Transistor Replacement Help

[mcaddie7]

Hi!

Looking to replace some transistors but am getting lost in long threads and my head is spinning.

Is any transistor replacement okay as long as the specs are higher than the last?

What about a website like this that just gives you comparable ones? Alltransistors.com

The transistors in question I want to replace are:
2SA564A
2SC644
2SC828

If you could please voided a link to a modern comparable or better equiv for an amp and tone board that’d be great.

Any additional info on matching, I was just going to buy a tester online that shows hFE and find the best match amongst 20.

Thanks!

 

[ivandezande]

What unit is this? Where are the transistors in circuit?

I have
2SA564A - KSA992
2SC644 - KSC1845
2SC828 - KSC1845

 

[mcaddie7]

What unit is this? Where are the transistors in circuit?

I have
2SA564A - KSA992
2SC644 - KSC1845
2SC828 - KSC1845

Harmon Kardon 930. These are the Main Amp transistors. Then the Tone board itself has a few which is a devil to get at so while I have it out I want to replace those:





So when replacing, do you just need to make sure specs are the same or better?

 

[ivandezande]

Harmon Kardon 930. These are the Main Amp transistors. Then the Tone board itself has a few which is a devil to get at so while I have it out I want to replace those:

View attachment 3185573
View attachment 3185568


So when replacing, do you just need to make sure specs are the same or better?

Honestly, if it's a small signal transistor in the signal path, I couldn't care less. KSC1845 and KSA992 are going to replace it 99% of the time.

That applies to Japanese gear, US is a different story. Also obviously not true for transistors in the amp stage.

 

[mcaddie7]

Bump.

So the in my previous reply two transistors are in the amp stage and two are on the tuner board.

So many posts here but none with actual modern recommendations. Any help is greatly appreciated.

 

[pwauk12]

as @ivandezande states:

2SA564 = KSA992
2SC828 and 2SC644 = KSC1845

on the main amp board match the KSA992 as close as possible

 

[ivandezande]

Bump.

So the in my previous reply two transistors are in the amp stage and two are on the tuner board.

So many posts here but none with actual modern recommendations. Any help is greatly appreciated.

I gave you modern replacements right off the bat….

Also Googling those transistors gives you the suggestions I stated. Not too hard.

 

[mcaddie7]

I gave you modern replacements right off the bat….

Also Googling those transistors gives you the suggestions I stated. Not too hard.

Sorry, I have covid brain still. Been really out of it these last two weeks. Thank you a ton.

So when looking it up on digikey they have a bunch of options with suffixes. The only difference I see are some voltages. Does this matter or can it be any of them? Not a design engineer so I'm not sure lol

 

[rcs16]

Ksa992fbta
It has the highest hfe grading and come on paper tape with 100mil lead forming/pitch
You can always use ksa1015 as well it’s lower voltage but has slightly higher current rating

 

[Mumbles]

Lots of info on choosing transistors in this thread by @dlucy

dlucy’s guide - how to find replacement transistors

Do you have a transistor that needs to be replaced? Figuring out what to look for in a replacement transistor can be difficult, especially if you haven’t been doing this for decades. The following guidance may help you understand how to better find and select a modern equivalent transistor...

www.audiokarma.org

 

[dlucy]

Sorry, I have covid brain still. Been really out of it these last two weeks. Thank you a ton.

So when looking it up on digikey they have a bunch of options with suffixes. The only difference I see are some voltages. Does this matter or can it be any of them? Not a design engineer so I'm not sure lol

View attachment 3185832

Your question "what are these suffixes" or "are these the same as KSC1845F" are answered in two of the posts in the Guide to replacing transistors:

dlucy’s guide - how to find replacement transistors

Do you have a transistor that needs to be replaced? Figuring out what to look for in a replacement transistor can be difficult, especially if you haven’t been doing this for decades. The following guidance may help you understand how to better find and select a modern equivalent transistor...

www.audiokarma.org

and

dlucy’s guide - how to find replacement transistors

Do you have a transistor that needs to be replaced? Figuring out what to look for in a replacement transistor can be difficult, especially if you haven’t been doing this for decades. The following guidance may help you understand how to better find and select a modern equivalent transistor...

www.audiokarma.org

You'll want to pay extra attention to the "delivery packaging suffixes" part.

 

[dlucy]

Hi!

Looking to replace some transistors but am getting lost in long threads and my head is spinning.

The transistors in question I want to replace are:
2SA564A
2SC644
2SC828

If you could please voided a link to a modern comparable or better equiv for an amp and tone board that’d be great.

Any additional info on matching, I was just going to buy a tester online that shows hFE and find the best match amongst 20.

I've answered your questoin over in one of your two other threads on your work on your HK 930: https://www.audiokarma.org/forums/i...930-restoration-process.1056015/post-17082589

You're asking good questions. However, you're on the edge of breaking a rule here at AK: generally, don't post more than once (at a time) about working on a given unit. You've got three threads on your 930 now. I advise you to pick one and concentrate your questions (and how you're doing) in just one of those.

We're here to help. Help us keep everything together and valuable for all... in one place at a time.

Good luck!