Bang & Olufsen Beosound 4 (RESTOMOD)

OSIB16 · « **on:** 16 Jun 2022, 01:55 am »

I recently purchased a nice Beosound 4 hifi unit with a faulty glass door mechanism (2007 model year). Everything else works fine. I got it for a great low price. However, the factory paintwork on it is deteriorating (common for the age). The sound quality is pretty extraordinary when partnered with my modded Beolab 1 speakers. Plenty of transparency, with a proper 3D soundstage. So my plan is to redo the paint, but with a better colour scheme.

As for the electrical modifications; there isn’t a lot of things that can be done, due to the extremely cramped cabinet as well as some other issues. Below is a list of the tasks that will be undertaken:-

1) PAINT THE MAIN BODY OF THE CABINET IN MATT SILVER (WITH A MATT PURPLE FASCIA).

2) INSTALL INTERNAL FIG 8 POWER CORD WITH CARDAS 11.5AWG COPPER LITZ STRAND (66.6666% PURITY).

3) INSTALL JUMPER CABLE BETWEEN POWER SUPPLY BOARD AND MOTHERBOARD WITH 22AWG OCC SILVER PLATE COPPER (66.6666% PURITY).

4) SWAP ALL ELECTROLYTIC CAPACITORS FOR THE VERY BEST AVAILABLE; MUNDORF HV+ , AUDIO NOTE KAISEI, NICHICON FINE GOLD, ELNA SILMIC II.

5) ATTACH A STATE OF THE ART ‘IFI ZEN BLUE MK2’ BLUETOOTH MUSIC RECEIVER ONTO THE REAR OF CABINET.

OSIB16 · « **Reply #1 on:** 16 Jun 2022, 01:58 am »

OSIB16 · « **Reply #2 on:** 16 Jun 2022, 02:22 am »

JCarney · « **Reply #3 on:** 16 Jun 2022, 03:35 am »

Oh good, he's at it again.

JCarney

Nick B · « **Reply #4 on:** 16 Jun 2022, 03:37 am »

Glad you’re back doing another B & O project

S Clark · « **Reply #5 on:** 16 Jun 2022, 12:10 pm »

Can I send you my two dead B&O turntables? Fix one for me, keep one.

OSIB16 · « **Reply #6 on:** 16 Jun 2022, 03:49 pm »

Quote from: S Clark on 16 Jun 2022, 12:10 pm

Can I send you my two dead B&O turntables? Fix one for me, keep one.

Unfortunately I am merely a novice when it comes to repairs. My skill is in re-engineering the cabinet of a hifi unit so that bulky/unwieldy components (i.e. giant Capacitors) can be safely fitted inside. I can do some basic solder work, but afterwards; I tend to leave the more complex stuff to my local Computer/Hifi repair shop.

Nick B · « **Reply #7 on:** 16 Jun 2022, 04:45 pm »

Quote from: S Clark on 16 Jun 2022, 12:10 pm

Can I send you my two dead B&O turntables? Fix one for me, keep one.

Beolover on utube has done a number of excellent videos on those turntables

https://youtu.be/IxIxHb8sZdg

OSIB16 · « **Reply #8 on:** 17 Jun 2022, 07:43 pm »

SClark
If you want your turntables to be fixed for the cheapest price, I recommend sending it to a guy called Brent Rowe at www.fidelityaudio.co.uk He is a genius and should be fully able to get it up and running.

Jeff · « **Reply #9 on:** 21 Jun 2022, 07:44 pm »

I'm not completely clear on your goal here, but I would have only considered changing the large cap on the Mother Board. Most, if not all, the others appear to be surface mount. While that might be a chore for a novice without proper equipment on a multilayer board that is using high temp solder... They appear to be long life, low ESR parts. The power supply, I'm ok with that, but would select parts carefully. I'd also look at the differential mode filter caps (I assume that is what the 0.1uF X2 caps are doing), and any common mode caps... A schematic would be great.

newzooreview · « **Reply #10 on:** 21 Jun 2022, 09:39 pm »

I really enjoy these adventures in passion (obsession?). Please have one vote of endorsement.

I don't know one bit about soldering and circuitry. My Ph.D. did not cultivate any expertise in that direction. So, the enthusiasm and facility you have in disassembling things and making them better or operational is a lot of fun.

I remember hanging out with a friend in high school. His parents had a B&O system in the front room and he put on Elton John's Greatest Hits, Bennie and the Jets. He was an aspiring bass player. I had never really heard the bass lines in that live recording. But on the B&O system I could hear it. It was a lot of fun and gave me a new perspective on the recording.

B&O is an ecosystem with unique pleasures (whatever the objective deficiencies might be).

Party on, Wayne! Party on, Garth!

OSIB16 · « **Reply #11 on:** 22 Jun 2022, 03:30 pm »

Quote from: Jeff on 21 Jun 2022, 07:44 pm

I'm not completely clear on your goal here, but I would have only considered changing the large cap on the Mother Board. Most, if not all, the others appear to be surface mount. While that might be a chore for a novice without proper equipment on a multilayer board that is using high temp solder... They appear to be long life, low ESR parts. The power supply, I'm ok with that, but would select parts carefully. I'd also look at the differential mode filter caps (I assume that is what the 0.1uF X2 caps are doing), and any common mode caps... A schematic would be great.

Jeff,
The sixteen year old Beosound 4 unit is getting on a bit now, so I wanted to replace the existing electrolytic capacitors before they dry out. The faulty glass door also needs attention. So no matter what, it needs to be sent to a Hi-Fi/Computer repair shop. While it’s there I can get them to do the modifications as well (they specialise in replacing surface mount components).

The best quality large cap I could find for the motherboard was Nichicon Fine Gold 3300uf/25v. Unfortunately Audio Note Kaisei, or Elna Silmic II doesn’t make caps in that value.

artur9 · « **Reply #12 on:** 23 Jun 2022, 01:56 am »

Are better components ever detrimental? Something like how some cars cannot tolerate synthetic oil...?

OSIB16 · « **Reply #13 on:** 23 Jun 2022, 02:44 pm »

Quote from: artur9 on 23 Jun 2022, 01:56 am

Are better components ever detrimental? Something like how some cars cannot tolerate synthetic oil...?

Yes, sometimes certain high end brands of capacitors are a bad match together which can result in a collapse of the soundstage or a strident treble.

OSIB16 · « **Reply #14 on:** 23 Jun 2022, 08:00 pm »

Below are images of the diy shelf I created which allows the giant Mundorf caps to be mounted onto the chassis. Unfortunately there is no room on the power supply PCB to accommodate these monsters.

OSIB16 · « **Reply #15 on:** 28 Dec 2022, 12:04 am »

These images show the rear panel that I painted matte silver, complete with easy access panel above and below the big caps…

OSIB16 · « **Reply #16 on:** 28 Dec 2022, 12:07 am »

These images show the large gauge jumper wires used…

OSIB16 · « **Reply #17 on:** 28 Dec 2022, 12:09 am »

Here is the larger than original gauge umbilical cord that I created with blue heat shrink wrap. It links the power supply board to the motherboard. This is the thickest high purity solid core wire that I could fit into the cramped plugs…

JCarney · « **Reply #18 on:** 28 Dec 2022, 12:12 am »

WooHoo! He's back. Been awhile OSIB16, you been ok?

JCarney

PS
A link to my madness on a pair of speakers I've had for 20+ years.

https://www.audiocircle.com/index.php?topic=183606.0

OSIB16 · « **Reply #19 on:** 28 Dec 2022, 12:19 am »

Quote from: JCarney on 28 Dec 2022, 12:12 am

WooHoo! He's back. Been awhile OSIB16, you been ok?

JCarney

PS
A link to my madness on a pair of speakers I've had for 20+ years.

https://www.audiocircle.com/index.php?topic=183606.0

Yeah ok thanks. Hope you had a great Christmas. That Martin Logan speaker project you did looks like a lot of hard work.