Harmon Kardon HK 330c - Fixing Noisy Transistor Issue

BG141 - Replacing all of the 2SC1344 & 2SC458 transistors that are known for causing noise in audio circuits. Also biasing the output transistors for good measure since we changed something in the driver section.

[@DougLucy]

Your video was a first for me. Up until now I'd never heard or seen anyone referencing my articles at Audiokarma. In a different 330/a/b/c thread at AK, someone didn't know they needed to rotate the KSC1845 devices 180 degrees when replacing the 2SC458 and 2SC1344 devices. Another AK'er posted "go watch this educational video". I was watching keenly and then you navigate to one of my threads. Startling in a nice way. Very good video!

[@DougLucy]

One of my other posts on AK is the collected knowledge of AK on "which transistors are known to go bad". The thread contains the original device number (e.g. 2SC458, 2SC1344, etc.) and the most-common replacement devices. www.audiokarma.org/forums/index.php?threads/top-ten-worst-transistors-noisy-failure-prone-whatever-and-replacements.731653/

[@Thetimeisnow78]

Just started on my vintage receiver voyage. AK has been so valuable. I reference it for advice on turntables as well. All thanks to good and people like you sir! From helping noobs like myself getting fair pricing to keeping our newly acquired vintage gear running. Thank you for taking the time!

[@milo963]

I love Dlucy, he can explain things in a way us dummies can understand because that's where he came from. Great video, just finished another 330B. Love these little things.

[@bp-kf9oy]

I have a 330C with the same issue (the noise only happens on Phono for my unit) and this video is great help, i thought I would have to toss mine but now i have a project to look forward to.

[@milo963]

Your PHONO will do that if you don't have shorting plugs in the RCA jacks. The PHONO input is a little amplifier and any noise on the line gets boosted.

[@Lee-NN7X]

I was thinking it was something in his hook-up wiring... Nice Mark, hope this does it.

[@Bunno1177]

Thank you, so many fantastic videos.

[@valakatz3967]

Thank you again for a great video!

[@mikecoackley6852]

nice clean bench! reminds me mine needs cleaning :)

[@bobkrueger194]

Hi. Curious to know if you have any other proven cross reference data sheets for other transistors? I have a Pioneer reel to reel and am looking to get this up and running. Thanks.

[@scooby2624]

Got to ask pulled my dad's out of the shop and it woulnt turn back on what do I need to do to fix that

[@kukko83]

Great info, thanks!

[@whynotme5926]

Nice video-I never hear anyone talk about safety on solid state as much as tube products.-What to do on these to make it safe to touch inside and such.Might be a good video.Thank you.

[@ManuLeisure]

Good video ! i have noisy 2SC458 transistors in trio ka2000 amplifier.should i replace them with 2sc2240 or ksc1845fta which one will be better replacement. Greetings from India!

[@sneakysnake109]

Good to know, thanks.

[@jackheinemann8780]

I've had an amp that would sit there for weeks and work just fine, and then for no apparent reason it would go DC then slip into protect. That particular unit turned out to just have a cracked solder joint on a resistor that I only managed to find by going through the amp and wiggling every single component with a wooded stick till i found it, then I had to quite literally use a microscope to confirm the crack. Worked flawless ever since. Intermittent problems are the worst

[@aparneomai]

Excellent! I have a 330b with what appears to be the same problem. Also, I have a Sansui 2000a that seems to exhibit the same problem. Does anyone know if this is an issue with the Sansui as well?

[@DougLucy]

The HK 330B has a number of variants under the cover, so you'll need to identify which one you have first, then chase down the known-noisy transistors to replace. There are several threads on Audiokarma that cover these questions. One of mine has guidance on both identifying which 330B you have and which devices to replace. www.audiokarma.org/forums/index.php?threads/harmon-kardon-hk-330b-recap-restore-and-upgrade-bom-part-list-kinda.739572/

[@DougLucy]

The Sansui 2000A has plenty of 2SC458 and a few 2SC871 devices that are known to go noisy over the years. Both of these should be replaced with KSC1845 devices, just remember to match the pinout order when installing the new devices, just like Blue Glow said.

[@TheLilsinister13]

I'm fixing my friends Concord MK-10 (which is really just a Sherwood s-1700) that uses the c458. Just a simple Google search put replacements on my mouser order for the thing.

[@RobertKohut]

Nice!!

[@dorelgogu8631]

Instead of replacing all the transistors, I would have try to heat them up with the tip of the soldering iron. The one(s) that's generating the noise is doing it on higher temperature, possibly in the lab the temperature was lower and the transistor didn't rich the noise threshold. After, I would change only the defective one and his pair from the other channel.

[@williamchow1624]

Is it necessary to match the transistors for sound quality?

[@DougLucy]

Modern transistors have more consistent output levels (hfe, beta, or gain), so it isn't quite as critical as it was in the past. That said, when you buy replacements, it is a good idea to buy more than you need and then use a cheap component tester or an expensive transistor tester (e.g. Peak Atlas DCA55 or DCA75) to find two devices that have very similar hfe figures and use those as matched pairs. As an example, you could take Blue Glow's suggestion of buying 100 KSC1845 devices (much lower price at this quantity), specify "reel" or "cut tape" as the packaging you want, and then measure and write down the resulting hfe for each device. If you write the hfe number on the packaging tape, right on top of the device's location, then it's easy to eyeball those measurements and select pairs that match which you can then pull and install.

[@michaelslevin8115]

@@DougLucy Great suggestion to leave in the packaging tape - and thanks for all of your helpful suggestions on other sites too. I'm using all of this information to rehab a fleet of HK 330, 430, 730. Love these receivers!

[@blueribb99]

Repeat ?

[@Blueglow]

I had uploaded this earlier today but got flagged for copyright issues on the song I played so I removed it and reuploaded

[@1959Berre]

I just don't get it. I've seen tons of videos that have been online for years, where people play tapedecks with copyright material, no problemo. And this one is flagged in the blink of an eye for a couple of lousy seconds.

[@grimtale69]

The video would have stayed up, just with the copyright notice, they take away my adsense monetization. So most likely those other videos have been flagged as well. It was easy to remove the song at the end and keep adsense happy. I don't make a lot off these videos, but every little bit helps.

[@fernarias]

I think it would be better if the complimentary pairs were also replaced with KSA992.

[@glasser2819]

fernarias yep, replace them with a matched pair for balanced gain

[@DougLucy]

Good point. When replacing transistors that are part of a complementary pair, it is best to replace both members of each pair and aim for matching hfe across the pair (and across channels for stereo). Luckily for 330B and 330C owners, there are no must-replace comp. pairs. The 330C has no complimentary pairs and the only complimentary pairs in the 330B are Q407+Q409 and Q408+Q410. Those should get KSA1220A+KSC2690A replacements.

[@zaldam]

I find it surprising that nobody comments on how Blueglow Electronics persists in using a wrong name for harman/kardon. It happened before and now twice in a row. They are usually quite meticulous with things technical...

[@zaldam]

That I'm a .....?

[@1959Berre]

I once read "Herman Karton"