STK-0050 replacement for SX-780 and others

STK0039 is a quasi-complementary darlington config and the STK0050 is a 2 stage emitter follower. Both require about the same amount of bias
I'd have to simulate the design to determine if current through the bias generator is correct to get the bias for o/p stage correct.
If you try the circuit out, measure the ops bias current to see if you can get what is required.
 
There is also 863-NJW0302G and 863-NJW0281G which are a bit cheaper than 2SA1962OTU / 2SC5242OTU and a bit more power.
Also Toshiba 2SA1943N/2SC5200N but 2SC5200N is on back order at this time too.
Good thing we have lots of choices available.
All should work fine.
Lets hope that this will fix the problem without further troubleshooting.

On another note, a previous post stated that they had some difficulty with getting the position of the bjt mounting holes to lead bend distance correct.
I use a ink marker to mark the spot on the leads to indicate the bend point. I use the pkg mounting screw to temp place the pkg in position to mark the spot as it is placed on the HS. then bend the leads with needle nose pliers, place pliers just slightly in front of the bend point. last op is to solder the pins to the pcb after insulators are in place and device is torqued down after you have mounted the pkg to the HS.
 
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What gauge wire are we using ffrom the module to the board on this replacement? 20-22?
 
Heads up, the MJE15032G is backordered untill feb 2018. check rcs16's post for subs. MJE15030G is due back in tomorrow.
Have you looked at the Mouser project BOM? use the link as indicated on the first page.

Q1: NJW1302G, (NJW0302G)
Bipolar Transistors - BJT 250V,15A, 200W(150W) TO-3P PNP

Q2:
MJE15033G,(MJE15031G),[FJP1943],{FJPF1943}
Bipolar Transistors - BJT 8A 250V 50W TO-220 PNP

Q3:
MJE15032G, (MJE15030G),[FJP5200],{FJPF5200}
Bipolar Transistors - BJT 8A 250V 50W TO-220 NPN

Q4:
NJW3281G, (NJW0281G)
Bipolar Transistors - BJT 250V,15A,200W(150W) TO-3P NPN

Q5: BD139 (Any hfe grade)

Bipolar Transistors - BJT 1.5A 80V 12.5W NPN SOT-32(TO-126)
 
Incorrect! You can NEVER intermix PNP / NPN.
Well shoot. The original Q4 from the BOM (http://www.mouser.com/Search/ProductDetail.aspx?R=NJW3281Gvirtualkey58410000virtualkey863-NJW3281G) is an NPN and I ordered PNP (http://www.mouser.com/Search/Produc...OTUvirtualkey51210000virtualkey512-2SA1962OTU) as a replacement. I guess I could have checked that better myself.

I ordered the NPN.

Is there a reason people listed the PNP/NPN options when Q4 was only an NPN? I'm curious.
 
That is because you should match up true complementary pairs for drivers and/or outputs. For example you should not use a Toshiba with a Onsemi or Fairchild npn/pnp pair as drivers nor o/p. It is okay to use a Toshiba pair as drivers and Fairchild pairs for o/p.
Certainly does not hurt to post your order here so that others can review what you are up too b4 you place the order.
 
That is because you should match up true complementary pairs for drivers and/or outputs. For example you should not use a Toshiba with a Onsemi or Fairchild npn/pnp pair as drivers nor o/p. It is okay to use a Toshiba pair as drivers and Fairchild pairs for o/p.
Certainly does not hurt to post your order here so that others can review what you are up too b4 you place the order.
Ah, this makes sense. I understand now. Thank you!
Q1:[NJW1302G](http://www.mouser.com/Search/ProductDetail.aspx?R=NJW1302Gvirtualkey58410000virtualkey863-NJW1302G_
Q2: [MJE15032G](http://www.newark.com/on-semiconduc...DGSGrOU4V5IcxN_cTHPV5GHd4Xx4haEUaArmDEALw_wcB)
Q3:[2SA1962OTU](http://www.mouser.com/Search/Produc...OTUvirtualkey51210000virtualkey512-2SA1962OTU)
Q4:[2SC542OTU](http://www.mouser.com/search/ProductDetail.aspx?r=512-2SC5242OTU)

Everything else is directly off of the BOM from the first page.

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=50f7dd2519

I'm guessing my Q3/Q4 pair is okay, not sure about Q1/Q2. I don't know why the original Q1 isn't showing up on the BOM link like I thought it used to.
 
Thank you so much! Hopefully by the end of next week I'll have soldered them on alright and can test them out.

Thank you again, I appreciate it.
 
rcs, I have a question, on your Mouser BOM you have R2 listed as a 75ohm 1/2 watt resistor, but in your PDF from page 1 you have R2 listed as a 1K ohm 1/2 watt resistor. which is the correct resistor?

Mouser.jpg PDF.jpg
 
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