Repair of 1967-69 Harman/Kardon Five-Twenty with blown amplifier - germanium to silicon conversion
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- Опубліковано 22 сер 2021
- This came in with a smoked left channel. It uses germanium outputs, which aren't available in any reliable sense.
Here we go over converting it to silicon outputs - the mj21193 - which are overkill, but provide little chance of failure if the wires get shorted again.
at the end of the video I get confused, because the right channel has distortion, making me think my conversion wasn't good - However I remember that the placement of the amplifiers is as seen from the rear! so the distortion channel is the original - my conversion works better than original. - Наука та технологія
You are not a pest. Your bonus footage is always awesome. You can thank Shango for turning me on to your videos.
Same here, was just about to comment and apologize that I've just seen the RCA resurrection video in recommended & have to dash over there and see that first. To quote Governator, I'll be back...
And with that, I return to watch more cool stuff.
Ditto.
EXCELLENT VIDEO! Love how you converted the bad channel to silicon as well. Your troubleshooting is top notch.
Also, I really like the looks of that receiver. ❤
The instructions say to use the capacitor wizard to look for shorted transistors in circuit because it wouldn't see the Transformer
I liked your speaker trick for capacitors. I started using it last year.
@@rsattahip So do I, Freaking genius idea! Shango, you may be able to filter your your speaker testing capacitors, but love the raw unfiltered blurted out diagnostic thoughts like faulty components are almost out to get you and die in a certain way just to throw you off typical diagnostic paths.
@@rsattahip What are you talking about?
Great diagnosis and fix by someone who really knows their stuff. Really enjoyed watching you bring this back to life and all the valuable insights you provided. Well done.
Nice SI conversion. Now if that was my receiver I would absolutely opt for converting the other channel. When you pointed out the distortion / oscillation at clipping I thought you knew it was the old channel doing it, I didn’t realize until the very end that you thought it was the converted channel lol.
Great work JP! Thanks for what you do here!
Great vid. Intuitive & highly skilled JP. I don't think I've seen a HK component without an issue recently. Must be the age.
Good video. I enjoyed this. Especially the conversion to silicon.
Great diagnosis and repair... WELL DONE!!! 10/10
Really nice looking receiver/amplifier and nice repair! Thanks it was a pleasure.
LOVE the early blackface integrateds and receivers! Thanks man
Great work and a rather nice receiver that will live on.
Awesome, love the diagnostics
Great job fixing this unit 👍👏👏
I love these audio videos!
thumbs up done excelent video tutorial presentation trouble shooting procedure new subcriber from the philippines
Good video buddy! I watched it all but forgot to like. Cheers! 🍻
It's cool when you can compare one channel to another :)
Hmm. A late 1960s receiver with no AM band. I didn't realize people gave up on AM that early.
I have some early 60s tube gear that has no AM.
This is a hot item A1 Pier :)
Thanks JP
Socketed transistors, that's cool.
I have exact same receiver I restored it back in 1987 and it still works today as it did then . That unit is rated at 35 watts RMS per channel I have the factory schematic some where among my stuff . when I got mine the right side was bad .
I am glad I have a spare set of transistors for mine .
I have a 1975 Harman Kardon 720 and it's a kick-ass machine. Weighs a damn ton. The left and right channel are each their own 45w amplifier. It's like there is 2 complete stereos in the machine.
Hi Richard. I don't see how it is possible that this receiver could be rated at 35 watts RMS. I think that Jordan's assessment of 10 watts RMS per channel is more likely.
Power transistors replacement..........sounds familiar. Cannot believe that BIAS adjuster functioned, Someone spent a considerable amount of time cleaning that unit. Jordan, if all goes well will see you Saturday with Kenwood 9000G, other repair person needs to put back together and why I did not make our appointment last Saturday.
Only fixing one channel kind of disturbs my OCD. When I work on stereo equipment and replace capacitors or transistors, I always do it on both channels, unless I am using the exact replacement for the part. Am I the only one?
Yes, I would say it's best to replace the equivalent components on both channels, especially on very old equipment like this where components could have gone out of spec.
I hear ya, however sometimes customers budget limits stuff
The OCD in me really would like to get that other channel converted.
Very interesting that it contains all discrete components. I would think that by 1969 stereos like these would a chip or two in them.
You really didn't start to see integrated circuits as common place until the mid 1970s. You did see integrated circuits in the IF strips on tuners like the UA707 - but other than that everything was discrete until about 1975, when you started seeing Sanken and STK power packs.
I saw a staple stuck into the carpet covering your work area. Be careful of "shrapnel" as it can scratch surfaces and coatings.
👍
Interesting how different technicians will take different paths and sequence of troubleshooting, I enjoyed watching. I used the ON semiconductor MJ21193G and MJ21194G devices on a Marantz 2275. The spec sheets on the MJ21195G and MJ21186G devices seemed to be the same. Do you think the 93 would have worked as well as the 95 in this device? Both being PNP, not sure what what the differences are. Thanks....
Both will work, they exceed the original part parameters by a long way, and will work there, as the requirements are not critical. Sometimes they are too good, and need to be damped down a little as they can oscillate, when the originals were struggling with gain dropping with frequency. That will need either small sub 100pf capacitors across base emitter, or a ferrite bead on the base lead, to stop oscillation. Originals might be substantially lower gain at 50kHz, but new are still strong at 30MHz.
Oooh nice. Good looking stereo too.
How do you select what component to feature in the videos? Do you need permission from the owner of the component to feature the component or not?
Thank you
Customers agree that their set may be used for educational purposes at the time they leave it. Never had anyone say no
I usually pick something that either isn't done much, or hasn't been thought of as far as repairs and service
@@JordanPier Oh I see. Well that makes sense.
Thank you for replying back.
You should also make sure the customer doesn’t have bad speakers, and uses actual terminals on the speaker wires, instead of shorting the output!
That's why I only have a demonstration warranty. I lecture them about their wires and how to properly connect them. I will even properly terminate them for a fee.
However the demonstration of the amp is the only warranty. If they take it home and blow it up again and they didn't bring in their speakers and wires for me to examine - it's all on them
Здравствуйте , если Вам не трудно , поделитесь ссылкой на схему.
Are you sure UA-cam is not going to hit you with a copyright violation because that sine wave resembles someone's so-called intellectual property? Good video, Thanks
Shame the owner didnt want both channels converted, the other germainium channel is likely to fail as well :-(
Short sighted customer.
It's a money thing. Everyone seems to think in the now rather than for the future.
I have a problem customer who did not want anything more than the bare minimum against my wishes. He didn't end up using the receiver until months after he picked it up. Has issues from sitting and needs work in all the areas mentioned previously when he left it for repair.
Come to learn he was flipping it on eBay. Oh well
Oh A Nitchycon Transister Huh?
Did You Check The Main Power Supply?
Meaningless if the other channel works along with the rest of the machine.
+19V -19V its in the video about a third of the way along. Looks fine to me.
My Guitar amp is 120Watts
🤘🏿🤘🏿
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"Word."
Move along rummie!