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Sansui AU-X901, replacing power transistors, 2SC3519 / 2SA1386, options?

Magnus Back

Magnus Back

AK Subscriber
Subscriber
I'm repairing an AU-X901 with lots of issues on the driver board.
It's getting closer to the end but I have some bad power transistors I need to swap to get it fully working (2SC3519 / 2SA1386).
I could take a chance on eBay but what other realistic options are there?
 
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MJW3281A (NPN) MJW1302A (PNP) would be the first that I found that match up well and were the cheapest in the list on mouser.
 
Sui-Yogi said:
Equally reliable source to mouser or digikey.
Depends where you are on the world , shipping , import taxes might make it expensive to purchase…..

gb.profusion.uk

2SA1386Y Power Transistor -160V -15A

Multi Emitter for High Frequency Complementary Type to 2SC3519Wide SOA
gb.profusion.uk gb.profusion.uk
Click to expand...
Profusion only sells within the UK. Too bad, I was hoping I could have shipped to my family within EU and then sent to the US.
Minimum quantity is 1,000 at DigiKey in the US ...
 
While I'm trying to find these I can mention I made a PCB for FT1 (2SK389 FETs) on the driver board, replacing them with SMD LSK389B.
Both were completely fried on this one.
Can't fully test them until I have one complete side/channel but it looks to be working and is similar size.

20260327_161607109_iOS.jpg
 
Magnus Back said:
Profusion only sells within the UK. Too bad, I was hoping I could have shipped to my family within EU and then sent to the US.
Minimum quantity is 1,000 at DigiKey in the US ...
Click to expand...
Magnus Back said:
Profusion only sells within the UK. Too bad, I was hoping I could have shipped to my family within EU and then sent to the US.
Minimum quantity is 1,000 at DigiKey in the US ...
Click to expand...
Change the store from the menu on their website and you will be able to buy and get them shipped to US
Their website is a bit of a puzzle to solve .
 
Sui-Yogi said:
Change the store from the menu on their website and you will be able to buy and get them shipped to US
Their website is a bit of a puzzle to solve .
Click to expand...

Be aware, as of last fall at least, they ship through DHL who will charge you separately for whatever the tariff is as well as an additional processing fee. The extra DHL fee is not obvious when you complete your order at Profusion. For me the extra DHL piece nearly doubled the cost of the order and the tariff seemed to be calculated on the order total which includes the DHL shipping. Yeah, I was pretty unhappy with DHL
 
I looked back at the order docs to get the real numbers from my November order:

Profusion charged $4.75 for 25 transistors + $15 for DHL shipping

DHL charged $4.20 for duties and regulatory charges + $17.00 for "Duty tax processing"

I expected to pay the tariff cost but the processing fee was not made known until the parts were actually in the country when they sent me an email indicating there was another fee to be paid before delivery.
 
DHL is the worst shipping company ever. Back in 2023 I ordered some electronics components from a company, which I have used many times before, in Thailand. Never had an issue. This time DHL held the shipment for more than a week, then required import duties and taxes. The order including tax and shipping was $27.66. Import duties and taxes, which had never occurred with dozens of orders before, was nearly $200. I reported it to the company I ordered from and, to my surprise, they reshipped it without question through DHL again. This time it arrived as it usually had. Why the frick DHL all of the sudden thought they thought they could extort $200 in bullsh*t fees I have no idea. Never will I ever use them on purpose personally if I can help it.
 
Ok back to this one. @Robisme gave me some transistors to use!!

I got one side behaving better now, not drawing excessive current and bias is ok.
DC offset is good from the new LSK389B board.
Found another fried resistor and a broken diode. Replaced all similar diodes and resistors on both sides.

Working through the other side now.
Found Q53 and Q55 broken which fixed excessive bias on one half so bias is under control.
Still draws too much current somewhere on that side on the output half.
More work to do ...
 
Magnus Back said:
Success, it's no longer sucking current. Found four more broken transistors, Q8 and Q9.
So I'm up to 82 broken components on the power amp board ... at least it's somewhat working now.
Click to expand...
That's a considerable achievement Magnus, well done!
 
fojica said:
Just as a sort of confirmation - I used (and counting) LSK389 in my DIY Alpha. Absolutely no issues since 2021, and I even made a couple of mistakes along the road....
Click to expand...
Excellent devise, no complaints for me either. I used it to replace 2SK129 everywhere.
Worth checking their LSK489A/B for
pre-amplifier duty’s and you might find your self in a great surprise !
 
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