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Old 03-04-2020, 10:41 AM   #21
SolomonMan
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Default Re: DC Power Supply QW-MS605D

All,
Got the Order in to Mouser electronics for this and some other items...It was delayed do to paperwork (not selling to foreign country stuff)...Got that all in and its been a few days but got a update its supposed to ship today!

Hopefully sizing and everything is right as we spoke previously....

Thanks everyone for the help,
Chris
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Old 03-14-2020, 03:20 PM   #22
SolomonMan
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Default Re: DC Power Supply QW-MS605D

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Originally Posted by SolomonMan View Post
All,
Got the Order in to Mouser electronics for this and some other items...It was delayed do to paperwork (not selling to foreign country stuff)...Got that all in and its been a few days but got a update its supposed to ship today!

Hopefully sizing and everything is right as we spoke previously....

Thanks everyone for the help,
Chris
All,
Got the parts in and got everything soldered in place....

To Recap on its replacements;
R13 - Metal Film Resistor 51R-3Watt - Replaced with Metal Film Resistor (51R) - Part # RR03J51RTB

R01 and R02 - SMD Thick Film Resistor- 51R - 3 Watt - Replaced with Part # 352251RFT

C41(original locomotive one -it popped) - Electrlytic capacitor 330uF 63 V - Replaced with Panasonic 330uF 100V - Part # EEU-FS2A331L

I replaced also the C34 - Electrlytic capacitor 330uF 63 V - Replaced with Panasonic 330uF 100V - Part # EEU-FS2A331L as well.

C24 - this one originally disengrated to nothing - thought according to Diagram to be CBB 2.2 uF 100 V - The capacitor was a SMD...I bought a 2.2uF 100V C1210C225K1RACAuto.

The SMD I purchased was way bigger in size. I went to place it on the pads and it completely covered it and then some.

I had some 25V 4.7 uF SMD (C0805C475K3RACAuto) and the thing was correct dimensional wise...So I am not sure if this will cause me havoc or not.

With that said...I fired it up and it appears to be cycling (Below is a MP4 from my google drive of what its doing);

https://drive.google.com/file/d/1UlK...ew?usp=sharing

Is this a Bridge Rectifier issue?

Any troubleshooting tips...Please...

Thanks again!
Chris
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Old 03-14-2020, 03:45 PM   #23
R_J
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Default Re: DC Power Supply QW-MS605D

C24 is off the CT pin of the ic, this is the timiing capacitor, Try using the correct value. I'm not sure what is causing the problem but it seems to be shutting down the whole power supply and restarting. If C24 poped, I suspect U4 was damaged, how else could C24 "pop"?

Last edited by R_J; 03-14-2020 at 04:03 PM..
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Old 03-14-2020, 05:57 PM   #24
SolomonMan
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Default Re: DC Power Supply QW-MS605D

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Originally Posted by R_J View Post
C24 is off the CT pin of the ic, this is the timiing capacitor, Try using the correct value. I'm not sure what is causing the problem but it seems to be shutting down the whole power supply and restarting. If C24 poped, I suspect U4 was damaged, how else could C24 "pop"?
R_J,
I was wondering if that SMD (C24) was going to be the issue or the KA7500B (U4) IC...

So U4 is a KA7500B which appears to be a switched-mode power supply controller, remember I am still a Novice , it does not appear to be pricey and its available.

I am looking at a Data Sheet and the diagram in this thread;
https://www.mouser.com/datasheet/2/3...0B-1301161.pdf

, it appears pin 5 is the one I am having issue...am I correct?

On the C24 could I use the original too large SMD with a wire setup to the pads to test this so I can confirm the KA7500B failure?

I can then get another order in to get this thing squared away.

Thanks Again,
Chris

Last edited by SolomonMan; 03-14-2020 at 07:22 PM..
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Old 03-14-2020, 07:27 PM   #25
R_J
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Default Re: DC Power Supply QW-MS605D

You said that C24 poped, I can't see how it did it on its own, even if the cap shorted, it would not POP, there is not enough voltage on it do cause this. C24 is connected to pin5 not pin 13, or was the cap that poped, off pin 13?
Did you check that D1 was not shorted? I would also check that Q1 and Q3 are not shorted.

Last edited by R_J; 03-14-2020 at 07:35 PM..
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Old 03-14-2020, 10:42 PM   #26
SolomonMan
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Default Re: DC Power Supply QW-MS605D

Quote:
Originally Posted by R_J View Post
You said that C24 poped, I can't see how it did it on its own, even if the cap shorted, it would not POP, there is not enough voltage on it do cause this. C24 is connected to pin5 not pin 13, or was the cap that poped, off pin 13?
Did you check that D1 was not shorted? I would also check that Q1 and Q3 are not shorted.
R_J,
Correct on the Pin 5 not 13...I corrected my post but I think we missed each other....

I should have not said pop...it basically fell apart...its not a big SMD at all...I think the heat made it just disengrate. (middle was gone).

D1 tests fine not shorted.

Q1 and Q3 are not shorted and test fine as well.

On the C24 I tried the original too large SMD with a wire setup to the pads to test KA7500B failure...there was no change in the PSU...So it appears the KA7500B is not doing its job.

What amount of voltage should be on the C24 pin (5) of the KA7500B IC?

Not seeing much voltage around the IC?

Thanks
Chris
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Old 03-18-2020, 06:53 AM   #27
SolomonMan
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Default Re: DC Power Supply QW-MS605D

R_J/All,
Ordered a 10 pack of KA7500B...it was cheaper then buying one...go figure that one out....They are coming out of China/Hong Kong.

On the C24 it says its a CBB 2.2 uF 100 V Capacitor.

I am thinking this capacitor needs to be sorted out (Size-Wise)...whats does CBB mean?

I found the below doing a google search;

http://www.vishay.com/docs/61042/cbbcbc.pdf

I guess another basic electronics question I have is....Is a Capacitor regardless of its type, assuming the Voltage and Farad sizes are the same, swappable?

Trying to understand capacitors...I know there are multiple types and certain types are better than others in certain circuits but in the case of just getting it running can you swap out different capacitors assuming Voltage/Farads are correct?

Thanks again,
Chris
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Old 06-29-2020, 06:07 PM   #28
pc7fan
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Default Re: DC Power Supply QW-MS605D

I have an MS605D here. Replace the P75NF75 FET and that should fix the cap popping and cycling issue (use 100V output caps instead of the 63V ones).
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