Harman Kardon HK770 Restoration

[@williambbrayford408]

I‘be got one of these on the shelf and never got to it. I will now! These new vids are great and by hitting the high points we get to see more of your work. Anyone who wants to get more detailed reviews of your approach to restoration can visit your earlier vids. Thanks for sharing. Cheers.

[@uncola6028]

You are truly the hk770 king

[@dexi9814]

Good work Connor!

[@potato-dd2xh]

Good work dexi!!!

[@BluShady__]

Awesome restoration bro! Im sure the people getting those will be stoked.

[@PrimeHiFi]

Thanks Simon! He’s very happy.

[@zoinkz8188]

Brilliant work Connor! Hope to see more videos like this from you soon

[@PrimeHiFi]

Thanks homie 👌🏼🥰

[@williambbrayford408]

Thanks!

[@Zazpi_Zezenak]

Wow. Great restoration Connor. The binding post really came out well. 👏👏

[@PrimeHiFi]

Thank you!

[@lesarnolfinis6775]

How much would such a restauration cost overall?

[@joeygonzo]

Love the new binding post and RCA jacks.

[@johndcosta1259]

Where are you located? I am sure there are other people who asked you the same questions before me.

[@yurkjaz1866]

Awesome work Connor! Nothing like those older Harman/Kardon amps! They look brand new now. Too bad the company is now only a shell of what they were back in the day.

[@1michaelricci]

Great video! I like your work and attention to detail. Are you still repairing amplifiers? I am considering a pair of HK775 mono block amps and looking for a quote on bench check and any required service or upgrades. Thank you.

[@kevinkennedy846]

Have you got any tips on where to source the (output?) transistors: 2SA1111 and 2SC2591?

[@PierreVdm-fc3dl]

Can you please explain where I should set the bias on the 10 mv, there are 2 places for L and R with VR 401 and VR402. On the main board you have two measuring points of 0.33 ohm for L and R two. Both 0.33 ohm on the center pin and ground are adjusted to 10+10mv. Then I have VR 403 and 404 that I have to set to 0 or 10 mv on the output of the speakers with a digital multimeter. Once you have pressed both speaker outputs, wait 15 or 30 minutes and then use the meter to adjust the output to 0 or 10 mV. What do you do first? I have already replaced the adjustment potentiometers for the better blue ones. I would like to hear from you again. Kind regards.

[@AudioElectronicsChicago]

I just got the same amp and preamp, I love them

[@keithtrauner1738]

If you were to recommend among the HK 770, the Sanyo P55, and the Technics SE-A7 - power output aside - which do you consider the most restoration friendly and which did you like the most when all was done? Thanks!

[@PrimeHiFi]

Definitely the SE-A7. It’s really a wonderful sounding and performing amplifier. I still use one in my reference system to this day. The hk770 is dead simple and incredibly easy to service, but the SE-A7 is still fairly straightforward.

[@PierreVdm-fc3dl]

Hello, I have been following you carefully on You Tube regarding service HK770. Replaced all electrolytic capacitors and replaced the 100uf and C next to it on the control boards. I checked everything for bad connections and replaced the 24V relay, but I still occasionally hear a kind of noise and then crackling or a kind of pop. The speaker output is regularly difficult at 10mV. I think it only comes from 1 channel, think small control board. What could this be and how do I approach it?

[@SteveBoobJobs]

Hi, I have a 725 hooked up to a 770; when i turn ON the 770, the red power light comes on, but none of the indicator LED's do not turn on. I purchased brand new RCA's just to be sure, but still no dice. I bought the pair from an ebay seller and he swears up and down that it "was working".... Any advice would be greatly appreciated

[@aegisofhonor]

just wondering, how would you use these as a headphone amp? They have no headphone jack and the RCAs on the back are inputs, not outputs, is there a way to just take the speaker terminals and plus them into your headphones?

[@tee-jaythestereo-bargainph2120]

Nice Job one of the best in the bizz !

[@mrdanger4851]

Hey there do you have any tricks or tips that you might share after this rebuild. I will be recapping my HK 770 and my pair of HK775s. Any od parse or sourcing issue's? I did an HK 870 and finding Nes Capacitors for the power board was challenge because it uses a FOUR pin design. Any heads up would be Appreciated, anything you would do different?

[@CneyTMS]

You could replace the four pin with 2 pin caps. W of the pins are dummy pins for holding the cap. I would recommend using some good heat and chemical resistant double sided tape from 3m or something or hot glue to stabilize them. I used Kemet (formerly BHC) ALC10 four pin caps on my Harman Kardon PM665. I think that they also have those in the "slit foil" audio grade version. ALC10S if I recall.

[@TheThatoneguy12121]

Hey Connor, I have a hk770 is there a way I can contact you about having you work in it by any chance?

[@PrimeHiFi]

Hi there, you can contact me via email

[@Some_D0nkus]

Excellent work dude. Two thumbs up 👍👍

[@PrimeHiFi]

Thanks dude, coming from you that means a lot 🤜🏻🤛🏻🙌🏼

[@eduardru2748]

Здравствуйте, подскажите пожалуйста у этого усилителя сколько выходных транзисторов на канал и какие? С уважением Эдуард

[@01sapphireGTS]

Very nice job.

[@eduardru2748]

И как у него звучание, он справится с напольной акустикой? Спасибо

[@stefanegger]

sad that you destroyed the original condition of those beautiful machines. disgusting.

[@Some_D0nkus]

Eggman.

[@fredsk1]

Looking forward to your restoration video where you leave corrosive glue in place to keep that "original condition" 🤡

[@zoinkz8188]

Doctor Eggman has spoken

[@stefanegger]

I meant the connectors on the back and the case (holes) etc.

[@kevinkennedy846]

I think it's called reliability, and improved audio quality. It's not like he added blue LEDs to the front panel....@@stefanegger