11-09-2008, 11:48 PM
I rescued a sansui 881 someone was throwing away. The sound out of the left side is a bit crackly. So I opened it up and did a quick cleaning and used an electronics cleaner spray on the inside and knobs. Still sounds good on the right but no improvement on the left.
On closer inspection I noticed three “burned” parts that look like resistors. They are located next to each other on a vertical board labeled “F-2436-1” (see pictures).
Is this something simple to fix? I'm not particularly knowledgeable about electronics but I have a soldering iron and could manage replacing a few parts. Any idea on the appropriate replacements? It seems a shame to throw the receiver out but I don't want to pay for costly repairs for something that was already being thrown away.
11-10-2008, 12:24 AM
I would be surprised if there was NOT a blown output transistor.
There will most likely be a bad transistor or two on the board in your pic.
The board appears to be the amp driver board.
If you have a meter, pull the outputs and test them.
Sorry I don't have the value of the burnt parts. Someone will.
11-10-2008, 12:26 AM
Check the other side of the board. The parts on the other side are the same.
One side is left and the other is right.
11-10-2008, 12:53 AM
That is the driver board. As Rob suggested, start by checking the output transistors for that side. You will need to check the driver transistors as well. They are mounted on the steel heat sinks on the driver board.
11-10-2008, 01:10 AM
Double check the resistors with the corresponding ones on the other side of this printed circuit board for correctness of values. Check transistors TR2 and 10
fuse F02 my be blown as well..
11-11-2008, 12:04 AM
So far i've found three resistors and two transistors (the ones with the heat sinks) that are damaged.
Google didn't turn up much on replacement transistors. I searched digikey and mouser with no luck. I could be using the wrong keywords since this is unfamiliar ground for me. The writing on the transistors reads “NEC B536 L5ZC” and “NEC D381 L610”.
Are these no longer made or are there good equivalents? Also should i be replacing transistors on both sides of the board? Will the sound out of one speaker sound different from the other?
11-11-2008, 12:14 AM
2SB536 and 2SD381
http://www.bdent.com/search/part.jsp?partnum=2SB536 or a Onsemi TIP32C (check pin out) http://www.mouser.com/Search/ProductDetail.aspx?qs=xZq1yRCsb1dy5xSR0KtGMQ%3d%3d
http://www.bdent.com/search/part.jsp?partnum=2SD381 or a Onsemi MJE15030 (check pin out) http://www.mouser.com/Search/ProductDetail.aspx?qs=HVbQlW5zcXVrl7yvawy6iQ%3d%3d
11-12-2008, 10:01 PM
Perfect, thanks for the links. I placed an order.
This might be a dumb question but I have some old 1/2 W resistors. Will they work in place of the 1/4 W resistors?
11-16-2008, 12:00 PM
Installed new transitors and resistors. I noticed a small section of trace is lifting off the board near a resistor. I guess from the heat of the original burned out transistor or my clumsy desoldering.
I turned the receiver on and like magic i can hear clear music from the left channel. I basked in my small sense or accomplishment but i can't wonder about the trace.
Is this thing gonna burst in to flames? Is there some sort of glue i should use or am i being paranoid?
11-16-2008, 12:06 PM
There are a couple of ways to fix the trace. Crazy glue works well to re-attache it to the board. That will hold it in place. The trace may have been weakened by the heat so the best fix is to bypass it with a piece of wire. Solder it to component leads on either side of the break.
11-16-2008, 01:26 PM
You have got yourself a gem...for nothing?
...Those 881's sound gorgeous!