Capacitor Checker
 

I'm thinking of getting a vintage capacitor checker, and not sure what to get.. I'm leaning more towards an Eico 950B, but I notice that checker only goes up to 500v... I'll be checking caps that are up into the 600v range and maybe slightly higher.. What does anyone recommend? Looking for something that tests leakage and that has a tube eye like the Eico, if there is anything better... I notice there is 950 and 950B models, virtually I don't see a difference..

Thanks..

Not many went over 450V, and most period caps rated for 600V will leak well below 450V if they are going south.

I kinda figured.. Just wasn't sure.. I think I'll invest an a Eico...

I'm partial to the Sencore units. They are available on eBay from time to time for reasonable money. They also do inductors, yokes-flybacks etc. My 2¢.

The sencore LC53 models i see on eBay are very expensive..

I have a Heathkit Model C-3 condenser tester coming next week.
I am told they are pretty good and they are very reasonably priced


http://www.byan-roper.org/steve/_Med..._1138_med.jpegI

For what it's worth, I use the Heathkit IT-28 and have had great luck with it.

I'll muddy the waters here a bit by adding another model to the contenders:


Solar CB-1-60


I'm quite satisfied with mine.

I just got the Eico model 950 on eBay.. This one doesn't have a "B" at the end of the model number, but looks exactly the same as those models.. I don't think it's an "A" model as those look different.. I need to know what it exactly it is so I get the right manual.. All manuals I see on eBay are for 950A or 950B..

Here's eBay link to the one I bought:

http://www.ebay.com/itm/Nice-EICO-95...vip=true&rt=nc

There's probably a way to figure it out by the serial number.

I'm pretty sure they are "B" models.. They just didn't put the "B" on some of them... Here's one that sold on eBay with it's Manual.. The Tester Shows a plain model 950, but instructions show 950B..

http://www.ebay.com/itm/EICO-Model-9...p2047675.l2557

If you are looking for a set of spare tubes Surplus Sales of Nebraska will have them.

I have the Heathkit Model C-3. What an absolutely sweet instrument. Testing new high grade film caps and the C-3 is spot on. Testing some of the cap's I removed from a Zenith T-O L600 I have and they not only bad, but "holy cow" bad. Tried the resistor check function and it too was spot on. It will not replace the Simpson, or especially the Extech but it works as designed.

It is a tradition that Ham Radio Operators do not read operator's manuals and if we do we don't let on we are doing it; a matter of pride. The C-3 is in this category is so intuitive that a "Caveman could do it"

One things that has always helped me in reading analog dials is the fact I learned how to use slide-rules back in the early 1970's just before the HP-35 calculator forever blotted them off the face of the planet in 1972. You learned the art of "reading between the lines" yes this is where the term came from. When you got the cursor positioned you looked at the hairline and learned to estimate the numbers between the lines. You got pretty good at taking it out to perhaps 3 digits after the decimal point. This is why the HP-35 calculator nuked the slide rule, and by nuked I mean they vanished it seemed like over night. No consulting log scales, square roots instantly, but the thing that had us actually mumbling was; 9 significant digits, 9 significant digits, 9 significant digits, 9 significant digits I am not kidding we would key numbers in and there was 9 significant digits after the decimal point, we where gobsmacked. After that it was a badge of cool to have an HP-35 in a leather case on your belt. Did I mention RPN logic, Reverse Polish Notation, and the famous "enter" key.

For those of you who have never even seen a slide rule here is a website that will interest you. It will teach you how to use one and even has a virtual slide rule to play with. If you did indeed use them this is a trip down memory lane. :D
http://sliderulemuseum.com/SR_Course.htm

The difference between the 950A and the 950B was the "A" used a neon lamp for indicating leakage.

Dave

I have been using my Heathkit Model C-3 condenser tester. What a fantastic instrument. Being able to actually test a capacitor with voltages of up to 450 volts is really nice it gives you confidence that the test will be accurate. It is already paying off. My Zenith Royal G503 Tip Top has a load of bad paper cap's, they are so bad it is a wonder the radio works as well as it does. The Magic Eye tube is very nice.

I picked up a Sprague TEL-OHMIKE T0-6A capacitor analyzer a few years back and now I just shotgun all vintage paper and electrolytic caps. It was 1 in 100 caps that would pass a test on the Sprague and so I found there was really no point in testing them.

Gregb

That depends on the era of the set! On 50's and older gear that is fairly accurate, BUT on 60's and newer gear (like what tvcollector is going to use it on) upwards of 70% of caps are often still good...Give 30% or take 20% depending on quality of brand of cap and the conditions the set was subjected to since new.

If you don't have the monies to throw at a total recap, and or are a newbie that is not good at finding their own wiring mistakes trouble shooting like this can be a very good thing.

From my prospective its all of them, the newest set I own is a Predicta Princess.

Gregb

I work on anything I can lay hands on from 1928 Atwater Kents to 70's SS Zenth TV's, and newer stuff if I have a manual and reason that are both good enough to make me bother.

The reliable plastic types started in the late 50's ~1957/58 and gradually phased out the paper based caps over the next ~5 years (some makers jumped on 'em others lagged badly).

Its a strange thing, I do repair work as a sideline and 98% of what comes in is 30's vintage with the balance 40'-50's. I cant remember the last time anything newer than 1955 came in for repair.

Gregb

If for no other reason, these R/C bridge testers serve a very important role when either totally shotgunning all old caps without testing if their bad or doing piecemeal replacements. That would be using it to verify the replacement cap(s) are indeed value as marked and that they are truly good and have no leakage; especially if they are used or N.O.S. I would doubt that all mfg's do/did 100% production line comprehensive verification testing, and probably just used some sample testing.

Tom (PK)

What is sort of interesting about late 1930 paper cap's in the Zenith portable radios of the time are often found with asbestos pads under the chassis of those that are in wooden cases. This was to prevent fires from paper cap's failing and then starting a fire.

I am glad to hear some good words about the Heathkit C3. I bought one from a member here that supposedly was "working fine." I had been wanting one of the tuning eye type testers for a while and not being an Ebay customer I got overly excited and paid way too much ($85) for the not so finely working tester.

Basically, all of my outputs are low (around half) on the leakage test, and most of my values are considerably off. In other words I bought a unit that needs restoration. Actually, I can still use the thing to a certain degree, but I must realize that the leakage test voltages are low and take that into consideration. I don't have a big concern on measuring value as I can do that with my digital meter. Yeah, I hate using digital stuff if I don't have to. In this case I have to until repairs are done.

I guess buying any old test equipment is a shot in the dark, and many folks think that if something lights up and doesn't smoke out then it is working. I just hate restoring my restoration equipment....

I recapped mine and it went from junk to a rather useful piece of service equipment. If you invest the capacitors and make sure all the resistors are within speck it will serve you well. There are articles online on ways to improve their performance and add features too.

Exactly! A couple of hours after my ebay purchased C-3 arrived, it was all cleaned up, suspect parts replaced, and ready to operate... very useful device for those of us working on older electronics. I used the info in this article:

http://www.old-timers.tuars.com/index.html

jr

Thanks; that link is great!

I recently got disgusted trying to land a Sprague Telohmike TO-6 without some vulture with more dollars than sense jacking the price through the roof. So having pretty good luck with the simple Heathkit C3s (I now have 3), I grabbed a very similarly designed Knight unit AND a vintage (40s) Solar for a third or less than I would have spent on the later model Sprague.

I guess some people go bonkers over extra push buttons and meters, but in reality the simply designed units do about the same thing minus the luxury of the current meter. The "magic eye" tells me all I really need to know about a capacitor and leakage.

I have a B&K 879B, which has "all" the bells and whistles. However when checking caps > 100WV I pop open the Solar first, and only if the Solar seems to think it's ok do I turn the 879B loose on it.

I picked up a Cornell-Dubilier Capacitance Bridge (Model BN) at Kutztown, the YL and I might tackle it this weekend.

I have to hand it to Solar. They made one heck of a good product; at least in their CB1-60(?) I think that's the right no. The most common one. Anyway, I have bought several Heathkits, a Knight, and the Solar. Out of everything there is some need for repair, or in the case of the Knight total rewiring of the multi-function switch. The switch is actually assembled wrong it and the hot shaft terminal is covering the wrong stuff at the wrong time. Lots of mistakes in the these because the were kits.

Anyway,THE SOLAR! Solar rules! Everything on that unit functions as it should and well! Looking inside for hot stuff and prior repair damage :yes: I found that at some point like probably the 60s someone tacked in a dual outlet 10mfd with a second in SERIES with one of the two 10mfds (sometimes 8mfd) in the power supply. That gives you what 5mfd and double the working volts. I need to find a schematic and see what is called for because 5 is low. I don't know what effect it would have, but those are almost always 8 or 10mfd

No real concerns other than a noticeable buzz in the transformer, mostly in the first 15 min or so. Nothing is hot. I jumped over the 10mfds individually just to see what may change. Nothing did. There is evidence that the transformer has run hot at some point. It just looks like it is missing a little wax AND there is an oily stain in the bottom of the box. It probably all has to do with why the power supply stuff is all that has been touched.

Everyone's Solar has a different story it seems.

Word to the wise: DO NOT POKE, PROD, BEND, WIGGLE, HEAT, SPRAY, TIGHTEN, LOOSTEN, LICK, or MEASURE the magical can of ohms buried inside. The moment you do anything directly to it (Measuring it by making your connections at the OTHER end of the wires connected to it might be OK.) it will flip its shit.

As to the filter caps: Schematic(Parts list) says 4µF, some have found Solar branded 8µF units in theirs, and mine had what appeared to be the factory original in it, which was a dual 10µF @450WVDC, and I replaced it with a pair of 10µF 700V film caps. (Yes I know, overkill all around, but at the time I was rebuilding it, nobody had a straight answer as to how much voltage they actually see, going consensus was 450v rated caps might not be enough, plus film caps are less likely to fail short and take out the delicious 1V rectifier...) These: http://www.mouser.com/Search/Product...1848S61070JP2C Not really expensive when you note that the only suitable electrolytic replacement which is only 450V is only a tad more than half the price... http://www.mouser.com/ProductDetail/...pA4A0AnJua4%3d Look at the load life figures... 100,000 hours on the film cap, and 2,000 on the good electrolytic. Sure there's probably never been a Solar CB-1-60 that's even seen 2,000 hours of operation, but I'll be damned if the next guy who restores it can fault my choice!


Here's the schematic and parts list out of the operation booklet for anyone who may need it, linked for table-destroying resolution. (Own hosting obviously.)

http://www.funkengine.net/vk-img/201...-Schematic.gif
http://www.funkengine.net/vk-img/201...parts-list.jpg


Regarding the whole 4/8/10µF thing, looking over the datasheets for the 1V rectifier there's no hazard with 20µF of filter caps hanging off of it. I wouldn't go much higher though.

Other tips:

Be sure to swap out R12 and R13 on the eye-tube, and also R4 and R5 up by the neon leakage indicator to be sure of getting proper results.

If your eye-tube is pretty much all used up and nearly dead, you can move the eye tube's plate/target B+ connection(along with the + side of C7) from the original junction of R9 and R10 (both part of cannedohm unit) over to the junction of R8 and R9.(So one lug further away from the grounded end of the cannedohm) This will increase the voltage on the eye tube by ~40%, so only do this to get the very last drips of use out of an already all but dead tube.

I got in on on a few of the Japanese 6E5s produced in the 70s/80s (Nobody knows for sure, but they're of visibly "modern" construction.) and I can actually use mine without difficulty even at 3500+ lux on my workbench. The tube it came with was still quite good, but I pulled it out of service and safely packed it away for future "complete period accurate" uses. My only gripe with the Japanese new-manufacture tubes is that the phosphor used on their target is the standard "ATM screen" grass green instead of the "any non-Tektronix oscilloscope made before 1978 screen" dark green. I'm actually considering splitting R10 into 3 sections and seeing how far down I can turn the wick to extend life via reduced target voltage.

Ok, so maybe the original tube was more like "5.5 ouf of 10" in terms of luminance, looking back over the photos... https://lh6.googleusercontent.com/-C...o/_MG_4177.JPG

Here's one of the "before" reference shots, the Solar badged dual 10µF electrolytic is dead center...
https://lh5.googleusercontent.com/-P...o/Zi6_1475.JPG

Now looking at the "after" photo I'm ashamed at how terrible it came out... Consider "re-work the Solar to improve mechanical and aesthetic conditions" moved much closer to the top of the "easy evening projects" list...

https://lh6.googleusercontent.com/-n...o/IMG_4165.JPG


Edit:

Show me the (inside) bottom of your lovely maple box. Inside of the lid too. What initially looks like overheating actually turns out to be shellac condensation from being stored in a warm/hot area from the few I've seen.


:scratch2:



Well, sometimes it gives you 10µF and the WV of whichever cap out of the two in series isn't dead-shorted. :D


Generally though yes, two caps in series works like two resistors in parallell, if they're the same value you get half the capacity, if they're mismatched values you reach for the nomogram and/or slide-rule. :beatnik:

Hey thanks! Lots of good information. I still don't like the taste of that 10mfd in series with one of the other two. With old repairs you never know what someone was thinking. Someone may have heard that if you have a bad capacitor just tack another one in and all will be great. Would that be in series? Of course not, but they may have just tacked another in without that thought in mind. I myself used to parallel in caps leaving the old cap in place, but I no longer believe that to be a good practice at all for a number of reasons.

These schematic links posted here will be tremendously useful! I think the thing to do is look at the tech data and check the existing components for clues as to what may have been going on. Oh, and my box lid does have shellac looking stuff around it, but the interior bottom looks more dirty, oily, waxy......

No problems! Glad to help whenever I'm able to.

I went ahead and tossed up the complete operation manual if you or anyone else needs it.

I also dug out the best datasheet for the 1V or IV (eye-vee) rectifier tube. It mentions a value of anything 40µF or more needing special design in terms of inrush current limiting. However if you use 10µF caps like most of us are, that's only 10µF directly on the plate, the other 10µF has ~20K ohms in series with it, nothing to worry about there...


Drip some ethanol (aka denatured alcohol, not rubbing alcohol though...) on the stain, then daub it with a paper towel after 30 seconds or so. If your paper towel looks like you just wiped up a spill of cola then that's all shellac, and unlikely to be transformer wax... (Ethanol usually won't touch any of the waxes used for potting, it will however pick up carnauba wax to some extent...)

Really as leaky as the filter caps were and knowing that some Ebay genius has applied wall current to it long enough to take pictures of the "magic eye" working and imply that it powers up great; I consider myself lucky that I have a working transformer at all. I love the one's who say the same thing if a pilot lamp comes on.:scratch2:

Everything on my unit works. Some bridge readings are dead on, then one will be too far off. Nothing is getting hot, but I know the tranny would have been hot quick on the filter caps I yanked with corrosion weeping out of the ends. Basically, I just don't like hearing my transformer to this degree. Are some 30s-40s transformers just louder in general? I wonder because my little Heathkit C2 also is quite noisy. The C3s I have are almost silent. I'm sure that wax in old transformers was in part to provide sound deadening properties & if it's gone perhaps you have what I have described.

I'm just sharing and gathering thoughts before I break out my Simpson 260 for current checks.