I have an older teac ag-v8060 receiver I got at goodwill yesterday. Can I replace the output transistors with other ones when all the specs have higher ratings except the continuos current? (1.5 vs. 4) Only reason I ask is because the max voltage is 150V higher, so at a lower voltage it can maybe take more current.
2SC4468 to MJL4281A
If not, please suggest better transistors because the ones in there are Sanken.....can't be too great.
2SC4468 to MJL4281A
If not, please suggest better transistors because the ones in there are Sanken.....can't be too great.
MJL has somewhat higher fT (good) but more than twice the Cob (not so good). I'd say it should usually work in an EF output stage, not sure about CFP. Also note TO-3P vs. TO-264.
???
Manufacturers wouldn't get away with underspec'd output stages nearly as well if (genuine) Sanken transistors weren't any good. They're not exactly too cheap.
ok thank you. The cases are about the same I compared the measurements. I will probably stick with the originals, I had no idea they were decent!
actually, there is a fair amount of hiss on them. like bad.
had to replace the psu caps they were bulging.
had to replace the psu caps they were bulging.
"so at a lower voltage it can maybe take more current."
This does not follow.
The published SOA curve will tell you.
Compare the currents at your rail voltage to see what difference the SOA makes to your choices.
Ah sorry. I have been learning a lot on terminology and I'm not quite sure what I was thinking. Instead, I might just put another one in parallel (proven method from ESP) to improve thermal and full power conditions.
If you want to improve on transistors use the pair 2sa2223 and compliment. These are excellent transistors also manufactured by Sanken.
This message from Sanken:
Higher grade products are as follows:
2SC3856 & 2SA1492 for 2SC4468 & 2SA1695
2SC6011 & 2SA2151 for 2SC3856 & 2SA1492
do people agree with this?
Higher grade products are as follows:
2SC3856 & 2SA1492 for 2SC4468 & 2SA1695
2SC6011 & 2SA2151 for 2SC3856 & 2SA1492
do people agree with this?
Just ordered a ton of Nichicon FG caps and NJM2068 op amps. I'll post pictures of the replacement process just for kicks.
I'll wait on the 2SC6011 and 2SA2151 for now as they are only from Digikey.
I'll wait on the 2SC6011 and 2SA2151 for now as they are only from Digikey.
Good luck, sounds like you may need it. I hope you have a scope and a bunch of 100n ceramic / film caps. The NJM2068 is no stranger to oscillation if the layout isn't up to par or when faced with capacitive loading; the significantly slower 4558 is more tolerant. If you see any spots were it's used as a plain ol' unity-gain buffer, chances are that the 4558 will be just fine.
I was actually looking into much of the same with an old Onkyo home theater receiver a while back, same story with NJM4558s in SIP. Unfortunately I have no idea how the NJM2068 fares in terms of input impedance nonlinearity with a 50k volume pot.
I was actually looking into much of the same with an old Onkyo home theater receiver a while back, same story with NJM4558s in SIP. Unfortunately I have no idea how the NJM2068 fares in terms of input impedance nonlinearity with a 50k volume pot.
Each power pin has a 0.022uF cap on it, so I'm hoping they will be ok where I put them in.
There are 2 buffers that I'll keep now that you said that, thanks, as long as they don't still add hiss or something.
As far as layout, how can I tell that it's good? I'm assuming short traces and good power/signal separation? I'm probably way off here.
Capacitive loading should be much of a problem here, and I've seen a 2068 in a Yamaha amp everywhere, so I'm assuming the volume pot should be tolerable for it.
There are 2 buffers that I'll keep now that you said that, thanks, as long as they don't still add hiss or something.
As far as layout, how can I tell that it's good? I'm assuming short traces and good power/signal separation? I'm probably way off here.
Capacitive loading should be much of a problem here, and I've seen a 2068 in a Yamaha amp everywhere, so I'm assuming the volume pot should be tolerable for it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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