Need help choosing replacement output transistors

[Scott75s1974]

I posted this as part of a thread in the SS forum, but it might be lost in my narrative of woe. So please forgive a double post.

I blew a PNP output (2n6029) on my Scott R75s. They are obsolete. I'd really appreciate advice on what to do for a replacement. There are some on eBay that look legit. One person has a set pulled and tested from an amp. Looking at $15-20 to get one (most legit seeming ones are priced as 2, or with its NPN twin).

It would not cost much more (maybe less) to by a full set of contemporary output transistors for both channels. I don't know enough to do this confidently. The MJ15003G/15004 pair often comes up as a recommended replacement. It seems pretty close in most measures, but I'm not knowledgable at all on what these specs mean. I'm told that a lot faster is not necessarily good. I also wonder about how changing the outputs might require changes to the bias settings. Is this "saturation voltage" and what does it mean that the replacements would be lower?

I attach the 5629/6029 specs with a few replacement options including the MJ21193 which I've seen recommended here several times. It's beefier all around. If that would work, it seems a good long term choice. I'd very much appreciate guidance from someone who has experience in this.

 

[jdurbin1]

I'm curious as to what the pundits say on this one... same output set was used on the Tandberg TR 2055 and TR 2060 models, specifically the Motorola 5629/6029 pair.

John

 

[Watthour]

Another possibility is the NJW1302G/NJW3281G, 200W, Vcb 250, Vce 250, Veb 5, 15A Ic (30A Pk), 150°, 30 MHz, 600pF, 45 hFE min, TO-3P case.

 

[elnaldo]

I think you can't go wrong with the MJ15003/04 . I'd go that route. They seem close enough, and widely used.

Adjusting bias is not difficult and you'll have to do that in any transistors replacement.

I'd definitely avoid ebay or used transistors in this case (where a modern replacement is available).

 

[Scott75s1974]

I think you can't go wrong with the MJ15003/04 . I'd go that route. They seem close enough, and widely used.

Adjusting bias is not difficult and you'll have to do that in any transistors replacement.

I'd definitely avoid ebay or used transistors in this case (where a modern replacement is available).

Thanks. The MJ15003/4's seem to be working fine. I've replaced both on the blown side and will compare with the old on the other channel for a while.
Could the slightly different specs require a different bias setting? Or is it all pretty much the same? I've set them to where they were on the old drivers and they seem fine.

 

[avionic]

Thanks. The MJ15003/4's seem to be working fine. I've replaced both on the blown side and will compare with the old on the other channel for a while.
Could the slightly different specs require a different bias setting? Or is it all pretty much the same? I've set them to where they were on the old drivers and they seem fine.

Always check/ readjust bias when replacing amplifier components. Even if they're like for like.

 

[Scott75s1974]

Always check/ readjust bias when replacing amplifier components. Even if they're like for like.

Thanks. I did readjust to original spec. Wondering whether the part substitution would require _recalculating_ the bias settings somehow?

...or does setting bias to proper level automatically incorporate whatever difference a new part would introduce?

 

[avionic]

does setting bias to proper level automatically incorporate whatever difference a new part would introduce?

Yes

 

[Scott75s1974]

Yes

Good news! Thanks.