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Old 10-08-2021, 05:17 AM   #1
dicky96
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Default Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

Hi guys can anyone identify this please

It's in a 1500W ATX PSU

Marking looks like BC729 or 8C729 but the B or 8 is a funny symbol with the top ha1lf smaller than the bottom half

I suspect it is a voltage regulator

The centre pin/tab goes to ground

The right pin goes to a CM6902 PWM chip VCC pin and only has 0.5V

The left pin has 0V but I think it should go to a 16V rail on the 5V STB
transformer but the PCB is too densely populated to see how it would get there on the other side.

On this side it only goes to two capacitors in parallel, the other end of the caps goes to ground. These look like they are input caps to me



best regards
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Old 10-08-2021, 06:03 AM   #2
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Default Re: can anyone identify this device BC729/8C729?

It looks more like an A or underlined A to me,but it could be the makers symbol
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Old 10-08-2021, 06:06 AM   #3
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Default Re: can anyone identify this device BC729/8C729?

Pin 2 counting from the bottom left goes to pin 10 of the 16 pin IC below it. Post the part number of that 16 pin IC, if there`s a datasheet available with a typical application circuit,it might help to ID that part

.

Last edited by SMDFlea; 10-08-2021 at 06:21 AM..
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Old 10-08-2021, 06:21 AM   #4
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

The PSU is Kolink Continuum 1500W Fully Modular 80 Plus Platinum

The 16 pin chip is CM6901T (typo in OP) Pin 10 is ground
https://pdf1.alldatasheet.com/datash...MP/CM6901.html

The possible output from the regulator goes to pin 15 (Vcc) on the CM6901T

The middle pin (pin 2) is ground

The left hand pin which I only see connects to two capacitors (input?) has 0V - and the other side of the caps is ground

Vcc on CM601T on 15 is 0.5V - it should be 10V-20V according to datasheet

The 5VSTB generates another rail 16.9V which is present

I think the mystery component is a 12V fixed regulator and there is a bad via or damage on the other side of the PCB that I can't see which is beraking the connection from input of BC729 to 16V - which also goes two two vias to the component side (visible)

The PCB is too densely populated to check without removing a lot of components - if it is confirmed input pin on a 12V regulator I will bridge a wire to 16V rail.

Last edited by dicky96; 10-08-2021 at 06:24 AM..
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Old 10-08-2021, 06:33 AM   #5
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

This is what I know and what I am thinking...

See pic

I showed 5V STB on the ground end of the capacitors, it is of course on the other end
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Old 10-08-2021, 06:46 AM   #6
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

Cm6901 datasheets http://www.champion-micro.com/product-en/CM6901.htm
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Old 10-08-2021, 07:22 AM   #7
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

I posted the datasheet
Post #4

I would just like to confirm my suspicion BC729 is a fixed 12V regulator

I suppose I could unsolder it and test it if no one knows
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Old 10-08-2021, 11:14 AM   #8
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

Hmm seems an obscure part number if no one knows.

I'm thinking now to inject 17V on the supposed input, set my bench PSU to a few hundred milliamps and see what happens. If I then get 12V or similar on the CM6901 Vcc then I can solder the wire from 16.9V

I could do this either with the mains supply to the ATX PSU off, or with it on using a light bulb limiter and see if the main rails power up

But if someone can identify the BC729 device all the better and a bit less risky

thanks
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Old 10-08-2021, 11:48 AM   #9
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

8C729 (8Cxxx) - L78L05ABUTR
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File Type: png L78L05ABUTR.PNG (358.5 KB, 6 views)
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Old 10-08-2021, 11:59 AM   #10
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

lotas beat me to it, but I agree 8C729, and the 8C being a +5 volt regulator, 729 date/mfg code
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Old 10-08-2021, 12:54 PM   #11
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

Quote:
Marking looks like BC729 or 8C729 but the B or 8 is a funny symbol with the top ha1lf smaller than the bottom half
Or perhaps a SMT version of the 2SC729, an NPN transistor? Omitting the "2S" from transistor markings is common practice.
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Old 10-08-2021, 03:44 PM   #12
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

Ahh now that makes this more interesting but doesn't really make any sense

A: If 8C729 is a 7805 equivalent, the output on pin 3 (assumedly 5V) is not enough for Vcc of the CM6901 which needs 10-20V and it connects directly to there (pin 15 CM6901). Doesn't appear to be correct

B: If it is a 2SC729 then it needs some base voltage to supply 10V-20V to pin 15 CM6901, acting as an emitter follower but this does not make sense as the TAB (collector?) is connected directly to ground

I think now back to an earlier plan I need to put some voltage on pin 1 from my bench PSU with current limit 100mA-200mA just a guess of something reasonable and see if 12V approx appears on pin 3 (output)

Last edited by dicky96; 10-08-2021 at 03:47 PM..
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Old 10-08-2021, 04:50 PM   #13
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

Quote:
Originally Posted by dicky96 View Post
Hi guys can anyone identify this please

It's in a 1500W ATX PSU

Marking looks like BC729 or 8C729 but the B or 8 is a funny symbol with the top ha1lf smaller than the bottom half

I suspect it is a voltage regulator

The centre pin/tab goes to ground

The right pin goes to a CM6902 PWM chip VCC pin and only has 0.5V

The left pin has 0V but I think it should go to a 16V rail on the 5V STB
transformer but the PCB is too densely populated to see how it would get there on the other side.

On this side it only goes to two capacitors in parallel, the other end of the caps goes to ground. These look like they are input caps to me



best regards
Richard
The "8Cxxx" has a different pinout, the input voltage is supplied to the right pin, and the output voltage of 5 volts comes out from the left pin.
Look for where the voltage comes from, which is applied to the right pin.
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File Type: png L78L.PNG (9.1 KB, 5 views)

Last edited by lotas; 10-08-2021 at 04:56 PM..
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Old 10-09-2021, 03:06 AM   #14
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Default Re: Kolink Continuum KL-C1500PL can anyone identify this device BC729/8C729?

Thanks for that info. It suggests that I should put about 12V on Vcc of the CM6902 (as I know this should be 10V-20V from the datasheet) then the 8C729 regulator will generate 5V output for whatever.

Two things for sure, the PSU can not power up unless the PWM is running, and PWM Vcc can only come from the 16V output on the 5V Standby PSU one way or another

Last edited by dicky96; 10-09-2021 at 03:11 AM..
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