Magnovox 32MF231D

[broksonic]

Re: Magnovox 32MF231D

TechShui, yes i still have the board. PM me a offer (which im sure i will take).

Also had a request for the ALT part numbers for that scaler board so here they are.. ( i havent tried any of these as an alternate, so understand using at your own risk)

313815886271
313815864951
313815866861
313815866881
313815868521
313815868281
313815868211
313815868221
313815866721 (which was my original)

Currently only see one at a fair price on E-bay

http://www.ebay.com/itm/Philips-32mf...item3cc73e1932

[TechShui]

Re: Magnovox 32MF231D

Hi broksonic,

It looks like I'm too late to take you up on that offer, by now you've probably put the TV back together?

That's OK, I think history has shown us that the most common failure is the crystal IC (1h00) and/or the tiny gray caps.

But please save me your old dead scaler board, I will have some money in my paypal acct next week, and will send you some money if you're willing to ship it to me? You can use the same box the new one came in, just cover it with a new shipping label.

Yours did not have a hole in the smps 12VS chip... so maybe it will be an easier fix, or I can salvage the components to fix mine.

[broksonic]

Re: Magnovox 32MF231D

Sorry for being gone so long. Work called me OTR for awhile and when i got back computer was fried. Had a storm come through and must have got it.

I ended up getting a different scaler board. Just installed it today and tv back up and working although havent pluged it into DTV receiver yet but screen comes up and menu does too.

Going to be a few days before i close it up ( need a new card for my other Direct tv receiver) is there anything you want checked while its open with a working scaler board in it?


Forgot to mention that there are 6 or 7 other scalers that supposedly work with this tv. If you want a list of the ones i found let me know. Dont have the list in front of me or i would post them now.

[TechShui]

Re: Magnovox 32MF231D

I have been lazy and not read the thread but is this information any help:
http://www.scribd.com/doc/50623833/2...f231d37TPE1-0U

Again didnt understand all the posts about 40R being the same as 400 etc I thought it would be 40R=40.0 but on smd components the R label is only used up to 10 ohms so that argument seems invalid.
Furthermore I am not now sure if budm is thinking 480 "label" is on the board or the schematic whereas I think TechShui means the "value" printed on the component.

The 480 value on the component in my opinion means that it is a 48ohm resistor which does not show at all on the schematic. As we all know that is not unusual as boards and schematics often differ.

In broksonics pic the component is quite clear tho not readable on screen I suggest you pm him and ask what value is shown on his save any guessing .

Thanks for reminding me about it, I discovered a similar post last month, I shared it in this same thread, post 28.

broksonic suggested I test the crystal IC with a frequency tester (or DMM with that feature). I can see those little grey caps on the output traces for the 1H00 IC. Those caps are indeed smaller than fly shit, I think I'll need a special tip to desolder them... hmm.

But I don't have a capacitance meter either. I guess I will have to get all these tools in order to confirm my suspicions.

TechShui,
I am working on the same board (except 6285.3) as you and have some bad news. The 10 ohm resistor you replaced at what looks like 3U22 was not 3U22. 3U22 is actually the 1206 size resistor labeled "100" close to the last "2" in "3U22" on the board.

The part you replaced with a 10 ohm resistor is actually 2U16 which should be an 0805 size, 1uF, 16V ceramic capacitor.

Also, the resistor that looks like 480 definitely says 488 on my board (see attached). I am bewildered by this as well. It appears to be part 3005, a 3.09k ohm resistor judging by the connections on the board.

EDIT: Here about half-way down, it explains a new resistor code. This explains the 48, but the other 8 must be an A for it to work out to 3.09K.

Thanks for noticing that, I guess I will cannabalize 2u16 from my rev 3 board to replace that component.

[reckhardt]

Re: Magnovox 32MF231D

Doh! Yes, 48B would make 3.09K. My mistake.

[tom66]

Re: Magnovox 32MF231D

http://www.marsport.org.uk/smd/res.htm

48 = 309 ohms
B = 10

= 3.09k ohm

[selldoor]

Re: Magnovox 32MF231D

WOW -Reckhardt, thanks for registering to tell us- that is a revelation - not come across that coding - doesnt seem to feature in WIKIpedia.

I think you may have tripped at the last hurdle though I think it is a 48B

48 = 309ohms x B (10) = 3090 = 3.09k

[reckhardt]

Re: Magnovox 32MF231D

TechShui,
I am working on the same board (except 6285.3) as you and have some bad news. The 10 ohm resistor you replaced at what looks like 3U22 was not 3U22. 3U22 is actually the 1206 size resistor labeled "100" close to the last "2" in "3U22" on the board.

The part you replaced with a 10 ohm resistor is actually 2U16 which should be an 0805 size, 1uF, 16V ceramic capacitor.

Also, the resistor that looks like 480 definitely says 488 on my board (see attached). I am bewildered by this as well. It appears to be part 3005, a 3.09k ohm resistor judging by the connections on the board.

EDIT: Here about half-way down, it explains a new resistor code. This explains the 48, but the other 8 must be an A for it to work out to 3.09K.

[budm]

Re: Magnovox 32MF231D

Yes, I am thinking about the 480 for deisgnator in the diagram which I do not see. The board itself does not seem to have any designator for the resistors at all.

[selldoor]

Re: Magnovox 32MF231D

I have been lazy and not read the thread but is this information any help:
http://www.scribd.com/doc/50623833/2...f231d37TPE1-0U

Again didnt understand all the posts about 40R being the same as 400 etc I thought it would be 40R=40.0 but on smd components the R label is only used up to 10 ohms so that argument seems invalid.
Furthermore I am not now sure if budm is thinking 480 "label" is on the board or the schematic whereas I think TechShui means the "value" printed on the component.

The 480 value on the component in my opinion means that it is a 48ohm resistor which does not show at all on the schematic. As we all know that is not unusual as boards and schematics often differ.

In broksonics pic the component is quite clear tho not readable on screen I suggest you pm him and ask what value is shown on his save any guessing .

[budm]

Re: Magnovox 32MF231D

3K09 (3005): The 3005 is the designator number for this 3k09 resistor, most diagram would have use R3005).
If you look at the Diagram:
2xxx is for capacitor
3xxx is for resistor designator.
6xxx is for Diode
7xxx is for Transistor

But where do you see the 480 in the diagram?

[TechShui]

Re: Magnovox 32MF231D

Let's get back on track here.

These resistors connect to pin 5 of the 7003 IC.

480 = 2.77k Ohms
273 = 3.4k Ohms
221 = 220 Ohms

The sch that budm attached on page 3, shows it like this:

Pin 5 > 3K09 (3005) > 27K (3007) > 220R (3006) > 1000u 16 cap (2006) > 12VS

What's this mean? The one labeled 480 is actually 3.09K Ohms... ?

And what about the 27K having a reading of only 3.4K, what could diminish it's resistance while in circuit.

[budm]

Re: Magnovox 32MF231D

From logical point of view, they do not have 4000 Mega Ohm resistor, it may as well be a open circuits. I did not follow the post lately to know how this resistor is connected to the circuits.

[TechShui]

Re: Magnovox 32MF231D

Yes, I know what the R stands for, but it doesn't really look like an R, more like an eight.

This is the last letter I'm referring to, so 40R and 400 are both 40 ohms, but an eight would mean 4,000 mega ohm.

EDIT: Took me a dozen tries, but I was finally able to focus the camera in such a way that it gave a clear focused zoom. I think it says 480, that would be 48 Ohms.

[retiredcaps]

Re: Magnovox 32MF231D

Yes, I did use a magnifying lens, there are not a lot of numbers that look like zero, so it has to be a zero or an eight, maybe an R, but I don't think so.

Resistances less than 10 ohms have 'R' to indicate the position of the decimal point (radix point).

http://en.wikipedia.org/wiki/Resistor#SMD_resistors

[TechShui]

Re: Magnovox 32MF231D

Hmm, I wonder what happened to broksonic?

Assume you are happy the trace went off in the opposite direction to what one might have expected?

Yes, that's where the trace leads.

What is at 8510 and 8511 solder on 8511 looks odd.

Those are the solder joint of the L-shaped heatsink in the upper right corner of the board. (above the tuner).

Dont know what the white block is- probably best you can do is to check it for resistance and see if the one on your other board is the same - and I think I see one other like it- you could check that also.


Blue barrel Inductor - they seldom go wrong just make sure it is soldered down. On that same picture is that a fuse - bottom right corner white block with gold ends possibly 1U01 perhaps a T 3amp

Also bottom left corner up from the 4 pin connector there is a green thing with F75? on it which suggests it is a fuse.

Are these the same two you mention.

Yes, those are the two fuses I checked. I've re-soldered the white block now too.

Did you download the service manual from my link? I'm guessing whatever is preventing the board from starting is somewhere near the IC at 7003.

I tested the schottky 6001 out of circuit, it's still 150 on forward, but infinity on reverse, so it's good. 6002 is, of course, also good, since that's the one I ordered from DigiKey.

I starting checking those tiny SMD resistors near 6002

These resistors connect to pin 5 of the 7003 IC.

408 = 2.77k Ohms
273 = 3.4k Ohms
221 = 220 Ohms

According to what I know about resistor labels, the last digit is the number of zeros. From this we can determine 221 is spot on...
273 however should be 27k, NOT 3.4k.

And what about 408? That's a VERY unusual ohm rating... 4,000 Mega ohms, seriously? Perhaps I'm imagining the line in the last digit, and it's actually 400 (i.e. 40 Ohms) but that's also unusual. 40 Ohms is so low.

Yes, I did use a magnifying lens, there are not a lot of numbers that look like zero, so it has to be a zero or an eight, maybe an R, but I don't think so.

The photo I posted has pretty good resolution, you could look at the resistor and make your best guess as to the marking.

In any case 2.77k Ohms is not consisting with the marking. Does this mean these two resistors are bad? Or they're being affected by each other and gives off reading? I don't think removing them for further is an option for me. The lamination on this board peels easily, and I don't want to risk damaging another trace.

[selldoor]

Re: Magnovox 32MF231D

Hmm - not easy- will look closer tomorrow.

If you get it working you should replace resistor with a fusible one - it, as name implies acts as a fuse.
Assume you are happy the trace went off in the opposite direction to what one might have expected?


What is at 8510 and 8511 solder on 8511 looks odd.

Dont know what the white block is- probably best you can do is to check it for resistance and see if the one on your other board is the same - and I think I see one other like it- you could check that also.


Blue barrel Inductor - they seldom go wrong just make sure it is soldered down. On that same picture is that a fuse - bottom right corner white block with gold ends possibly 1U01 perhaps a T 3amp

Also bottom left corner up from the 4 pin connector there is a green thing with F75? on it which suggests it is a fuse.

Are these the same two you mention.

[TechShui]

Re: Magnovox 32MF231D

OK everyone,

While we wait for broksonic to reply, I really need help figuring out my rev4 scaler board. It seems like a better candidate for repair since the IC I put into it did not explode

This will be the first time I post pictures of the rev 4 board.
I hope some people will take a look and let me know if anything looks suspicious.

To summarize what has happened with this board:

When it arrived, I could tell it had been worked on by someone even more novice than me. The 6002 schottky diode was missing, luckily the solder pads are intact.

The SMD resistor at 3u22 was yanked off, probably with pliers? Leaving a missing pad and trace damage.

I got a new diode, exact match (from Digikey) also got a 10 Ohm resistor. Repaired the trace by soldering a small red wire to the trace and new resistor. (see photo)

Note: The resistor is not an exact match, the SM describes
3u22 as a fusible 10 ohm resistor, made by Vishay.
After an hour of searching all I could find was a normal 10
ohm resistor by Panasonic. The wattage is the same though.
Does it really matter if it's fusible or not?

I replaced 7003, the 12VS smps IC. (remember I ordered 2 from DK)

The TV does not turn on at all with this board, not even a split-second flash, like I was getting with the other one. I checked both fuses and they're good.

Voltages for the new IC:

1 - 0.00v
2 - 0.00v
3 - 0.00v
4 - 4.82v
5 - 0.07v
6 - 0.02v
7 - 0.00v
8 - 17.3v

So the IC is turned OFF, hmm...

More observations: I see a couple of crooked components,
I circled them in red in the photos.
One's a white smd (resistor??) the others a blue smd
inductor with 330 printed on top.

I guess the dude tried to pull those out too? What are they?

[TechShui]

Re: Magnovox 32MF231D

Sorry for not posting in a while, I sort of expected the thread would continue in my absence.

Broksonic, your voltages look alright to me... I'm no expert though. Hopefully, budm or Tom will give their opinions.

Of course, the burning question is where to check next?

I've put my rev3 board on the back burner, because I just don't feel safe putting another 12VS smps IC, since a) it will probably blow, and b) another of the solder pads flaked off. (these are very delicate PCBs).

I've checked 6001 on the rev4 board that I got from ebay.

In circuit, with diode test it's 150 on forward bias, 565 on reverse. Is this a cause for concern?
Seems unusual, it should be infinity, right? So I de-soldered it, and it tests 150 on forward bias, infinity on reverse.

So it must be good, but I wonder if something else in the circuit is causing the 565 reading.

broksonic, please put your multimeter in diode test and check your board's 6001 schottky, is it also 150 / 565?

UPDATE: I was just looking at your photos, here: https://www.badcaps.net/forum/showthread.php?t=20153#7

Click the first one, and zoom into the upper left corner, there's an 8-pin smps IC, and just above that a SOT-23 transistor labeled 7P16.
I want you to check that transistor, there's a mark on it that look suspicious, like a hole or a tiny gash.
Use the Ohm setting on your multimuter, check all 3 pin combinations, (1-2, 1-3, 2-3). The side with one pin, is pin 1 (aka base pin of the transistor). The numbers go clockwise.

[budm]

Re: Magnovox 32MF231D

@techshui, the IC supposed to have shorted circuits protection, but it does not act fast enough and so it blew the MOSFET inside. The 9v and 10 Ohm trick should work, it will be even better if you have Adjustable power supply with Voltage and current limiter. You should monitor the voltage drop across the resistor to see how much current you are drawing from the 9V batteries, the batteries may not have enough current capacity to supply the power, the IC is rated up to 2.5A output current capability.