KINKI Headphone Amplifier Repair (Vision THR-1)

Mark takes a look at a rather high end Headphone Amplifier, from Kinki Studio in China. It was made in 2019, but has no output after 5 years. What went wrong?
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[bobgrob]

70K subs and climbing. We need to get Mark up to about 5 Mil

[ralphalder]

If Kinki Audio ever teamed up with Schiit Audio they’d have a fantastic opportunity for a new brand name !! 😅😅😅

[Mulch]

Tom Evans should take inspiration from this chassis. Beautiful

[pabloluchi]

Burnt mosfets, overheathed PCB .. and there is no ventilation holes in that chassis.. My guess, , It will happen again soon. Anyways.. Great repair on this, Mark!

[petercornell]

That amp is SERIOUSLY over-engineered. Something like 2 x 15w for headphones? I love it! Good to see you back Mark.

[PrimeHiFi]

All the thermal mass of the over-built chassis and they choose to mount TO-3P lateral mosfets which are no doubt biased into class A to a tiny piece of metal as a heatsink! You can tell they’ve been getting excessively hot by the board discoloration. Even the cases of the MOSFETs have discolored. And scraped part numbers on the components! This amp is over-engineered except for where it counts. Good for the warranty period and then will give you a bunch of trouble afterward. The company scraping part numbers and not providing even a simplified schematic screams stay away…
Great work on the repair, Mark 👍🏼

[LincolnTank-StillOnTheSprue]

After watching several of your vids now I'm still completely clueless about how electronics work, but watching you fix these unfathomable puzzles is entertaining

[maksqwe]

Just got out of the shower, got in bed and thought let’s watch a few videos before bed.. and Marks video pops up!!!

[RobGem]

Without doubt the best electronic fixing channel on YouTube please please longer videos I have learnt so much from watching your videos please keep the vids coming

[HighPoweExpress]

I never se so perfect craftmanship, all components straight and perfectly placed. Someone had pride making that.

[michaellazaar]

If anyone is interested: The name Kinki comes from the makers wife’s name. This brand makes some very serious stuff, over engineered and built to the highest standards. In this case the mosfets were faulty and caused the damage to the PCB. Another point is the toroidal transformer isn't the only component made in the UK, these mosfets are too.

[jeremywh]

Great video as always! Regarding those power transistors; Kapton tape has poor thermal conductivity vs thermal pads - perhaps the root failure was from someone trying to use this as a regular speaker amplifier, overheating to short? But as @pantelisEVs noted, using the chassis seems like a much better idea too (with thermal pads 🐱).

[andygrove]

Those fets are based on the Hitachi 2SK1058 series, but the UK manufacturer never seems to have solved fundamental maufacturing problems. What seems to happen is that wafer or packaging impurities migrate into the channel due to heat, resulting in shorts or at least low resistance episodes that cause a positive heat feedback loop.
What you see there is a charred board, you can imagine what happens in a big amp and +- 100V rails.
They were touted as an equivalent, and superior replacement to the Hitachi audio fets, and they do provide excellent performance on the bench. But they are not reliable. You will see this kind of failure with them over and again.

[cancer]

I know this is a grown man with a business, but he just seems so happy. Almost like a kid playing with his toys

[TpBaNaNa]

I literally threw my hands in the air when i got the notification 😂....Haven't even watched it yet 🤗

[paulb]

Hi Mark, these fabulous fets based on Renesas J162/K1058 have unusual pin-out; the beads actually went on the gate and drain.

[Mickey-Knox]

I love these retro Phil Collins videos!

[danhorton]

Interesting you saying the MOSFETs not needing a heatsink considering how hot they’ve clearly gotten. Excellent video.

[trickyd]

Best electronics channel, keep it up Mark!

[DarrenMossAU]

Nice repair. I wasn't expecting that amp to be so well made. Really good workmanship on everything, even the case!