EICO 950B Repair & Some Notes on Capacitor Testers

[@mikaelmcleod4698]

So far, the best explanation of capacitors and capicitor checkers I have seen! Thanks for the great job!

[@dhpbear2]

45:17 - Do'h! I'm happy that the voltage was set to zero, or you'd have burn marks on your pristine front panel! I also noticed that there is no ''push to test" button like the equivalent Heathkit model. One *must* set the voltage to zero to discharge the cap!

[@MrMac5150]

Good video on Capacitors, you should do more videos just like this.. thumbs up.

[@CovertCulvert]

I just picked up one of these, so I will be viewing this vid a few times to get my new to me gear in shape. Thanks Tony!!

[@cp-ib5hv]

Thanks for this. Refurbed an estate sale buy and learned how to use it. This was very interesting. Must have for tube amps.

[@hestheMaster]

What a great piece of test equipment to have. I'm glad Tony covered it so well! PS, just bought one for $43 bucks. I believe that is the price an assembled one had cost back in the day!

[@levi2bear]

Outstanding video, excellent tutorial on capacitors and capacitance. Really enjoy your very through teaching style.

[@edmckinney8457]

Thanks Tony. I bought one for $50 bucks on Ebay. Had a couple of broke wires but now works great.

[@bikematt5781]

I have just restored an old Eico 950B. I first I replaced the 2 electrolytics. Later I had the same Voltage issue that you did (way less than the -520V specified @ the negative terminal of C1). I also noticed the specified Voltage at the positive terminal of C9 was higher than the specified +200V. First I tried tuning the value of R7, no help. Then I tried tuning the value of R8 (remembering the higher voltage than expected that I measured). Ahh, Success followed: I finally got the optimum value of about 55K ohm for R-8. I added 3 750K 1/4 watt resistors in parallel with my near perfect 68K ohm that I replaced already. The voltages vary a bit but are usually within 3V of specs :), Thanks for your inspiration! I also saw better (higher) voltages when I replaced the tube with a 2 diode tube replacement, bringing it right on spec!

[@stevefoster2700]

Thanks for this Tony. I have had my grandfathers 950B for some time. Now I know how to use it. He had done some modifications to keep it going. I assume the magic eye burnt out so he cut a horizontal hole under the eye and wired in a similar type of green glowing indicator. My parents had one in their Blaupunkt stereo console to show when a station was tuned in. Also the power switch went so he wired another in beside the power factor dial. I think the factor works. The horizontal indicator works but is open for about 20% of the value on the cap. I'm sure components inside the unit need replacing. Very cool none the less.

[@Tysman909]

I payed 750$ for my sprague tel-ohmike to-6 a. Works very well also for testing caps. Thanks for explaining power factor I now know more about its function :)

[@RapperBC]

What an absolutely outstanding explanation of all of the things. Bravo!

[@johnpeet1913]

Great video. I learned a lot. Bought one at an estate sale $10. Not knowing really what it was. Needs all the upgrades. Will be fun. Also bought an eico 232 vtvm for $5. I was stoked.

[@MichaelLloyd]

Great video on the wonderful Eico 950. I've had one for a few years. It's almost but not quite as pristine as yours is. It still had the plastic film on it when I got mine. The only thing I did different was to add an X/Y cap on the line to ground. Higher frequency would also be for electrolytics in a switchmode power supply 73 NE5U.

[@victorsalcedo8127]

very pleased with the video. That is an excellent way of explaining the operation of an important piece of equipment. it kept me very interested from beginning to end.. really interesting for Hobbist, students and whoever enjoys this science...I greatly appreciate your way of teaching if I may say so. Thanks again and look forward to more..

[@richardgoebel226]

This is a very good video full of info all in one place. The length of it is justified.

[@The1jonnyz]

Fantastic video! Glad to see someone speak of the many advantages and disadvantages of the different capacitance testers! FYI... I read, on TubeSound I believe, that when discharging a cap you need to turn the power rheostat down SLOWLY. He says that turning it down too quickly will burn out the rheostat. I refurbed a 950B and absolutely love it. Pretty shocking how accurate it is for its age. I made a pair of short, heavy duty leads with alligator clips which makes it much easier to get caps in and out of the testing circuit without risking a zap. On a parting note, check out TubeSound.com as Bob is a wealth of knowledge and has a plethora of info and schematics on vintage test equipment!

[@josephsirois2353]

Extremely clear explanation, thank you, keep the good videos coming

[@tommessina5973]

Great synopsis on the area of capacitor checking. I also love my little 950B.

[@danielhildebrand6892]

Finally just picked one of these up. Looking forward to doing more and better testing. Great video!!

[@ao2528]

Thank you, excellent explanation and info, you just answered to my many "vintage" questions, nice tester and nicer restoration job.

[@carolmartin7042]

I have an old Eico 950. I have just used it to measure capacitance. Thanks for the instructive video! Glen, N0QFT

[@The1jonnyz]

Wow, what a find!! That is beautiful!! I have one that I refurbed and it is very accurate, and just looks really cool!

[@sanjursan]

Excellent, thank you sir. Operational notes start at 31:00.

[@terencekaye9948]

Seemingly find of all finds(these days), I was able to find a 100k 5 watt wire wound pot... I bought my Eico 950 with a blown voltage pot,, was told it worked but,, now to find the Caps.. Not sure who the reply was for but,, I'm looking on the range.. and It looks like Up to around 500 volts or what voltage this can put out .In my limited experience looking at old radio equipment, the caps looked to be High voltage low capacitance,, The new equipment seems to use High capacitance low voltage caps,,, I'll add a voltage bleed resistor to the cct and be careful to turn the voltage control down slowly after testing Higher value/voltage caps.. This video is great.. Thanks Tony.

[@jordan390a]

The "death" cap on the AC input line was intended to shunt AC line noise to ground. I'd install a 3 wire AC line cord and have a .01@1Kv cap on each side to ground.... I have a 950B, but I use a Sprague TO-6 for serious cap testing... You can also check ESR using a 200khz square wave across the cap and connect the ckt to your scope...For more precise analysis, terminate the cap across a 50 or 600 ohm load(depending on the output impedance of your function generator) at the scope input....There are YT videos on how to do that.....

[@hestheMaster]

I did the very same death cap mod to a Heathkit SG-8 and am satisfied that it is safe to use now ! Will do the same with my 950B next.

[@peteleoni9665]

Absolutely priceless info with no "cutesy" b.s. Love your channel!!!!❤

[@aspensulphate]

I happen to like a little cutesy b.s. once in a while.

[@ignacioanaya3403]

Great video! I just bought one of these, I will restore as you did, thank you again!

[@wireworks616]

Very good explanation of capacitors and how to test them.👍👍👍

[@V109FM]

Thank you for the great video on the 950b and I learned a lot about the one I have now so I can start using it. 👍

[@notajp]

I actually have one of these units, along with a whole bunch of other Eico test equipment, and a bunch of other vintage electronic test equipment. It was all given to me many years ago, along with a stack of old tv service manuals. I’ve never messed with any of this equipment, but I hope to get it all out and play with it someday. At least I’ll know what to look for on this unit as well as how to use it.

[@tonybalm1513]

My late Father built one of these while in the army in the 1950's.He used the Mullard EM81 magic eye indicator.I remember getting a nice electric shock as a child playing with this went he wasn't about.

[@dhpbear2]

48:30 - Interesting. I can't see how applying AC to a polarized electrolytic cap! I believe it sources a constant current through the cap and then measures the voltage rise over a 1-second (or so) interval.

[@rosshollinger8097]

Very nice. I just bought one of these and learned some useful info. Thanks.

[@erin19030]

I built several of these while I was in the Army. We used them on the bench at Signal Depot Shop

[@Charlee2015]

Very good video overall! But I really enjoyed the usage demonstration of the equipment.

[@tubeDude48]

Well done, Tony! Personal, I don't believe in re-forming! I toss it.

[@dhpbear2]

I used one of these in HS electronics class in the early 70's. I love the new-old stocki-sm of this unit! But what unit will you use to test the electrolytics? :) Answered! (07:59)

[@prettygoodradio]

Helpful, informative, juuuuust slow enough for me. Thanks!

[@nor4277]

I like my vintage knight kg 670 capacitor tester it does more then my esr meters ,or mulitmeter,Mine has been restore to not by me ,someone.much better then.me ,I very happy with all the test that one.can.do for me working on vintage radio as a novice.thanks for sharing your video ,I learn something from you .

[@repairfreak]

Great video, very clearly explained. I cant wait to receive my Paco C20 from Ebay, which is basically similar. Bought it for checking vacuum tube guitar amps with high voltage stage coupling caps. Thanks for a very informative video that explains thing accurately sir! 🙂👍👍

[@paul.alarner6410]

For what its worth i have a hunts crb capacitor and resistance analyser that was made in 1945,pretty much the same,nice explanation of the power factor ,as that baffeled me,your vid cleared it up,cheers 73 Paul de M3-VUV.

[@terencekaye9948]

Great Video,, Very informative and educational!

[@DaveMcAnulty]

21:21 R7 resistor value for Voltage pot. I plan on adding a 60V DC safety switch (via a resistor) in parallel to R7 provide a 60VDC limit. TODO 23:27 Safety Additions for 110v - 1Amp Fuse and type Y “line to ground” safety capacitor on Neutral input. DONE 35:57 Using power factor knob to get ESR ratings. 41:12 Using voltage knob to find Leakage. There are notes for myself as I plan to refurb my unit, but maybe others will find them useful? Remaining questions: 1. Is it beneficial to have a X capacitor across the input? 2. How would you go about grounding the chassis, it is attached to the secondary side of the transformer, is that okay? 3. I added a 75ohm 10W resistor on a momentary SPST button to short the cap, what happens if I press this under test? Tested up to 400v, no issue. Actually very handy if you want to redo a leakage test.

[@Cavemannspace]

For #3- The idea of discharging the capacitor before removing it from the tester is not a bad idea, but if the switch is only a momentary short and you leave the voltage turned up, then you will obviously short the power supply in the unit, never a good thing. If I remember right, the switch used in Heathkit capacitor testers they do not apply voltage until testing and short the cap before and afterwards, so just momentary contact for the testing. I'm thinking that a simple break before make switch would be the best. One position will make the normal connection to test the cap or reform an electrolytic cap, and the other position will disconnect the cap from the tester and discharge the cap without any chance of shorting the power supply. Honestly, most would just use an alligator jumper connected to one side of the cap and after disconnecting the cap from the tester, simply short the cap out. You could solder a resister in series with the alligators clips in the jumper just for this purpose. No mods to the tester.

[@giovannimai2717]

A very interestant video, a good school ! Thanks !

[@old64goat]

Great looking EICO, I have one but the expanded scale does not work, every capacitor has been replaced and any resistors the were off were replaced. I love that SENCORE but like you said they are expensive.

[@xraytonyb]

The potentiometers that they use in those are wierwound. If they get intermittent, a lot of times you can't fix them with deoxit. The only good solution I found was to replace them. I found suitable replacements at Elliot Electronic Supply in Tucs,AZ (Just do a search for them online). They only cost me around $10 and were rated for 5 watt instead of 2 and 4 that is originally used. After replacing them, it worked perfectly. Elliott was the only place I could find the 100K used in the leakage pot. As for the 10K for the scale, they are available in a lot of places. Just make sure you get wirewound and NOT carbon. Also, if the two electrolytic caps are leaky, they will trow off your readings. Good Luck!

[@old64goat]

ALL caps were replaced and all pots test good except the 100k voltage pot, I put in a NEW 5 watt from EBAY seller MARVAC+_2001 "NEW 100K Ohm 5 Watt Wire Wound, Long Shaft Potentiometer - Centralab WW104" I bought two of these from him NEW for $5 each.

[@barryg41]

xraytonyb I can't say thanks enough for finding these 100k 5 watt pots. I blew mine out three weeks ago and could not find one. I gave up looking and then saw your video. Like others I really like this cap checker. So I'm very happy to find a proper fix. thanks again. subbing you for sure!!!

[@xraytonyb]

Glad I could help! These are really great things to have on the bench. Hope you get yours up and runnung soon!

[@barryg41]

Just letting you know its up and running again. I bought trwo, one of the pots was very close to 100k, so I went with that one. I looked up old64goat's link but he doesn't have any right now. thanks again, glad to get it up and running again.

[@rusty1187]

Man! That is one nice condition EICO!!!

[@dhpbear2]

11:00 - Those 16uF electrolytic caps should be the *first* ones you test when you get the unit working!

[@peterchambers1868]

Thank you so much...I learned so much!

[@toltec13]

I always use a multimeter with my Eico 950 when measuring the voltage of a capacitor. What the multimeter indicates in voltage and what the faceplate indicate are off. I restored my similar Eico. At 10 volts at faceplate is actually around 30 volts on the multimeter. I changed out the voltage adjuster and I got the same reading. The max voltage I get is 450 volts. In all, I guess it's pretty accurate for tube radios.

[@1badpete999]

Very informative video a great help i have the same machine i will probably recap and check resistors to rebuild it ! Up to now i only used to check the esr and the capacitance numbers ! didn't really check it under voltage load !

[@elivazquezsantisbon2362]

Very good video. Congrats.

[@raucousrowdy6540]

Is it possible to add a modern 3 pin power cord ( ground to chassis ) and remove the cap 7 altogether?

[@dhpbear2]

11:40 - They went with 2 16 uF's to get a higher voltage rating. 12:11 - Since 4 uF (C9) is not a standard value, they went with the closest standard value of 4.7 uF

[@SkyWire88]

Nice video and explanation. (you need a heavier marker on that bright paper).

[@tectalabyss]

Very well explained. Thank you Sir.

[@peteleoni9665]

Awesome video. I so appreciate how you do this. So clear, so precise. No crap to show us how "cute" you think you are. Just the info that you promised in the title. *Take Note* all of you guys who do this and overly *fluff* up the video to make it "interesting" to your boyfriend/girlfriend or whatever. Take a lesson from xraytony. *This* is how its done. Thanks Tony. Irony is my comment is also too "cutesy" 😂😂

[@Electrolab28Ag]

Hi Toby, its been a long time I have been asking for a video like this on caps. Job well done. However I would like to see more on testing SMD capacitor. I don't know if you can make one on those, especially on the SMD that don't have any marking. Thanks again for the great Vid.

[@Electrolab28Ag]

Tony, sorry about your name misspell above, a type "O" Anyhow, I have a Sencore TF 46 Cricket Tester that I bought off eBay and the seller claims that everything works, but that's not the Case. The Leakage does not work and I cannot perform a calibration on it. Can you do a tear-down repair on one of these? I have a service manual but for some reason it does not comply with the TF46... it shows components that are not in the meter and wrong numbering etc. Can you assist me? Thank You.

[@xraytonyb]

I haven't seen a Sencore cricket since the 1980's when I was working for an industrial electronics shop. They are for testing transistors and FET's. I don't have any info for them, but I remember them being pretty good for testing transistors "in circuit". Sorry I don't know much more than that about them.

[@Electrolab28Ag]

Thanks anyway. Nice work you are doing... Keep it up.

[@jeffreyhaynes5774]

Do you have an extra working power transformer for Eico-950B?.500 v.winding is open on mine.Thanks.

[@tomdoyle3727]

Excellent video, and enjoyed all the explanations . Learned a lot. I have seen some other capacitor vids about what the proper positive end is on a cap. Meaning that the black line on some caps could be wrong . Is there a test on the Eico 950 that can determine the proper positive side of a cap. I would use this test in the passive audio circuit world. Thank You

[@michaelmacdonald3408]

Just repairing an old 1937 ultimate radio i finally got it to run some am but there is lots of rf noise or interference in the middle of the tuning range both on am and shortwave 2 bands not sure if it is outside the the radio or being generated inside like leaky ceramic caps some help would be most welcome.

[@Sloxx701]

Just picked up one of these units a couple weeks ago for pretty cheap, but a lot of components have drifted over time. It works but just doesn't seem to be as accurate as my other meters. I do have a question, looking at the schematic what would be good type of replacement caps for C2 and C3? These are both supposed to be precision caps so maybe mica? The micas are expensive though. The guy who did work on this thing previously just used plain polyester film caps in those spots and they read off value a little. Thanks for excellent videos.

[@Sloxx701]

Figured it out. Also I had to replace the 100k pot as well, the tiny wires inside were a mess and broken.

[@TheJuddlar]

Hi Tony.... I really enjoy your videos. Keep em coming!! I am working on an Eico 950B. As was figuring, the 100K 4W wirewound pot is bad. Where the heck might I find one.....or something that will work? I know you are a busy man, but any help sure would be appreciated.. Thanks.... Judd

[@thegodzone]

good vid very helpful keep them coming

[@VintageLabSilvioPinheiro]

Thank you for share some importants issues. A really good class for me. I learn a lot with yours videos, keep going 73 DE PU2SRZ

[@yusdiy]

Hello Mr. Tony, I know this an old video. I just bought an Eico 950B and intend to rebuild it. For now I found the 100k wirewound pot is dead. Do you have link of the source you use. Thank you

[@CatsElectronics]

Have you considered replacing the rectifier tube with diodes?

[@scottjohnston804]

Great video, I need to pick up one of the Eicos to restore. How can you tell in the circuit that a cap is a electrolytic vs a plain cap? Is it just the size?

[@xraytonyb]

Electrolytics will be marked with a polarity (+ and -). If you put them in backwards, they can fail very abruptly and vent out nasty smelling smoke. Non-electrolytics are non-polarized and can be connected either direction without hurting the capacitor. This is not to be confused with the "outside foil" marking, which denotes the lead that should be connected to the point closest to ground potential for the purpose of noise shielding.

[@terencekaye9948]

Hi Tony,, just wondering if you had to replace the 100k 4 watt voltage control pot... ? If you did or even if you didn't would you know where a guy can get one,, My recently acquired 950B has the curse of the 100k 4 watt pot. Great video. Thank you.

[@dembydish]

Rebuilt my Eico 950, but the magic eye starts to look fuzzy testing electrolytic caps when voltage exceeds 350-400v. The shutters are not sharp. Any idea what might be causing this? Does this signify a problem or problem component etc. Nice video, nicely explained.

[@johnnytacokleinschmidt515]

denbydish Check the online owner's manual. I believe it addresses this. May be related to power factor.

[@bennoheritt8154]

Hi. I have one of these. And the problem is the same. The voltage potentiometer. Cant find them here in Brazil. Only 50 k are avaiable in wire wound version in 5 watts. Is there any other way to repair this instrument. The 50 K pot can be used. ?

[@michaelmacdonald3408]

Good stuff i like this channel.

[@rpbale]

Great video. I have the similar model and will go through it like you did. One note though. You charged that cap up in the beginning and then started sticking your fingers in there without discharging it. Kind of dangerous for you or for your viewers who may copy you. Was there a discharge function on the Sencore tester. I like that tester too.

[@xraytonyb]

The cap bleeds off very quickly. Regardless, all viewers should read and follow the disclaimer at the beginning of this video!

[@rpbale]

This really is a great video. I'm still watching it and I am going to change my cord to a polarized cord too. What is the purpose of not going to a 3 wire cord? Is it to keep the chassis ground isolated from the earth ground for safety?

[@xraytonyb]

Good question. The answer is really not what you would think. The main reason I didn't put a 3 prong plug was because it wouldn't fit through the opening on the back of the case! I didn't want to cut anything because this unit is almost new. In reality, it doesn't need a three prong. The power transformer provides isolation from the line. It does benefit from the polarized plug, just because of the line filter capacitor. If you don't have a polarized plug, you could possibly plug it in so that the hot side of the line is on the capacitor end. The small amount of current that gets through the capacitor would then be connected to the chassis. Touching the chassis and something grounded at the same time could possibly cause a mild shock through that capacitor. If the cap shorts out (unlikely because I'm using an X/Y safety cap), you could get a bad shock. That's why I use the polarized plug! (Long-winded answer!!!)

[@rpbale]

Okay, I finished the video and I have to say this truly is the most educational video I've seen on electronics and I watch a lot of them. I happen to be at the stage of wanting much better testing measuring abilities on caps because I work mostly on tube amps. So good timing for me. Great job and I look forward to watching your other ones.

[@Finom1]

Could you share the link to where you found the schematic & manual? Thank you, we are new subscribers to your channel.

[@Tysman909]

The spot that i could see very easily when you where zoomed in the wires are tore up in that spot.

[@peterchambers1868]

what is the difference between the eico 950 and the 950b...

[@V109FM]

I was wondering if I were to use the 950 to heal an electrolytic capacitor do you think it would be a good idea to put a 15k limiting resistor in line with the cap during the healing process?

[@erin19030]

You cannot heal a capacitor. Just change it!

[@giovannimai2717]

Hallo ! May you tell me the brand and model of your capacitor/inductor tester with red display ? Thanks in advance.

[@xraytonyb]

Sencore LC-53

[@duanethompson2360]

What’s that other tester you used to test this unit? You said z meter, is there a model to get?

[@Shnick]

I got this same tester and it has the original 8 uf 525v cap. Can’t find one anywhere.

[@jakewells9403]

connect two 22 mfd @ 450 v in series it will give you 11 mfd at 900 v and will work just fine for replacement. i have the same model and that is what i done.

[@Shnick]

Jake Wells thanks, that’s what I ended up doing. I also swapped out the .01uf 400v caps with 103Ks and now it works great. Still might swap out P3 pot for voltage.

[@Paqqqman]

I have a heathkit C-3 version of this, which is almost identical (and has an 8uf cap) ...check DigiKey/Mouser, or worst case scenario you might have to venture into high end/crossover caps. Luckily enough 8uf is a fairly common value in vintage guitar amps ....actually there's 'Sprague Atom' 8uf/450V axial's at PartsConnexion ;)

[@jdmccorful]

Justradio.com. you cant go wrong!

[@hestheMaster]

I went to Just Radios website. Bought two 16uF 350V caps and put them in parallel . That gave me the 8uF at 700 Volts.

[@victorsalcedo8127]

Tony, the 10 K pot does not have the wattage specified. Would you please advise on it. Thanks in advance..

[@xraytonyb]

Anything 2 watt or greater would be fine. The main hing is that it must be wirewound and not carbon type.

[@victorsalcedo8127]

Your time is greatly appreciated..

[@erin19030]

Leakage can be tested in circuit if you know what you are doing.

[@lelandclayton5462]

Did you replace the Line-to-Ground cap with a Y class cap?

[@xraytonyb]

I use an X1/Y2 safety cap.

[@tubesound746]

great video!

[@drdave337]

I've had trouble finding those precision caps. Where did you get them?

[@xraytonyb]

The precision caps were still like new, so I didn't have to replace them. They don't seem to go bad very often. They should be available from Digikey or one of the other big parts vendors if you need them.

[@drdave337]

xraytonyb thanks!

[@jeffreyhaynes5774]

Do you have a good Eico 950b power transformer for sale?.

[@michaelmacdonald3408]

I have a cheap multi meter and on all the cap ranges is does nothing so it sounds like i need a dedicated cap meter.

[@harryshector]

ESR means heat. It's the reason why capacitors get warm when working. The higher the ESR or 'Power Factor' the warmer that cap is going to get. Under heavy loads, the ripple voltage increases, which will generate more heat, due to the increased ripple current through the ESR.

[@rich1051414]

It causes a feedback loop. ESR increases heat and reduces it's ability to function at higher frequencies(leading to ripple), which causes damage to the capacitor, which causes the ESR to rise even more, and so on and so on. Capacitor death spiral. Some are worse than others at this. Aluminum and tantalum caps are pretty terrible. Ceramics are pretty much immune to the problem. They have microphonic issues and capacitance limitations though.

[@dedskin1]

yes it increases heat, its not it self heat , its also caused by Parasitic resistance , and leakage , also some Caps have parasitic Charge , that is also a reason , some Caps are not discharged and eventually recharge by them selves to about 20% of initial charge , all kinds of stuff , you have indirect and direct causes as well , ESR would be direct there .

[@caspianwendell]

Does anyone make a replacement transformer for these? I lost the high voltage on mine so can I add another transformer just for the 560v secondary?

[@peterchambers1868]

I will find an old EICO and maybe the CEM also...Thanks!

[@RuneTheFirst]

Good move on the fuse. A fuse is a must when a device has a 6X5 rectifier. They are prone to shorting and killing the transformer.

[@glasstronic]

Outstanding. Thanks man! Sub'd.

[@bobvecchi7981]

Why didn’t you install a 3-wire power cord?

[@xraytonyb]

The unit uses a power transformer, which provides isolation from mains. Additionally, this isn't the type of test equipment that you connect "in-circuit" or to other test equipment. That said, if you wanted to install a grounded power cord, it wouldn't hurt anything.

[@Electrolab28Ag]

Hi Tony where did you get the service manual for the EICO 950b? i tried searching but could only get a manual without the schematics. Also the .01 and .02, 400V wax capacitor, are they polarize or non-polarize?

[@Sloxx701]

They're not polarized. The schematic and build manual is available here - elektrotanya.com/eico_950b_construction_manual.djvu/download.html

[@Electrolab28Ag]

Hi Tony, Thanks for the Link... I have a couple question if you don't mind me asking. 1. I change all the caps and I am getting 368 Volts across C9. Is that normal? it blew the 250 volt cap I installed because the volts were too high. 2. My Eye tube is not lighting bright, I check the resistor and it reads 1 meg. Is it that the eye has gone bad and where can I get one to buy? 3. I think my rheostat 100K pot is bad. Can I use a normal 100K pot for a replacement? I would really like your help as you have some experience on this product. Thank you.

[@Sloxx701]

I'm not Tony but I'll answer, just tryin to help. 1. 368V across C9 is pretty high, should be around ~200V. I just rebuilt my Eico and it's reading 196V across C9. Check the resistor R8 - make sure it's 68k. 2. They sell eye tubes all over Ebay, maybe other places as well. Boosting the voltage to the eye tube will make it brighter also. Many people have done this to make an old eye tube brighter, the eye tube can easily handle 700-800V, but it might shorten it's life. 3.No, you need a wirewound linear 100k 5 watt pot. I found mine from here for $12 - www.elliottelectronicsupply.com/5-watt-wire-wound-potentiometer.html - it's the only place I've been able to find them.

[@Electrolab28Ag]

Thanks Dacke, this helps a lot. The 68K is reading 76 K so I will change it and retest. Thanks again for the info.

[@Sloxx701]

Strange, I knew it would drift a bit but that's not off by much. Something else may be going on. Could be a issue with the eye tube. Check R10 also

[@solidstate90]

whats the difference between ESR and leakage

[@johnnytacokleinschmidt515]

solidstate90 ESR is acronym for "Equivalent Series Resistance." It is as if a resistor was in series with a perfect capacitor. It is not leakage. Probably best to understand passive devices can be thought of as perfect resistances, inductance, or capacitances. In actuality the geometrical, mechanical, chemical make-up impart them with other electrical characteristics. This is why the electrolytic capacitor seems out of circuit at the high frequencies. It's physical construction causes this. That's why there is a small paper or disc capacitor in parallel with the electrolytics in many devices. On filtering the line frequency ripple and transients in that frequency range. The other filtering at much higher RF frequencies.

[@johnnytacokleinschmidt515]

Leakage would be like a resistance in parallel with the capacitor.

[@GlennSpitzer-mi4cl]

I've worked with vintage electronics a good part of my life. The thing with Cap testers and tube testers If you don't really understand the makings you can't really look at the results and say ok this is bad and this is good you will get fooled. Because of the higher current used in the circuits. 50 yr old 600v caps should be replaced anyway. and tubes that show bad are actually good and vise versa. I worked as a qualified amp tech. Never bothered with them. As a matter of fact I would leave a scope on only because the trace looked cool for effect. lol

[@josephn2xbn321]

Wow new old stock, mine is old and used, it stopped working 3 years ago, I used it all the time. I have to fix it.

[@nawlins8609]

eico must be ELCO ??

[@davidward9935]

@Nawlins EICO is Electronics Instrument COmpany from New York city. They made electronic test equipment in kits to be built by the user

[@bobvecchi7981]

@Nawlins didn’t ELCO make boats in the 40s?

[@mikem5043]

Just picked up one of these at a ham swapmeet for $2

[@JosephLorentzen]

Look up death cap. You should remove that cap.