Accuphase E-480

@foolishman how big is the board that needs to come out to get at the jumpers? It’s hard to see the edges of it in the link picture from your original post. Or is there enough space to solder from the top?

just wanna confirm that change its 100v for 120v, I only need change below jumper setting 

J4 -> J5

J10 -> J8

J6 -> J11

From previous experience of Accuphase amplifier voltage conversion, change 100V to 120V only required move two jumpers!

I hope some one can posts images of E480 power board (front and back) so I can verify the correct jumper settings.

 

My E480 was running great about a year after voltage conversion, till this morning  after I left it on overnight, the E480 meter start to flicking after playing music just for few mins, and does not make any more sound. I did turn it off, and on, change power cord, speaker cable it still does same thing it play for few mins, the meter start to flicking, and all sound disappear right after. any idea what may cause this issue? 

It requires solder.

@foolishman for these jumper on E480, does it require solder, or it can be just pull out wire, and push it in to other jump position?

@foolishman 

Really appreciated that your share these info with us here, I have E480 now, and looking forward to do the voltage conversion 

just wanna confirm that change its 100v for 120v, I only need change below jumper setting 

J4 -> J5

J10 -> J8

J6 -> J11

Thanks!

I believe the trim pot is for bias adjustment and the +/- test point should has a reading of 4mV...

Correction:

I believe the trim pot is for bias adjustment and the +/- test point should has a reading of mV, perhaps you should measure and recorded it for future reference.

Congrats! @sp33ls2

One thing I was a little bit surprised by was that some of the rails to the power amp board were raised by a few volts (like 65VDC to 69VDC) when compared with the 100V step down... My AC mains are 122VAC rather than 120, while the stepdown is at exactly 100V -- maybe that's part of explanation of the increase of a few volts?

Yes, that's the reason and nothing to worry about.

I see one trim pot on each amp board, but not sure if that's for DC offset or bias. Do these units have a self-biasing circuit, I wonder?

Most new design Accuphase power amp has no dc offset adj pot. I believe the trim pot is for bias adjustment and the +/- test point should has a reading of 4mV, but I not 100% sure since I don't have a service manual on hand, perhaps you can measure it to confirm.

I can confirm that the above jumper configuration results in the orange & yellow taps @ 120V, thanks @imhififan 

One thing I was a little bit surprised by was that some of the rails to the power amp board were raised by a few volts (like 65VDC to 69VDC) when compared with the 100V step down. That being said, the test points for +-5V, 12V, 15V tested correctly. The +130V was previously around 135VDC and is now 139VDC. I see one trim pot on each amp board, but not sure if that's for DC offset or bias. Do these units have a self-biasing circuit, I wonder?

That being said, the 5V supply to the IC's remained at just under 5VDC, so I think all is well. There was no impact on the DC offset, and the unit appears to sound the same as before, and the heat output appears similar as well.

My AC mains are 122VAC rather than 120, while the stepdown is at exactly 100V -- maybe that's part of explanation of the increase of a few volts? I'd imagine the regulators would clean it up anyhow, right.

@imhififan 
Thank you!!

Here's the jumper setting changed for 120v:

J4 -> J5

J10 -> J8

J6 -> J11

Thank you again.

@foolishman,
Congratulations! Please let us know the jumper settings for 120V, maybe a close up picture will be nice, it will help other members if they need to do voltage conversion. Thank you in advance!

Nice Accuphase is really nice gear.

@imhififan 
I would like to inform you that I have successfully changed voltage on E480. Thank you again.

@imhififan 
Thank you for providing information on E480 voltage conversion. I will try to do accordingly and post result.

I don't have any experience on E480 voltage conversion, however, based on previous experience, brown & red wires are 100v windings, and orange & yellow are 120v windings. You need to trace the circuit to connect jumpers for orange & yellow wires and disconnect jumpers for brown & red wires.
From the picture, seem like j1, j2 & j3 are jumper for soft-start resistors circuity. Connect j2 and disconnect j1, j3 for 240v main. No change required for 100v and 120v main.

Interested in this...