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For your reading pleasure - www.chemtronics.com/ultimate-guide-to-diagnostic-freeze-spray

Understand, but I have 2 sprague capacitor checkers that have 600v cap checkers Sprague Tel-Ohmike Model: TO-5 Capacitor Analyzers that work and I recapped they don't make em like they used to

It make me wonder how many manufacturers are guilty of the same documentation errors

Some "weren'ts were definitely involved, that is for sure

Thank you for your comment! I think I will try to make a video on the user manual's example of doing a qualitative ESR measurement by paralelling an oscilloscope set to AC input (as exampled on PG21 of the operation manual) and observe the residual ripple that is left when connecting a electrolytic cap, as according to Sencore, there should be a fairly clean sawtooth pattern ripple evident on a cap with good ESR, but the waveform will be peaked / spiked on a cap with unacceptable ESR levels. I am also wondering about the difficulties of calibrating for inductor values, as inductors by their own nature have widely varying values depending on the frequency they are subjected to under test ( and in use) , and, if the frequency isn't known and or a controlled constant, I would think it is going to cause great difficulties in calibration.

I don't think you will have any problems with frequency when it comes to calibrating the inductance adjustments. All Sencore LC meters measure inductance by measuring a voltage generated by 6 different sawtooth ramps, with 6 different rates of rise. This is why there are 6 pots to adjust the 6 ranges. Using this technique, the inductance measured is independent of frequency. There is no bridge circuit that is frequency dependent. A coil has an inductance of 1 Henry, when the current flowing through the coil changes at a rate of one ampere/second, (A/s ). The voltage induced in a coil, with an inductance L, with a change in current is: Voltage of (coil) = - L(henries) di/dt, where di/dt is change in current over time. This is how Sencore gets their inductance measurements, by creating a voltage across the coil from a sawtooth ramp and measuring it. They use a sample and hold circuit for the peak voltage (or almost peak voltage) developed across the coil. They then calibrate this voltage on the digital voltmeter in the LC53 to make it equal to the inductance of the coil. BTW, on my Sencore LC53, I found more schematic errors this morning. All the 6 pots that calibrate the inductances are 1000 ohms. Up to 33 mismatches between schematic and hardware.

@@caseymulcihy89 Casey, thank you for that in depth description of the inductance measurement configuration! Also, now that you said you found the trimpots to be 1K components on original install, I will have to double check what I have, but, those are configured as series - rheostat variable resistors so they will still fall into proper adjustment range with a 2.5K trimpot. It's very aggravating to find so many "discrepancies" between the actual build and the schematic & parts list, but I guess it's part of the hobby to find these things out, and also to figure out workarounds if trouble arises.

I bought the 75 in 1984 I think? I paid $999 and it had interest free monthly payments of $100. Best $1K I ever spent. Still use it today.

@@charlesg5085 Well, there you go!

I am not going to debate that in this video, as I really didn't make a comparative stance on that here, it would be more pertinent of a comment on my E_001 video. I also hope you bring this to Mr. Carlson's attention, I am sure he would love the info.

I was lucky on this unit to the point that none of the board mounted caps were showing parallel leakage or actual physical leakage, but I have seen at least one video where a device with the light blue Rubycon caps had caps out of tolerance and with bad ESR's. The main axial power supply cap, C4, 2000uF, on the other hand went high ESR, I would look at that one first as it would drag down most other operating voltages. If you have the darker colored rubycon's, they may be new/good enough to not need to be shotgunned as of yet.

That is an option, I usually reserve that one for aerosol cans of cleaners and lubricants that somehow have a clogged or broken valve and became depressurized with some contents still left in the can. Thanks for thinking of that one.

Good points about solder removal, everyone is free to use what hey are comfortable with, and can afford, I just decided to spring for a solder / desolder station, but I also often use wick dabbed with a bit of no clean flux since its's 35 years old, and it seems to still do the job well. Granted, point to point wire wrap connections were the standard on a LOT of electronic devices back then, they at least allowed some ability to connect and disconnect wiring on a boards topside to get to remove or reposition it to get to the foil side, but, proper tools and technique were never really developed and shared over time for handling them. I came from a field of telecom equipment installation and repair, where I was well versed in handling them with proper tools ( provided by the company - but can be purchased, or, I did make a budget DIY unwrapping tool - info in my "Tech Tips" videos) but they are still widely used in Telecom work for connecting copper circuits from analog voice frequency to digital T1 data speeds, as well as low current power and alarming needs.

Hola. Que tal te fue con las medidas en corriente alterna y en corriente continua ? Cual fue la medida más baja en la escala de.miliamperios???

Your comment google translates to "What a pity for him not stabilizing. But with this video it helped me a lot as he treats it" I am taking it to mean that the DC millamp current measurement does not stabilize. That is a pity, yes..

​@@poormanselectronicsbench2021👍 isso mesmo. Obrigado pela resposta🤝👊

Considering that, with "open circuit" leads, it is not creating enough leakage to light the LED, the 3904's's I used, which, are most likely counterfeit's ( I sourced them from amazon I believe), still work acceptably, AND, if for some reason they blow up due to hooking to a charged capacitor, they can be cheaply replaced as well. Anyone can feel free to modify this circuit as they choose though :) I just went the "low cost" route.

Thanks for your comments and feedback! Starting out with a item in reasonably good condition will make the work less complicated for sure, the tough part is to find one with a properly functioning slider switch on the far right, as that switch operates the discharge resistor function, is spring loaded with one of its mounting pins used as a latch to keel the capacitor connection in circuit until released, and that single part/function cannot be easily recreated nor is a viable modern replacement produced. I can't say that my capacitor replacement of the E-Caps was "the right way" , as some may choose to put in terminal strips and make them more accessible for future replacements, but my version of restuffing the original "dynamite sticks" looks more original, does not take up any more space or create mounting issues then the originals, and and can also be re-entered fairly easily if a future rework is needed. I chose to make some test cords with 2mm banana plugs to use the original jacks, which were cleanable, and that saved me some disassembly work as well. Good luck with your restoral! 👍

@@poormanselectronicsbench2021 My slide switch is OK. I will mount the new capacitors on a terminal switch. The new Banana jacks on the front look very nice. I will send you a picture when I get it completed along with a dozen other summer time projects, In The Heat!!! 😞

I have not tried "The Pink Stuff" , but, seeing there was some blemishing from corrosion, I figured that sanding with a few grits to leave a bit of a brushed finish was the way to go. I'm not saying that what I did was the "be all - end all" process, it was just documenting what I did, and the results I got. Someone may have a better process to share, as a lot of Eico equipment has these inlayed/stamped stenciled panels that need refurbishing.

@@poormanselectronicsbench2021 I agree with you. I also have restored a EICO with those nice inlayed letters. in my case I took it down the street where I had it San Blasted clean then they placed it in an acid bath for me. Started with an all new looking piece of metal.. I get this done free as I helped the owner get his internet and streaming working perfectly when the cable company could not get it to work correctly. 🙂

@@myradiovideos Nice! I do have an Eico model 249 VTVM ( with the BIG analog meter) to get to sometime soon, It had some weird corrosion damage on the bottom of the panel, but I think I will try a finish technique called "Engine Turning" which will leave an overlapping circular polishing pattern on it, just to make it a bit unique.

@@poormanselectronicsbench2021 That EICO is a great meter.. I had it for about 5 years, mint in the box from a local estate sale. But sold it late last year after getting a near mint HP 410B. I was looking for a nice unit for over 2 years and finally got one at a reasonable price, $200. Came with several spare parts, like a new AC tube that goes in the probe head. Original owners manual, and a complete set of spare tubes.. Sold my EICO for $150 and that was a very high price but it was mint, original factory box and operating instructions.. Now I am trying to enhance my Tube Checker collection, I have 4 right now, but after a few more... Sometimes one checker will not check several types of tubes, so you just need more then one! 🙂

@@myradiovideos I know that it's not a "lab standard quality" meter by any means, but the freakishly large analog meter in itself would make a good view for working on vintage tube equipment, where "ballpark" measurements are acceptable. I need to make an RF probe for it, The RF probe schematic I have just lists a 1N34 diode, a 100pF cap, and 2 resistors, I don't have it, but should be easy enough to fabricate one.

THAT....is a good spot, BUT, that is also the OUTPUT of the PA251 going to the LC102. If you go to part 1 @ 15 mins and 40 Seconds, you can see that the line cord's green lead is connected to the other end of that screw and to the transformers core laminations, so, all is well. Why they chose the output color configuration they did is a mystery, but in order to correct it I would need to rewire the socket on the LC102, and then it would not conform to other units that have been made in case they ever get separated and connected to different units. Thanks for the note though, it made me investigate it better.

@@poormanselectronicsbench2021 True I did not see PART 1, glad all is good, I had thought that was the line cord HOT side....LOL

@@old64goat If in fact that were the case, that would be QUITE troubling, I agree!

I do have some "third hand" kinds of things, but I am used to doing work with manual dexterity, I can still tie good fishing line knots, so I do OK. Thanks for the suggestion!

Thanks! Almost every "auction item" LC53 I see does not have the factory test leads, and from playing with the 2 units I have, it seems that 50pF is the "sweet spot" for lead capacitance to be able to zero the units. This isn't a "be all-end all" assembly procedure, but the components I used and the assembly process seemed to make for a good. finished product. There are also some leads for sale on Ebay, but it's best to contact the seller to verify that they used a low capacitance coax, and also verity that they take returns in case the leads are out of spec.

I didn't investigate it, but there looks like a spot for another E-Cap on the opposing edge of that board, that may have a high value bleeder resistor installed in it. I'm not going to go any further with mods on it, because the LC102 itself has some more filtering once it gets inside. It looks like it hits a 0.1uF first, then in and out of an LM317, then a 220uF bridged with another 0.1uF. If it had symptoms of bouncing readings, I'd look into it more, but it seems fairly stable with most measurements.

Just what I showed to test the 50pF cap in the beginning of the video, the "Capacitor Value" button.

Thanks! I'm kinda skittish about even doing a recap on this one. It has the later model Nichi purple caps, and they seem to hold up well over time, and since its working well, I figure "Don't fool with a Running Piece" , as they say. I did open up, and replace the PA251 DC power brick, might post that as a video, it's only got one cap, a 4700uF - 35V and although it tested great, it is aged so I updated it.

@@poormanselectronicsbench2021 I agree. If it ain't broke... The cap in my power brick was out of spec so I replaced it. Helped a lot with ripple.

@@pcwrangler09 I also figure that mine might be, since that item is plugged in and probably powered almost all of the units life if set up on a bench, so, yes, was a good thought for you to do that also.

If you are looking for a better waveform sync, set your trigger function to trigger on a downward slope on the pins that are already HIGH at a idle state, that's what I did and they seemed to lock in well.

Cpu chips do fail and yes the suffix letters or numbers can make a big difference on these type of chips as in speed or built in ram/rom/eprom/nvram. Fortunately we have the net now.

I believe it's in the "tagged" information, which should lead a search to it, but I have also grouped it into a playlist for the entirety of this unit's work, but TY for the suggestion.

Next Video it won't be there, I just wanted to "time stamp" this one.

It's nice to find an old warrior for next to nothing that still functions well. Thanks for the view.

The English language version of the user manual PDF can be downloaded here www.mediafire.com/file/efyz5m85w42gre9/ACM91_User_Manual.pdf/file and it states that in the 6A range, set to AC, it can measure down to 0.001A, so the meter should be capable of it, but I did not verify this because I was more concerned with the DC milliamp measurement issues.

Hola, y en corriente continua es capaz de medir 5ma ? 10 ma?​@@poormanselectronicsbench2021

@@adrianpuentes7299 Obtener mediciones de miliamperios de valor bajo usando la pinza amperimétrica es difícil debido a la forma en que se comporta este medidor, como se muestra en el video. / Obtaining a low value milliamp measurements using the clamp meter is difficult due to the way this meter behaves as shown in the video.

Pero cual fue la medida en miliamperios mas baja que usted obtuvo en corriente continua ? Usted hace referencia a la forma en que se comporta este medidor ....por favor usted puede explicarnos mejor ??e​@@poormanselectronicsbench2021

@@adrianpuentes7299 Durante un breve periodo de tiempo, pareció observarse una diferencia inferior a 5 mA, pero, debido a que las propiedades del medidor no pueden poner a cero, no puedo estar seguro excepto por el hecho de que no puede medir adecuadamente ese nivel bajo. / For a short time, a difference of under 5 mA seemed to be observed, but, due to the properties of the meter not being able to zero, I cant be certain except for the fact that is is unable to properly measure that low.

Can I ask what type/brand and maybe date code of can you used as this way we can keep a running list of what may work well.

​@@poormanselectronicsbench2021 Of course! "Dust Off" Duster, blue cap, date a little smudged but I think it reads 05-07-2122, maybe 2182

I edited my reply, as I thought you just had a manual. I would suggest a larger auction site for the sale, possibly hooking up a scope to it and doing a demo video would increase it's potential value as well. IMO, the transistor curve tracer part is functional on the 443, , but not as good as some newer units, BUT, the diode test function is unique for checking reverse breakdown voltage well over 1000 VDC, and has to be treated with care and respect as well. Besides the gain po circuit t being designed and wired inversely to the panel markings, some resistors that drifted out of tolerance, and the NE2 neon bulb needing to be replaced, my factory wired unit was functional as purchased, the second "kit built" unit still awaits my attention, and I'm sure I will sell the factory wired one and keep the kit after I get that one going.

@@poormanselectronicsbench2021 Thanks. I will have to think about that.

That is a good suggestion, granted that I find myself thinking for the best words / phrasing while I am trying to work with items, but it takes spontaneity out of it then, which, adds adventure and possibly humor. I don't mind the "human element" in most of the other electronics channel's I view here though, I accept them for what they present and the way they present it. If someone does take too long on something, skipping through it, or just choosing to not follow them anymore is always another option. Thank you for the feedback!