So many gems in this video! Thanks for sharing knowledge and expertise. Well done.

Is this similar to the MEP803A regulator?

Hi Erik, You have explained everything in great detail in your video and you would be the best Electronic Tech on this planet. Thank you very much for all your time.

Bad design? They only offer a 2 year warranty.

Bad design? They only offer a 2 year warranty.

Hi from Norway! From your first name, are you of Scandinavian origin? That is a very versatile, and complicated power source, must have been very expensive new. Nice!

Great video, just one remark: Y-capacitors are often even more safety critical than you described. Nearly every class-II SMPS uses Y-capacitors between the primary and secondary side of the transformer to surpress EMI. If a Y-capacitor fails in a class-I device - like you have shown in your sketch - then usually the failure current is going through PE and the RCI or even the circuit breaker trips. But if a Y-capacitor in a class-II device fails, then you have mains voltage directly on an output that usually is not earthed - e.g. on the output of your smartphone charger. An electric shock is more or less unavoidable in that case.

I worked on an Oscilloscope in high school that had 48 tubes besides the crt. Tektronics made it Motorola donated it. I found out why Dad told me to use the high voltage probe for voltages over 300 volts. Ouch! 😅

Terrible device?

Great Video! Thanks for sharing your knowledge! Is that fuse that is mounted across the selector switch factory or an after-market repair/modification?

Wow. Module is quite quality

Great video and well done trouble shooting!

Great Erik .

Really very helpful diagnosis !

Great diagnosis! Lambda made some great supplies

Excellent !, I love your videos, thanks .

Thank you for another great video! One minor note for someone trying to replicate the high frequency AC voltage measurement: The 34465A is specified for up to 300kHz, but most hand-held DMMs are much more limited, e. g. Fluke 179: 1kHz, Fluke 87V: 20 kHz, Brymen BM789: 100 kHz. An isolated oscilloscope (consider max. voltage) or a HV differential probe can help here. One more thing: Did you happen to measure the waveform/peak voltage at this cap afterwards? Would give some peace of mind that the selected capacitor with its voltage rating is properly chosen. (I'm pretty confident it is...)

Hi Eric, interesting and informative video; thanks. I see the logic in arranging the items as you do on your bench and indeed i used to have mine configured in the same order but, quite frankly, I couldn't put up with the noise. Since moving house, I now have the space to move the 'lab', such that it is, from a very drafty, cold garage to a nice warm ground floor room in the house. Whilst setting up, I decided I needed to do something about the 'growling' noise emanating from my toroidal iso-transformer: it really is quite offensive and not the sort of thing one would want next to their ear for any extended period!! I it put the first in the chain originally since it is a 2kVA unit and my mechanical engineer's logic suggested it would be better to put the 50VA variable behind it. Anyway, long story short, when I started the new setup I reversed the positions and had the variac first in chain. Lo & behold, the horrendous 'growling' ceased. It does return to a degree when I give it full mains voltage but below about 90-95% full power it is almost unnoticeable now, though I do not have the bulbs in circuit yet. They have always been last in the chain. Any ideas as to what the cause may be? I surfed the 'net' for hours trying to find clues as to what aggitates the toroid enough to make it angry, though without noticeable success. It does seem voltage dependent but I am at a loss with this one. Any advice or suggestions would be much appreciated as I do not like being 'growled' at by 240 of His Majesty's finest volts. Keep up the good work. 👨‍🎓

Is there a simple analog soft start circuit?😅 plan to use for angle grinder

Good job Erik ! Imagine measuring 4000 volts with the meter, who does that ? Do you know where these meters are still professionally used ? As someone mentioned in the previous video, they are still available on the market, made where !

What are these things used for?

Thanks!

so I assume your secondary stage of the iso transformer has no ground reference , therefore the variac will have no ground reference and neither will the dim bulb and device under test. so besides placing two ground probes on the dut which can cause voltage potential if not in the same place, are their any other vunerabiltys , can yo be shocked by touching the metal casing of the Variac as it is not grounded or something of that sort. thank you.

Your 'test cord' has a name. It is called a suicide cord. It should have a fuse wired in it!!

You only had chan 1 selected on your scope

great video.. I like your variac, mine shows voltage not amps. this is good.. glad to know my setup ( the 4th one) is good.. and I need to check inside the ISO and fix that !

Great video, learned a lot here! Wanted to ask if you've seen this or might have knowledge of whether this has become a common problem with the newer version amps (555se) or if this is pretty well an isolated case? Was admiring and looking into these and then found this video. Thanks!

I am a repairman in the welding equipment field and Lincoln Electric used to use the Mag-Amp output control in many of their designs. Simple but not very efficient. Thanks for explaining this generator control system. I also repair a few AC gensets and I have two of my own (10kw and 15kw) that I must repair before use. So many things to fix - so little time. Oh, I'm also a growing audio nut and I have couple power amps that I must repair and use. It's a bit tough learning PCB testing and repair in my late 50's, but so worth while.

Does it have Sync and Droop mode?

Also, if the ohms scales will not stay zeroed or the needle moves when you tap the side of the meter case, replace the big fuse. It has an intermittent connection. This happened to me. I know it is odd, but it really can happen. Save yourself a lot of trouble shooting time!

I watch a lot of videos about older electronics, and they often mention RIFA caps in passing but don't elaborate. This was the perfect explanation. Thank you!

Nice old meter. Love them.

I’m getting some static in my right channel that almost sounds like it’s getting a radio signal from a router or phone. Curious if this is an issue with my amp? Also where are you located if I can have you look at my amp?

Thanks Eric for the fine video with tour

Always good stuff

Enjoy every much your video, subscribed, will look out for all your future videos, thanks Erik for your excellent work.

Very well done. Thank you

I love these meters too. I was taught on the Simpson but in less than a years time Fluke came out with the 8060A(B) and the company went with that for any new purchases. Reading any common return AC on Airliners made them wig out. For some reason, I don't have that issue anymore.

330+470 also conveniently adds up to exactly 800. I'd guess most of the resistors have aged up slightly over time, I'd look at ordering new ones (R10, R12, R14, R15) for the next time you need to make a buy from a supplier.

I have one of these meters from the 60's still in the box. Where can I find batteries for it?

Thanks for trying to get this meter working again. They are quality instruments and they still have applications today that cannot be handled with DMMs

Excellent meter. Still made. I use one all the time. Makes you understand what you're attempting to measure. If you purchase new in 2024 between 550-750 dollars.

This is a classic, they were everywhere !

Enjoy very much your explanation, glad I found your channel. Hope to see more of your video in the future.

Imagine designing a device that will sell at retail for thousands of dollars and deciding to use a cheap-ass fan.

That's a pretty cool multimeter when was it made ?

I used to own this preamp a long time ago. It sounded great and I am an Adcom fan. But seeing the inside of this one before you fixed it up leaves me less impressed with the build quality in this instance. The same is not true with my GFA 555 II. Maybe they contracted out the assembly of this preamp?

Nad have the same kind of power demand system.

Thanks for this refresh, very clear and well explained! The use of metal boxes and conduits in domestic situations is making me somewhat nervous. The reason is that so many things can go wrong with these and the 'user' cannot safely or visually detect it is wrong or not without measurement equipment and the knowledge on how to use it. I believe the lower metal box itself on the isolation transformer should be earthed too. After all it is a metal box and the internal wiring can come loose and put the box on a dangerous potential. _Only the box_ and NOT the socket, as you correctly point out. (KZfaq police mode on) Constructive criticism: Although you correctly explain that on the analog meter the red scale is applicable for AC, you're actually pointing to the black DC scale multiple times. The AC scale is not completely linear, the first 10% is shorter than on the DC scale. Admitted, this doesn't make a significant difference in this context and I would probably have made the same 'mistake'. (KZfaq police mode off ;-)

something i don't understand with isolation transformers. The voltage is still the same so must still be dangerous but you are also isolating from the RCD protection circuit so how does that male it safer? I guess if you touch both live and neutral on the other side of an isolation transformer you are more likely to just burn yourself rather than have the current flow through you (possibly essential organs) to ground but if you touched one of eack terminal in one of each hands then you would be at a greater risk.