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Old 27th July 2005, 10:56 PM   #1
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Default Output transistor question

hey I have an aiwa cx-nmt50 system. Cant find specs on it anywehre but I do know the output transistors if someone could approximate output power from the complimentary sets. The main channels are as follows : B1625 and D2494 ( front left/right channels)
the center channel amp has these transistors on it : D2061 and B 1370
the rear channels I'm assuming are single ended because I can only find one complimentary pair? Their the same as ther center channel amp transistors. Also on the same board ( all the surround channels are on one board) is one option that says "BTL" (bridge tied load) but is apparently not used. What could that be for?
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Old 28th July 2005, 01:58 AM   #2
dimitri is offline dimitri  United States
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These are Sanken 100V 6A complementary darlington

http://www.allegromicro.com/skncatlg/pwrxtr/2sb1625.pdf
http://www.allegromicro.com/skncatlg/pwrxtr/2sd2494.pdf

other are 60V 3A complementary from Rohm
http://darasemi.com/stock%20pdf/2SD2061.pdf
http://darasemi.com/stock%20pdf/2SB1370.pdf

Quote:
single ended


Quote:
approximate output power
please measure the rail voltages ...
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Old 28th July 2005, 02:05 AM   #3
clem_o is offline clem_o  Philippines
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do a google on your transistors, you should be able to find some specs on them. Add a "2S" as a prefix, and keep the characters together.

To be sure, you'll need the actual supply voltages and the number of output pairs to get an idea of dissipation and current capability per amplifier. Regardless of what the calculations turn out to be, it will probably be on the 'optimistic' side since most AV amplifiers are current-starved via the power transformer - generally incapable of keeping all channels running at full rated power.
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Old 28th July 2005, 02:26 AM   #4
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no idea........ugh this brings us to the not having a mm again...... dont ask.

anyways, the caps are 50 volt and 25 volt, the transformer has 125 volt 5 amp and 10 amp outputs on it. I think theres an on board rectifier on the ciruit boards, but seeing the 50 volt 3300 uf caps the voltage cant be high.I'm guessing all thr tranny is is an isolation transformer?
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Old 28th July 2005, 05:08 AM   #5
jaycee is offline jaycee  United Kingdom
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It sounds similar to a system i recently repaired. There is the master amp for front channel which uses the Sanken darlingtons, and the left and right rears use some small TO-220 ROHM devices (I didnt check them as they all worked - the fault was with the cd player)

The BTL amplifier is probably for the centre speaker and from what I could work out it was a VERY low power chipamp on the pcb.

It'll be something like - front 30W, rear 10W, centre 5W
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Old 28th July 2005, 06:44 AM   #6
AJT is offline AJT  Philippines
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Default Re: Output transistor question

Quote:
Originally posted by ThSpeakerDude88
hey I have an aiwa cx-nmt50 system. Cant find specs on it anywehre but I do know the output transistors if someone could approximate output power from the complimentary sets. The main channels are as follows : B1625 and D2494 ( front left/right channels)
the center channel amp has these transistors on it : D2061 and B 1370
the rear channels I'm assuming are single ended because I can only find one complimentary pair? Their the same as ther center channel amp transistors. Also on the same board ( all the surround channels are on one board) is one option that says "BTL" (bridge tied load) but is apparently not used. What could that be for?

======
as jaycee has said, "It'll be something like - front 30W, rear 10W, centre 5W"

another way to look is by the value of the rail voltages! also the filter caps will give you some clues!
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Old 28th July 2005, 07:45 AM   #7
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hmmmmm......I know the system says "160 watts total power @ less than 1% THD" on all theones on ebay I've seen. My cd player was broke too, all it needed tho was an adjustment of that trimmer pot on the back of then lens- works great now. no room for it though, so I need to sell it.
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Old 28th July 2005, 07:57 AM   #8
clem_o is offline clem_o  Philippines
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"160W total power" means all channels combined output, I don't know if the spec means peak or rms.

30x2 + 10x2 +5 = 85Wrms total. Usually the peak power is 2x the rms power rating, so I'd say that's about right!!

Do yourself a favor and get a MM, even an inexpensive one is good enough for most jobs, and I think you'll be much happier!

Cheers!
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Old 28th July 2005, 06:16 PM   #9
jaycee is offline jaycee  United Kingdom
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It will mean "Music Power" which is peak power + whatever figure comes into your head first.

As for the CD laser, yeah, I tried that and it improved things, but the constant skipping was only 100% cured by a new laser. The new laser looked much higher quality (sealed trimpot for example) than the factory one it replaced.
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Old 28th July 2005, 06:35 PM   #10
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well mine wasnt skipping per se, it just plain wouldnt read cds. It would spool em up looking for the cd but it would put it back down and move on to the next ones and do the same. LOL would yall quit it with the multimeter thing!! I reallllyy cant afford one right now, as soon as I get a job that will be the first thing I get- after new floor boards, seats redone, gas tank, brakes, exhaust etc. in my falcon.


I've found that if you tripple check yourself on everything you dont mess up usually, and its fine if you have lower voltage circuits. I wont start messing with higher than 30 volts voltages untill I get a multimeter, stuff such as my tube radio. I just make sure I do everything right the first time and if I do something wrong theres consequences! If I break something I trace the problem out and I've learned from the experience

btw thanks for the power ratings. I wasnt sure on what that guy said about the 85 watts because he didnt say it was RMS. Duh on my part I see that manufacturers tend to rate their RMS at very high THD levels....dont you even get me started on that ... but 1% THD @ 160 watts sure is a lot less than other companies with 10% THD slapped on their RMS ratings. Aye, all that means is that the system can do say 100 watts continuous with ten percent of the signal distorted without hurting the equipment, but being horrible to our ears, doesn't it?! sorry, you got me started ANYways, is it possible that the peak is slightly higher than the 160 watts it states or is that about it ?
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