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CAudio SR808

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Sergio B View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sergio B Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2022 at 2:25pm
as for the R24 R34 R50 resistors, I confirm that they are originally 22k 1/4 watt

therefore the three must be replaced with 27k 1w


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Post Options Post Options   Thanks (0) Thanks(0)   Quote simonp1100 Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2022 at 2:30pm
Here is an updated version of the soft / start PCB





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Post Options Post Options   Thanks (0) Thanks(0)   Quote simonp1100 Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2022 at 2:32pm
Here is the updated protection circuitry.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote simonp1100 Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2022 at 2:35pm
Here is my version of the updated driver card.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote simonp1100 Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2022 at 2:42pm
The soft start PCB has updated components, including allowing you to use two versions of the 47R resistor (clad or PCB solder type) and added NTC's as well.

Also have the originals & updated versions of the following as well.

RA Series (1001-3001 T03 & Plastic FET's PCB board, including all mods & re-entrant circuit added to main board & a few other tweeks).
GB602 (just original main board & input PCB).
ST1000 (just original main board & all other PCB's).

Would like to do the RA4001 as well at some point.

SmileSmile
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Sergio B View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sergio B Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2022 at 2:43pm
great job, congratulations Smile

you can put the wiring diagram with the parts list and values ​​if you don't mind
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Sergio B View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sergio B Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2022 at 2:03pm
Hello
today i mounted the driver board but i noticed that the volume is lower and that the transistors
of the channel give strange values ​​compared to the other channel. disconnecting power and audio i / o and checking with the multimeter
I noticed that one pin of all transistors does not give any value between pin and GND. it would be a nice "blow" to the wallet
15 pairs of transistors to replace and who knows where to find them. someone gives me some info where to buy them. thank you


Edited by Sergio B - 30 May 2022 at 8:30pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbl_man Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2022 at 2:43pm
The SR808 Has 15 MOSFETS per voltage rail, so each channel has a total of 30 MOSFETs (15 X  Hitachi 2SJ50 & 15 X  Hitachi 2SK135.

You could try Ebay for good used ones. Beware of anything from China or any reporting to be "new", as doubtless there are fake ones around.
Be seeing you.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2022 at 3:47pm
Originally posted by jbl_man jbl_man wrote:

The SR808 Has 15 MOSFETS per voltage rail, so each channel has a total of 30 MOSFETs (15 X  Hitachi 2SJ50 & 15 X  Hitachi 2SK135.

You could try Ebay for good used ones. Beware of anything from China or any reporting to be "new", as doubtless there are fake ones around.


Getting that quantity of those is nigh impossibe these days. And yes - watch out for the fakes.  Dead

You might be able to find enough of the Exicon 10N/P16 or 10N/P20. They should be ok as a replacement.






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service dept Steve View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote service dept Steve Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2022 at 4:11pm
I wonder what a pulled, used but tested j50 or k135 is worth these days, us old boys have lots of strange stock tucked away
We are not "They", We are "The others"http://www.servicedept.co.uk -
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbl_man Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2022 at 4:21pm
Be seeing you.
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Randy Bohannon View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Randy Bohannon Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2022 at 5:03pm
Cricklewood electronics reckon theirs's are real and they want £30 for them  

https://www.cricklewoodelectronics.com/2SJ50.html

The Batwing ones are where the money is:  

https://www.cricklewoodelectronics.com/2SJ83.html

Makes me want to sell the two pairs I have in the working bank of a random 80s DIY amplifier I have and replace them with Exicons at a profit! Confused

(sorry, can't get hyperlinks to work...)


Edited by Randy Bohannon - 30 May 2022 at 5:05pm
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