I just finished replacing a defective power supply filter capacitors (one short and the second one bulging - Koshins replaced with Rubycons) on the same model and stumbled onto your video. I purchased my HK3480 new in 2006 and that says what I think of the quality and initial cost of this model - excellent. Thanks for the video and James' comments for what to expect next.
Very cool video. On the Q301, that is a KTC3200. I have found that many of those KTC3200s degrade over time significantly. My suggestion is to replace these pairs on both amplifiers with matched KSC1845 transistors (or better?). After this, you can send the DC offset to zero by adjusting the R311/R313 pair by about +/- 25 ohms (or less).
Interesting, I had exactly the same transistor go out of spec on mine. Same problem with a d.c. off set. I also have had to replace the volume rotary encoder, replace the blue diodes behind the volume knob that died and resolder loads of dry joints. I also had to re flow the input selection chips after it went mute on me. I have had this thing apart a lot! The amp Sounds great though 👍
Trevor's Bench I expect you know but there are four LEDs in series and a series resistor. I think the resistor is too low value, I doubled its value and the LEDs are still bright but hopefully they’ll last a bit longer.
Hi Interesting video. I have an HK 3480 with a bad main transformer (primary winding is broken). Trying to figure out the voltages. Judging from the service manual there are a few One winding with three taps (pins 1,2,3 on CN64) is rectified to -+15 VDC. I Guess the taps give 15-0-15 VAC or something like that. Also, there is no info about B+ and B- voltages in the service manual but you mentioned -+55 VDC in the video. My man issue is with the display power supply. If anyone is currently working on one of these, I would very much appreciate if you could make the following measurements on the trans secondary windings: Transformer PCB, secondary taps, counting from top to bottom. AC voltage 7-8 9-10
OK, i backfed the main transformer on one secondary winding with known voltage to get the other voltages. They should be: Transformer PCB, from top to bottom 1,2,3 - 40v-0v-40v 4,5,6 - 15v-0v-15v 7,8 - 30v-0v 9,10 - 5.5v-0V
Hi there. I have the exact same receiver. The left channel has distortion even at low volumes. I checked the voltages of the speaker outputs and on the left I'm getting 40mv dc with the volume at minimum. The right channel has 0v. The left channel blew out the tweeters on my Polk Audio bookshelf speakers. What do you think it could be?
Hi, sounds like you have a few things at play here, might or might not be related. Tweeters blown could have been from high frequency oscillation as a 40mv DC offset alone is not high enough to do damage to speakers. As for the DC offset on the left, this amount isn't uncommon to see on amplifiers so it's not overly concerning but the distortion is definitely not right. The offset and the distortion are probably two symptoms that are related to the same fault. Without diagnosis & testing there's really no way I could advise what's wrong with the amplifier at this point
@@TrevorsBench Thanks for responding. To test I removed the pre amp jumper in the back and connected another source. The left channel still plays disorder sound. I'm no electronics expert but my guess is the distortion is within the amp circuitry and not the pre amp portion. Looks like 4 transistors attached to the big heat sink may have been replaced and appear to be smaller than the original. 2sb1570 x 2 2sd2401 x 2 I guess if this can't be fixed I can still use it as a pre amp and hook it up to one of those Crown amplifiers. They have class A AB or D. Which would you recommend for sound quality and the units longevity.
@@Mr-Clark Good job on isolating the fault to the power amplifier by removing those jumpers, I totally forgot about those. If you think somebody's been monkeying around in the amp & changing parts it's anybody's guess what could now be wrong. Distortion can create high frequency harmonics that can have enough energy to wreck a tweeter. Maybe it's best to turn your back on the power amp and use another one in it's place. At least until you can get it properly serviced. I've got no preference to amplifiers, use what ever your ears enjoy the most. My experience lays mostly with class AB amps so I am probably biased in my opinions but I'm sure there are others that sound good as well
Ingeniero no hablo ingles, compre un amplificador Harman Kardon HK 3480 sin el subwofer es necesario o cual me recomienda le conecte unas bocinas JBL modelo EON 1500 de antemano gracias
Hi, i've a HK3380, it's sems the same mainbaord, but the noise on speaker are very very low. have you an idea of faulty components. thanks. DC Bias are ok
Bonjour j'ai un souci sur ampli hk 3380 parfois sallume tout seul et s'éteint , une fois allumé passe de la FM a position VID 1. Est il question d'un reset .? Et comment le realiser! Merci
Your symptoms are hard to pin down. It could be a internal fault with noise at the remote circuit or microprocessor. It could also be a external light interference that's confusing the remote sensor. LED lighting can cause problems for infrared remotes. Sorry, I can't help you more than that through youtube comments
seeme you do not have so much experience, harman kardon has many problems wirh capacitors, so it is totally possible, not regarding of its age, that there are problems. The age of a capacitor does not tell you if it is working or not, it is the values who need to be okay. I even had to replace caps in BDP 10 Harman Bluray player, if they are broken they are broken regardless of age. It depends on manufacturer, quality, heat, use time, etc.
