Looking for datasheet on Mitsubishi M62503FP Horizontal deflection chip
John Kimball
Does anyone have the English .pdf?
Thanks.
KenyD
manual.
KenyD
"John Kimball" <john...@hotmail.com> wrote in message
news:qptsmug3fuank6dlk...@4ax.com...
John Kimball
Message id: <S6wb9.6730$z21.1...@news20.bellglobal.com>:
>What model and location is this from? I may be able to scan from service
>manual.
It's a Viewsonic 21" monitor, model number P225, chassis #VCDTS21492 -
which, apparently, was originally made by Panasonic and remarked.
The original problem was a vertical line only - after replacing two
power devices and the fuse in the horizontal deflection circuit, I
regained sweep, but have a pincushion problem (the front panel controls
have no effect). I suspect this chip may have something to do with
adjusting the pincushion as it drives a TO-220 medium power FET in the
circuit.
By location, do you mean reference designation on the circuit board? If
so, it's IC850.
Thanks, Ken.
Franc Zabkar
<john...@hotmail.com> put finger to keyboard and composed:
>On Thu, 29 Aug 2002 17:12:59 -0400 "KenyD" <ke...@bellnet.ca> wrote in
>Message id: <S6wb9.6730$z21.1...@news20.bellglobal.com>:
>
>
>>What model and location is this from? I may be able to scan from service
>>manual.
>
>It's a Viewsonic 21" monitor, model number P225, chassis #VCDTS21492 -
>which, apparently, was originally made by Panasonic and remarked.
>The original problem was a vertical line only - after replacing two
>power devices and the fuse in the horizontal deflection circuit, I
>regained sweep, but have a pincushion problem (the front panel controls
>have no effect). I suspect this chip may have something to do with
>adjusting the pincushion as it drives a TO-220 medium power FET in the
>circuit.
I found the same datasheet:
http://www.semicon.melco.co.jp/semicon/pdf/004/004/015/048/M62503FP.pdf
This URL ...
http://www.semicon.melco.co.jp/semicon/html/004/004_015_048.html
... describes the IC's function as "synchronous horizontal deflect
control for display monitor", which is ambiguous IMHO.
Instead the application circuit on the last page of the datasheet
suggests to me that the IC functions as an EHT regulator. Its PWM
output is used to drive a DC-DC converter consisting of a MOSFET
chopper and an L and C. The chopper's input appears to be the HT
supply rail. The output of the DC-DC converter powers the primary
winding of the FBT. The FBT provides EHT feedback to the IC by means
of a secondary winding.
I think you need to look elsewhere for a cause of your pincushion
problems. Can you find any other potential candidates?
-- Franc Zabkar
Please remove the 'g' from my address when replying by email.
John Kimball
in Message id: <3d72a86b...@news.dodo.com.au>:
>On Fri, 30 Aug 2002 13:40:53 -0400, John Kimball
><john...@hotmail.com> put finger to keyboard and composed:
>
>>On Thu, 29 Aug 2002 17:12:59 -0400 "KenyD" <ke...@bellnet.ca> wrote in
>>Message id: <S6wb9.6730$z21.1...@news20.bellglobal.com>:
>>
>>
>>>What model and location is this from? I may be able to scan from service
>>>manual.
>>
>>It's a Viewsonic 21" monitor, model number P225, chassis #VCDTS21492 -
>>which, apparently, was originally made by Panasonic and remarked.
>>The original problem was a vertical line only - after replacing two
>>power devices and the fuse in the horizontal deflection circuit, I
>>regained sweep, but have a pincushion problem (the front panel controls
>>have no effect). I suspect this chip may have something to do with
>>adjusting the pincushion as it drives a TO-220 medium power FET in the
>>circuit.
>
>I found the same datasheet:
>
>http://www.semicon.melco.co.jp/semicon/pdf/004/004/015/048/M62503FP.pdf
>
>This URL ...
>
>http://www.semicon.melco.co.jp/semicon/html/004/004_015_048.html
Yup. That's the one I found too. As the data sheet was in Japanese, I had
no luck reading it. <g>
>... describes the IC's function as "synchronous horizontal deflect
>control for display monitor", which is ambiguous IMHO.
>
>Instead the application circuit on the last page of the datasheet
>suggests to me that the IC functions as an EHT regulator. Its PWM
>output is used to drive a DC-DC converter consisting of a MOSFET
>chopper and an L and C. The chopper's input appears to be the HT
>supply rail. The output of the DC-DC converter powers the primary
>winding of the FBT. The FBT provides EHT feedback to the IC by means
>of a secondary winding.
Interestingly enough, this thing is not driving the Flyback. Only the
horizontal sweep for the yoke. I think it *may* be modulating the
horizontal sweep to correct the pincushion. The chip doesn't seem to be
outputting anything from pin 1 to the FET.
Circuit looks like this:
+185v ----FET---Horizontal yoke----HOT transistor---GND
| |
| |
M62503FP chip Horizontal signal
Note that I've already replaced the FET and the HOT for the yoke, and the
HOT does *not* drive the flyback - the flyback has a separate HOT. Note
also that both the FET and the HOT in the yoke circuit were both shorted
out across all three pins (taking out a pico fuse in the middle too.)
Also, I think the failure occurred in the HOT first by someone at UL
mucking with the gate drive to force a failure.
>I think you need to look elsewhere for a cause of your pincushion
>problems. Can you find any other potential candidates?
I Haven't been able to find anything yet. Thanks a lot for your reply,
Franc.
Franc Zabkar
I would think that if your IC is performing pincushion correction, as
it appears is the case, then it would need to be receiving an input
from the vertical oscillator. IMO, that would be the clincher.
John Kimball
in Message id: <3d755b3d...@news.dodo.com.au>:
There is an input on the M62503FP chip called H_SIZE_DAC, and it goes back
to the jungle chip, which of course controls the vertical as well.
There's also another device which I initially overlooked. It's pin 5
output is connected between the FET and the horizontal yoke, and the link
is below:
http://www.panasonic-industrial.org/componentsanddevices/e-data/L21/S01/AN5764N.pdf
Lastly, there's a H/V convergence chip which drives sort of a secondary
yoke around the neck of the tube - it's datasheet is here:
http://www.panasonic-industrial.org/componentsanddevices/e-data/L21/S01/AN5769.pdf
What do you think?
Thanks a ton for your help again.
Franc Zabkar
If the M62503FP IC were performing pincushion correction, then the
H_SIZE_DAC signal would need to vary according to the beam's vertical
position and would thus be at the vertical frequency. For proper
pincushion correction the h/yoke current would need to be max at the
centre of the CRT and min at the top and bottom. Therefore I suspect
that the H_SIZE_DAC signal waveform would need to be either triangular
or parabolic. I would also expect that the voltage at the output of
the DC-DC converter, at the junction of L and C, would have a small
parabolic ripple, also at the vertical frequency.
Another possibility is that the H_SIZE_DAC signal is not involved with
pincushion correction, but that it is there to accommodate different
line rates, ie it could simply ensure that the horizontal size does
not vary when the monitor is switched between 35kHz and 56kHz, for
example.
>There's also another device which I initially overlooked. It's pin 5
>output is connected between the FET and the horizontal yoke, and the link
>is below:
>http://www.panasonic-industrial.org/componentsanddevices/e-data/L21/S01/AN5764N.pdf
This IC appears to control Horizontal Centring by injecting a DC bias
current into the h/yoke. All it does is shift the beam to the left or
right of centre. I don't think it's your culprit. In any case you may
like to observe what happens when you disconnect pin 5.
>Lastly, there's a H/V convergence chip which drives sort of a secondary
>yoke around the neck of the tube - it's datasheet is here:
>http://www.panasonic-industrial.org/componentsanddevices/e-data/L21/S01/AN5769.pdf
I'm not sure how this IC works, but I notice that in the application
example the IC has no way of knowing where the beam is. Therefore it
cannot possibly know when to apply the pincushion correction. In any
case it may be instructive to observe what happens when you disconnect
the outputs at pins 7,8,10, and 11.
>What do you think?
I don't know, but in your original IC I'd check for shorts between
pins 1 & 14 (Gnd), or pins 1 & 2 (Vcc). Also check where pin 12 goes.
In the application example it goes to a trimpot. Is there a trimpot in
the vicinity and, if so, is it labelled?
John Kimball
in Message id: <3d77f02...@news.dodo.com.au>:
You're right. I ordered and installed a new M62503FP - there was no
change. However, there's an OP-AMP IC512 1/2 whose output is connected to
the M62503FP pin 8 (IN+) it's output on pin 7 was shorted to the +12V rail
- I found another device on a junk chassis, and replaced the chip.
Success!
The unit is now functioning and is on my desk top as I type this. Thanks a
ton for all your help, Franc.