Electrolytic caps. Will you be testing new caps or ones that are 70 yrs old?


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sat 19, 2012 3:25 am 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
The ESR of a 0.02 capacitor would show up as D on a bridge. If you want to know the ohmic
value and reactance of a 0.02 capacitor with a current of 10 amps passing through it, that's a different matter.

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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sat 19, 2012 10:00 am 
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Joined: Apr Wed 18, 2012 2:05 am
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Thanks for your time to answer :P

Im a rookie, so its mostly for learning, and with time i would like to learn how to reform Electrolytic caps.

I would like my equpment to test:
Leakage at full voltage cuz in my search, i found out that leakage sometimes can fail in higher voltage.
Shorted capacitor.
ESR for my SS gear.
If possible i wanna try to reform bad Electrolytic caps.

I like to test new and old caps.

I already bought a Amprobe 37XR-A its also able to measure the capacitance.

Right now im finding the Sencore LC53 "Z Meter" interesting, speacilly because of the display, but with my rookie knowleadge the Sencore are not able to measure ESR.
Maybe i need to buy another test equipment only for testing ESR?


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sat 19, 2012 12:17 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 289
Location: Staten Island,NY
Reforming caps is simple,just get a variac.Although,in my experience if you think you need to reform a cap,it is better to just replace it with a fresh one.Not a fan of "reforming" but I do preform new electros with a variac,power supply connected to a meter you can monitor leakage as you form them.As for non electro's I just check them in circuit for leakage.Have never been concerned with ESR myself,it really isnt a concern in the work I do with guitar amps.


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sat 19, 2012 6:19 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 6117
Location: Powell River BC Canada
If you tell us what type of work you need this testing for, what kind of equipment the caps
are used in, you might get more specific answers.

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sat 19, 2012 9:28 pm 
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Joined: Aug Wed 31, 2011 11:23 pm
Posts: 345
Location: Tucson, AZ
Use a Sencore LC103, this or the LC102 are nice easy to use units if you can find one in reasonable shape and that works, but still pricey. If something breaks, parts are almost unobtainable (Choice Electronics is the only retail source I know of that carries some parts at $$ and fixes units). Both BK 879B and Mastech MS5308 have reasonably priced handheld LCR units in the 200-250 range that can test ESR. Haven't used them but have other equipment by both manufactures, BK has probably better quality. Larger bench top units, like the Sencore will also cost significantly more to ship. Can find additional information on-line.

BK Precision 879B
The 879B 40,000-count handheld LCR meters measures inductance, capacitance, and resistance quickly and precisely. The 879B can also calculate impedance,Theta, and ESR, features typically found in bench LCR meters only. Fast auto ranging and quick measurement configuration such as measurement parameter and test frequency selection make the 879B very simple to operate. The meters also includes handy functions such as data hold, Min/Max/Average recording, tolerance sorting, and relative mode. Measurement data can continuously transfer to a PC via the meter's mini USB interface, using either the provided data logging software or SCPI commands sent from a custom program.
Measurements L, C, R, Z, D, Q, θ, ESR
Test frequency 100 Hz, 120 Hz, 1 kHz, 10 kHz
• 40,000 counts resolution on primary and 10,000 counts resolution on secondary display
• L, C, R and Z (879B only) primary measurements
• Automatic calculation of secondary parameters D, Q, θ, and ESR (θ and ESR for 879B only)
• 0.5% basic accuracy
• Fast auto range design for rapid, easy component measurements
• Relative mode
• Data Hold and Min/Max/Average recording
• USB (Virtual COM) interface
• SCPI compliant commands for remote communication
• Software for datalogging and front panel emulation available as free download
• Selectable auto-power-off options
http://www.bkprecision.com/downloads/da ... asheet.pdf
http://www.bkprecision.com/downloads/ma ... manual.pdf

Or Mastech MS5308 digital bridge LCR intelligent detection and measurement
Dual LCD 19999/1999
Series and parallel measurement mode selection
Measurement of the items quality factor, dissipation factor, phase angle and equivalent resistance measurement
Resistance of DC measurements
Five different measurement frequency 100/120/1k/10k/100k Hz,
RS232 infrared port / PC display records
15mA low-power operating current
Power supply 1.5 V x LR6 AAA-
Dimensions: 224mm × 172mm × 59mm
Measurement range and accuracy:
L: 20 m H --- 2000H The highest accuracy (0.5% + 5 words)
C: 200pF --- 20mF The highest accuracy (0.5% + 5 words)
R: 20 Ω ---- 200MΩ The highest accuracy (0.3% + 5 words)
Impedance / frequency DCR 100/120 1k 10k 100k


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sat 19, 2012 10:09 pm 
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Joined: Apr Wed 18, 2012 2:05 am
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radiotechnician wrote:
If you tell us what type of work you need this testing for, what kind of equipment the caps
are used in, you might get more specific answers.


It is mostly for learning how things works, and it could be nice with time that i could find bad caps by my self.
Also new caps. could be nice to match before installing.

mksj wrote:
Use a Sencore LC103, this or the LC102 are nice easy to use units if you can find one in reasonable shape and that works, but still pricey.


The Sencore LC102 is in my price range, the only LC103 on eBay now is buy it now, so i dont know what the normal selling price is for the LC103. both of them looks very interresting.
mksj do you have one of these tester?


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sat 19, 2012 10:30 pm 
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Joined: Aug Wed 31, 2011 11:23 pm
Posts: 345
Location: Tucson, AZ
I have the LC103, but in general the last series of Sencore LCRs are overpriced and often in questionable working condition (membrane switches and display often have problems/bad). The costs have come way down, I would stick with a new BK LCR mentioned and save some $$.


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sun 20, 2012 3:40 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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I have an LC75 and would not do without it.
It does do ESR and most important, it is very serviceable.
I would not wish one of the later Sencore testers on my enemies. Be patient.


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sun 20, 2012 3:44 pm 
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Location: NJ, 07645
I see there is a LC75 on the bay right now. It is overpriced for a non tested unit and worse, it has no test leads. Make sure you get the proper test leads for whatever you purchase.


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sun 20, 2012 4:32 pm 
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Joined: Apr Wed 18, 2012 2:05 am
Posts: 6
Scott wrote:
I see there is a LC75 on the bay right now. It is overpriced for a non tested unit and worse, it has no test leads. Make sure you get the proper test leads for whatever you purchase.


First i was recommended a LC53 but lost interest because of no ESR options, so your heads up is very appreciatet, Thanks :P

The BK Precision 879B is still looking interesting but, its a discountinued product :cry:


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Sun 20, 2012 10:57 pm 
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What is nice about the Sencore is that you can test leakage all the way up to 600v. Some caps won't show leakage at low voltages. I use my handheld more for checking an unknown value rather than determining if a cap is good to use in a circuit or not.


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Mon 21, 2012 1:46 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7865
Location: Minnesota
You don't need a ESR tester or cap tester for working on old radios. Replace the caps and electrolytics and you will be fine. Reforming electrolytics is like putting a patch on a 50 year old tire, you may make it around the block but forget about going on the freeway.

Dave


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Mon 21, 2012 5:00 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
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Location: Long Island
Problem is, only a bench LCR meter like the Sencores "do it all," measuring all the capacitor parameters including leakage at high voltages. Unfortunately, Sencore departed the test equipment business a number of years ago, so you're "out on a limb" if you spend serious money on one and it has problems. They often end up on eBay when the membrane keypads wear out or the LCD displays start darkening.

I do not have any first-hand experience with either, but looking at the spec sheets on the above-mentioned handheld meters, the Mastec appears to have more possibilities, but you'd have to know how to get the most out of it. The B&K is probably easier to interpret. In either case, you would need some other way of measuring HV leakage. This could be an "eye tube" capacitor tester, an insulation tester, or simply a HV power supply and a microammeter or a neon bulb for that matter. It is absolutely true that certain kinds of leakage phenomena do not become apparent until higher voltages are applied.

Of course, it is possible to make the same measurements with older gear and save some money. There are lots of old General Radio 650A and 1650A LRC bridges on the market which will do a fine job of measuring D, Q, and C at 1-kHz. D, Q, and ESR are related terms, and you can calculate one from the others if you have a scientific calculator handy. In fact, most modern digital LCR and Z meters only make one set of measurments, then calculate the other readings in software.

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 Post subject: Re: Need to test caps. with low value
PostPosted: May Mon 21, 2012 5:39 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 6117
Location: Powell River BC Canada
Sencore says that capacity is somewhat defined by the measurement method. The Z meters
look at the initial charging current which means the ESR that bedevils switching power supplies
is a resistance term that an AC bridge at cost levels for general use would not easily found. Marlin
D. Westra's (assgn Sencore) sort of snags this concept for the omnibus dielectric
absorption patent.


On the other hand, the power factor knob, on the 50/60 Hz bridges (Heath , Eico, etc ) is
very helpful in evaluation of capacitors in the mictofarad range used in tube radios an TVs.

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Wed 23, 2012 12:32 pm 
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Joined: Oct Sun 15, 2006 12:57 pm
Posts: 3801
As Chris mentioned, there are a number of older bridges which can give you the information you need. The GR-650 is quite old, but still a good bridge nonetheless. The more modern GR-1650, I think would be a better choice though.

Spend a couple hours with any older GR/HP bridge and manual, and you'll find they are accurate, pretty straight forward, and easy to use. Certainly not as fast as modern microprocessor driven equipment, but rock solid and accurate enough for anything You'll ever need.

Image

HP also made a few LCR bridges starting in the '50s, and the 4260A is a good example their earlier manual offerings. Both GR and HP made Microprocessor versions of their earlier bridges, but they are pretty pricey.

Image

With older gear like these examples available at reasonable prices, I would stay far away from any of the "service" or "Kit" versions of the day, they weren't very good then, and certainly haven't gotten better with age.


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 Post subject: Re: Need to test caps. with low value
PostPosted: May Wed 23, 2012 5:05 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 6117
Location: Powell River BC Canada
The kit versions of the Eico and Heath bridges, the ones with the round eye tubes,
have a distinct advantage of the HP and General Radio types.

They are very simple, and can be repaired by anyone who has the skills to restore a
tube radio. Parts can be found, adapted, or even made, to keep them running.

Anything you need to measure that will affect operation of a tube radio can be checked
to the extent that it will function properly.

The strange thing is you will be paying around the same price today for Heath and Eico
bridges that they sold for when new.

The same thing applies to the the radios you find and restore.

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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