Diagnosing and Repairing faults or defects in transistor radios, without special test equipment

[@roberthead127]

Nice one I`m just starting working on old radios for a hobby age 63 making that little radio works real good so inspiring big RESPECT an luv to all

[@mfbfreak]

Good luck. Many basic problems are easy to solve. Even as a beginner you can have some success. As time progresses, you can fix more difficult problems. The radio in the video is a really hard nut to crack.

[@daleburrell6273]

...I'm a vintage transistor radio enthusiast MYSELF-!

[@marcb8874]

moi je suis plus que débutant mais avec une aide et votre méthode je pense peut être arriver a quelque point positifs à 65 ans @@mfbfreak

[@louco2]

Thank you for taking the time to do this video, love to learn something new!

[@fins59]

Nice work, you're good at explaining radio repairs.

[@acmefixer1]

The transistors seldom go bad. The transistor will have nearly the same voltage on the emitter and collector when it has been biased into saturation - the base bias current has turned it fully on. When there is something wrong with the voltages, it's a good idea to check the capacitors, especially electrolytic capacitors. They often fail, causing leakage and excess bias current.

[@mfbfreak]

RF germanium transistors, as well as certain silicon transistors (the bc148 series), can in fact go bad. It doesn't happen too often, but it definitely does happen.

[@acmefixer1]

@@mfbfreak You must not be in the US. Here, where the first transistors were unreliable, the US government and military were the first large purchasers of transistors and very early they developed tests to determine the reliability of solid state devices. The hermetically sealed metal packages solved most of the problems with germanium transistors. Tin whiskers were never a problem and when the Japanese imported a huge amount of consumer electronics, their transistors were equally as good. I've read about the major problems the Europeans had with tin whiskers in the AC117, etc. germanium transistors.

[@mfbfreak]

Bit of a late reply, but the Japanese also suffered from bad transistors though a bit later on, in the 1970s. Particularly notorious are the 2sc458 transistors in Akai GX-series tape recorders. They go noisy or fail completely. Akai recorders made before or after that time have none of those issues - that i'm aware of, i mostly worked with GX4000 and GX630 recorders. Although transistors are fairly reliable and definitely more reliable than electrolytic caps, if a device is malfunctioning you cannot assume that transistors never fail. With soviet transistors i have no experience at all. American transistors are rarely seen here, and all the american equipment i have had (Marantz) was either made in Japan, or from before the tube era (Hallicrafters and other such radio stuff)

[@acmefixer1]

@@mfbfreak The smallest wafers that are made are 200mm, but most are 300mm. For a BC547 or a 2N3904, each transistor 'chip' or die is a half mm on a side, so a 200mm wafer can be cut up into 20 thousand or more transistor dies. So the wafers may be made in any country that has a wafer fab plant, and a box with fifty or more wafers, more than a million transistor dies, can be shipped to any country where the wafers are cut up and assembled into transistor packages. A close country to the US where labor is low cost is Mexico. So the transistors are tested and separated into various performance categories, labeled and shipped to customers, which might be Japanese, Chinese, American, Korean, or a European company, among many others. So when you say American transistors, they may have been made and assembled in any of a number of countries, along with the same transistors sold by other companies around the world. Many transistors say on them where they were assembled. And it seems that few if any of them were made in America, because labor is much cheaper in other countries.

[@LarryDeSilva64]

All very good tips for diagnosing what might be wrong with a transistor radio. Oh and I subscribed to your channel as well. I normally work on tube radios on my channel but just getting into working on Transistor radios.

[@mfbfreak]

Enjoy!

[@Radiotreehut]

This is a beautiful radio you repaired..keep bringing in more videos

[@michaelhiggins7365]

This video is so informative it is not even funny !!! Wow, what an excellent teacher you are. You better believe I mashed down on the Subscribe Button.

[@mfbfreak]

Thanks! For some reason, it's the one video that keeps drawing hundreds if not thousands of views.

[@gustavoangelero4068]

Can´t miss the ice cream container to store the small pieces! Good video. Greetings from Uruguay.

[@mfbfreak]

Yep! Though the one on my work bench is mostly used to catch little bits of metal when i'm using steel wool to clean and polish things.

[@colinevans7134]

You've made this video easy for me to follow with thanks

[@gonedoneggonedoneg9863]

U have a MILCOV 7 from Romania there-change the electrolyte caps and big tuning capacitor-the variabile capacitor can cause thatvu find ONLY 1 station everywhere...

[@mfbfreak]

Although caps can absolutely go bad, in this radio the problems were not the capacitors. Capacitor swapping wouldn't have fixed this radio.

[@gonedoneggonedoneg9863]

@@mfbfreak not that was what i mean- an old tehnician told me that the tuning cap is in most of the cases what become faulty

[@marcb8874]

Merci monsieur , très très bonne méthode afin élémine une partie des circuits , j'aime beaucoup

[@Ronei70]

Congratulations! Excellent explanation! One question: is it possible to use the same method for FM?

[@mfbfreak]

My apologies for the late reaction. Yes, in theory you could try the same for FM, with two FM radios. Keep in mind the IF on most FM broadcast radios is 10,7MHz, so if you want to hear the local oscillator of one radio, you have to tune it 10,7 lower or higher. You will hear that oscillator as a silence, when you normally hear noise.

[@cid99]

The design and all the components are Romanian. It is possible that the Albanian company that claims to have produced it took a license from the Tehnoton factory in Iasi, Romania.

[@mfbfreak]

Local assembly from imported parts seems likely. In the former eastern bloc parts got shipped for thousands of kilometers to factories in random places.

[@xhonivlore7653]

Hello that radio 📻 was manufactured in Albania 1975 where did you find it! Nice work by the way 👏 👍

[@brianronoh7134]

1975😂😂😂

[@xhonivlore7653]

@@brianronoh7134 sorry 1985

[@mfbfreak]

I bought it from a dutch radio collector, who in turn got it from a friend of his who lived in eastern europe - i don't recall exactly if he was from Albania or Ukraine.

[@oasishut3120]

0.7 v should be difference in base and emitter voltages , you mentioned between emitter and collector?

[@rectify2003]

Precisely

[@mfbfreak]

Whoops, yes indeed, the B-E voltage should be 0,7v for silicon transististors.

[@rectify2003]

@@mfbfreak Wow, 2 months to respond

[@MohamedRagab-dq8ur]

Very helpful. Is there another videos of troubleshooting different transistor radios?

[@mfbfreak]

Currently not, i mostly do tube radios. But a customer will bring in a transistor radio about next month. I don't know what's wrong with it yet, and if i can make a video about it. So maybe there will be another video.

[@mfbfreak]

Update: the customer brought in the radio, but there was nothing wrong aside from some dirty switches, so i didn't make a video about it.

[@agustinramos7847]

muy bueno tus video,estoy tratando de reparar mi radio sharp GF8585 años 70, que solo recepciona una sola emisora. y el resto ruido. aqui en buenos aires ya no hay tecnicos que la quieran arreglar.y me inscribi en un curso de electronica pero prefiero tusclases practica. saludos desde bs.as.argentina

[@Atomshamradio]

Ive done that before the human touch is a ground its impurities in ower fingers

[@hadibq]

Great video!! Thanks a lot for sharing 🙏 Qst pls: what's that component you used to touch the Sanyo's diode?

[@mfbfreak]

That's a ceramic capacitor. You can try out anything between 10 and 100pF.

[@robertdestefano1409]

ha ha yes we make great signal generators , we also make great Gound paths like you said careful with line radios

[@chrissmith7655]

Hi many thanks very well explained.

[@erin19030]

You can also make a pitch only Theremin with two radios.

[@drstrangelove09]

BRILLIANT!!! Thank you! Very instructive. Question: for the case where you pick up the internal oscillator of the one radio with the other... is the internal oscillator just a sine wave? If so then how does the other radio pick it up? Doesn't it need to be modulated?

[@mfbfreak]

Yes, it is an unmodulated sine wave. If you tune the receiving radio to a quiet spot, you will hear the noise disappear. You won't hear a tone, but the background noise disappearing is a clear sign the oscillator works. If you tune it just to the side of a weak radio station, you can hear a tone, which is the heterodyne (difference) beat note between the carrier frequency of the radio station, and of the oscillator of the radio.

[@drstrangelove09]

@@mfbfreak thank you... I've forgotten the details of the video.. so you're saying that the radio's internal oscillator will be picked up on the other radio as a "blank spot," correct? that makes sense... and then one can tune the radio to a weak radio signal and then off of it a bit and one will hear a tone? ... but that's not related to diagnosing the not working radio, correct? And, in your video, did you not imply that one would hear a tone from the bad radio if the bad radio's internal oscillator is working? but you are saying now that it is not a tone but a silent "sound"? correct?

[@Atomshamradio]

Great information friend 👍💯⚛

[@hadibq]

I just love that Sanyo :)

[@mfbfreak]

The type number is RP1270 and they are very common. I have another one, in white. That one i've had since i was a kid - it even has tooth marks when a 3 year old me for some reason put it in his mouth...

[@عبدرضاعباس-ف2ه]

nice work

[@signature50]

Excellent, thank you

[@beekaybeetee3911]

I repairing Valve radios tape recorders televisions Transistors casset recorders televisions Radios ,VCRs plasma TV computer games LCD TV ,LED TVs From 1970 to 2020 WITH a silmpe ANALOG multimeter......

[@masoudmontazery907]

Good luck sir 🎉

[@iceberg789]

but, where is that transistor replacement video ?

[@mfbfreak]

Ended up not making it, because there seemed to be another issue; the first IF filter is bad and i have to figure out which IF can from the west i can put into this radio from the east. Also, idk if people wanted to actually see it. It's only recently that people have started to subscribe to my channel, a year ago it was at just 20 subscribers hehe.

[@daleburrell6273]

@@mfbfreak ...I can remember when you could buy transformers for transistor radios from Radio Shack!! You could probably substitute an IF transformer from a Japanese transistor radio for the bad one in this radio (I've seen them for sale on ebay- but I don't remember if the first IF transformer has a yellow or white colored slug), but make sure that the substitute IF transformer has the same pinout as the one in the radio(!)

[@iceberg789]

@@mfbfreak all right, did subscribe ! but if you want to attract more subscribers, you need to work on those presentation, editing, lighting and thumbnail qualities !

[@deanagoes2791]

​@@iceberg789yea..like shango066 and Jordan pier

[@moogdome2562]

Excellent thank you.

[@mohabatkhanmalak1161]

Its a very clever and down to earth method of troubleshooting faults. Thanks for sharing and I just subscribed.🎿

[@mfbfreak]

Thanks!

[@DanielSmith-rw9ms]

helpful, thanks

[@viorelpopescu4990]

....... daca unora li se pare ca depanarea unui radio fie el si eftin este la indemina orcui, cu o surubelnita, un patent si un letcon se inseala amarnic In primul rind trebuie sa ai cunostinte serioase despre electronica in principal si in special despre radio Electronica,, grea "( industriala) este total diferita de electronica R-Tv chiar daca se folosesc in mare de aceleas componente Prin urmare este mai mult decit necesar sa studiati niste manuale de specialitate care sa va introduca in lumea R-Tv Aceste manuale sint greu de gasit mai ales astazi Atit radiourile cit si tvse repara dupa o sinoptica generala mai intii apoi se adapteaza in functie de schema Cum se procedeaza este ceva mai complicat dar voi sari multi pasi ptru a va explica o metoda simpla de identificare a etajului defect fara masuratori si fara scule sofisticate Ap de radio il putem imparti in 3- 4s-au mai multe etaje dupa complexitatea schemei (diagramei, desenuluiu) in general in 3 si anume 1 etaj de alimentare ( compus din toate circuitele ce concura la alimentarea cu (U) a aparatului 2 etajul de putere (esire) numita si partea AAF simplu ( amplificatorul de audeo fregventa) compus ca si primul din circuitele de redare a semnalului audeo 3 etanul de intrare sau RF ( radiofregventa) compus la rindul sau din alte etaje mai mici ( intrare antena, OL oscilator local, mixer urmat de 1- 3 etaje de FI fregventa medie S-au fregv intermediara, apoi etajul de detectie si RAA reglaj automat al amplificarii Ne vom ocupa de AAF amplif de audio fregv s-au esire, putere Cum se verifica presupunind ca ap este alimentat la baterii ele fiind noi Actionind intrerupatorul pe deschis cu pot de volum dat la un nivel peste jumatate se va auzi clar un pocnet distinct in difuzor urmat s-au nu de zgomotul clasic de fond Asta dovedeste ca cel putin dif este in stare buna si ca ap se alimenteaza cu electricitate lipsa orcarui simptom anunta clar defect din circ de alimentare Pocnetul se aude si poate si un usor fisit ( zgomot de fond) cu ajutorul unei surubenite se tine in contact cu mediana pot de volum iar cu mina cealalalta cu virful degetului aratator umezit usor cu saliva se atinde pe rind bornele Dif pe una din ele ( calda) in Dif trebuie sa se auda un fluerat puternic s-au un uruit caracteristi de semnal Daca se aude semnal etajul e bine in st de funct, nu se aude semnal defectul este in AAF si trebuiesc continuate investigatiile Daca AAF ESTE TRANZISTORIZAT se merge din aproape in aproape prin aceias metoda cu diferenta ca de aceasta data mentinem degetul pe borna calda a dif si tatonam bazele tranzistorilor urmatori in afara de cei finali cu cit ne apropiem de finali semnalul va fi mai slab iar pe final nu se poate auzi la baza tranzistorului de la care nu se mi aude semnalu se sfla deranjamentu (intrerupere in rezistorii de polarizare condensatoare de cuplare defecte, tranzistor defect Se incepe prin masurarea U de polarizarea Tz Lipsa U pecolector anunta intreruperea R de colector sau intrerupere in Trf de defazare Existenta u pe C la Tz ne conduce la masurarea U pe E Tz intrerupta R de E ori scurtcircuitul C electrolitic din E Lipsa orcarei U pe B s-au o U mai mare decit normal cu mult conduce spre Tz Defect ori R ce asigura pol a Bazei intrerupte etc este o munca ceva mai laborioasa dar nu imposibila daca dispuneti de un injector de semnal traba e mai usoara si mai rapida si asta se chiama a intra in detalii si spatul nu permite

[@cowboy3234]

This is a romanian Milcov radio

[@mfbfreak]

As far as i am aware, it's an Albanian produced radio (URT Iliria, Durres) likely based on a Romanian design. Milcov has indeed made identical radios.

[@zekeionica2028]

Milcov for export

[@sibajiray6811]

You are godsend Lima

[@mfbfreak]

Thank y ou!

[@daleburrell6273]

7:38..."signal substitution"-!

[@mfbfreak]

Yep! Take the IF signal from one radio and shove it into the other.

[@JesTheii]

this is so cool

[@mfbfreak]

Thanks!

[@naveedahmad795]

Great tips

[@rectify2003]

Brilliant Subscribed

[@milantrcka121]

Brilliant! But the plot thickens. Progress from sticks to hammers...

[@mfbfreak]

Haha, i'm not yet at the hammer stage. But sometimes i do resort to poking things with a wooden rod until something crackles or starts working again.

[@zekeionica2028]

Radio Milcov tehnoton Romania

[@MohamedAshraf-g6p]

Hi de VU3UUI from India, Thanks

[@aanandreassudiro8375]

Hello Salom Radio aiwa stanby solusi

[@Atomshamradio]

Those are germanum transistors

[@fins59]

The radio has a mixture, the audio transistors are germanium but the BF255 and BF254 are silicon transistors.