PrimaLuna Prologue One output transformer 'repair'

  Рет қаралды 37,674

Electronics Old and New by M Caldeira

Electronics Old and New by M Caldeira

7 жыл бұрын

PrimaLuna Prologue One output transformer repair attempt.
This great amp has a problem and is blowing fuses, and has been diagnosed as having a shorted output transformer on the one channel. The other channel works fine.
Because shorted output transformers are not very common, I'm hoping that this is not the case. However, sometimes our hopes are shattered ...
See a series of 'Restoration Building Blocks' videos on detailed steps in the restoration process:
• How to safely check th...
See also playlists on some other completed restoration projects.
GRUNDIG 1070:
• Grundig 1070 tube radi...
SCHAUB-LORENZ GOLDY 58 type 3020:
• Schaub-Lorenz Goldy 58...
BUSH VHF64:
• Bush VHF64 tube radio ...
GRUNDIG 3060A:
• Grundig 3060a tube rad...
TELEFUNKEN OPERETTE 8:
• Telefunken Operette 8 ...
GRAETZ SUPER 171W:
• Graetz Super 171W tube...
LOEWE-OPTA MAGNET 3737W:
• Loewe-Opta Magnet 3737...
Braun Atelier 3:
• Braun Atelier 3
LOEWE-OPTA TRUXA STEREO 4741W:
• Loewe-Opta Truxa Stere...
GRAETZ COMEDIA 616:
• Graetz Comedia 616 tub...
SABA FREIBURG W2:
• Saba Freiburg W2 (WII)...
GRAETZ MUSICA 4R417:
• Graetz Musica 4R417 re...
You may also be interested in ...
CAPACITOR LEAKAGE TESTER:
• Capacitor leakage test...

Пікірлер: 104
@garyhope2
@garyhope2 4 жыл бұрын
My goodness,....I admire and respect your expertise, persistence and patience in finding the fault of this amp. Amazing. The world functions better because of people like you. Thank you.
@electronicsoldandnew
@electronicsoldandnew 4 жыл бұрын
Thanks
@johnh539
@johnh539 Жыл бұрын
As a Prima luna owner myself it is nice to see a non industry perspective.{even if it proved unfixable}. Fortunately no nightmares so far and the evo 100 integrated sounds lovely.
@electronicsoldandnew
@electronicsoldandnew Жыл бұрын
👍
@jamesepler7156
@jamesepler7156 5 жыл бұрын
Great channel. Love to see you work and talk the problem out. Your the Mystro....
@pauladickerson6082
@pauladickerson6082 2 жыл бұрын
My Primaluna HP dialogue HP has lights in front of each tube to she when tubes fail. I had a KT150 tube go bad here it caused some mice smoke and sound on startup. I plugged in a old El34 tube and replace the one fuse and food to go. Love love this amplifier!!!!
@electronicsoldandnew
@electronicsoldandnew 2 жыл бұрын
👍
@borayurt66
@borayurt66 6 жыл бұрын
PrimaLuna amps are not cheap, and the company is quite proud of their strict quality control, and they emphasize their strong designs. A blown transformer when everything else is fine sounds very much like a manufacturing defect, most probably they will change it under warranty.
@electronicsoldandnew
@electronicsoldandnew 6 жыл бұрын
Bora Yurtoren : I agree with you on the quality and control, but unfortunately it is quite easy to blow an OT. All you need to do is short the outputs, which can happen quite easily through no fault of the amp itself, so they do not acep. this as a manufacturing fault.
@martinda7446
@martinda7446 5 жыл бұрын
First thing to do when transformer is suspect is a dc winding resistance check. First thing. Nice to see this unit inside. beautifully filmed.
@electronicsoldandnew
@electronicsoldandnew 5 жыл бұрын
Martin D A : thanks Martin.
@montygore
@montygore 2 жыл бұрын
What a beautiful layout!
@electronicsoldandnew
@electronicsoldandnew 2 жыл бұрын
👍
@allthegearnoidea6752
@allthegearnoidea6752 5 жыл бұрын
Always nice to see someone repairing valve gear. I would have a done a insulation resistant test a bit earlier, I’m am expert when it comes to fixing other people’s gear. Funny I have so many problems fixing my own stuff. I assume it was the primary these will flash over very easily if the amp was run with the speaker disconnect and is common even in high end gear. Thanks for sharing regards Chris
@electronicsoldandnew
@electronicsoldandnew 5 жыл бұрын
AllTheGearNoIdea : thanks Chris. In Portuguese we have a saying: “in a Blacksmith’s house you’ll find wooden stakes”. I’m the same. Other people’s stuff gets done pronto, but mine ... well, let’s just say I let it age a while :) I don’t get as much tube gear to repair here on the island of Madeira, but when I do, I really enjoy it. Also enjoy your videos, thanks. Manuel
@allthegearnoidea6752
@allthegearnoidea6752 5 жыл бұрын
Electronics Old and New by M Caldeira keep up the good works my friend. Thanks best regards Chris.
@vintagestereobuff7005
@vintagestereobuff7005 6 жыл бұрын
Last Christmas I bought a cheap Chinese Audioromy Model 808A class A/B/Push Pull amp using four KT-88 outputs, two 6sn7's, two 12at7's, and one 12ax7. It is mostly point to point wiring. A week ago the right channel went out. I found the problem to be a bank of 3 power resistors had come unsoldered at both ends, one from the copper bus bar. I fixed it and made a youtube video of the repair. I posted it to the PrimaLuna Facebook site, and one of the first responses I got was from some primaluna owner telling me I needed to upgrade from my inferior Audioromy to a primaluna unit. Well well, it looks like their stuff has occasional problems too. Mine was an easy fix, yours not so easy. Maybe primaluna owners should consider getting a Chinese amp.
@electronicsoldandnew
@electronicsoldandnew 6 жыл бұрын
vintage stereo buff : each to his own. All equipment can fail, it’s only human :)
@125southernnh2
@125southernnh2 6 жыл бұрын
Prima Luna Amps are built in China. They're just built better.
@philpembroke5373
@philpembroke5373 5 жыл бұрын
Prina Luna is a Chinese amplifier. It’s made by Spark Audio in Guangdong.
@DCLLS-um7rb
@DCLLS-um7rb 3 жыл бұрын
Great video. Very informative.
@electronicsoldandnew
@electronicsoldandnew 3 жыл бұрын
👍
@nunovieira905
@nunovieira905 4 жыл бұрын
Hi, Mr. Caldeira This is the first video of your channel that I saw and I immediatly subscribed. I just bought my first tube amp ( a used Jolida 302 A , a push pull ultra linear EL 34 design) paired with my vintage Kef 104.2 ( 92 Db sensitivity)and I am loving it and trying to learn more about tube amps. I find your video really interesting , and very well explained. I just learned alot with it. Curious to see other of your videos. I am now in the process of understanding my amp schematics ( I still have some doubts) in order to open it and try to see if everything is alright inside , the capacitors are ok, etc, but my knowladge is still very limited. By the way, I don´t know if you are portuguese or just living in Madeira Island, but I am portuguese from Cascais, Portugal, and the family of my dad is from Madeira and I have lots of relatives on the island, witch is beatifull. Congrats on your work and quality of the video, Best regards, Nuno Favila Cascais, Portugal
@electronicsoldandnew
@electronicsoldandnew 4 жыл бұрын
I’m Madeiran, grew up in south africa, and came back to Madeira after university (that was over 30 years ago!). Have you got the schematic for your amp? This one seems to be it, but I’m not sure. www.hifiengine.com/manual_library/jolida/sj-302.shtml Just make sure your tubes are good and the bias is well set , and that amp will last a lifetime or two.
@DoRC
@DoRC 7 жыл бұрын
just the fact that they previous guy didn't do anything to insulate the wire he disconnected from contacting the transformer make me question his credibility.
@tee-jaythestereo-bargainph2120
@tee-jaythestereo-bargainph2120 3 жыл бұрын
Nice job thanks man !
@electronicsoldandnew
@electronicsoldandnew 3 жыл бұрын
pleasure
@garcia20801
@garcia20801 Жыл бұрын
Marcel Croese in The Netherlands is de designer of the prima luna(you can always contact him)
@electronicsoldandnew
@electronicsoldandnew Жыл бұрын
👍
@rmabgoi
@rmabgoi 5 жыл бұрын
Um canal português de electrónica audio ??!! Que agradável surpresa ! Claro que irei subscrever. Saudações M. Caldeira.
@electronicsoldandnew
@electronicsoldandnew 5 жыл бұрын
rmabgoi : obrigado.
@rmabgoi
@rmabgoi 5 жыл бұрын
@@electronicsoldandnew Eventualmente irei ter umas ofertas um pouco utópicas...Quad II monoblocos, pré Quad 22, gira discos Thorens TD 124... e aguardo para saber quais as colunas, creio serem umas monitoras Spendor, ou similares. Caso se concretize, irei trocar todos os condensadores, pondero a Mundorf, e necessitarei de algumas directrizes, assim como conselhos. Na devida altura irei recorrer aos seus conhecimentos, caro M. Caldeira, se fizer o obséquio. Até lá, paz e saúde. Ricardo Barradas (Ericeira-Lisboa)
@6JM6tube
@6JM6tube 3 жыл бұрын
The tubes are made to amplify the problem in this case is the complex load that is the transformer and it is very reactive with which if the speaker is accidentally disconnected while it works, high voltage harmonics are produced that pierce the thin insulators (thin paper or modern capton tape) between the layers of the primary and secondary and as the secondary has one of its terminals to ground, it causes an arc and a short circuit. I build amplifiers and use a trick to avoid this which is to place two varistors in series on each plate branch connected to the B + on the primary of the transformer. Thus, when an accidental flyback is generated in either of the two branches, the resistance drastically decreases towards B +. The varistors I use are of the 10SK250 type (250VACx2 and 320VDCx2 connected in series) for each board always towards B +. It gives me good results and I have used it with other absolute vacuum tubes (807, EL519,6146B) and thus I have avoided having to rewind the transformers due to a short circuit between layers. I liked the video a lot. Thanks for sharing and greetings.
@electronicsoldandnew
@electronicsoldandnew 3 жыл бұрын
thanks for the tips. always welcome.
@alancordwell9759
@alancordwell9759 7 жыл бұрын
It would be worth fitting a replacement pair of transformers on a high end amp like that, yes they will be a few hundred quid but how much to replace the whole thing?! One thing to check, if I may suggest it, is that the arcing on one of the EL34 valve holders, and the failed transformer, can both be a symptom of it having been run at a high level into an open circuit, so it may be worth checking his speakers and their connections as well. Under those conditions the peak voltage on the anodes can reach many kV. Great video as always! :)
@electronicsoldandnew
@electronicsoldandnew 7 жыл бұрын
+Alan Cordwell : thanks Alan. The speaker connections were my first thought, but they seem to be ok. But who knows? I don't see any other possible explanation, but he left the amp on at very low volume and went out for a while. When he returned it was dead. I also think a replacement is worth it.
@johnsweda2999
@johnsweda2999 6 жыл бұрын
Alan Cordwell they are supposed to have a protection for that built into the biasing circuitry
@hohsiewchuanschoh6270
@hohsiewchuanschoh6270 2 жыл бұрын
My Primaluna Prologue one facing the same problem. I never run my amp without unload, and all the tubes are still working good. Can't figure out what is the problem causing the primary winding blown. The local dealer quoted me about USD 450 for replacement. End up I leave it in my store.
@goodun2974
@goodun2974 Жыл бұрын
At 17:45, you misspoke slightly: the ultralinear tap on the output transformer goes to Grid #2 (the screen grid, at pin 4).
@electronicsoldandnew
@electronicsoldandnew Жыл бұрын
You’re probably right. It’s been quite a while since I did this one so I can’t really remember. Thanks.
@johnsweda2999
@johnsweda2999 6 жыл бұрын
But actually heating in up the whole can, get it nice and hot so it goes runny could actually seal the short. They are a Dutch company from Holland who makes these Transformers
@abeleballestri612
@abeleballestri612 7 жыл бұрын
Thanks very much for this interesting v ideo ,looking for the short in the output transformer. Are you going to get a new transformer?
@electronicsoldandnew
@electronicsoldandnew 7 жыл бұрын
+abele ballestri : yes, that's the plan.
@lyntonprescott3412
@lyntonprescott3412 5 жыл бұрын
What a shame. Looks like a well built piece of equipment.
@electronicsoldandnew
@electronicsoldandnew 5 жыл бұрын
It sure is.
@Stelios.Posantzis
@Stelios.Posantzis 5 жыл бұрын
Have you considered heating up the transformer in an oven to melt the potting away?Some people do that, although I wouldn't recommend doing it in an oven that is used for cooking due to the potentially toxic stuff inside the tx. Now, I don't know what potting substance is used in this tx but if you search the internet, various people that have tried it raise the oven up to a certain temperature slowly so that the substance has a chance to heat up slowly. Before doing this, however, you might want to unsolder/remove any plastic parts on the transformer that might also melt off. Also make sure you have a photo of the coloured leads so you know which is which even after "cooking" the tx. You'll probably want to save the potting compound in a non reactive container so that you can re-use it when re-potting the transformer.
@patrickboudville7951
@patrickboudville7951 3 жыл бұрын
I have same amp when I play four or five tracks all good then left channel cuts out changed tubes around still same results any thoughts
@douro20
@douro20 5 жыл бұрын
If I had to replace putput transformers in these I would probably put in a couple of James JS-6223HS hermetic transformers. These Taiwanese transformers are very well regarded and are a real bargain for what they are- about US$265 a pair.
@hohsiewchuanschoh6270
@hohsiewchuanschoh6270 2 жыл бұрын
It is equivalent? My Primaluna Prologue one exactly facing the same problem, one of the output transformer primary windings blown without any reason. My tubes are still working good, and I never run the amp without unload.
@rmabgoi
@rmabgoi 5 жыл бұрын
O "PrimaLuna DiaLogue Premium Integrated Amplifier" está debaixo d'olho. De facto, não encontro nada que se assemelhe ao rigor, qualidade de construção, componentes, tipologia, na sua gama de preços. Estou em crer que com a PrimaLuna qualquer audiófilo encontra o equilibrium entre preço/qualidade/satisfação, não embarcando no esoterismo latente destas andanças, entenda-se andanças como a procura do santo gral. Saudações M. Caldeira.
@leonardorohr9261
@leonardorohr9261 4 жыл бұрын
Great job! Did you get another output transformer (or a pair) ? Cheers
@electronicsoldandnew
@electronicsoldandnew 4 жыл бұрын
Unfortunately not. The owner did not go any further.
@dambuster6387
@dambuster6387 6 жыл бұрын
Used with no load ??
@MichaelBeeny
@MichaelBeeny 7 жыл бұрын
Not a manufacturer I know but must be one of the neatest and well made amplifiers I have ever seen. Wonder what it sound like? 35 watts sounds a bit high for EL34s, depends on the distortion level power is measured I guess!
@electronicsoldandnew
@electronicsoldandnew 7 жыл бұрын
+Michael Beeny : yes it is really neat. I also think the rating is too high, but you never go near those power levels anyway in normal listening.
@frankgeeraerts6243
@frankgeeraerts6243 6 жыл бұрын
High power and good looks are sales arguments ..... Chinese cultural ( and commercial ) mindset is quite different than ours ....they can build real neat products but sell you to often nice looking but questionable and crappy quality ....it's a different culture and we make the mistake to think with our standards and morality . If you order large quantities of tubes , they will ask what brand should be labeled on the tubes ...when you ask for samples you will be send only good quality , when you receive the final bulkpack you get anything . For them you are the fool to pay .... Good quality tube amplifiers lasted and often still due their job up until today , almost forever....( with proper maintenance )essential parts like the OPT's and PTF rarely fail.... Chinese production LOOKS ( very) nice.....time and experience will tell the difference.. If something goes wrong in this kind of modern amplifiers , often the SS components in the tube amp go wrong first followed by transformers ( mainly the PTF ) , cheap capacitors and bad quality tubes , ....but yes it looks nice and seems to offer a lot of technology for the price..... I forgot to mention the problematic and crappy chinese made tube sockets .....those who do like tube rolling know what i mean ! The best sockets I did ever used were heavy duty Russian military ....you could even sometimes risk to brake the glass tube envelop when trying to pull out the tube.... Worse .....you can sometimes see the little blue arcing inside a Chinese tube amp in the dark inside the chassis... A twenty watts EL34 PP amplifier usually sounds good.....but it's the 40 watts version that goes out the hifi shop.....with a lot of over engineered SS features like the SS automatique bias control....( one could build a fairly reliable 100 watt amplifier with a pair of EL34 , i mean real nos EL34 , don't ever try to do this with EL34 reissues.... ) Top quality OPT cost more than the sales price asked for many Asian tube amplifiers , quality has always had a price and good aftermarket service is to often a thing of the past . Well thought and engineered amplifiers like a Dynaco, Mc Intosh and many other older respected brands are stil running fine after more than Fifty years of loyal service and the OPT's sound better as they age... I see many faults in modern amplifiers were the looks and specifications are sales click baits and the knowledge of how to build these amplifiers is mostly gone or lost with the generation of engineers who really understood vacuum tube technology and had the skills to avoid those mistakes . When quality, long term reliability , service and the reputation of the company was more important than today . Yes it had a price , a price that many people could not afford ....but in the long run it was cheaper than limited lifetime, planned obsolescence and questionable quality ... Same is going on today in the car business ad so on ...
@125southernnh2
@125southernnh2 6 жыл бұрын
You need to do more research on Prima Luna.
@125southernnh2
@125southernnh2 6 жыл бұрын
Prima Luna is marketed and sold here in the US. Chinese 'culture' has nothing to do with anything here.
@125southernnh2
@125southernnh2 6 жыл бұрын
They sound amazing with EL34 as well as KT120 and everything in between.
@Dutchamp
@Dutchamp 2 жыл бұрын
For this Amp I think the owner had driven the Amp without speaker load If load is absent the secondary windings 4 or 8 ohms gets loads of high voltage course no current is running though the transformer. That may be the damage in this transformer.
@hohsiewchuanschoh6270
@hohsiewchuanschoh6270 2 жыл бұрын
My Primaluna amp facing the exactly same problem, I never run my amp without unload and all my tubes are still working. I can't figure out how the transformer blown.
@duanethompson2360
@duanethompson2360 4 жыл бұрын
You can remove the potting, and repair the short, just a lot of work!
@electronicsoldandnew
@electronicsoldandnew 4 жыл бұрын
Huge amounts of work :)
@Stelios.Posantzis
@Stelios.Posantzis 4 жыл бұрын
@@electronicsoldandnew Well, it would make for a great video! You'd need an oven that's not used for cooking as I'm not sure I'd want to cook in it after having melted potting resin! The counter argument to this is, the short is buried deep in the windings and there's always the chance that there's even more damage or that the transformer is totalled. There has to be a coil winder somewhere - no place can survive without one. However, the cost of the repair might not be economical as this is essentially reverse engineering.
@printzapper
@printzapper 3 жыл бұрын
Are those hand wound toroidal transformers like the Dialogue? Ooof, that gonna hurt. Also, surely not a rolling tubes boo boo on that socket...some tubes don't have a tab ya know.
@gizmothewytchdoktor1049
@gizmothewytchdoktor1049 6 жыл бұрын
looks like a faulty auto bias circuit has struck again. seen that before.
@mikerdaniels1
@mikerdaniels1 2 жыл бұрын
I’m hoping you can give me a wild guess. My Prima Luna amp has low level on the left channel. After warm up, if I play it at moderate levels I can hear the left level come up to normal. This takes about 2 hours of playing. All of the usual swaps Have been tried including new tubes, cables, speakers etc?
@electronicsoldandnew
@electronicsoldandnew 2 жыл бұрын
You need someone to check the signal level at the grids of the output tubes with a test signal to see if they are the same. If not, the problem is in the “pre-amp” section. If they are, the problem is on the power section. If you swap the output tubes and the fault stays on the same channel, the it looks like an output transformer issue, I’m afraid. Hope that helps.
@jochvomberg5541
@jochvomberg5541 4 жыл бұрын
My Prima Luna prologue premium preamp left me after 4 Years.Only the right channel works,on the left channel all tubes are death.Voltage on left channel 180V on right channel 450V. Think it is also the Transformer for the left channel.
@electronicsoldandnew
@electronicsoldandnew 4 жыл бұрын
I hope it’s something simpler. Good luck.
@cgavin1
@cgavin1 4 жыл бұрын
Oops sorry i deleted my comment. I didn't see the whole video before commenting! :)))
@siukslynas
@siukslynas 7 жыл бұрын
its second time I can hear Primaluna has blown transformer. Not sure do I have to worry about mine Dialogue Premium now..
@electronicsoldandnew
@electronicsoldandnew 7 жыл бұрын
+siukslynas : I shouldn't think so. Output transformers usually burn out if run without a speaker connected or shorted. Just make sure your speakers are tightly connected and won't come loose, and I'd imagine you won't have a problem. Enjoy.
@joachimplanchon9093
@joachimplanchon9093 4 жыл бұрын
Hi same problem with my dialogue premium preamp repair was at high cost 800€... but i still use it every day for more than2 years after the repair and they have done some upgrades also all is ok so far! I also have a prologue premium preamp in a studio room with no problem i have buy it when PrimaLuna launch it! i just change the tube for a cleaner bass (with gold lion 12AU7) and Prima luna adjust it for those tube at a fair price so good service but transformer change is not a cheap repair!
@hohsiewchuanschoh6270
@hohsiewchuanschoh6270 2 жыл бұрын
My Primaluna amp facing the same problem, repairing cost very expensive.
@fakundofrontera
@fakundofrontera 3 жыл бұрын
Hello, can it be that is like an mirror capture from the cam when u film the soquet of the EL34 and count pin 1 to the left side? or is like the drive in England that is on the other way that in america? hehe,...
@electronicsoldandnew
@electronicsoldandnew 3 жыл бұрын
The tube socket pins are counted clockwise from underneath and counter-clockwise from above.
@fakundofrontera
@fakundofrontera 3 жыл бұрын
@@electronicsoldandnew thanks!
@moodyga40
@moodyga40 7 жыл бұрын
you can email or google upscale Audio they deal with theses amps i am sure he will help you
@electronicsoldandnew
@electronicsoldandnew 7 жыл бұрын
+ian forster : thanks, but this amo is in madeira, Portugal, so the cost of shipping is a major issue. My buddy is talking directly to the company head office in Holland right now.
@DrBroncanuus
@DrBroncanuus Жыл бұрын
2 min 7 sec...so the output transformers give each Amp brand their 'sound signature'...e.g. 'the McIntosh sound' ?
@electronicsoldandnew
@electronicsoldandnew Жыл бұрын
Yes, but also the output tubes and the entire signal chain components and design.
@DoRC
@DoRC 7 жыл бұрын
I can only find those realcap capacitors on AliExpress. I wonder why they would make such a beautiful thing and put crap caps in it.
@20CycleMonger
@20CycleMonger 6 жыл бұрын
Did this ever get resolved??
@electronicsoldandnew
@electronicsoldandnew 6 жыл бұрын
Carlito Melon : no. My friend has still not bought the transformer.
@Stelios.Posantzis
@Stelios.Posantzis 3 жыл бұрын
5:15 : Someone left the B+ cable dangling inside the case! Nice... Suppose someone just plugged the amp in the mains socket being none the wiser. I just can't believe how lazy some techs (?) are.... assuming that was a tech that had a go at it in the first place, but even for an amateur that is inexcusable.
@electronicsoldandnew
@electronicsoldandnew 3 жыл бұрын
true
@Dutchamp
@Dutchamp 2 жыл бұрын
I repaired the one with 4x kt88 It blew the 10 ohms cathode resistors one after another. I have put down the current a 30% lower now it works fine but it isn't normal. I would never buy this kind of amp. My opinion no chinees for me. One thing I added a fuse between B+ and the output transformers yes it is hear able but I wanted to protect the outputtransformers it can handle its maximal current but not anymore then maximum.
@electronicsoldandnew
@electronicsoldandnew 2 жыл бұрын
👍
@Dave30867
@Dave30867 6 жыл бұрын
Shame for the many thousand dollars they do cost sometimes things just die .
@audiophool864
@audiophool864 4 жыл бұрын
Output transformers should not be failing on an amp this new.
@electronicsoldandnew
@electronicsoldandnew 4 жыл бұрын
No, they shouldn’t, unless you mess up and short the speaker cables or something.
@leonardorohr9261
@leonardorohr9261 4 жыл бұрын
Could've been a short in an output tube IMHO
@frankgeeraerts6243
@frankgeeraerts6243 4 жыл бұрын
Chinese transformers, ...they look good but .....................
@electronicsoldandnew
@electronicsoldandnew 4 жыл бұрын
It’s the “but” that is the problem 😊
@martbosma5976
@martbosma5976 2 жыл бұрын
It's a PL Design Error: The Transformer blew by a (internal tube) shortcircuit G2 to G3 (the latter is wired to Earth) Thanks for the nice video. Very informative.!! I, j ust on time, caught my Prima Luna Prologue 5 ( 4 X KT88) burning one of it's Output Transformers, in the same manner. The failure is as follows: A worn EL34 or KT88 tube sheds some debris from the getter and a shortcircuit occurs between G2 and G3 G2 is fed (via a 1 KOhm resistor and a winding of the Output transformer by some +425V DC from the Power supply. G3 is connected to earth. A sortcircuit G2 -> G3 will result in a strong shortcircuit current! (NB The 325 mA fuse in the Plate circuit does not blow in such a case,).It is too strong and a Slo Blo. The shortcicuit G2 -> G3 results in a current from +425 V Power Supply via the transformer , via the 1K Ohm resistor and next the G2 connection (and then inside the tube to G3 and to earth).. In the original GEC design the G2 resistor is only 0.25 W (270 Ohm for a KT88) and the resistor will burn as a fuse resistor and protects the transformer winding. However, in the PL design a 1W (or even 2W) 1 KOhm resistor is used and the resistor only get's hot, but does not burn (Note the brown ring, rather than the original RED ring) and the transformer windinding yields (i.e burns), being the weakest link. I had such occurrence but is was lucky that the 1 K Ohm resistor got so hot that it unsoldered itself from the tube base connection (it acted as a spring resistor!). This process goes very fast (I only spent 15 seconds to power off the AMP and nevertheless , I would have been too late, if the resistor had not unsoldered itself, by shear luck!. A nasty burning stench indicated that it was not only the 1 K Ohm resistor, which started to burn, but also the transformer winding. Note: The Genalex KT88's had 8000 Hrs running time , so I should have replaced them earlier. (projected life of some 5000 hours). Remedy ( I have not yet dne this myself ), but advice from the the Dutch "Circuits OnLine" forum: -> Incorporate in each G2 line (the yellow wires) a F 50mA Fuse (Fast Acting Fuse), which will protect the transformer against a faulty tube with an internal G2 -> G3 short. I Recommend to incorporate this update in your amps!! It is an easy MOD for protecting your Output Transformers . I will do this shortly and report back!
@electronicsoldandnew
@electronicsoldandnew 2 жыл бұрын
Thank you very much for this. It makes perfect sense and is indeed easy to do. I have never had anyone explain this fault procedure as you have done, and hope all who read this follow your advise.
@DoRC
@DoRC 7 жыл бұрын
I can only find those realcap capacitors on AliExpress. I wonder why they would make such a beautiful thing and put crap caps in it.
PrimaLuna ProLogue Five Poweramp Review by Upscale Audio's Kevin Deal
6:24
Upscale Audio High Fidelity
Рет қаралды 16 М.
Audio Dummy Load design and build
25:33
Electronics Old and New by M Caldeira
Рет қаралды 28 М.
Пранк пошел не по плану…🥲
00:59
Саша Квашеная
Рет қаралды 6 МЛН
MISS CIRCLE STUDENTS BULLY ME!
00:12
Andreas Eskander
Рет қаралды 20 МЛН
Output Transformers: A Discussion of Basic Principles
25:36
Uncle Doug
Рет қаралды 306 М.
How to safely check the Power Transformer on tube radio or amp.
16:03
Electronics Old and New by M Caldeira
Рет қаралды 35 М.
Peavey Butcher Output Transformer Design
17:26
DeepBlueHarp
Рет қаралды 46 М.
How to Reform Electrolytic Filter Capacitors on tube radio or amp.
22:51
Electronics Old and New by M Caldeira
Рет қаралды 47 М.
Tube Amplifier Troubleshooting Tips
18:47
Mr Carlson's Lab
Рет қаралды 192 М.
How to wind Fender 5e3 Output Transformer
21:06
Delatsch
Рет қаралды 65 М.
PrimaLuna DiaLogue Premium Preamplifier ~ Introduction
5:56
Hi-Fi Corner
Рет қаралды 10 М.
How to safely test the Output Transformer on tube radio or amp.
7:11
Electronics Old and New by M Caldeira
Рет қаралды 27 М.
The Parts That Make Up a Tube Radio - Tube Radio Restoration Back to Basics part 1
35:02
Electronics Old and New by M Caldeira
Рет қаралды 8 М.
Todos os modelos de smartphone
0:20
Spider Slack
Рет қаралды 65 МЛН
ноутбуки от 7.900 в тг laptopshoptop
0:14
Ноутбуковая лавка
Рет қаралды 3,5 МЛН
Look, this is the 97th generation of the phone?
0:13
Edcers
Рет қаралды 8 МЛН