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Old 22nd June 2003, 12:16 PM   #1
shyfx is offline shyfx  Australia
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Default Japanese Transistor Replacement

Hi, I have an old Yamaha A-520 amplifier. It isn't working since my mate blew it up somehow. I opened her up and there is a transistor split intwo, black marks everywhere, obviously it bit the dust

A1306A it reads, did a search on google. http://www.epanorama.net/wwwboard/messages/181.html was the only page that I could find that was useful. So I checked up the 2SA1306A as the page recommended and found a bunch of results, however I can't seem to find anything that says where I could buy another one, or even enough details for myself to find an appropriate match. Then again I am not very experienced so I am not sure if I can find a replacement.

There are as much details as I can find

2SA1306 SI-P 160V 1.5A 20W

Can anyone suggest a replacement if possible, or maybe someone knows where I can find hard to get transistors.

Mikey
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Old 22nd June 2003, 01:19 PM   #2
Netlist is offline Netlist  Belgium
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You could try 2S1606, 2SA1332, 2SB1186A.
Make sure you replace them all.
Check the driver transistors as well.

/Hugo
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Old 22nd June 2003, 05:12 PM   #3
shyfx is offline shyfx  Australia
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There is only one transistor of that type. There are some other ones, but they seem all fine (physically).

Do you have any other suggestions for a replacement outside of the 2SA family that is a little more easier to get? Would I just have to match the volts (160), amps (1.5) and frequency (?) or would other specs of the transistor be important?

If there is no other suitable chip it is fine, since I found a lot of the transistors I am after now while searching for those transistors you gave me, under the name 2SA1306 without the last A. They are all just in other countries and the postage costs and/or minimum orders are pretty high.
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Old 22nd June 2003, 05:57 PM   #4
Netlist is offline Netlist  Belgium
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Shyfx
Without a schematic it's difficult to tell.
If there's only one of those transistors it will likely be the driver.
Check the outputs as well!!!
You might try a MJE15031 to replace your 2sa1306A.
What's the complementary part of your 2SA?

/Hugo
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Old 26th June 2003, 11:09 AM   #5
shyfx is offline shyfx  Australia
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Complementary pair I assume is the chip closest, I am not that great with electronics at th design stage yet, but it is C3298A which I assume is 2SC3298A.

There are two others in the same line on the circuit board (about 8-10cm apart) They are
(2S)C2238 and (2S)A958

The main driving pairs per channel are
(2S)C3182 and (2S)A1265.

I ordered a few MJE15031 transistors anyway, even if I don't use them, might come in handy one day.

-Mike
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Old 26th June 2003, 11:35 AM   #6
Netlist is offline Netlist  Belgium
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Mike,
The 2SC3298A indeed is the complementary transistor.
You must know that you can't judge a transistor if you didn't measure it.
If you have a DMM (multimeter), it's fairly easy to do.
Here's a good link:
http://www.eatel.net/~amptech/elecdisc/ampfail.htm
You will have to take them out of the circuit to measure accurately.
So definitely check the other transistors as well.
I predict that the one you found blown-up will not be the only one broken.

/Hugo
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Old 29th June 2003, 11:32 AM   #7
shyfx is offline shyfx  Australia
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I imagine the complementary FET in my amp is an N channel so I did those tests according to the N-Channel tests.

2S3298A -
Diode test (probe polarity in brackets):
Gate(+) to Drain(-): 200
Gate(+) to Source(-): 0
source(+) to Gate(-): 0
Drain(+) to Source(-): 198
Source(+) to Drain(-): 200

I assume the values are in mV, since that site mentions 0.4-0.5V
so I guess this transistor is fudged.

Should I test the 2SA958 and 2SC2238? Or are they different? I can't find anything online to tell me what type of transistors they are.

Mike
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Old 29th June 2003, 11:44 AM   #8
shyfx is offline shyfx  Australia
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I checked the 2SA958 as a PNP Bipolar Junction Transistor and the results were consistent with those assumed for a healthy transistor by that website.
Base to Collector - 543
Base to Emitter - 557

I checked the 2SC2238 as an NPN bipolar junction transistor and results were also consistent.
Base to Collector - 595
Base to Emitter - 600

I also talked to my mate, who gave me the amp, he blew it up by putting both left and right channels into one speaker. HEHEHE

Mike
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Old 29th June 2003, 12:07 PM   #9
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Mike,
Basically you have 2 kinds of devices.
The bipolar transistor and the Fet.
Bipolar transistors pins are called Base, Emitter and Collector.
Fet pins are called Source, Gate, Drain.
All devices in you amp are bipolar transistors.
So forget the fet's for the moment.
Scroll down to the bottom of that Eatel page and you'll find how to measure bipolars.
Basic measurements on a transistor (I'm only talking bipolar from now on) are very easy.
You switch your DMM to diode test and a cross measurement on all 3 pins should only measure 0.6V between 2 of them. From the moment on you measure more (or less) than two times average 0.6V between different pins, the transistor is broken.
Some very old transistors measure only 0.2V, but none of them will be in your amp.
Indeed, 0.6V = 600mV
All 2SA and 2SB Japanese transistors are PNP-types, all 2SC and 2SD's are NPN's
Here's a short data of your transistors:
2SA1306A:NF/S-L, 180V, 1,5A, 20W, 100MHz
2SC3298A:NF/S-L, 180V, 1,5A, 20W, 100MHz
2SA958:NF/S-L, 200V, 2A, 30W, 20MHz
2SC2238:NF/S-L, 160V, 1,5A, 25W, 100MHz
NF=Audio frequency
S = Switch
L = power
Again, you definitely should check all of them.

/Hugo
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Old 29th June 2003, 12:21 PM   #10
shyfx is offline shyfx  Australia
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Sweet, well the 2SC2238 and 2SA958 are both the results I gave earlier. The 2SC3298A gives:

Base to Collector - 199
Base to Emitter - 1
in reverse polarity it gives the same results. Collector to Emitter in either polarity gives 199-200. So this one definitely seems fried.

So it is pretty much stuffed it seems.

I know that I don't have a schematic, but would it be possible to suggest a replacement, even if it means replacing all of them?

One last question, I noticed the main drivers mounted on the heatsink, have a pair of two chips. So 2x2SC3182 and 2x2SA1265, I assume so the left and right have one of each and are the same.
How come there are four different transistors here and no matching pairs? I am assuming that these transistors are driving the main ones, so why are they different?
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