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I restored a Beomaster 1000 about two years ago and got a lot of help from this forum. Something went wrong and i need new transistors. As many of you no doubt know, the 2N5034 transistors are hard to come by. I remember reading that later versions of the BM1000 had a different, more modern and easier-to-find transistor, in I think a TO3 package. Can anyone tell me which one it was? Thanks
Here:
https://beoparts.com/2014/12/28/beomaster-1001-1200-transistor-2n5034-8320103/
Replacing with 2N3055 would require quite a bit of work...
Martin
Wouldn't a TO220 version of the 2N3055 work? Might not be as good as the original thermal wise but from the schematics it looks like they are not being pushed that hard. Just a suggestion
BEOVOX141: Wouldn't a TO220 version of the 2N3055 work? Might not be as good as the original thermal wise but from the schematics it looks like they are not being pushed that hard. Just a suggestion
Why?
The OP mentioned the TO3 package and you the 2N3055, I can see why the TO3 would be a difficult fit, where as the TO220 might be a lot easier.
Merely a suggestion
Thanks Martin and BEOVOX141 for your helpful replies. Just to confirm the 2N3055, I found a service manual that mentions that it was found in some models instead of the 2N5034. I didn't realise that the 2N3055 also came in a TO220 package.
Do the electronics require any changes, or is it a matter of just putting in the 2N3055 and biasing the same?
FYI here is a picture of my Beomaster with Beovox 2400 in my office where I use them every day
2N3055 (TO-3) was indeed used in some versions of Beomaster 1000.I don't remember if the rest of the electronics are any different, butreplacing 2N5034 with 2N3055 would require other insulator parts and plastic covers as a minimum.
But why bother when you can get the right parts?
Dillen: 2N3055 (TO-3) was indeed used in some versions of Beomaster 1000.I don't remember if the rest of the electronics are any different, butreplacing 2N5034 with 2N3055 would require other insulator parts and plastic covers as a minimum. But why bother when you can get the right parts? Martin
Thanks Martin.
When I first did the restoration I bought one 2N5034 from ebay, and was very lucky to have two donated by a local B&O enthusiast.
But now the problem is that given the price of these items in Europe and getting them to me in South Africa means they cost too much (and some sellers won't even ship here), whereas I can get the 2N3055 for less than $2 each at my local components store.
Fine.Just don't buy chinese counterfeits. That could easily be the case at that price.
Noted - thanks Martin. It is supposedly a reputable dealer...
Oh, I've returned many counterfeit parts from reputable dealers. Also several 2N3055.Noone knows what is what.For the same reason, I like to buy up old stock whenever possible.
A little more reading:https://archivedarchivedforum2.beoworld.org/forums/t/2388.aspx
Oh dear! Thanks for the heads up.
Does a schematic for the BM1000 showing the 2N3055 exist - anybody know?
ElSid:Does a schematic for the BM1000 showing the 2N3055 exist - anybody know?
I am pretty sure you can just drop in the 2N3055 in this configuration.
BTW I love this BM1000 upside down schematic
If you get really desperate I can send you some TO220 2N3055 from a 1985 batch, I have built enough power amps in my lifetime, so the ones in the inventory are just sitting there
Be careful though,
Transistors are, generally speaking, robust. If yours are failing recurrently, I would investigate around that circuit...
The 2N3055 is one of the most robust transistors in existence. You can literally fry eggs on them, if you want. They are not fast though. The slew rate is terrible, by today's standards. I was suprised to see 2N3055s in a higher spec model, such as the Beomaster 3000.
Ninni: The 2N3055 is one of the most robust transistors in existence. You can literally fry eggs on them, if you want. They are not fast though. The slew rate is terrible, by today's standards. I was suprised to see 2N3055s in a higher spec model, such as the Beomaster 3000.
Couldn't agree more. I have built many power block based on the 2N3055/2N2955 and from experience I can guarantee they are absolutely capable audio parts! The beauty is they are cheap and reliable, and if you are concerned about SOA simply add more in parallel...
But as Martin said,- Beware there are many fakes out there, but a quick screening will reveal them pretty fast, I had some fail @ 2 amps...