Once more Sansui transistor substitutions

[eizner23]

KSA1015 might be a better match for 2SA726 **unless a low-noise device is required, use KSA992F**

Type Designator: KSA1015
Material of Transistor: Si
Polarity: PNP
Maximum Collector Power Dissipation (Pc): 0.4 W
Maximum Collector-Base Voltage |Vcb|: 50 V
Maximum Collector-Emitter Voltage |Vce|: 50 V
Maximum Emitter-Base Voltage |Veb|: 5 V
Maximum Collector Current |Ic max|: 0.15 A
Max. Operating Junction Temperature (Tj): 125 °C
Transition Frequency (ft): 80 MHz
Collector Capacitance (Cc): 4 pF
Forward Current Transfer Ratio (hFE), MIN: 70

 

[DeltaForce]

Hello good guys, I am new to the forum, but I have a long time reading them.

I have basic electronics knowledge and am recap a Sansui AU-7900 that I recently purchased.

I am working on the F-2596 board, I have read in the list of replacements that the ZD01, ZD02 (EQA01-13R) 13V/0.5W, can be replaced by (1N5243B) or (BZX55C13), but in my country I do not find those replacements.

My question is: Can I replace (EQA01-13R) with (1N4743A) 13V/1W.?

Sorry for my poor English.

 

[Sdp81]

[QUOTE = "DeltaForce, post: 14009624, miembro: 326011"] Hola, muchachos, soy nuevo en el foro, pero tengo mucho tiempo leyéndolos.

Tengo conocimientos básicos de electrónica y estoy recapitulando un Sansui AU-7900 que compré recientemente.

Estoy trabajando en la placa F-2596, he leído en la lista de reemplazos que el ZD01, ZD02 (EQA01-13R) 13V / 0.5W, se puede reemplazar por (1N5243B) o (BZX55C13), pero en mi país I No encuentre esos reemplazos.

Mi pregunta es: ¿Puedo reemplazar (EQA01-13R) con (1N4743A) 13V / 1W.?

Perdón por mi pobre inglés. [/ QUOTE]
Were are you from?

 

[DeltaForce]

[QUOTE = "DeltaForce, post: 14009624, miembro: 326011"] Hola, muchachos, soy nuevo en el foro, pero tengo mucho tiempo leyéndolos.

Tengo conocimientos básicos de electrónica y estoy recapitulando un Sansui AU-7900 que compré recientemente.

Estoy trabajando en la placa F-2596, he leído en la lista de reemplazos que el ZD01, ZD02 (EQA01-13R) 13V / 0.5W, se puede reemplazar por (1N5243B) o (BZX55C13), pero en mi país I No encuentre esos reemplazos.

Mi pregunta es: ¿Puedo reemplazar (EQA01-13R) con (1N4743A) 13V / 1W.?

Perdón por mi pobre inglés. [/ QUOTE]
Were are you from?

.
.
Venezuela.

 

[Skywatcher]

Hello good guys, I am new to the forum, but I have a long time reading them.

I have basic electronics knowledge and am recap a Sansui AU-7900 that I recently purchased.

I am working on the F-2596 board, I have read in the list of replacements that the ZD01, ZD02 (EQA01-13R) 13V/0.5W, can be replaced by (1N5243B) or (BZX55C13), but in my country I do not find those replacements.

My question is: Can I replace (EQA01-13R) with (1N4743A) 13V/1W.?

Sorry for my poor English.

Please start your own thread on your unit in the Sansui forum so this thread doesn't get all clogged up. BUT, I wouldn't recommend using a 1W Zener to replace a 1/2W because the knee voltage is different and won't regulate properly. Here is a basic explanation. https://www.elprocus.com/knee-voltage-of-pn-junction-diode/
Start your own thread to continue please.

 

[itsikhefez]

In a Sansui 5000X, I need to replace TR803 in the F6013 driver.
Manual says 2SC984, in practice 2SC281 is used.
Typical replacements I've seen are KSC1845 or KSC1815 both seemed under-specced (maybe they are fine in practice?)
I've got ZTX694B, which seem to fit the bill, but are significantly higher hFE. Any issues with that?

| 2SC281 | 30  | 20  | 5 | 100mA | 200mW | 80Mhz  | hFE=170
| 2SC984 | 50  | 30  | 5 | 500mA | 350mW | 115Mhz |
| KSC1815| 60  | 50  | 5 | 150mA | 400mW | 80Mhz  | hFE=210
| KSC1845| 120 | 120 | 5 | 50mA  | 500mW | 110Mhz |
| ZTX694B| 120 | 120 | 5 | 500mA | 1W    | 130Mhz | hFE=750

EDIT: I originally confused 2SC821 with 2SC281! Seems like KSC1815 is a fine choice

 

[DeltaForce]

Please start your own thread on your unit in the Sansui forum so this thread doesn't get all clogged up. BUT, I wouldn't recommend using a 1W Zener to replace a 1/2W because the knee voltage is different and won't regulate properly. Here is a basic explanation. https://www.elprocus.com/knee-voltage-of-pn-junction-diode/
Start your own thread to continue please.

Thanks for your reply and sorry for interrupting the thread..

 

[Skywatcher]

I finally found the time to have a look for the reason for the black burnt board and the beefy TIP replacement driver transistor that the previous owner installed on my G-4700. It turned out to be the old brown glue shorting-out trick! I couldn't find an original 2SD357 replacement in my transistor stash but I found a 2SA913 and its complementary 2SC1913. Will these two be suitable replacement drivers for the original 2SB527 and 2SD357 by any chance? I would have thought so but just to be sure I would like to run it past the people, gods and gurus here who know a lot more about these things than I do, just to be sure. View attachment 2192255

The 2SA913/2SC1913 are high speed (120MHz) transistors and are best to keep for use in a high speed amp. The MJE15032G/15033G would be better since they are both close to the 30/35MHz speed, and are also a little heavier duty than the original transistors.

 

[JoseHH]

A good match seems to be the KEC KTC3228/KTA1275 if you can find them. Another choice, albeit, a little shy in total power dissipation KSA1013/KSC2383 may work there if you can fit a small heat sink on them. I have seen tables where they show a transition frequency of 70MHz for the originals, but the datasheet i found does not show this value. Another one may work there is the Rohm 2sb1086/2sd1563 pair. Check the datasheets.

 

[JoseHH]

Usually the KSA1220/KSC2690 are suggested as substitutes for the 2SB527/2SD357, but they are also fast transistors. With the exception of the TO-126 Rohm parts i mentioned above, my TO-92L suggestions are borderline because the KSD357 is capable of dissipating more heat with its built-in heat spreader. Without knowledge of the exact circuit, circuit location and voltage and current I would go with the 2sb1086/2sd1563 or even with the ksa1220/ksc2390, but in certain locations you may be able to get by with a a smaller part if the operation of the circuit is judiciously evaluated.

 

[JoseHH]

So it is in a power supply regulator?.If that is the case, then you may be able to use something cheaper, may be a BD140/BD139 pair. They are slow transistors, but for a +/-12V power supply they will work ok. My TO-126 suggestions above are more expensive, and you can still use, but they are better as audio drivers, for driving the base of the output power transistors. The MJ transistors suggested by Skywatcher will also work well in a +/-12V power supply application especially if the current needs to be on the order of a couple of amps. Based on the information you gave, the BD139/140 are sufficient.

 

[Skywatcher]

Are you sure about this because the 2SD357 is 0.8A, 1W and the MJE15033G is 8A, 50W?

I use them all the time. Yes, a bit overkill, but they work just dandy. You can go higher in voltage, current, and watts, but never lower than what the circuit needs. Matching the rest of the specs of course to meet the originals. Speed being one that should always be close, unless it doesn't matter in a particular circuit.

 

[GrisPato]

@JoseHH

BD140/BD139 pair. They are slow transistors,

Just curious, learning still. With slow you mean Ft? Because I found this doc

Or does this depend on manufacturer?

 

[JoseHH]

@JoseHH

Just curious, learning still. With slow you mean Ft? Because I found this doc
View attachment 2194068
Or does this depend on manufacturer?

Actually you are right. I Was wrong .. While searching for a part to help the OP, I saw the ON, Fairchild and ST datasheets for their BD140 which do not show ft data, then I was at some point looking at another TO126 part, BD180 which has an ft of 3 MHz, and somehow I thought the BD140 was similar. I honestly ignored the fact that Philips does show an ft value of 140MHz for their BD140. Thanks for bringing this up to my attention. I wonder why Fairchild does not report this parameter.
In any event, I apologize for misleading others with my comment.

 

[GrisPato]

Actually you are right. I Was wrong .. While searching for a part to help the OP, I saw the ON, Fairchild and ST datasheets for their BD140 which do not show ft data, then I was at some point looking at another TO126 part, BD180 which has an ft of 3 MHz, and somehow I thought the BD140 was similar. I honestly ignored the fact that Philips does show an ft value of 140MHz for their BD140. Thanks for bringing this up to my attention. I wonder why Fairchild does not report this parameter.
In any event, I apologize for misleading others with my comment.

I ordered some of these to experiment with replacements for the sb/sd 3xx/5xx transistors that Sansui uses in the regulated ps and often in the driver, in my au 417. Also some sankens and Toshiba transistors mentioned here.
That's why started looking at the datasheet. Because I am really a novice in this electronics thing. I also found that the ft was not mentioned in most, until I found the one from Philips. So my first thought was that maybe it is different per manufacturer.

 

[GrisPato]

Now I am at it anyway. I would like to understand what is meant with fast.
I can understand fast switching but fast gain?!
I understand that the transition frequency is the frequency where gain is down to zero.
So I can see that you want gain up to the high frequencies with some margin. Especially when you have an amplifier stage with high bandwidth, low risetime and high slew rate what should mean you have an amplifier that can keep up with the dynamics of music over the whole bandwidth . But is this a fast transistor. Or a transistor that enables a fast circuit design?

 

[Hyperion]

But is this a fast transistor. Or a transistor that enables a fast circuit design?

The key is the fast devices, around that you can design a circuit to take advantage of that - exchanging transition frequency for wide bandwidth, low distortion, and fast rise/fall time.

There is no advantage in using 'fast' transistors in a slow design, maybe even the opposite in some cases. And many say a noticeable difference if using 'slow' transistors in a 'fast' design, and if you can hear it you should be easily able to 'measure it' - the difference that is.

 

[JoseHH]

Now I am at it anyway. I would like to understand what is meant with fast.
I can understand fast switching but fast gain?!

My limited understanding is that the transistors can amplify ac signals but at some cut-off frequency their gain begins to decline with a 6db per octave and by the time you get to the transition frequency the gain is 1, which means the signal is not amplified. Above the transition frequency, the signal is actually attenuated. Although the transition frequency may be 100 MHz, the effects of the 6db/octave decline begin at much lower frequencies. Together with the 6db/octave slope, there is a phase shift of 90 degrees that begins to occur at the cut-off frequency and goes on above that frequency. These are two of the issues engineers worry about when designing an audio amplifier. The transitio frequency is defined for a transistor in a common emitter configuration, very common audio circuits. The drop in the gain at frequencies greater than the cut-off frequency fc is aproximately beta=hfe*fc/f, where hfe is the DC gain of the transistor. The frequency at which beta=1 is the transition frequency ft, and this equation says that ft=hfe*fc.
Note that the cut-off frequency is usually much lower than the transition frequency: For a transistor with a dc gain of hfe=100, and a transition frequency of 10 MHZ, fc=100KHz not too far higher than the harmonics of the upper part of the audio spectrum. Because the amplifier feeds back the amplified signal the 90 degrees phase shift may cause problems in the correction of the distortion for the harmonics of the high frequency end.
Another issue which is related to the speed of the amplifiers is the parasitic capacitance of the transistor. The most relevant is the capacitance between the collector and the base "Cob" because in a common emitter configuration this capacitance appears magnified by the hfe gain of the transistor and thus, a few tens of pF turns into a few nF when the amplifier is operating and this causes problems too especially in the voltage-amplifier-stage (VAS). For me, fast transistors are high ft and low Cob. One example is the 2SC2705. There used to be many transistors like this one, in the vacuum-tube TV and monitor era because of the very high speeds at which the electron beam needed to be steered to generate an image at video rate. These also needed to be high voltage transistors so the audio engineers had a lot of options back then.

 

[Hipocrates]

Now I am at it anyway. I would like to understand what is meant with fast

As someon explained to me.
"The reason why the Ft of the transistors is so important, is high frequency distortion. Basically you need a huge amount of gain in the audio band to be able to get enough negative feedback to have very low high frequency distortion, and this is exactly why these high bandwidth transistors were chosen in the first place.
A "slow" transistor has lower gain at high frequency, and therefore has inadequate gain to support the amount of negative feedback which would make a wonderful sounding amplifier"
And here you can read a nice article.
https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf

From emperic, anecdotic experience, BIG deal with 100mhz (SA968/2SC2238)driver transistors units. (big G for example)
Not much on the others. (717, 517, 999, BA5000, X0X0 and X0X0 DB)
YMMV

 

[GrisPato]

And here you can read a nice article.
https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf

Thanks for the information. Read that article a few times already for learning more about the 'new' amplifiers with the advertisement of less global feedback and more local feedback, very interesting.
I was mostly wondering about the use of fast and slow. I can understand that because some transistors have high gain at higher frequency and was wondering what is the fast. May be something like high frequency means more changes from 0 v to peak voltage for each polarity so it needs be able to keep up and that is the explanation for fast. But could be wrong. Just because people explain it as a fast amplifier but I don't want a fast or slow amplifier I just want it to follow the music signal.
And if I understand it the right way the use of fast transistors means the possibility of less distortion.( More negative feedback and more bandwidth)
But please correct me if my view is wrong.