Harman Kardon "150+"

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reblast

New Member
Hello everyone, i'm new here...
I obtained a h/k quadro receiver called 150+ from a friend some time ago. It weights a ton and one of the rear channels is broken, missing a speaker screw, a fuse, and a few lamps are blown. I would like to make this baby work like new, but it seems like there is not much information about these receivers available on the net.

Would you say it's worth getting repaired, is it a good unit? I've added a picture.

Any answers would be nice.
 

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I had a 75+ and it was a kickin little receiver. was 25x4 or 50x2. Had lots of inputs. The only thing I didn't like about it was the decoders. They did a very poor job of turning two channel stereo into four channel. One channel was out on mine as well, the rear right I believe. Check all connections around the "sound field balance" control. I had an intermittant that caused the dead channel symptom. Also check all four quck acting fuses. Each fuse controls a channel, so if one's blown the channel goes out.

If you like the 4 quadraphonic thing, it'd be a keeper. You can always put it in 2ch mode and crank it. i believe this was a "twin power" Good sounding receivers IMHO.
 
Now that was quick. Thank you!
It is actually a dead channel, the power transistors are missing. I need to get a replacement. On another channel the fuse was blown, and i replaced it with the ok fuse from the bad channel, so i got 3 out of 4 channels running. Contacts are ok. Tuner works fine. The h/k seems to have two power transformers, and large capacitors.

No clue about the output power, consumption is 200W so it can't be higher than maybe 4x35 RMS watts.

As long as this one isn't 100% fixed, i'll be listening to my Technics SA-5370K, so i'm not in a hurry.

I'm still thankful for more info...
 
I would pull one of the output boards and see what kind of transistors it has. Give echowars a PM. he usually gas great knoledge of where to get older replacements such as the ones in your HK.
 
I will take a look inside tomorrow, and post.
By the way, is it normal that this receiver takes a few seconds until sound comes out of the speakers? I don't mean a relais, it feels more like switching on a tube unit.
 
That was the TOTL Harman Kardon from a time when that was a good thing! WELL WORTH REPAIRING. I'm looking for one myself....after the Holidays are over, of course.
 
Its normal for there to be around a 7 second delay for the sound to finally appear. My 75+ was like that as well. Its some kind of early protection circuit I think.
 
reblast said:
I will take a look inside tomorrow, and post.
By the way, is it normal that this receiver takes a few seconds until sound comes out of the speakers? I don't mean a relais, it feels more like switching on a tube unit.
Click to expand...
That is normal. There is a circuit that is designed to mute the output at startup. The clamp board shown on page 12 of the service manual is where the turn on muting is accomplished. If you use the search feature on this forum you will find additional information. Also search for the Harman Kardon 900+. It was the successor to the 150+ and is very similar. Welcome to AudioKarma.

tcdriver
 
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I just spent a few minutes looking over the schematic. It seems that one important difference between the HK 150+ and the HK 900+ is that the latter has a CD-4 demodulator that would allow one to play the discrete four channel LP records. If you do not have any such records then it is no big loss.
 
I'm 22 and so i don't have a single quad media. The reason why i got into the old hifi stuff was being more and more dissatisfied with today's equipment, spent a lot of money on a new quality stereo (rotel, onkyo) 4 or 5 years ago and never got that "punch" and "warmth" of the old receivers i've heard here and there.
Now as i enjoy more and more 1960s - 1980s rock the sound of a vintage receiver fits quite well, and i've always liked their technical, solid appeal. I hope i will find quad vinyls at a flea market. Do they have a special sign to show they're 4ch/quad recordings? and do i need a special stylus/turntable?
 
Quadraphonic Formats

reblast said:
Do they have a special sign to show they're 4ch/quad recordings?
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Your receiver has a built-in SQ style decoder. That was the most popular quadraphonic LP format. There were thousands of titles released in SQ quadraphonic. Most SQ records are clearly marked. If you do a search on ebay you will see that many of them have very distinctive covers. Once you know what to look for you should have no trouble finding them.

reblast said:
Do I need a special stylus/turntable?
Click to expand...
You do not need a special stylus/turntable to play SQ or QS format records. The CD-4 format records do require a cartridge with a special stylus shape, a turntable with low capacitance wiring and a CD-4 demodulator. The CD-4 system used a 30kHz. frequency modulated carrier frequency to hold the additional information necessary for the other two channels. The Harman Kardon 150+ does not have a built-in CD-4 demodulator. If one wishes to play back CD-4 records, one needs a demodulator and a record player fitted with low capacitance wiring and a CD-4 capable cartridge. Harman Kardon, Marantz, Panasonic, JVC and others sold phono preamplifier/demodulators as an external add on that could be used with your Harman Kardon or other brand receivers. CD-4 demodulators as well as suitable turntables and phono cartridges and records can still be found on the famous internet auction site. These can be tricky to set up. However, when everything is right they can provide performance (separation between channels) that the common SQ and QS decoders can only dream about.

If you are seeking music from the quadraphonic era, one option is to buy a Q-8 quadraphonic 8-track deck and Q-8 tapes. There were thousands of titles released in the 70’s using the Q-8 quadraphonic format. These tapes are truly discrete four channel recordings. However, they suffer from all the drawbacks of the 8-track format.

Q-4 reel to reel tape decks and tapes were the highest fidelity format of the quadraphonic era and the most expensive. There were a lot fewer titles released and even today they tend to be expensive.

The modern day option is to buy a universal multi-channel (SACD, DVD-A, dts and Dolby Digital) disc player and discs. Highly recommended! Most players will down-mix the 5.1 channels to four and you are then all set to go. There are lots of good titles including many from the quadraphonic era.
 
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I have also acquired a HK 150+ which has several different fuses in the speaker fuse slots. What is the original fuse supposed to be? The only channel on this receiver that works is the front left. I have looked at the schematics drawing, thanks to tdcriver, and I am at a loss as to where I should begin to test this receiver for the problem. I did purchase a digital multimeter today. It is the Sperry HDM2. I have notice some of the Marantz threads that have walked thru the procedures of how to test and adjust the bias, Is there a thread for the HK 150+ that is similar? I also bought 3 other Marantz receivers the same day, all for 20.00/each. Marantz 2220, 2215, 2238. I would love to understand-learn how to repair these old jewels. Is there a good manual or any text out there that is a DIY friendly, like a layman's term "how to book"?
 
seabisquit2 said:
I have also acquired a HK 150+ which has several different fuses in the speaker fuse slots. What is the original fuse supposed to be?
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Congratulations on your purchase of a great quadraphonic receiver. The proper speaker fuse value should be printed on the back of the receiver near the fuse holders. On my 900+ the speaker fuse value is 5A. That information is located in the area right in-between the four speaker fuses. Have you checked to see if any of the present fuses are blown open? Any blown fuse may be an indication of a damaged channel.

seabisquit2 said:
… I am at a loss as to where I should begin to test this receiver for the problem.
Click to expand...
If you have no sound from three channels, the problem could be as easy as oxidized switch contacts. DeOxit is your friend. The AudioKarma website search feature is very useful for finding many threads explaining the use and effectiveness of DeOxit. Cleaning the switches will often bring many a unit back to life.

This receiver uses direct coupled outputs. If you have a bad channel the likely result will be a high DC voltage at the output until or unless the speaker fuse blows open. Do not connect a speaker to a channel with a blown output. The speaker could easily be damaged. Here is what I recommend doing to analyze the problem:

1. With the receiver turned off set the STEREO/4-CH switch on the rear of the receiver to 4-CH.
2. Disconnect all speakers.
3. Check all speaker fuses and replace any that are blown open.
4. Press in the Front and Rear MAIN SPKRS buttons on the front of the receiver.
5. Power on the receiver
6. Connect a voltmeter between the + and – terminals of each MAIN LEFT, MAIN RIGHT, REMOTE LEFT and REMOTE RIGHT speaker connections. For good channels, the readings should be near zero plus or minus no more than 0.1V DC. A reading in the range of 20 to 30V DC indicates a blown channel / shorted transistor. Based on your readings you should be able to identify which channel(s) is bad.
 
Thank You TC,
Sorry for the late reply but have been swamped on the J>O>B>:tears: I have directed my attention to only marantz gear and the HK has been put on the back burner, maybe even craigslist???? I have a few coins I have to my disposal and am trying to acquire all of the silver faced Marantz I can get my hands on. I feel that if I am going to make this my latest hobby I will stick with one of the best middle of the road gear, being the Marantz. I am fascinated with the appearance and the sound of this masterpiece. I have a couple of gran to kick around and I started to just dump all the projects and buy the latest marantz has out but I can't seem to part with my old gear that sounds so sweet. So, I have settled for searching for estate deals and fixing and selling until I fund myself a nice Mac or Equivalent and give up the repairs and enjoy the rest of my ride on this big blue ball.
This site has been one of the most enjoyable sites I have found in my 18+ years of surfing the internet.

Thanks to all for this hobby,
Rick:thmbsp:
 
This really is a fantastic site. It's become my favorite too.

The HK is a great looking receiver. I never got into quad, would love to find some old quad r2r tapes....that should get me started!
 
seabisquit2 said:
… So, I have settled for searching for estate deals and fixing and selling until I fund myself a nice Mac or Equivalent and give up the repairs and enjoy the rest of my ride on this big blue ball.
Click to expand...
It looks like you are well on your way to finding what matters most to your listening pleasure. I hope your Harman Kardon 150+ finds a good home. Good luck and good listening. :music:

Tc

zenith2134 said:
I never got into quad, would love to find some old quad r2r tapes....that should get me started!
Click to expand...
Quadraphonic reel-to-reel tapes often show up on that well know internet auction website. :yes:
 
New find

Hey TC,
I now know how it feels to be a giddy little schol girl!!! I just purchased a Marantz 2270 and got home from work and have been playing with all night. I can tell that it will need re-caped but this thing really makes my little Klipsch KG 3.2's ROCK!!!
It is funny tho that my 2238 will have a popping sound at high volume but playing the 2270 at the same volume does not produce the same pop. All this time I thought it was my speakers, but when I hooked up the 2270, no more popping at any volume level???????
Any thoughts?

Thanks,
Rick
 
seabisquit2 said:
… when I hooked up the 2270, no more popping at any volume level??????? Any thoughts?
Click to expand...
Rick,

Congratulations on your new 2270. I never owned one, however, my next-door neighbor has owned several and he was very impressed by them. I can not explain the popping you get on your 2238. The sound level difference between a 38W/ch and a 70W/ch receiver is only 2.6dB, not very much, so, I would think that the power difference is not the issue.

You might get a better reader response by posting a new thread in the Marantz forum. I expect there are some real Marantz experts over there. Good luck.

tc
 
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