Finding A Power Supply Schematic

[Reinhard Zwirner]

Ian Field schrieb:

"Reinhard Zwirner" <reinhard.zwirner@t-online.de> wrote:
Ian Field schrieb:
"Reinhard Zwirner" <reinhard.zwirner@t-online.de> wrote:

Hmm, can't you see my posting as of May 24 with the link to that
schematic?

The only link I can see on that post is carousel-design.

?????

Maybe you could repost?

Here is it:

http://www.bilder-hochladen.net/files/big/12b4-a6-6c52.jpg

As advised; you should replace C6 ...

It is Michael Karas who should try to repair his power supply by
replacing the capacitor corresponding to C6 (or the resistor
corresponding to R1) - not me! _I_ just tried to explain N_Cook's
"bleed-through" route by a typical SMPS schematic as an example.

Regards

Reinhard

 

[Arfa Daily]

<PlainBill@yawhoo.com> wrote in message
news4h4q81ntael1864ve7itccsds96mm8jrq@4ax.com...

On Sun, 26 May 2013 04:25:52 -0700, Michael Karas
mkaras@carousel-design.com> wrote:

[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article <9usvp85m2404b7f1ci9nbvcnn5rsjvlcm6@4ax.com>,
PlainBill@yawhoo.com says...

On Fri, 24 May 2013 06:08:53 -0700, Michael Karas
mkaras@carousel-design.com> wrote:

[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]


I am repairing an LCD monitor that has the very common turn on
problems.
This is an I-INC IF281D unit with model number showing as HSD1040. I am
in the process of replacing all the capacitors on the PhiHong power
supply board (model PSM217-404-H-R) and have noticed that one
transistor
looks like it got excessively hot. I would like to replace that
transistor but have to first ID the part number. To this end I have two
questions...

Does anyone know where it may be possible to get a schematic for the
PSM217-404-H-R power supply board?

The overheated transistor is an SMT device with a code DFRG marked on
top. Any idea as to what that part number may be?
Google 'marking code DFRG' and see if anything makes sense. Also, SMT
is a very generic term. If we knew the specific package, it would
help us help you.

Another resource, especially whre power supplies for LCD monitors are
concerned is www,badcaps.net/forum. Pictures help.

PlainBill

Here is a link to a picture of the transistor in question.

https://docs.google.com/file/d/0BxTbL_E1KhGvSWVSX2tEMTlDaW8/edit?
usp=sharing

(Note link above may be split by a line break).

The transistor package body is 2.5mm x 4mm. Lead spacing is 1.5mm.
According to a document I checked here at the next link this package is
a SOT-89 (also apparently referred to as a T0-243 or an SC-62).

http://www.nxp.com/documents/outline_drawing/sot089_po.pdf
Excellent pictures, thanks. I believe the actual marking code is DF;
the R indicates the gain and the G is a prouction lot or date code.

My favorite source for arcane marking info: http://www.s-manuals.com

Which leads to: http://www.s-manuals.com/smd/df

And the datasheet: (watych out for line breaks)
http://www.s-manuals.com/pdf/datasheet/2/s/2sd1733%2C_2sd1768s%2C_2sd1863%2C_2sd1898_rohm.pdf
IF you are in the USA, they are available from Digi-Key
(ww.digikey.com) for $.53 each. (Choose USPS First Class Mail for
lowest shipping cost.)

As a general rule, I dissaprove of replacing parts because they 'look
bad'. A few minutes making measurements with a DVM can give a wealth
of information.

PlainBill

Based on years of experience at component level, +1 on that. Unless there is
a very good reason, I've never been an advocate of 'shotgunning' for the
hell of it ...

Arfa

 

[Arfa Daily]

When I get a power cord setup to be able fire up the board I will do
some checking. I may also need to rig up a temoprary heatsink for a
large diode bridge that gets screwed to part of the case that had to be
removed to get at the board. Initial tests can probably avoid that if I
just put small loads on the output rails for testing,

--

Michael Karas
Carousel Design Solutions
http://www.carousel-design.com

If available, I would strongly recommend the use of a proper bench isolating
transformer when working on this. I'm sure that it is probably a case of
grandmothers and egg-sucking as you seem to be saying the right things, but
just in case ...

Switchers are of course extremely dangerous on a 'raw' line supply. I
usually have a variac connected as well. This can be either a help or a
hindrance depending on design, but I always initially make the assumption
that it is going to be a help, when I don't have a schematic. Although some
supplies have UVLO on the control IC, so won't start with a reduced input
voltage, it does at least allow you to carry out checks on - for instance -
the startup supply, in a safe manner, and without the risk of a Disney-esque
fireworks display, when your meter or 'scope probe slips, which it always
will sooner or later, depending on how urgent the job is, and how rare the
supply is to obtain a replacement for ...

Good luck with it, and do let us know how you get on !

Arfa

 

[N_Cook]

Michael Karas <mkaras@carousel-design.com> wrote in message
news:MPG.2c0c0badb776665a9896fc@news.eternal-september.org...

[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article <p4h4q81ntael1864ve7itccsds96mm8jrq@4ax.com>,
PlainBill@yawhoo.com says...

Excellent pictures, thanks. I believe the actual marking code is DF;
the R indicates the gain and the G is a prouction lot or date code.

My favorite source for arcane marking info: http://www.s-manuals.com

Which leads to: http://www.s-manuals.com/smd/df

And the datasheet: (watych out for line breaks)
http://www.s-manuals.com/pdf/datasheet/2/s/2sd1733%2C_2sd1768s%2C_
2sd1863%2C_2sd1898_rohm.pdf
IF you are in the USA, they are available from Digi-Key
(ww.digikey.com) for $.53 each. (Choose USPS First Class Mail for
lowest shipping cost.)

As a general rule, I dissaprove of replacing parts because they 'look
bad'. A few minutes making measurements with a DVM can give a wealth
of information.

PlainBill

THanks for the info. I had also done some research on some other sites
and find that there are multiple possibilities for this device marked
with a DF.

Sanyo NPN 2SD1623
Philips PNP BF621
Siemens PNP BNF21
Rohm NPN 2SD1898 **

** The part that you located.

I agree that this part should not be replaced if it is working. I had
done some preliminary checking with the meter and it did not seem to
respond with any forward biased junction readings and so I needed to get
information as to whether this was some type of FET or a blown BJT
transistor.

When I get a power cord setup to be able fire up the board I will do
some checking. I may also need to rig up a temoprary heatsink for a
large diode bridge that gets screwed to part of the case that had to be
removed to get at the board. Initial tests can probably avoid that if I
just put small loads on the output rails for testing,

--

Michael Karas
Carousel Design Solutions
http://www.carousel-design.com

Probably just incidental and irrelevant to the main problem, as it can only
get stressed while the SMPS is operational. I've still not seen you state
the identity of the supervisor/controller IC/s ? or is it discrete
componentry?

 

On Sun, 26 May 2013 13:08:53 -0700, Michael Karas
<mkaras@carousel-design.com> wrote:

[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article <p4h4q81ntael1864ve7itccsds96mm8jrq@4ax.com>,
PlainBill@yawhoo.com says...

Excellent pictures, thanks. I believe the actual marking code is DF;
the R indicates the gain and the G is a prouction lot or date code.

My favorite source for arcane marking info: http://www.s-manuals.com

Which leads to: http://www.s-manuals.com/smd/df

And the datasheet: (watych out for line breaks)
http://www.s-manuals.com/pdf/datasheet/2/s/2sd1733%2C_2sd1768s%2C_
2sd1863%2C_2sd1898_rohm.pdf
IF you are in the USA, they are available from Digi-Key
(ww.digikey.com) for $.53 each. (Choose USPS First Class Mail for
lowest shipping cost.)

As a general rule, I dissaprove of replacing parts because they 'look
bad'. A few minutes making measurements with a DVM can give a wealth
of information.

PlainBill

THanks for the info. I had also done some research on some other sites
and find that there are multiple possibilities for this device marked
with a DF.

Sanyo NPN 2SD1623
Philips PNP BF621
Siemens PNP BNF21
Rohm NPN 2SD1898 **

** The part that you located.

Note that the marking codes seem to be chosen by the manufacturer.

Always make sure you are dealing with the same package type.

PlainBill

 

[Michael Karas]

[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article <HFwot.7179$ZU7.4143@newsfe28.iad>, arfa.daily@ntlworld.com
says...

If available, I would strongly recommend the use of a proper bench isolating
transformer when working on this. I'm sure that it is probably a case of
grandmothers and egg-sucking as you seem to be saying the right things, but
just in case ...

Switchers are of course extremely dangerous on a 'raw' line supply. I
usually have a variac connected as well. This can be either a help or a
hindrance depending on design, but I always initially make the assumption
that it is going to be a help, when I don't have a schematic. Although some
supplies have UVLO on the control IC, so won't start with a reduced input
voltage, it does at least allow you to carry out checks on - for instance -
the startup supply, in a safe manner, and without the risk of a Disney-esque
fireworks display, when your meter or 'scope probe slips, which it always
will sooner or later, depending on how urgent the job is, and how rare the
supply is to obtain a replacement for ...

Good luck with it, and do let us know how you get on !

Arfa

I will post back here when more work on this power supply has happened.
Normal workweek obligations force one to set aside tasks like repairing
monitors.

--

Michael Karas
Carousel Design Solutions
http://www.carousel-design.com

 

[isw]

In article <MPG.2c0e41cd5fd276ad9896fd@news.eternal-september.org>,
Michael Karas <mkaras@carousel-design.com> wrote:

[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article <HFwot.7179$ZU7.4143@newsfe28.iad>, arfa.daily@ntlworld.com
says...


If available, I would strongly recommend the use of a proper bench
isolating
transformer when working on this. I'm sure that it is probably a case of
grandmothers and egg-sucking as you seem to be saying the right things, but
just in case ...

Switchers are of course extremely dangerous on a 'raw' line supply. I
usually have a variac connected as well. This can be either a help or a
hindrance depending on design, but I always initially make the assumption
that it is going to be a help, when I don't have a schematic. Although some
supplies have UVLO on the control IC, so won't start with a reduced input
voltage, it does at least allow you to carry out checks on - for instance -
the startup supply, in a safe manner, and without the risk of a
Disney-esque
fireworks display, when your meter or 'scope probe slips, which it always
will sooner or later, depending on how urgent the job is, and how rare the
supply is to obtain a replacement for ...

Good luck with it, and do let us know how you get on !

Arfa

I will post back here when more work on this power supply has happened.
Normal workweek obligations force one to set aside tasks like repairing
monitors.

I see that even after all these years, you still haven't got your
priorities right 8^}

Isaac

 

[mkaras]

On Tuesday, May 28, 2013 9:52:46 PM UTC-7, isw wrote:

... like repairing monitors.

I see that even after all these years, you still haven't got your

priorities right 8^}

Isaac

:^)

Priorities are just that . . . something that somehow gets set by what we choose to do.

Michael Karas

 

[Michael Karas]

[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article <m2a7q85s92jbp4k91mp9v2bmk0mfck5n7f@4ax.com>,
PlainBill@yawhoo.com says...

On Sun, 26 May 2013 13:08:53 -0700, Michael Karas
mkaras@carousel-design.com> wrote:

[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article <p4h4q81ntael1864ve7itccsds96mm8jrq@4ax.com>,
PlainBill@yawhoo.com says...

Excellent pictures, thanks. I believe the actual marking code is DF;
the R indicates the gain and the G is a prouction lot or date code.

My favorite source for arcane marking info: http://www.s-manuals.com

Which leads to: http://www.s-manuals.com/smd/df

And the datasheet: (watych out for line breaks)
http://www.s-manuals.com/pdf/datasheet/2/s/2sd1733%2C_2sd1768s%2C_
2sd1863%2C_2sd1898_rohm.pdf
IF you are in the USA, they are available from Digi-Key
(ww.digikey.com) for $.53 each. (Choose USPS First Class Mail for
lowest shipping cost.)

As a general rule, I dissaprove of replacing parts because they 'look
bad'. A few minutes making measurements with a DVM can give a wealth
of information.

PlainBill

THanks for the info. I had also done some research on some other sites
and find that there are multiple possibilities for this device marked
with a DF.

Sanyo NPN 2SD1623
Philips PNP BF621
Siemens PNP BNF21
Rohm NPN 2SD1898 **

** The part that you located.

Note that the marking codes seem to be chosen by the manufacturer.
Always make sure you are dealing with the same package type.

PlainBill

Well, I received the new capacitors for the monitor power supply and got
those installed. The power supply fired right up and produced its 5V
STBY output. I then tested the other outputs by connecting the PSON
signal on one of the connectors over to the 5V STBY and all of the +5, +
12 and +24 volt rails all came up. I tested the thing on the bench with
some load on each output and it works nicely.

Unfortunately when the PSU is mated up with the video controller board
in the monitor it fails to come up and act like a monitor. The only
thing that does appear to work is that the EDID device does provide
valid data back out through the D-Sub HD15 connector to a host computer.
It shows the proper native monitor ID strings and the correct native
resolution. But no other functioning is in operation.

Since this thing was given to me for free and the fact that it only
supports analog VGA signalling (no DVI connector) I will probably not
spend any more time futzing around with it.

--

Michael Karas
Carousel Design Solutions
http://www.carousel-design.com

 

[isw]

In article <MPG.2c19d2e2b0201aa69896fe@news.eternal-september.org>,
Michael Karas <mkaras@carousel-design.com> wrote:

--snippage --

Since this thing was given to me for free and the fact that it only
supports analog VGA signalling (no DVI connector) I will probably not
spend any more time futzing around with it.

A while back, I acquired a very nice LCD monitor with both VGA and DVI-D
interfaces. At the time, the only interface adapter I had was VGA (this
is on a Mac which uses an external adapter). Later, I got a DVI-D
adapter and cable, and was able to compare the two. Despite my most
careful comparisons, using both text and images, I was unable to see any
difference in the image quality between the two.

VGA is not all that bad.

Isaac

 

[Michael Karas]

[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article <isw-42C5F7.21270306062013@[216.168.3.50]>, isw@witzend.com
says...

VGA is not all that bad.

Isaac

I am inclined to agree that analog VGA can be pretty good. A lot depends
upon the quality of the cables, its lengths and how well the video
controller outputs are terminated.

Since LCD type panels will digitize the analog signal anyway there is
also a lot that can be done on a decent monitor regarding how the signal
is sampled.

In my personal experience with quite a variety of different LCD monitors
attached to an almost equally diverse array of different video driver
implementations I have both situations. In some instances where an
analog VGA to DVI direct comparison was done there was virtually no
discernable difference. On the other hand there were examples where
there was a distinct difference in the displayed image - even on a
monitor that had both DVI and analog VGA connections fed the same
content from the same video controller.
--

Michael Karas
Carousel Design Solutions
http://www.carousel-design.com