A few questions about my sansui 9090

Johnnyhigh5

Member
Hello everyone! I'm new to audio karma. I have some things that need fixing on a 9090 that I picked up a week ago like the on/off switch was replaced with a toggle switch(would like to put an original switch back on), a new treble post and knob, and a set of feet. My first question is , is there a trick to getting the switches and tuning knob off? I don't want to pull too hard and break something. Is there an online store besides ebay to get parts? Also, my dial pointer light is out, and is also far from pointing at the right station. Any way to fix either? Thanks!!
 
Pull hard, the knobs will come off. E-bay for parts, or, spend $25 and become a subscriber. You can post wanted ads.

Welcome to AK.

Rob
 
Thanks! I'm thinking I need to replace a few power transistors. The part called out in the service manual is 2sc1116a. I found them on ebay. Is that what I should replace them with? Here is a link to the ebay listing.



I'm new to fixing electronics. Any help would be appreciated. Thanks!
 
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I am no authority. My working on electronics is a hobby. (I did repair the Pershing Missile whilst in the army though)

There are many FAKE transistors out there. Read the feedback from this seller. I am not sure, but many of his/her buyers have found out that the transistors are fake.

I have no association with the seller but only offer advice to you. Hope it works out well. "Caveat emptor"
 
Thanks! I'm thinking I need to replace a few power transistors. The part called out in the service manual is 2sc1116a. I found them on ebay. Is that what I should replace them with? Here is a link to the ebay listing.


I'm new to fixing electronics. Any help would be appreciated. Thanks!

Those transistors have not been made for decades, any you find for sale must be viewed with extreme scepticism as fakes are very common.

There are modern equivalents available from reputable sellers like Mouser and Digikey.

Cosmetic issues are one thing, but replacing power transistors (that is, if it is required at all) is not a job for a total beginner in my opinion.
 
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Does anyone know the new equivalent? Believe me, I won't be replacing them until I know exactly how to do it. After testing of course. The problem is, when all four fuses are in and the drive board in it blows the f10 fuse. Without fuse f10 and f08 in and the drive board in it comes out of protection mode. With fuse f08 in it stays in protection mode. I would say that one of the transistors attached to the fuse f10 is shorting.
 
If they are 2SC1116 then the transistor in the link is the right replacement.

http://uk.mouser.com/ProductDetail/ON-Semiconductor/MJ21194G/?qs=HVbQlW5zcXVQxZkOqmVvOA==

Mouser P/No 863-MJ21194G (in case the link doesn't work)

Test the pre-driver transistors, and driver transistors before you put the new outputs in, and I recommend you build yourself a Dim Bulb Tester (DBT).

Also do some searching and read up on fuse resistor problems with 9090 / 9090DB.
 
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Ok, thanks! Which board would the pre driver transistors be on? I checked the transistors on the drive board. They seem to be good, and match the readingsof the ones on the good (left side) side of the board. I did find a few bad fuse resistors R30 and R 40. Not sure if that would cause a 6a fuse to blow. Are the fuses protecting the cap or the board and output resistor? I wonder if the conductor is flowing through the base, but the resistor between the drive board and output transistor tests good.
 
I tried to order some 390 ohm 1/4 watt fusible transistors, but digikey is out. Do they have to be fusible? If so, is there an equivalent that they might have?
 
Thanks for all the help! Replacing the 4 output transistors on the right channel fixed the fuse blowing problem, and replacing the 390 ohm resistors got it out of protection mode. I bought a new on/off switch and board with the bass, treble, midrange pots and both defeat switches. It looks as good as new now.
 
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