BGW 250d

[Michael F]

I came across a nice example of a `78 or so vintage and I just had to have it . I`ve owned many 750B and C models over the decades and have always been impressed with their build quality, reliability, ease of service and sonics. They also responded favorably to recapping in the signal and feedback paths and to bypass caps, I`m guessing the same would apply to his intermediate model as it seems to share similar DNA.
For starters, I`m thinking C1, C11 and C12 and possibly C4 but I`m not sure about that one, maybe a couple of 47uF across the filter caps.
I`m anxious to install the unit but before I do, I would welcome any comments from owners of these amps either in stock or upgraded form or if anyone had the opportunity to compare it with any other model?
If it sounds anything like its bigger brother, I would be very pleased.

 

[Mark Johnson]

Maybe you know what "C1" , "C11", "C12" , and "C4" mean.

Your readers do not.

 

[Max Headroom]

I rebuilt a whole wall of the 750's that were in continuous service for 20++ years in an Omni theatre.
I measured all amps before recapping and all showed significant low frequency loss of response.
I replaced all caps excepts the main supply caps in these amplifiers and all came up to within 0.1dB of each other.
I used Hitano EXR (low esr) caps and all amps performed perfectly to spec, and sounded fine.

Dan.

 

[Audio1Man]

Maybe you know what "C1" , "C11", "C12" , and "C4" mean.

Your readers do not.

Input coupling , Bootstrap caps & Feedback on the Amplifier modules. They are mostly the same for any of the BGW amps that use the LM318 opamp in the input stage.

Duke

 

[Robbie44]

Hello i need a bit of help

I need a few pictures of your relayboad please

Thank you Robert

 

[Michael F]

I need a few pictures of your relayboad please

Thank you Robert

Here you is..

 

[Robbie44]

Hello And thank you !
but do you have on that maybe is one just of the relay board ?
i need to kinda do a visual diode placment

Robert

 

[JMFahey]

Hello And thank you !
but do you have on that maybe is one just of the relay board ?
i need to kinda do a visual diode placment

Robert

The relay board is in that picture and diode orientation bands are clearly visible.

Your board is not *exactly* like that one anyway, but 90% the same; one of your diodes , the lone one at the bottom right corner in your picture seems to be the wrong way around.

Just click twice on each picture, the second time in the bottom left "full screen enlargement" square and both will be large enough for an easy comparison.

 

[Robbie44]

THANK YOU!!!

Hello i think the same the thing that makes me crazy is
when you look in a 750b Service man the number on the board macth but when you read the scamaatic its seems there are extra parts that are not on the board it self somewhat confusing !!