AG Neovo E-19A (E-191)

[thraxarious]

Hello,

Part time reader, first time poster here.

I've done a couple recappings before, so I have been learning steadilly.

I got a AG Neovo E-19A monitor that went out a bit ago, plugging everything back again today has the image pop up, but immediately shut off. The green light stays on, so I have to turn it off and back on again to see the image. I don't think that the CCFLs are on at this time, but its hard to tell without fully tearing this monitor apart. (its got a nice glass front).

It has a separate 12v DC source, and that reads fine at 12.3 steady. I looked the board over and it doesn't seem to have any blown caps or things that are noticeably bad. There was the fact that on the video board, the glue holding some of the caps down looked dark, but those capacitors looked fine.


There was also some darkening on the inverter board for the CCFLs, but I didn't see anything that would look damaged. There was also some odd coloration to the video cable to the panel, but I'm not convinced it would cause issue.

I haven't done any readings on the board yet, as I am not positive where to start on those.

Any hints or help would be swell! Thanks!

[PlainBill]

Re: AG Neovo E-19A (E-191)

Good pictures, thanks. It makes a big differentce. You've got 'two seconds to black'.

This is our old friend the Royer oscillator (OK, two of them). C1 and C2 are automatically suspect; Elite caps are worse than Capxon and the heating on the board doesn't help them.

Check transistors Q7, Q10, Q12 and the other one - Q6? Q5? for shorts. Resolder the transformer pins.

As a test, disconnect all but one CCFL, power up, and see if you get backlights for the two seconds. Do the same for the other three backlights. You are hoping to see one backlight that doesn't light.

PlainBill

[thraxarious]

Re: AG Neovo E-19A (E-191)

Awesome, thanks! Yeah, I was thinking I might need to wait a bit, and with moving a month off, put the monitor back together. I might disassemble it again this or next weekend.

Just curious, C1 and C2 are both 220uf @ 25v, how close is the general rule for replacing caps? I have some 330uf 25v from an earlier repair.

I've heard some people here say go ahead as long as you get the minimum, and others say not to put caps that are too much higher (cautioning someone for putting 1kuf instead of 820uf).

The thing that had me worried was the darkening over by T2 and to a lesser extend T3.

Q6, Q7, Q10 and Q12 seemed to have good solder points, but I'll tear things down and take a peek maybe tomorrow.

I keep putting off getting/building an ESR meter... bleah.

[PlainBill]

Re: AG Neovo E-19A (E-191)

Awesome, thanks! Yeah, I was thinking I might need to wait a bit, and with moving a month off, put the monitor back together. I might disassemble it again this or next weekend.

Just curious, C1 and C2 are both 220uf @ 25v, how close is the general rule for replacing caps? I have some 330uf 25v from an earlier repair.

I've heard some people here say go ahead as long as you get the minimum, and others say not to put caps that are too much higher (cautioning someone for putting 1kuf instead of 820uf).

The thing that had me worried was the darkening over by T2 and to a lesser extend T3.

Q6, Q7, Q10 and Q12 seemed to have good solder points, but I'll tear things down and take a peek maybe tomorrow.

I keep putting off getting/building an ESR meter... bleah.

The darkening is not excessive, but I would be interested in that components are causing it, although the FETs are a prime suspect.

When you do open the monitor up, the very first test should be testing with one CCFL at a time. That requires minimal work and could identify the problem quickly. If only one CCFL doesn't work, you have a bad CCFL or wiring. If two don't work, you have a problem on the inverter.

PlainBill

[querido]

Re: AG Neovo E-19A (E-191)

Was there any follow-up on this problem? It would be interesting to find out!
And it would surely be interesting if someone found a service manual!

[thraxarious]

Re: AG Neovo E-19A (E-191)

Well, I just got moved into my new place and fixed up a couple other monitors I had on my list to fix.

So I am back to having this on the bench.

I guess I have to figure out the best way to test these parts, I have a multimeter, but no ESR tester sadly.

So I disconnect the other CFLs and see if that makes a difference?

[thraxarious]

Re: AG Neovo E-19A (E-191)

Well, looks like it might be the inverter. CN2, CN3 both stay dead black, CN4, CN5 both are 2 seconds to black.

[retiredcaps]

Re: AG Neovo E-19A (E-191)

CN2, CN3 both stay dead black, CN4, CN5 both are 2 seconds to black.

1) Did you do the checks that PlainBill asked for in post #2?

2) Check the secondary inverter transformer pins on both transformers. They should be within 3% of each other.

[thraxarious]

Re: AG Neovo E-19A (E-191)

I'm planning to do, right now I can only find a crap import multimeter I bought a while back. From what I can read, the transistors all seem to read nearly the same, it doesn't look like they have any shorts.

Its the Transformers that read differently, and I'm figuring out how to read them properly...

I guess the secondary loop on them is the pins at the side heading to the CFLs?

[thraxarious]

Re: AG Neovo E-19A (E-191)

Okay a little better, found another meter. around 955ohms on the two outside pins of T3, getting 82k ohms on T2's outside pins. both T2 and T3 are around 374ohms from the first of the six inner pins to each pin down the line, except the last.

Going from the top of the six to the bottom of the six, looks like I might be getting around 1 ohm. Same as I measure the 2nd to the 5th, 3rd to 4th.

Ugh, I need a new multimeter.

[PlainBill]

Re: AG Neovo E-19A (E-191)

I'm planning to do, right now I can only find a crap import multimeter I bought a while back. From what I can read, the transistors all seem to read nearly the same, it doesn't look like they have any shorts.

Its the Transformers that read differently, and I'm figuring out how to read them properly...

I guess the secondary loop on them is the pins at the side heading to the CFLs?

Correct. The only readings that are important are the resistance between the two left hand pins of T2 and the resistance between the two right hand pins of T3. Those two readings should match to within 3%.

PlainBill

[thraxarious]

Re: AG Neovo E-19A (E-191)

Great! That means its T2. Since I am getting 82k Ohms from its secondary loop. Now to find a replacement...

I see "0235NI26S" written on the side (of both), Though the 5's and S's look close, I am almost positive that is what is written.

I was not finding any hits on Digikey or Mouser (or Google for that matter) for that number, and there is no other information written on it anywhere.

Any good hints what to be looking for?

[thraxarious]

Re: AG Neovo E-19A (E-191)

Oh yeah, melty.

[PlainBill]

Re: AG Neovo E-19A (E-191)

I'm not good at remembering transformers. A picture of the actual number on the transformer will give me more to work on identifying a replacement. The numbers are usually a combination of an identifier and a date code or production lot.

Or look at LCD warehouse, IIRC they carry inverter transformers.

PlainBill

[thraxarious]

Re: AG Neovo E-19A (E-191)

Awesome! Thanks, I really appreciate the time you are spending with this. I've been sifting through the forums and learning a good deal.

Yeah, not finding any hits on that supplier, some Ebay seller, but only a couple monitors.

Here's the pic, showing both off.

[PlainBill]

Re: AG Neovo E-19A (E-191)

Awesome! Thanks, I really appreciate the time you are spending with this. I've been sifting through the forums and learning a good deal.

Yeah, not finding any hits on that supplier, some Ebay seller, but only a couple monitors.

Here's the pic, showing both off.

No luck identifying it. I ran through all 8 possible combinations of 5 and S, I and 1, and S and 5.

PlainBill

[thraxarious]

Re: AG Neovo E-19A (E-191)

So, is there anyone else out there who might be better at identifying transformers?

I've been doing some casual looking for wiring diagrams for the board, most of the model numbers I've tried brought up nothing so far.

[selldoor]

Re: AG Neovo E-19A (E-191)

Hi - I cant find it either - if you search the board number there are a couple of polish sites you can translate.
One of them suggests an alternative but you have to register to see the attachment.
I am thinking they may have used one of these
http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=300735454929
It is cheap and cheerful and if you're really lucky your connector might fit.

Another idea is to just work off the specs for your good one and try and find something similar like this
http://lcdparts.net/TransformerDetai...ProductID=3192

What does your primary winding measure?
Ask lcdparts what the physical size is.

[ben7]

Re: AG Neovo E-19A (E-191)

Or you could just get another one of the same inverter boards, and harvest one of the transformers.