Відео

The GE Transistor Manual. Thank me whenever you want.

Great work. I'll echo what Herb said, these multisection caps have an inverse reaction to their stationary ESR rating. Essentially, if it sits for a year or two without use, the ESR value will show rather high. However, once power is applied the caps will reform after a few days of regular use the capacitance value will settle and the ESR value will go down considerably. What that means is they'll warm up due to the resistance, but as they reform you'll notice that they go cold - this is when they've been reformed. In the same way, anytime you have an amp running and the multisection cap is hot, it has developed permanent series resistance, time to replace.

Did a Facebook market place search like you suggested, found me a 576 for $500 20 minutes away from my house. Barely any wear on it, user and service manual included.

I'm not an audio guy per se, just an analog-ish EE. Bob Pease's book was originally a series of articles in EDN magazine, and it was great! I saved most of them and used them to help teach my friends the principles of troubleshooting analog stuff. The Art of Electronics is a great book on the big world of electronics too. The semiconductor companies used to publish a lot of books. National Semiconductor had an Audio Radio Handbook that had a lot of good design guidance. Not sure if it appeals to this audience, but I enjoyed it.

Fantastic video, Phil. As hobbyists, information found in books such as these is indispensable. I’m definitely going to follow your recommendation and purchase some of these. I’m still very green, even clueless, when it comes to much of what’s covered in many of these books, so it’ll be a good place to start. Thanks!

A very informative video. Thank you. You might want to have a look at "Vacuum Tube Amplifiers" by George Valley and Henry Wallman.

If you want to learn a millio- fold more, go for your ham radio license and the world of electronics will open up.

At 31:22 , definitely a UK-centric book; although Ive worked in audio sales and repair all my life, I've never heard of Lin, Tobey and Dinsdale, Bailey, or Hardcastle and Lane amplifiers! (Linn, yes, having once worked for a Linn/Naim dealer, but not not Lin). Interesting to see several sections listed on "dead amplifier technology". I've never heard of ultrasonic biasing....

Good list. I can personally attest that the Theory and servicing of AM, FM, and FM stereo receivers is an excellent book. I’ve been enjoying Douglas Self’s small signal audio design for the last two months and it is excellent as well. I would add in two books to your list - The benchtop electronics handbook by Victor F.C. Veley, it’s a great reference book to keep on your bench when you need to look something up quickly (i.e. resonance in a series LCR circuit, page 202, Millman’s theorem for AC circuits, page 243, etc.). The second book that I would add to your list is Practical Electronics for Inventors by Paul Scherz & Simon Monk. I really appreciate the straight forward to the point writing style of Practical Electronics. I’ll be checking out some of your recommendations for tube amplifier reading material. Good video, thanks!

Thanks for this video . Well done I will check some out mate.

This is a great reading list. I wasn't aware of any of the FM servicing/theory books except the first one which is great indeed. I can recommend Terman as a general electronics book for valve circuits. It is worth getting a nice edition. It goes into more depth and theory than the RDH, it's a proper textbook -- not a handbook. There is a huge audio engineering handbook -- I forget whose it is -- which goes into all the aspects of audio engineering and recording to an adequate depth for a handbook. Other books I could recommend are for very esoteric subjects and perhaps slightly controversial so not much point mentioning them in the context of building a general list.

Great channel - great work!

Phil, by and large , the F&T caps get better with use. I check leakage and ESR with my Sencore LC71 prior to install. After some time , they measure better with some hours of use. I have several newish CE caps in my junk box that got leaky in a high voltage use situation. BTW Vishay offers a HVR series metal film resistor specifically for high voltage circuits. In a three wire power cord , consider using a bridge rectifier as a ground lifter ( 1.2 volts ) rather than a direct ground connection to the chassis. This eliminates most ground loops but keeps the user safe.

7:33 I would leave it as it is. It will only take one slip and you will be regretting you ever did it. Nothing easier than blowing up an analogue meter--I know because I have done it. They don't make them anymore so if you blow them, it will be quite an ordeal to fix it and it most likely never be the same as before. Why mess with a perfect instrument? Besides, this set up you could easily replicate with cheap modern components if you wanted--a lot of people build their own for a portion of what this is worth.

5:56 You can find plugs for these sockets still. They sell them new if you know how to search for them but if in doubt you can always find them on ebay. I thought they were rare but they are not. They go for a range of prices so you may need to be a little judicious in your selection but on the other hand most of those on ebay look like they were made at the same factory.

This is awesome. I never knew these existed.

Have you got any explanation why Dynaco decided to have this huge square hole on the chassis exposing the circuit board? I cannot think of any reason for it other than it being a marketing gimmick. If I owned a pair of these, I would ensure this hole would be covered by a sheet of metal and the circuit board lowered in the case as it is a safety hazard.

4:12 I am a bit sceptical about these thermal camera photos: could it be that on shiny, reflective objects they merely read the reflected radiation off these objects instead of the emitted radiation? Have you ever tested that by measuring the object's temperature with a thermometer/probe? My reasoning is that if the object was truly 125 degrees, then all of it would show up red. Instead it shows up with many colours resembling shadowing in a photograph's film negative which to me this says the object is not that hot but instead reflects the radiation emitted from the tubes nearby.

It's such a shame to think the owner put his trust in the previous "expert" only to have him do such shabby work. It's a good thing these timeless units are in good hands now.

Do I see some Shinkoh resistors ? I hated working on tube amplifiers that were hacked before i got them to repair .... Often they asked for retubeing but when opend up I saw the real horror and messing up done by so called tech repair shops .......... Thank you for the upload. Upgrading ( expensive components ) must be done with experience and real evalution after the work..........sometimes so called better may be your worst enemy.....or exposing the limits and intrinsic distortion of a circuit....my attitude todaéy is only to try an upgrade aon an amploifier when the mp performs well and sound, when I DO NOT feel the need to upgrade ...that is mostly when it realy works.

I assume that you will get into this in the testing, but I would be curious to see if the inrush limiter limits current during max transients, maybe you can chart across the limiter. Might be interesting to see a 50hz square wave into a 4ohm(?) load at full power. I probably would have chosen a thicker silicone flexible cord purely for aesthetics, but that would be a minor nit-pic. You do very nice work. I am envious of your test gear collection!

Great instructions. Built mine today and it works perfectly. Just getting into vintage audio repair as a hobby. Replaced the two filter caps in a 1974 Pioneer SA-7100 amp. Wanted to test it to make sure nothing was going to blow. Thanks.

the ac line cord is wired wrong

Yes I quite agree , Polystyrenes in a tube amp are a no no. COG MLCC are a better choice. The F&T made quad can caps are much better. Have had bad luck with CE distribution can caps in the past. I always use inrush current limiters in every build. JJ tubes … nah. Film caps are voltage derated in higher temps . I always use .22 uf at 800 volts. This insures a less leaky output tube coupling cap when hot . Yes the UL tap screen resistor is a valid mod . NO mechanical connections for ground returns . Add a star ground off the PT HV center tap , run all grounds with soldered connections to a 5 lug terminal strip . Better yet , use silicon carbide rectifiers to replace the rectifier tube with 30 ohm TO220 slugging resistors . A modern 5AR4 is poor compared to the original 1960’s Mullard UK made rectifier tubes. The analyzer indicates healthy tubes . Call Kevin at Dynakitparts if interested in the Waters / Ward PCB upgrades.

Great video Phil! So cool to see the inrush current testing before and after. Keep up the great work.

Holy cow, when your vref draw is 90% hermetic sealed metal cans, you got a good deal... Those LTZs are like $500 at the very least by themselves... used one yet? I have a non-A i bought for more than your $20USD lmao, trying to source the resistors to use it All the S102K resistors are no slouch either Those metal power transistors are nice to have if you know they're genuine and not crap fakes I think you can even use a photodiode to make a compressor audio filter...

dream workshop!

Ahh "Fully functional" and probably "Pulled from a working environment" :) These are great pieces of kit - If you haven't got the sensor head, the manual contains information on how to use an RF relay and an 8400 series sensor in its place. Looking forward to watching part 2.

I love these but would like a way to clip a can cap over the capacitors . Some holes on the pcb and a cylinder with small legs to put through the holes and bend in to secure :)

I have being buying for years 25 and 40 watt bulbs for lava lamps; I currently have four lamps going at all times. I think I am up to about 40 each. In the central North US a DIY store called Menards has an extensive collection.

Had slightly different issues. “Fm mute”button didn’t work and no stereo at all. Had low reading at J114. Capacitor trick didn’t help. I Pulled transistor H302 but no stereo still. All voltages there. I replaced HA1156 and got stereo to work an “fm mute” button as well. In the end just did little adjustments of L107 for maximum readings. Your video helped a lot. Thank you

For God's sake put a cushion on your bench top!

EXCELLENT!!! I am going to have to try that script for THD on my 3585A when I get some time in the future. Thank you.

Excellent job troubleshooting that. I would have thought 50 ohms also because the output is labeled 50 ohms.

Isn’t most hum created by the AC outlets? I lived in a vintage house built in 1928 that had some hum in my audio amp via a Tripplite Surge unit. I had an electrician install a medical grade $150 AC outlet. The hum when away.

Maybe he used a record player with it. Hum magnets.

Great lab! What is the stand you are using with your Hakko FX-301 desoldering gun? I use the same gun, but I haven't found a good matching stand yet.

Really enjoyed seeing the vintage equipment used to diagnose. That cut plug blade makes me suspicious that if plugged in backwards, a secondary device that is plugged into the switched or unswitched pass-through outlets on the back could be causing these ground loop issues.

Some amplifiers "hum" because they don't know the words (lyrics).

Nice gift!

Good job fixing the unit

I didn't know that they made these? I designed and built my own! But I added an isolation transformer and went with volt and amp meters. My bulbs are on top ! My unit is very similar to this one, a little bigger though,,,

Nice!

Nice one. Like your working bench. Regards from Portugal

Looking forward to the second part

Thanks for the shoutout - Excellent use of smart glasses for first person recording!

I’m glad the lever was of use to someone else !

Hey man! Thanks for this video, I have to do the plate on my MR77. Corner shattered.

You dont have an ultrasonic cleaner? :(

Nice👍👍