Transistor Replacing Substituting & Testing - Part 1

[@mackfisher4487]

Tony your electronic expertise is unquestioned, but what makes your videos enjoyable is your personality your stories clarify the points you are trying to make. I thank you for sharing your hobby and In-depth explanation of theory using schematics as well as good sound practice.

[@JohnnyUmphress]

Great information. Thanks. Most, if not all, of the old books and manuals you mentioned can be downloaded for free at American Radio History. A very safe and reliable website with thousands of vintage radio/tv books.

[@josephsirois2353]

Thanks again Tony this is a great video for the newbies, I wonder if you could make a vid or two covering how the audio amplifier circuitry actually works ,for instance negative feedback, differential , current mirrors , protection, snubbers and the like , some of the textbooks I have are written in engineer language, and you have a great way of explaining things in plain English, thanks please keep up the great work

[@morrisonagen4222]

Man, every time I think “I wonder about...” Tony comes in with a killer video! Thank you again!

[@williamsquires3070]

Hi Tony. I should also like to add that if you’re into repairing transistor radios (AM and FM), boom boxes, CB radios, or even high-end receivers, you’ll often come across a bad RF transistor and need to replace it. Sometimes, even a brand new one from the factory with the same part # and specs may not work. RF circuits can be REAL picky; you may have to try several transistors of the same type (NPN or PNP) before you find one that’ll work. That’s just the nature of the RF beast. This just goes to show the adage is true; the best tester for the component is the circuit it operates in. 🤠

[@zulumax1]

Thank you Tony for sharing you experience with the community. I have spent so much time with google and audio-karma looking for semiconductor devices that are not made anymore. Getting back into bench work now that I am retired from electrical assembly work over the last 40 years. I used to repair 8 track decks back in the 70's for guys in high school. That should give you an idea of my age. Seemed easier then, had a parts house to go to and pick up the Motorola direct replacement output devices, remove and replace, and done. Just replaced T-03 outputs in a Marantz 2275 and currently working on a Sansui G-8700DB. Both use ON semiconductor replacements MJ21193G (PNP), and MJ21194G (NPN) to save someone else the searching. The 95G and 96G have similar data sheets, but could not find what the differences were.

[@glenwhatley4125]

I grew up as a tech in the 70's-90's and worked mostly on Japanese items so I'm most familiar with the Japanese 2SA'S, 2SB's, 2SC's, and 2SD's and the subs within them. Amazing how much i remember about those at this point.

[@JohnnyUmphress]

Mr. Carlson's Lab, on YT, has a video explaining 2SA... transistors.

[@Beexzz]

This is great video. Great both in topic and substance. I am in exact same situation and have been learning lately all about (mainly) small signal transistors as much as I can and from many different sources. Obviously, Tony's videos on vintage hi-fi repair and restoration is invaluable source of knowledge. When it comes to transistors I have to be honest about one thing. One can find some good info around, sometimes even for exact part number but what nobody can tell you is how "exact" will some transistor of new(er) production "fit" in circuit. As Tony said, majority of "info" on original transistor is where and in what type of circuit transistor goes. There are some good audio forums but it's always good to see and hear how Tony goes about some things. I even contacted him directly! Thanks Tony for all your nice replies and information! Now, regarding transistors, I have noticed that older ones usually are of higher transition frequency. My Amp if full of Japan old style 2SA, B, C and D's. I got to tell you, finding one of newer production, even good branded manufacturers, can be PITA. But, having Tony, AK and some other sources usually can help. Some info will be missing. Most of the time. Info like exact Gain range or something. Some transistors have markkngs but most of them do not. Then I find myself coming up with headache because new (substitute/replacement) transistor comes in (just saying an example) let's say 4 ranges according to hFE (Gain). Which one to go with? Ugh... there is a learning curve here for sure and all content such as this one (btw, I enjoy Tony's long-ish videos for great and detailed teaching approach!!!) is God sent gift. Thank you Tony! Keep up the great content coming. Especially regarding this topic! Can't wait for yet another sequel!

[@StuartWoodwardJP]

As a fresh faced graduate in in 1989, in the dark ages before the Internet, I found myself in a job in Tokyo and I was sent down to small part shops under the tracks in Akihabara to buy some parts for the chief engineer to make a circuit that he had found in a book written in the US. I asked at all the shops for a US part number and the little old men behind the counter all just shook their heads. Finally, one of them sighed, pulled out a conversion book and sold me an equivalent. I went back to the office and told the boss and he laughed. He said all the shops had conversion books and only the last one could be bothered to look it up for me. He then showed me the rack of books in the cupboard right behind my desk where all the conversion books were housed. I learned the hard way.

[@jeffberwick]

Thanks Tony! This is so helpfiul, and it's rare to find this kind of content especially with your level of experience.

[@doubledigitdreams]

Collaboration time. Xraytonyb, blueglow, and Mr Carlson. If they got together and worked on a replacement list it would be a game changer for us in this hobby.

[@gregquinn6827]

What a great joy to find this info online! I’m a tube swapper from the 60s. Thank you so much Tony.

[@marcodoria]

As always, great content. And, by the way, experience such as the one you have on parts and circuit analysis will always beat a quick Google search. Keep them coming! Thank you sir!

[@TheTrueVoiceOfReason]

Another well done video, full of good tips and gentle encouragement to use the old gray matter. Thanks for helping to grow the community.

[@alanvandusen76]

Thanks for taking the time to cover this. Very helpful and appreciated.

[@1959Berre]

If you want to make the best chocolate cake, be sure to use Belgian chocolate. Granny would agree. 😂

[@billphillips110]

Good Video!!! Saw that Y-Town address and just had to give you a comment. I graduated YSU in '88 w/ Chem E degree. Recently became fascinated with learning electronics. If I had to do it all over again, I think I would have pursued Electrical Engineering. I love the fact that I can put together an entire electronics hobby bench relatively cheaply and test electrical theory right on a breadboard. Guess I could have put together a chemistry lab in my younger days but that would have been crazy expensive and a lot more dangerous!

[@wolkewietje01]

Excellent video, this is what I was searching for. I'm in the process of restoring a Pioneer SA-7500 and 8500 right now.

[@johnbonham7515]

Great video, as usual. Way back in the day, when the dinosaurs roamed the electronic components shops, I used to use the vrt manual from ECA Electronic, it was a german semiconductors guide, substitution, cross reference, info, etc. 2 volume book, it was very good, and saved you a lot of time... They are still around, in electronic form, and on paperback too (they haven´t updated this in years though). Thanks.

[@toddtonis]

Thanks for making this video. I'm rebuilding my 2nd 80's receiver (it's an HK brand) and up until now, the transistor substituting really stumped me. Your video is really helping. Thanks again, well done!

[@kennethiman2691]

Just recapped my first vintage tube radio....and it worked! But my vintage stereo receivers need transistors replaced. This was super helpful! Thank you!

[@gregnewberry4813]

Fantastic information. I really enjoy your videos Tony. I ran across the 2SC3228 & 2SA1275 the other day that are really usable. Thanks for all your hard work and knowledge!

[@jdmccorful]

A good how too , nuts and bolts session. Couldn't ask for better info. Thanks.

[@Satchmoeddie]

ECG was owned by Phillips and Phillips had bought up Sylvania by sometime in the 1970s. Dutch Phillips went under the Norelco brand in the USA for a long time. Amperex was also another name for Dutch made Phillips tubes in the USA. Most of those old sub books are just filled with more obsolete part numbers, many of which are equally as useless as the number you are chasing. Good video!!!!

[@Satchmoeddie]

One of my prized vintage ECG catalog has an ad for Sylvania vacuum tubes on the back of it. I have a small ECG catalog that is mostly stuff for CB radios and some analog synth stuff.

[@Gerrit-Max]

Yet another very good educational video in a way pretty much everyone can understand it. Thank you Tony.

[@adamwolfram6126]

Great video, Tony! I look forward to part 2!

[@petedazer3381]

Great information sir, thank you! I’m extremely familiar with vacuum tube amplifiers and recently, I’ve been remembering my tech electronics classes from 44 years ago to help me troubleshoot and repair solid state amps.

[@R.AudioElectronics]

Great video Tony. Your never gonna get a thumbs down from me. Thank you for sharing your knowledge and expertise with us. God bless. Mike G

[@e.emerald3224]

cool video, THANK You ... renewed my interest in fixing the phono section of my Sansui C2101

[@srtamplification]

Great Video!!!! I just had a discussion about this the other day in the lab with my students. I showed them some of the same things you used in this video. We have the old Texas Instrument Semiconductor cross-reference in our Lab and we use that a lot. I also showed them the NTE app.

[@tenminutetokyo2643]

NTE’s web site is cool because it always shows direct modern replacement part numbers for ancient parts from 40 years ago.

[@apolinarmartinez5723]

Tony, I always learn something new in your videos, I really enjoy it, thanks to share with us your knowledge, thanks so much.

[@Jwil3743]

Many thanks! I've wanted this video for a long time. Unsolicited input here, but if there's no penalty in editing the description content for your videos, I would strongly recommend somehow adding phrases like transistor compatibility or anything that will increase the chances that this video would come up on a search. I've searched for this type of content numerous times for learning purposes and refreshers, and I know this would have populated the list. Thanks again!

[@KameraShy]

Just what was looking for. Finally getting around to tackling long festering projects, including some mid-50's transistor radios, with some Zenith's where they sometimes (not always) use proprietary part numbers. I suspect my issues are more capacitor related, but I want to be prepared and understand. What would be interesting here is to look at substitutions using Russian germanium transistors. They seem to still be plentiful, but prices are rising.

[@rolfts5762]

Thank you so much Tony, for these videos. Its very enjoyable and educational (as always). :-) //br, from norway. And your endings of videos to us viewers is very nice, Peace joy happiness health. (The World/Tellus need more of that sort of inner-attitude.)

[@g.fortin3228]

Awesome ! I learned some good tips and took some notes. Thank you again. Had to resort to ebay recently and went by positive feedbacks and "nearest" filtering.. time will tell if the transistors work as the spec sheet says or not. Great channel Tony! the :all: bell has been rung!

[@-______-______-]

Excellent information. Hats off

[@daveinthailand]

A good transistor book is the towers transistor substitute manual it gives you the specs on 100000 transistors and characteristics used this all the time in the 70s and 80s but still available in the UK

[@ferenclucas2842]

Thank you, another brilliant informative video.

[@davido.hamilton3254]

This is the 1st. time I recall seeing your face, Tony. Good to see you in person Mr. Bevilacqua.

[@sanolivo6867]

Excellent video. I learned my lesson the hard way 🤣. When I rebuild my Akai reel to reel player. I replaced the old 458 with NTE85. Well it didn't work out. I finally tried Toshiba 2sa2240 and it worked better than the original 458.

[@chickenfoundation9323]

How come the Toshiba worked better ?

[@RobertChampion1]

Thanks Tony, excellent info as always! As a next step could you talk about selecting substitute transistors to improve amp performance. For instance in my Harman Kardon Citation 12, I replaced the original RCA 2N3055As with SK3027s. Sounds great! But I saw online that a tech had used MJ21196s which have significantly higher max voltages and power dissipation and claimed better performance.

[@georgeschmid1862]

I found your video helpful. Thank you

[@joemazza1011]

Thank you very much I appreciate the feedback now I know what transistor I need

[@paulpaulzadeh6172]

thanks Tony , I wait for that list many years , great as usual, need also for mosfet and power transistor too if you have it

[@dicko195]

Great info Tony! Also repair techs can go to HiFi Engine Manuals and hopefully get their transistor specs from the manual's parts list online. I did for my STA-2100. Thanks. Keep up the good work.

[@assistantto007]

Adverts on KZbin channels usually bug me - but I think you should have more then you currently have...all the great work you put into your terrific videos should reap you more rewards

[@Gerrit-Max]

I agree.

[@Asriazh]

Another viable option, I think, is, to go to a new-old-stock electronics parts seller website and often, when You enter the part number, they also list other parts that can be replaced with the one You entered, which means, the other way around is true too. You can replace the part You entered with the ones also listed as well. But like Mr. Xray said, always check all specs, to see if it really is a good match. I've seen the NTE crossover reference on their website recommending things to me that weren't even close to the original when it came to specs. Beware! :D

[@zopilotesky3014]

Good information. Thanks for sharing!👍

[@6StringPassion.]

Brings back memories. Idora. Mill Creek Park. Lived in Cleveland too, where I first discovered Heathkit and Lafayette stores.

[@unablemaker]

Great video, informative and a good one to learn from:-)

[@James-dt7ky]

[@Wizardofgosz]

Where my dad used to work, they stocked GE and Sylvania replacement semiconductors. So we had the GE and Sylvania books at the house, and whenever we needed semis, dad would bring them from work. (gov't contractor. Our tax dollars at work!)

[@larryshaver3568]

i have used both ecg102 and nte 102 and the results were better than i expected

[@ZenwizardStudios]

Thanks for this very valuable information.

[@larryshaver3568]

i have THREE radio Shack semiconductor replacement guides and it's amazing how transistors i can use in much of my "stuff'

[@bobdoritique7347]

Merci, very usefull video.

[@YugoZex]

2N222, 2N3905, 2N5551 are preamp or boost transistors mostly used in guitar pedals I have them in stock for my experiments. Bc 547, 548, 549 Npn or 557/558/559 Pnp are fantastic to drive (turn on) relays or C945 General purpose Npn also. But there are different versions of power transistors like Fast switching or power transistors also Mosfet, Jfet... Back in the days there was not internet so books were only manual you could have...

[@jaroo25041980]

Superb material.😍

[@poypoy9028]

Thanks for sharing big help for my studies

[@truthfinder6996]

very informative video, at least a sigh of relief after I burnt my sansui G6000 2SC2261 and 2SA981 TO3 transistors.

[@bixy9347]

Note quickcross is a great app, thanks for the tip, very grateful 🙏

[@2tallB]

Good tip, searching with PDF! Thx

[@lewiskhan9825]

grate video!

[@adamwolfram6126]

From what I've gathered, McIntosh applied their own part numbers because their transistors were selected for specific operational characteristics. The same manufacturer's model of transistor might be marked with multiple different McIntosh part numbers depending on its Hfe tolerance. Then again, they also gave every other part a McIntosh part number, so I'm sure they had multiple reasons, like specification and quality standards, as well as just plain ol' stocking organization practice.

[@PeterMilanovski]

And I was just in the middle of re watching old tutorial videos to see if there's anything that I missed because I understood it less back then and this video shows up! Heck yeah! I live for this! Right off the bat, a 2N3055 TO3! My favourite transistor! I have never tried to put in the ground work to find a suitable candidate for replacement of the humble 3055, truth be told I don't know if anything in the TO3 case is manufactured by anyone other than the Chinese copies, some of those things seem to be okay but I have seen some faked with small signal transistor's inside! I would love a transistor stress testing device that can put the rated voltage or current (switchable) at it's rated wattage across the transistor so I can literally sit down for hours just doing a Paul Carlson testing and binning the transistors because I'm an electro nerd like that LoL... Besides, I personally prefer to know if a copy has what it takes to be used before a customer finds out for me! Not everything out of China is terrible and if they weren't making copies of unobtainium components, there's basically nowhere else to turn to! My favourite little 13W amplifier is using Fairchild semiconductor TO66 output transistor's and good luck trying to get them, I don't think that even Chinese copies exist! There's a modification that the designers came up with using the TO220 package but it's just not the same! No chrome, no gold and not made in Australia.... LoL nothing is made in Australia anymore! But that's another story... Thanks for the amazing tutorial videos Tony... I have some datasheets to download and keep me busy for a while until the next video shows up LoL... Thanks 👍

[@geoffreykeane4072]

As far as I'm aware, you can certainly source the 2N3055 in a TO-204 package - which I believe is the exact same package dimensionally as the TO-3.

[@johncoops6897]

2N3055 are so common that you can simply buy NOS (new old stock) from Ebay etc. For example, buy Motorola ones from Ebay like this www.ebay.com/sch/i.html?_nkw=2n3055.

[@YugoZex]

When you replace original with substitution transistor it is recommended to write original part marking from component you replaced so next time when someone have to repair he have original info of the component so he can find replacement maybe better than you if there is better one...

[@johnnytoobad7785]

That KSA1845 is hard to find. I have used the BC500 series with good results for most small signal circuits.

[@sharepointpro479]

Thank You Tony!

[@dkmmhdk]

Interesting to see the super common European transistor pair on your list BC 547 / BC 557. Possibly the once you get to know first here.

[@AeroModule]

Great, informative video. Just my observation -- for the world of audio repair, 99% of transistor substitutions can be found by googling. Between AK and DIY Audio, you've got a great shot of finding what you need. How many situations are you likely to encounter that someone else out there hasn't already hacked thru?

[@johnjames378]

Excellent video, looking forward to the next one.

[@minlee6048]

Hi. First of all, I thank you so much for your video. I’m kinda new to repairing gears and your video helped a lot. I have a question actually. I have a gear that 2SC2878 needs to be replaced. It says 2SC2878 on the service manual and I found that there are C2878 A and C2878 B. I was confused so I checked darasheet and they seemed to be same. So is it okay if I use both C2878 A or C2878B ? Or not? Also there are 2 transistors soldered on the board but one A and one B

[@Wizardofgosz]

This is very useful. BC560C and BC550C are becoming scarce. I need a readily available drop in replacements for both.

[@johnnytoobad7785]

Its look like the BC550C's are (still) easy to find..but the (PNP) 560C's are only available via eBay. Low noise - high beta PNP's in general are hard to find. Not sure why.??? The MPSA18 is a good high-beta low noise substitute for most small signal NPN's. (similar to BC549C)

[@pulesjet]

The most important consideration is the Function of the Transistor. Switching, Audio is gravy easy pretty much. RF is a complete different critter. Operating Freq is the main issue.

[@sorcererstan]

Sure wish the Japanese sub manual was available online. Can't find one for less than $1000! That's the only one I'm missing.

[@Renegadeproject]

Thank you sir!

[@DAVIDGREGORYKERR]

I would just try implementing the module that has gone on the fritz as C++ code compiled for the Texas Instruments Blackfin DSP processor driving a discrete R2R DAC which takes it input from a ADC operating at 176400KHZ, I suspect that if you have the FFT of the RIAA Equalisation curve and a FFT of the input signal of the record when multiplied together using complex multiplication it is just a matter of applying the IFFT to recover the wanted signal and this can be implemented in such a way that it can be used as a module to replace a broken RIAA Preamp.

[@mmaranta785]

That sounds easy

[@larryshaver3568]

I have a Magnavox stereo record player with a 3 tube amplifier[1-12AX7 and 2 50EH5]my question though is is deviating on ceramic capacitor values in small amounts ok?

[@Wizardofgosz]

Tony, what you need to do, is make a PDF or something of all the replacements you've found and used so far in your restorations.

[@AmadonFaul]

I would kill for this!

[@Beexzz]

Guys, go to AK Forum (Audiokarma). There are a few guys out there who do all kinds of repairs and restorations on vintage hi-fi equipment. A few of them compiled exactly that, an Excel file (table) full of old Japanese (and others, of course) transistors and their new(er) "equivalents/replacements/substitutes" according to their experiences but also on transistor values. Be careful, it may be that one TR will not work in your specific circuit! Just saying...

[@uglsas]

Excellent Video, I have also one question regarding Sansui au-919 what should be adequate substitute for NMC1012/NMA1012 transistors, thank you

[@teresitamontebon5342]

Tony,what is the substitute transistor of my sansui r-70 the no. B528 pnp

[@kevinc5201]

Xraytonyb effect - the ONE copy of "Modern Japanese Transistor Data and Substitution Manual" on Amazon is now $738.00 with free shipping! I don't think the years old reviews of the book paid that price for it. Lol

[@xraytonyb]

That's insane. A case of them shouldn't cost that much. I think list price on it was around $17. I know it was quite a while ago that I bought mine, but I know I didn't pay much more than that for it. In case you want to search by ISBN number, it is 978-81-7029-970-7 and was sold by BPB Publications. I think there were also two earlier books for the transistor data and substitution separately. This later one combined both of the older books into one.

[@jdmccorful]

Supply and demand, they got you!

[@kwacz]

looking for a replacement to the TR733 transistor but cant even find the specs on the original. How do I go about finding the replacement to the TR733 output transistors in my amplifier?

[@mohammedisaa9952]

"IF"...... anybody in the community could help this guy to find this part, it would be a great gesture of kindness... I would have helped him, but i neither have the experiance, or competance to do so. In advance i would like to thank the person who is capable for helping this guy out and im sure many people will need this item........... """"" Please """""" include his name when you reply to him..... thank you so very much for helping him 🙂❤️🏅🏆......

[@billkalina3089]

Tony, I don't understand why Toshiba for instance, stopped making the k170 jfet. It is still highly sought after, and originals are fetching 7-8 bucks apiece! If you can find them. Linear Systems makes a new version, for 10 bucks at the diy audio store. Surely there's a suitable sub now?

[@TheyreStillOutThere]

Vintage transistor cross referencing can be a real pain in the ass, especially if you’re trying to avoid NTE parts and want to stick to more reliable and higher quality components like Fairchild Semiconductor. The Audiokarma forum has been a godsend in my restorations, but I would pay real money if someone compiled a bunch of modern cross references into a PDF and sold it. It would be an invaluable resource as a lot of the original data sheets for older transistors are very difficult to find online and it’s difficult for a layman like me to figure out all the correct compatibility requirements for doing substitutions. I highly encourage @xraytonyb to compile a master list and offer it for sale.

[@villacoya]

Hi Tony, I really enjoyed your 50 plus minutes tutorial about transistors, but still cant find the answer on how to replace or upgrade a MASPOWER MSG50N350FH from a friend welder machine, there is like 15 of this semiconductors inside and like 6 are carbonized. I'm guessing bad quality or not sufficient heat dissipation, thank you so much for any sugestions.

[@larryshaver3568]

Zenith transistors have their own numbers too such as 121-234

[@skidkev6421]

Please help!! bel 2n6254 6a NPN metal transistor replacement?

[@cemkara4322]

hello for old auido amplifier i want to change two transistor with subsitude transistors . the original onces has frequency 30MHZ new substitude one has 4MHZ is this make a problem ?

[@billkalina3089]

Digikey has a forum thread on that subject.

[@PhuckHue2]

On Semi makes great stuff

[@BobWilson84]

ROSS RADIO!!!!! I’m thrilled to hear that you knew about that gem. MVR for lunch, and Ross Radio for parts! Are you still around the Youngstown area!? I’m just 30-45 min north

[@xraytonyb]

I was about 40 minutes drive from there. I just ran into the last owner of Ross radio last week. After he closed the store, he ended up working as a field service engineer for GE. He now repairs X-Ray equipment like I do and we had an opportunity to work on a project at a hospital together . He still has a few of the items from the old store, but most of the inventory was sold. Small world!

[@larryshaver3568]

Are you on facebook? several people there have had trouble replacing transistors in a Magnavox with a 204 chassis. i told them for the preamp board all 6 can be substituted with an SK3004 or nte 102

[@truthfinder6996]

hi there, can you help me finding a replacement for Sansui G6000 FET 2SK109. I will really appreciate it.

[@joemazza1011]

I really enjoyed this video and I did get something out of it. However I had a question I don't know if it's okay to ask or not I'm trying to fix an old Sony ICB 350 walkie-talkie and I'm pretty sure one of the transistors is bad transistor code is c945 tp 247. On the transistor when I look it up it only comes up with c945 and in a different code on the bottom would that be the correct one do you know I'm sorry to impose I've tried everything thought maybe I can get some insight from you it would be really appreciative thank

[@xraytonyb]

Try ksc945 or 2sc945

[@mnoxman]

Rule of thumb from the WABAC time of two-way radio. A replacement: Identical part number. E.g. HP part number for HP part number. If there is OEM documentation that says you can use a different part number that is a replacement. Usually means it will work in 100% of all cases. Substitute: Use of a substitute guide. Will work in 98% of cases. Closest match: Parametric search. e.g. Dual gate FET GE 19A116818P3. GE documentation says it is a 3N187. Both are dead part numbers. Dual gate FETS are 'old skewel' and in many cases "Not for new designs" by OEMs. A close match using parametric search would be 3SK263 but the 3sk has different capacitance values and may not work in all circuits. Will work in >50% but not guaranteed

[@truthfinder6996]

hi there, can you help me finding a replacement for Sansui G6000 FET 2SK109. I will really appreciate it.

[@mnoxman]

@@truthfinder6996 Not really. I have a full time job doing IT security. The package is obsolete. You will need to use one of the PCB houses to make your own. Find parametrically similar devices using some place like DigiKey or Mouser.

[@KameraShy]

Maybe a Wikipedia-like website developed by the community to list transistor replacements/substitutions. A master list of numbers, searchable on partial number, that links to known good replacements/substitutions and experience comments from registered users. I wonder to what extent interest is confined to just a limited number of transistors, not the overwhelming volumes shown in the manuals.

[@larryshaver3568]

2N3055 is a substitute for a 2N3027 which my Dynaco SCA-80 had four of

[@cameronstolhand7149]

If I substitute a transistor how do I know what to bias it to? And how do I bias it? From what I understand you change out the resistors until you get the correct voltage but what is the correct voltage? Would that voltage be the same for the transistor no matter what circuit it's in? Would the data sheet tell me the exact voltage to bias the transistor or does the voltage I bias the transistor to vary depending on the circuit?

[@mohammedisaa9952]

@cameronstolhand7149 Watch more videos, its all explained and shown in the "restoration" videos. Each machine is particular to its self, but the "service manuals" will explain what the voltages are expected in the circuits, and how to bias each machine and where...... hope that helps 🙂👍🏻

[@larryshaver3568]

i have a few books from radio shack that show which archer transistor[s] can be used and it is amazing how many germanium transistors can be substituted with an archer 276-2007

[@mmaranta785]

Can you still buy that Archer part?

[@larryshaver3568]

@@mmaranta785 i doubt it but a sylania ecg 103 or nte 102 can be used

[@lewiscole5193]

@@larryshaver3568 Not that it matters in the slightest, by my 1974 Archer Transistor Substitution Guide says that the 276-2007 is a "direct commercial equivalent" to the 2N1305 which still seems to be in stock at Digi-Key.

[@larryshaver3568]

@@mmaranta785 unfortunately no unless on ebay and that's only if someone has one