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BM4400 Spares or Repair

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Craig
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Craig posted on Tue, Feb 13 2018 10:08 AM

How hard can it be?


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Beo_Jean
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Craig,

You may want to look if you can fit this type of switch instead?  There is a bunch of different models available at Mouser and maybe one would fit.  You will have the ON/OFF function but you will lose the input release switch mechanism...


hemenex
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Dillen:
Sadly it isn't.

Are you sure?

BM4400 mechanical parts list pos. 45 mains switch # 7450010

BM4000 mechanical parts list pos. 90 switch # 7450010

BM3000 mechanical parts list pos. 89 switch # 7450010

or isn't that the switch we are talking about? What am I getting wrong here? Sad

I know you are the expert...

  hx

Dillen
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Dillen replied on Wed, Feb 28 2018 7:35 AM

Correct for the early version of Beomaster 4400.
The switch was changed (together with the rest of the switch row, the potentiometers, the tuner front-end and a few other things) from s/n 1524001 to a different type.
The old and new parts are not interchangeable:
https://type181.files.wordpress.com/2014/07/7450010.jpg

Martin

hemenex
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Ok then as my BM4400 type 2417 SN starts with 1424... and that proves it's an earlier one. Its switch looked equal to BM3000. What about craig's SN?

Did they change the type number on redesign? I don't think so.

Thanks,

  hx

oops, should have read the whole thread where the different mains switches were already mentioned. But couldn't find craigs SN.

My power transistors are mounted in a different style; looks more like a plastic screw instead of the nut in Craig's pictures Does this point to a newer SN?

Craig
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Ok.....serial No for my latest endeavour is 1601023, the weather has prevented any deliveries of the bits and pieces I have on order to progress so I have spent a little time looking at the darlingtons I removed, I acquired this transistor analyser and thought I would give it a run out.


Beo_Jean
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I bought this analyser a while ago; very useful tool!

Craig
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Craig replied on Thu, Mar 1 2018 7:30 AM

It certainly would appear so.......it provides a huge amount of information about the device under test when connected to the laptop, unfortunately almost all of it means little to me given my current level of understanding, I need to condense the information down to the meaningful parameters, the ones that identify if the piece is good to go or not......I think comparing the readings with the published data sheet is a good place to start, any member opinions are welcome on this ;¬)

Beo_Jean
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Craig,

The values important to me are the HFE and the leakage.

HFE where for a given transistor, the value must meet the minimum requirement of course.  Also, when they are pair matched, I'm trying to match them within 10% to avoid one working harder than the other.  It is also preferable to balance right and left channel HFE... but not always possible unless you change them all...

Leakage, well you don't want a transistor to leak current when it is not supposed to...

 

Søren Mexico
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Craig: I may have a working switch for you. I have a newer model BM 4000, bought for spares, newer tested it.

Collecting Vintage B&O is not a hobby, its a lifestyle.

Dillen
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BM4000 never used the newer switch.
It's unique to the later BM4400.

Martin

Craig
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Craig replied on Fri, Mar 2 2018 7:50 AM

Søren Mexico:

Craig I have a BM 4400 coming in after Xmas, bought it for parts, maybe the top cover is better than yours, the top free to go for shippingcosts

I was hoping Soren was referring to this BM4400 and not a BM4000

;¬)

Søren Mexico
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Craig:

Søren Mexico:

Craig I have a BM 4400 coming in after Xmas, bought it for parts, maybe the top cover is better than yours, the top free to go for shippingcosts

I was hoping Soren was referring to this BM4400 and not a BM4000

;¬)

It was a typo, of course I mean BM 4400, let me check this weekend if it works.

 

Collecting Vintage B&O is not a hobby, its a lifestyle.

Craig
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Craig replied on Sat, Mar 3 2018 8:32 AM

Soren

That would be great, some pictures of how you get it out would be appreciated too Big Smile

Søren Mexico
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Craig:

Soren

That would be great, some pictures of how you get it out would be appreciated too Big Smile

Will do, stay tuned tomorrow

Collecting Vintage B&O is not a hobby, its a lifestyle.

Craig
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plywood shapes arrived today, had them cut to the overall size but without any shaping....


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