Magnovox 32MF231D

[retiredcaps]

Re: Magnovox 32MF231D

I cant even GET a download of the manual. Everytime i try i get some .cgi file only about 517 bytes long.

Disable all adblocking software. Goto the site. Wait 60 seconds and the get manual button will appear after it does all its "stuff".

[broksonic]

Re: Magnovox 32MF231D

I cant even GET a download of the manual. Everytime i try i get some .cgi file only about 517 bytes long.

Will try the plug disconnected and see what i get.

[TechShui]

Re: Magnovox 32MF231D

broksonic, have you tried testing that plug while it's disconnected from the scaler board? Obviously, they should stay steady when it's by itself.

The scaler is turning off and on in a loop. The voltage drops when it does. Something in the circuit is causing that, but I can't make heads or tails of the service manual's scaler board sections. They seem to be divided into subsections detailing microprocessor pinouts, digital signals, etc

I can't find anything detailing power distribution or where the 16v goes once it enters the scaler board? Not even a diagram of the whole board.

[broksonic]

Re: Magnovox 32MF231D

I went back and looked at your photo. Looks like burnt flux to me. Nothing to worry about.

You can clean it off with an old toothbrush.

I'm more interested in testing the crystal ocillator IC (1H00).

I suppose an ocilloscope is required for that? My question is directed to everyone. I've never tried troubleshooting an LCD mainboard, it just seems futile with all the hundredss of tiny components to comb over...

Dont think this will help me but you might have equipment for testing.

Found this web page. http://www.electronicrepairguide.com...t-crystal.html


It mentions...

Second method is to use frequency counter to check the frequency of the crystal oscillator. The measurement must be taken when the equipment power is ‘On'. Put the probe of the meter or frequency counter to the crystal pin and read the measurement. Make sure your frequency counter meter has the range that is higher than the crystal frequency you are checking.

If the crystal is 8 mhz then your meter should have the range to be able to check that frequency. Assuming the readout of the crystal is 2.5 mhz then you know that the crystal is not functioning well and need to be replace. Normal digital multimeter usually has a small range for checking frequency. However the digital meter (Greenlee brand) that I'm using is able to measure up to 24 mhz. You can read the specification of your meter manual and see how high is the range is.

[TechShui]

Re: Magnovox 32MF231D

I went back and looked at your photo. Looks like burnt flux to me. Nothing to worry about.

You can clean it off with an old toothbrush.

I'm more interested in testing the crystal ocillator IC (1H00).

I suppose an ocilloscope is required for that? My question is directed to everyone. I've never tried troubleshooting an LCD mainboard, it just seems futile with all the hundredss of tiny components to comb over...

[broksonic]

Re: Magnovox 32MF231D

My point exactly. When I wrote 15.61~.78v I was referring to pins 1 and 2

Pin 5 is just a signal. It doesn't provide power for anything in particular.

Page 55 of the manual says 16v, so again I will assume that your power supply is good.
NOTE: The slight variation might be an indicator that it'll soon be time to replace capacitor 2074, it's a 25v 2200uf Elite (known as a problematic brand).
It's not a major concern since the variation is 0.17v, but if/when you order any parts for your scalar board you might as well get a Panasonic FR capacitor to replace 2074.

The mainboard (aka scalar) is where you should focus.

This post might be of some help: http://www.riddledtv.com/forums/magn...-down-t45.html

I wonder if it might have something to do with that 5001 inductor with all that staining around it? Is there a way for me to test that? Or should i just go board shopping?

[selldoor]

Re: Magnovox 32MF231D

I have done a pic of the connectors from the pdf

[TechShui]

Re: Magnovox 32MF231D

My point exactly. When I wrote 15.61~.78v I was referring to pins 1 and 2

Pin 5 is just a signal. It doesn't provide power for anything in particular.

Page 55 of the manual says 16v, so again I will assume that your power supply is good.
NOTE: The slight variation might be an indicator that it'll soon be time to replace capacitor 2074, it's a 25v 2200uf Elite (known as a problematic brand).
It's not a major concern since the variation is 0.17v, but if/when you order any parts for your scalar board you might as well get a Panasonic FR capacitor to replace 2074.

The mainboard (aka scalar) is where you should focus.

This post might be of some help: http://www.riddledtv.com/forums/magn...-down-t45.html

[broksonic]

Re: Magnovox 32MF231D

Hello RC, earlier in this thread, budm linked to another thread with the 37MF231D service manual.

His post was #4

Here the manual:


AFAIK, the 32MF231D does not have a seperate manual, but they both have the same TPE1.0ULA chassis. And the power board (and probably the scalar) is exactly the same.

I have 2 of these same power boards now. Model 3138 103 6162. Both of them have 16.3V at pins 1 and 2 of the 1089 connector. So the reading seems OK.

Broksonic, maybe if you press a little more firmly, you will get a steady reading, instead of fluctuating 15.61~.78v

I started a thread almost 2 weeks ago, because I had the exact same problem, but then my symptoms changed when the scalar board's green LEDs stopped lighting up at all... to make a long story short, Retired Caps helped me determine the power and main (scalar) boards were bad.

In your case, it sounds as though it might be just the scalar board that has gone bad.

The only flux i had was in pins #1 and #2. The .78v was just in pin #5.

I did retest both sets (10pins and 12pins) and got almost identical readings (within .02).

[broksonic]

Re: Magnovox 32MF231D

Is there a legend or label on the backside of the power board that lists the voltages? Some of the reported voltages are common among TVs except the 15.xx on pins 1 and 2 on connector 1089. Now it could be correct, but I cannot find a service manual so I don't know what the voltages should be.

Sorry didnt see anything on back of any of the boards that would list voltages.

[TechShui]

Re: Magnovox 32MF231D

Is there a legend or label on the backside of the power board that lists the voltages? Some of the reported voltages are common among TVs except the 15.xx on pins 1 and 2 on connector 1089. Now it could be correct, but I cannot find a service manual so I don't know what the voltages should be.

Hello RC, earlier in this thread, budm linked to another thread with the 37MF231D service manual.

His post was #4

Here the manual:


AFAIK, the 32MF231D does not have a seperate manual, but they both have the same TPE1.0ULA chassis. And the power board (and probably the scalar) is exactly the same.

I have 2 of these same power boards now. Model 3138 103 6162. Both of them have 16.3V at pins 1 and 2 of the 1089 connector. So the reading seems OK.

Broksonic, maybe if you press a little more firmly, you will get a steady reading, instead of fluctuating 15.61~.78v

I started a thread almost 2 weeks ago, because I had the exact same problem, but then my symptoms changed when the scalar board's green LEDs stopped lighting up at all... to make a long story short, Retired Caps helped me determine the power and main (scalar) boards were bad.

In your case, it sounds as though it might be just the scalar board that has gone bad.

[retiredcaps]

Re: Magnovox 32MF231D

Is there a legend or label on the backside of the power board that lists the voltages? Some of the reported voltages are common among TVs except the 15.xx on pins 1 and 2 on connector 1089. Now it could be correct, but I cannot find a service manual so I don't know what the voltages should be.

[broksonic]

Re: Magnovox 32MF231D

On the power board, there are two connectors, 1088 and 1089.

1089 is numbered 1 to 10. 1088 is numbered 1 to 12.

4) Report all your findings and note if the voltage changes or is steady.

Connector 1088 (no voltage changes)
pin 1 -24.2
pin 2 -24.2
pin 3 -24.2
pin 4 -24.2
pin 5 -24.2
pin 6 -3.20
pin 7 -0.76
pin 8 -0.00
pin 9 -0.00
pin 10 -0.00
pin 11 -0.00
pin 12 -0.00

Connector 1089
pin 1 -15.61-15.78
pin 2 -15.61-15.71
pin 3 -24.2
pin 4 -3.20
pin 5 -0.78
pin 6 -0.00
pin 7 -0.00
pin 8 -0.00
pin 9 -1.25
pin 10 -0.00

Had readings change when lights flashed.. (refer to post #1 and #16). Also noted when lights went out connector 1089 pin #1 voltage continued to climb up into the 18.00 range. I assumed when the lights went out power was cut off, but guess i was wrong there.

[retiredcaps]

Re: Magnovox 32MF231D

On the power board, there are two connectors, 1088 and 1089.

1089 is numbered 1 to 10. 1088 is numbered 1 to 12.

All readings will be done with TV plugged in and power on. Do NOT touch any of the heatsinks or any part of the power board.

1) Put your black probe on a the ground screw where the number "2" is. It will be left there the entire time.

2) Put your multimeter on 20V DC.

3) Take readings of all pins on both connectors. If a voltage reads "1" or "0L" on the left hand side of the screen, that indicates "out of range". For that pin, switch the multimeter to 200V DC. Take the reading and then switch back to 20V DC.

4) Report all your findings and note if the voltage changes or is steady.

[retiredcaps]

Re: Magnovox 32MF231D

Ok, New DMM purchased (see pic).

I think these are sold at Home Depot in Canada.

With the new DMM set at 200 ohm the F75 (fuse) showed a .07

The 3 voltage regulators (refer to picture) are as follows..
DMM set at 20V DC

7T10 pin 3 (top one in picture) 12.03
pin 2 - 5.01
pin 1 - 0.00

7B45 pin 1 (right side in picture) 5.15
pin 2 - 3.30
pin 3 - 0.00

7U28 pin 1 (bottom one in picture) 4.12
pin 2 - 3.26
pin 3 - 2.60

The readings above indicate your fuse and voltage regulators are good.

[broksonic]

Re: Magnovox 32MF231D

Two things to check on the board in pics 1 and 4.
On the underside left hand side bottom there is a 5001 looks like a cold solder on pin?

Looked ok, but retouched it. No change.

Also the area is stained - can you look at closely and see if you can see why?

Have no idea on the stained areas. There are stains in multiple locations... maybe heat related? Used a bit of rubbing alcohol on a q-tip and it came back light brown but didnt come up easy and i didnt rub long.

On the other side - pic 4 top right ah-ha its actually near 5001 inductor again! there is a small white box what does it say on it . I think it may be another fuse could be that F88 sticker is telling us something. Please test as with other fuse.

Showed a 0.08

Please also look at the soldering on cap 2002 - probably just shadow but looks odd.

Looked fine

[broksonic]

Re: Magnovox 32MF231D

Set your meter on 200 ohms and touch the probes together - what do you get?

0.03

Can you take "macro" photos of them and post, sometimes easier to see that way.

Not sure which # on the chip is the part #, but here is what is on the chips

7U28
PHD38N02
LT
PEm0610 A1

7B45
L1117
33
GK1S0613

7T10
L1117
50
GK1LJ610

[selldoor]

Re: Magnovox 32MF231D

Two things to check on the board in pics 1 and 4.
On the underside left hand side bottom there is a 5001 looks like a cold solder on pin?
Also the area is stained - can you look at closely and see if you can see why?
On the other side - pic 4 top right ah-ha its actually near 5001 inductor again! there is a small white box what does it say on it . I think it may be another fuse could be that F88 sticker is telling us something. Please test as with other fuse.
Please also look at the soldering on cap 2002 - probably just shadow but looks odd.

[selldoor]

Re: Magnovox 32MF231D

Set your meter on 200 ohms and touch the probes together - what do you get?

"Wasnt sure about the part numbers. If they are stamped on the top of the regulators i couldnt really read them (@49yrs old my eyes are
not the greatest anymore) have to get a stronger magnifying glass."

Can you take "macro" photos of them and post, sometimes easier to see that way.

[broksonic]

Re: Magnovox 32MF231D

Ok, New DMM purchased (see pic).

With the new DMM set at 200 ohm the F75 (fuse) showed a .07

The 3 voltage regulators (refer to picture) are as follows..
DMM set at 20V DC

7T10 pin 3 (top one in picture) 12.03
pin 2 - 5.01
pin 1 - 0.00

7B45 pin 1 (right side in picture) 5.15
pin 2 - 3.30
pin 3 - 0.00

7U28 pin 1 (bottom one in picture) 4.12
pin 2 - 3.26
pin 3 - 2.60

Only flux i seen was when the lights flashed (refer to 1st post in thread)

Wasnt sure about the part numbers. If they are stamped on the top of the regulators i couldnt really read them (@49yrs old my eyes are not the greatest anymore) have to get a stronger magnifying glass.

Also noticed a change in the lights flashing. (refer to 1st post again)

Now when plugged in front power light comes on as well as the scaler board green light, the master backlight inverter boards red light flashes once.

Both green lights stay on for about 25 seconds then flash off and the red backlight flashes 2 long flashes.

Green lights come back on for about another 35 seconds and flash off while red backlight flashes1 long 2 short.

Green lights come back on for about another 30 seconds and system powers off.

Power switch on front will now turn set back on (wouldnt before), and the flashing will repeat.