Sony Str v4 Transistor substitute cross reference ?

[secrets]

All 4 Transistors are shorted . Really need help searching for substitutes . They are Batwings ,
2sd735 and 2sb699 .The unit would blow the fuse when turned on .I removed the heatsink and tested with no hope . Searched everywhere for subs with no luck .Any info would be great that will work even if I have to drill new tapped holes . I am sure I will have to replace the resistors and drivers as well .

 

[Robisme]

I have replaced those with other styles and not has to replace anything else.

Any chance you can post a pic of how they mount to the heat sink?

Rob

 

[Robisme]

Here is one I did.

Rob

 

[secrets]

Can you tell me the transistors you used in yours? Was it for the vintage Sony Str V4 Silver face ? Let me post the heatsink

 

[secrets]

Here is the heatsink for the sony v4 with the dead transistors.

 

[dlucy]

Using the 2sd735 specs and general "high power audio amp" parameters, I come up with these replacements available at places like Mouser:

MJW21195 NPN & MJW21196 PNP

MJW3281A NPN & MJW1302A PNP

MJL4281A NPN & MJL4302A PNP​

Take a look at these.

 

[Robisme]

Or these.

Whatever you decide on will need some new holes in the heat sink unless you mount them sideways and extend the leads.

Rob

 

[secrets]

Drilling and tapping new holes might be the way I might go .let me take a look at those subs ?

 

[secrets]

I think I will go for the https://www.mouser.com/ds/2/308/MJW3281A-D-107810.pdf
They seem great and hopefully more robust althought I am worried about the vbe on
Base emitter on voltage?

 

[secrets]

Also the icmax amps was 12 and these are min 15 to 25 max just worried they would not turn on so might have to look up those resistors and install a higher rated one? Tell me what you think ?

 

[secrets]

Didnt know you like hk’s just sold a citation 12 working nice but a little ugly.
Thank You Rob and Doug I will order these transistors and update you guys soon.

 

[dlucy]

Also the icmax amps was 12 and these are min 15 to 25 max just worried they would not turn on so might have to look up those resistors and install a higher rated one? Tell me what you think Doug?

I am definitely not an expert, just a hobbyist. That said, I can tell you the Ic max is the maximum current the device can handle. So, if your original device had a Ic of 12 amps and the new one can handle more amps, 15, then you're ok... on the current-handling parameter.

 

[dlucy]

Didnt know you like hk’s just sold a citation 12 working nice but a little ugly.

I have a Citiation Twelve with the Nelson Pass updates and upgraded PCBs. It is excellent.

 

[secrets]

I really loved the sound out of the citation and it was a little heavy unit as well . I have a long way to go and a lot to learn and one of the obstacles for me is finding and/or cross-referencing components .

 

[dlucy]

I really loved the sound out of the citation and it was a little heavy unit as well . I have a long way to go and a lot to learn and one of the obstacles for me is finding and/or cross-referencing components .

Im a newbie as well and I documented one of my looking-up-replacements for others to poke holes in and correct me where I'm wrong here: http://audiokarma.org/forums/index....r-substitution-question.754182/#post-10253865

Maybe that thought process will help.

 

[secrets]

Oki doki The sony str v4 is up and running so far . I installed the mjw1302ag and mjw3281ag in this unit using metal bars to clamp the transistors down then fired it up using the 100 watt bulb and I am amazed they worked and sound good .They idle a little warm so I am wondering if the 2 variable resistors or pots would be the bias ? When I play it at normal levels it gets to the hot point after a while ?

 

[Phillip007]

Reviving an old thread -

I am currently trying to replace the output transistors on my Sony STR-V4 and was hoping to ask you a few questions -

Did your installed mjw1302ag and mjw3281ag fit in between the preexisting drilled holes in the heatsink? Or did you have to drill new holes?

How many holes did you have to drill in the copper buss bar you made for sufficient pressure to be applied to the new transistors? Or did you use 4 individual buss bars per transistor?

Any help or guidance will be much appreciated.

Thanks