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Yamaha A-1 Transistor Replacements

ZeRask

ZeRask

Member
Hello good people of Audiokarma!
Since this is my 1st original post here, here's a couple of words about myself.
I am from Canada and just like most, if not all of you I enjoy good music, good sound and some DIY-ing during my non-existent spare time. I've been a quiet observer of Audiokarma for the past couple of years, learning from the best. My first project was the CNC Phono stage, which inspired me to dive deeper into the DIY rabbit hole. There's no returning from it now.
I'm not very technically skillful, however I am learning a lot thanks to the participants of AK. I have a multi meter, component tester, but no ocsilicope or any other advanced equipment.

Recently a friend gave me his old Yamaha A-1 Integrated amplifier, which I decided to recap/service. I'm done with the most of it and hopefully I will post a write up once I am finished.
While working on the ElCap board I accidentally damaged a 2SA913 transistor. One of the legs stayed in the PSB board and the transistor body is cracked. I assume it's not fixable.
On this board there are two pairs of 2SA913 and 2SC1913, marked as TR133 & TR135 and TR134 & TR136 (attached is the schematics).

I am wondering if someone could answer a few questions about the replacement?

1. Nobody seems to carry the 2SA913 anymore except for sellers of the big online auction. Should I assume those are counterfeit?

2. What is the closest replacement, suitable for this application in Yamaha A-1? I saw multiple posts with the same question, however I am not sure if suggested replacements will work in the A-1.

3. Will I need to also replace 2SC1913, to "match" the performance etc. of the 2SA913 replacement?

I know some AK-ers are very familiar with Yamaha A-1 model and I hope someone could help me find the right part.

Thanks in advance!ElCap schematics.jpg
 
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Nashou66 said:
here ya go, this might help you :D
Click to expand...
Great, thanks for this summary!
And thanks for your old write up on A-1 restoration. I find it very helpful!

I've seen the MJE15033 as a common replacement part but had my doubts. Some people said it didn't work for them. Others sad it has a lower "bandwidth" and it's not ideal. Sorry, I'm not well-versed in the terminology and can't interpret this as being an issue.
 
MJE15033 might work, meaning you’ll get sound out, but it’s not a direct replacement for 2sa913. 2sa913 is a strange animal in that it’s a 15W part with Icmax of only 0.1A. You might have better luck with something like MJE210G:

MJE210G is not a direct replacement transistor either but much closer to 2sa913. It’s compliment is MJE210.

If MJE210G works out, remember you’ll have to replace the complimentary pairs in both channels to maintain audio and parametric symmetry. Sometimes it’s easy and sometimes challenging.

Edit: MJE340G is also a good option and might be even closer to 2sa913.
 
Sparkplug said:
MJE15033 might work, meaning you’ll get sound out, but it’s not a direct replacement for 2sa913. 2sa913 is a strange animal in that it’s a 15W part with Icmax of only 0.1A. You might have better luck with something like MJE210G:

MJE210G is not a direct replacement transistor either but much closer to 2sa913. It’s compliment is MJE210.

If MJE210G works out, remember you’ll have to replace the complimentary pairs in both channels to maintain audio and parametric symmetry. Sometimes it’s easy and sometimes challenging.

Edit: MJE340G is also a good option and might be even closer to 2sa913.
Click to expand...
Thanks a lot for your input and advise about replacing them in pairs. Intuitively I assumed this may be necessary and you confirmed my assumption.
I'll certainly check those out. Ideally, I would like to keep everything as close as possible to the original parameters and if these devices may help.
 
ZeRask said:
Thanks a lot for your input and advise about replacing them in pairs. Intuitively I assumed this may be necessary and you confirmed my assumption.
I'll certainly check those out. Ideally, I would like to keep everything as close as possible to the original parameters and if these devices may help.
Click to expand...
:thumbsup:
 
Sparkplug said:
MJE15033 might work, meaning you’ll get sound out, but it’s not a direct replacement for 2sa913. 2sa913 is a strange animal in that it’s a 15W part with Icmax of only 0.1A. You might have better luck with something like MJE210G:

MJE210G is not a direct replacement transistor either but much closer to 2sa913. It’s compliment is MJE210.

If MJE210G works out, remember you’ll have to replace the complimentary pairs in both channels to maintain audio and parametric symmetry. Sometimes it’s easy and sometimes challenging.

Edit: MJE340G is also a good option and might be even closer to 2sa913.
Click to expand...
As a general rule, while looking for the replacement should I look for similarities in all specs or are there any specific specs which matter the most?
 
ZeRask said:
As a general rule, while looking for the replacement should I look for similarities in all specs or are there any specific specs which matter the most?
Click to expand...
Barring parameters that seem innocuous at first but become crucial under certain conditions, some of the main make or break parameters, as a starting point, would be,

Max Dissipated power Pd
DC current gain hFE
Vcemax
Vbemax
Vbcmax
Continuous Icmax —> very important
Gain Bandwidth product fT

Beyond this point, you’d have to actually look at the data curves provided in the data sheet to make sure the part behaves well in the entire range of bias conditions. This requires engineering skills you could familiarize yourself with in various available books, etc. and generally takes time.
 
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Sparkplug said:
Barring parameters that seem innocuous at first but become crucial under certain conditions, some of the main make or break parameters, as a starting point, would be,

Max Dissipated power Pd
DC current gain hFE
Vcemax
Vbemax
Vbcmax
Continuous Icmax —> very important
Gain Bandwidth product fT

Beyond this point, you’d have to actually look at the data curves provided in the data sheet to make sure the part behaves well in the entire range of bias conditions. This requires engineering skills, you could familiarize yourself with in various available books, etc. and generally takes time.
Click to expand...
Thanks again
 
Sparkplug said:
MJE15033 might work, meaning you’ll get sound out, but it’s not a direct replacement for 2sa913. 2sa913 is a strange animal in that it’s a 15W part with Icmax of only 0.1A. You might have better luck with something like MJE210G:

MJE210G is not a direct replacement transistor either but much closer to 2sa913. It’s compliment is MJE210.

If MJE210G works out, remember you’ll have to replace the complimentary pairs in both channels to maintain audio and parametric symmetry. Sometimes it’s easy and sometimes challenging.

Edit: MJE340G is also a good option and might be even closer to 2sa913.
Click to expand...
Hello Sparkplug,
I'm wondering if you could help me to figure out whether TTA004B transistor would be a good replacement for 2SA913?
Aside from packaging (TO220 vs To139) they seem to be quite close in my uneducated opinion, however the power dissipation rating is quite different. The original one is rated at 15W and this current model is 10W max.

The 2SA913 specs are as follows:

Material of Transistor: Si
Polarity: PNP
Maximum Collector Power Dissipation (Pc): 15 W
Maximum Collector-Base Voltage |Vcb|: 150 V
Maximum Collector-Emitter Voltage |Vce|: 150 V
Maximum Emitter-Base Voltage |Veb|: 5 V
Maximum Collector Current |Ic max|: 1 A (based on the datasheet, however per alltransistors site it's 0.1A)
Max. Operating Junction Temperature (Tj): 175 °C
Transition Frequency (ft): 120 MHz
Forward Current Transfer Ratio (hFE), MIN: 65
Noise Figure, dB: -
Package: TO220

The datasheets for both transistors are attached.
I also found a part of schematics that show how these transistors are connected in the receiver, the path is highlighted in purple, maybe this will help.
Thanks in advance!
 

Attachments

ZeRask said:
Hello Sparkplug,
I'm wondering if you could help me to figure out whether TTA004B transistor would be a good replacement for 2SA913?
Aside from packaging (TO220 vs To139) they seem to be quite close in my uneducated opinion, however the power dissipation rating is quite different. The original one is rated at 15W and this current model is 10W max.

The 2SA913 specs are as follows:

Material of Transistor: Si
Polarity: PNP
Maximum Collector Power Dissipation (Pc): 15 W
Maximum Collector-Base Voltage |Vcb|: 150 V
Maximum Collector-Emitter Voltage |Vce|: 150 V
Maximum Emitter-Base Voltage |Veb|: 5 V
Maximum Collector Current |Ic max|: 1 A (based on the datasheet, however per alltransistors site it's 0.1A)
Max. Operating Junction Temperature (Tj): 175 °C
Transition Frequency (ft): 120 MHz
Forward Current Transfer Ratio (hFE), MIN: 65
Noise Figure, dB: -
Package: TO220

The datasheets for both transistors are attached.
I also found a part of schematics that show how these transistors are connected in the receiver, the path is highlighted in purple, maybe this will help.
Thanks in advance!
Click to expand...
Hope all is well.

Since these are being used in the output section, though very similar, I, personally would not make the substitution. In the output section, they’ll probably see large currents through them and may be stressed which will affect their performance even if no damage occurs. I think you’ll be better off considering KSA940 and its complimentary pair KSC2073. You’ll have some healthy breathing room.
 
Sparkplug said:
Hope all is well.

Since these are being used in the output section, though very similar, I, personally would not make the substitution. In the output section, they’ll probably see large currents through them and may be stressed which will affect their performance even if no damage occurs. I think you’ll be better off considering KSA940 and its complimentary pair KSC2073. You’ll have some healthy breathing room.
Click to expand...
Thanks, your time and advice is very much appreciated!
 
Sparkplug said:
Hope all is well.

Since these are being used in the output section, though very similar, I, personally would not make the substitution. In the output section, they’ll probably see large currents through them and may be stressed which will affect their performance even if no damage occurs. I think you’ll be better off considering KSA940 and its complimentary pair KSC2073. You’ll have some healthy breathing room.
Click to expand...
Do you think that the fact that these have ft of 4MHz vs 120Mhz with originals will matter much?
 
ZeRask said:
Do you think that the fact that these have ft of 4MHz vs 120Mhz with originals will matter much?
Click to expand...
Probably not, some of these transistors were originally designed for VHF band use as well where the fT rating would matter very much. I think you should be okay.
 
@saabracer23 Dan, thanks for you comment in my post re: replacing the 2SA913 with TTA004b (admins removed that post as a duplicate to this one). It was very reassuring! I've actually realized that I've read your other thread about experimenting with TO-126. Thanks, it's very helpful!
 
ZeRask said:
@saabracer23 Dan, thanks for you comment in my post re: replacing the 2SA913 with TTA004b (admins removed that post as a duplicate to this one). It was very reassuring! I've actually realized that I've read your other thread about experimenting with TO-126. Thanks, it's very helpful!
Click to expand...
lol, my thread about a Sansui BA-2000 restoration was deleted because of duplicate, but it was put back, I think I know why now. Yes, I would put them in and have no qualms about it. I think you would be perfectly fine. I do wish that they were rated for a bit more dissipation, but can always get what you want lol.

Dan
 
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