Hi, I have a JVC Nivico 5020u amplifier which i got from my dad, the only problem with it is that the transistors are blown. The blown transistors are four NEC 2SD180 and it says MA9X under it (I've also added a photo of it). I would appreciate if someone could help me find a replacement part.
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I’d trust a 2N3055 more than I’d trust Littlediode. IIRC, the D180 is an old single diffused type, and if you had old RCA hometaxial types on hand they would be ideal. Modern epi types will almost always work so if you had to buy new I’d go straight for a 2N3055 from ON. No point in going with anything “bigger” for a 6 amp 60W part.
Main problem is that the industry moved away from TO-3 encapsulation.
Most of good bipolar transistors (even better and cheaper than this 2SD180) uses other encapsulations.
The 2SD180 is relativelly fast for a power transistor (FT=10MHz) while others available such as 2N3055 (FT=2.5MHz) and MJ15003 (FT=2MHz) are far slower.
You migh run into oscillation issues, but sure you can try. I'd try in one channel first and turn the amp through a 40 to 60W bulb in series with mains so as to check if there is no oscillation - you'll need a scope here.
Would a physical adaption in the heatsinks be possible?
If yes, there are many cheap and good transistors in other encapsulations to be used.
Is this amp based on quasi-complementary push-pull (only NPN)?
Very popular design at that time.
Did you check other components such as driver transistors?
Most of good bipolar transistors (even better and cheaper than this 2SD180) uses other encapsulations.
The 2SD180 is relativelly fast for a power transistor (FT=10MHz) while others available such as 2N3055 (FT=2.5MHz) and MJ15003 (FT=2MHz) are far slower.
You migh run into oscillation issues, but sure you can try. I'd try in one channel first and turn the amp through a 40 to 60W bulb in series with mains so as to check if there is no oscillation - you'll need a scope here.
Would a physical adaption in the heatsinks be possible?
If yes, there are many cheap and good transistors in other encapsulations to be used.
Is this amp based on quasi-complementary push-pull (only NPN)?
Very popular design at that time.
Did you check other components such as driver transistors?
Sadly I don't have an oscilloscope.
I think it is since its using four 2SD180 transistors which are NPN.
I haven't. I don't know where they're located and don't have the amplifier schematics.
This amp was originally my grandfathers and it got passed down to my father and now its mine. My father kept saying that the transistors are the issue and they need to be changed, but when i got it i turned it on, and worked like a charm, i used it for months until a loud crackling sound appeared randomly in the left channel. After that happened i let it "rest" for 2 months before turning it on again and it was back to normal until the cycle repeated and now its back to loud crackling.