Emerson BLC320EM9 A

[Tedybear]

Hello.

Picked up a couple of sets this afternoon. Long drive for a headache(s).

Got the one fixed (Mit 62" DLP projection) Looks great, but out of date. Hope to flip it quick to recover the expense of the trip to pick up.


The problem child that is confusing me. Emerson BLC320EM9 A

Picked this one up at the same time for cheap enough. Screen does not appear cracked (which is not my #1 check, look for damage)

The TV does not make any effort to switch 'on'. Upon plugging it in, I do hear a relay click. (I get that if I allow everything to discharge over time and then plug it in)

No clear signs of cold solder joints, or bad capacitors. (They actually all look very good).

I'll post up some photos in the daytime when I get back to being fully awake. I've done some basic poking around.

Does anyone have a schematic of the power control system(s)? Fuse tests fine. The set just has zero power? The gent I picked it up from stated he was watching it in the morning fine...shut it off... Came back several hours later and it was totally 'dead'.

Like I said. I'll get some photos up in the morning. Just wondering about direction to take. I did some basic voltage checks on the main board. (Power board I think (and I'll double check this) puts out 170vdc to the main board. The main board has a transformer and a series of diodes and such. Most of the voltage readings at the various test points are odd. One points to a blown diode (hence asking for a schematic) It's the 3.3vdc line. It's reading 1/2 of the expected voltage.

Just asking for ideas. I'll post the photos quickly in the morning.

S-

[kasfamily]

Re: Emerson BLC320EM9 A

[Tedybear]

Re: Emerson BLC320EM9 A

Yep, found that one last night when I was working on this. It's just a notice about minor changes from the service manual(s) to update anyone working on them. Sadly nadda thing about schematics and such.


I'll do some photos after I eat. At least we got the 62" Mit working. (comedy of errors. Defective bulb wiring--resolved. PO installed the bulb and punched the electrical connecter into the back of the set. And then we spent about an hour chasing down flippen safety switches. (We figured the set wasn't turning on due to the lamp cover switch being bad. Yeah...didn't see a micro switch for the rear dust cover....)

S-

[Tedybear]

Re: Emerson BLC320EM9 A

PICTURE TIME!!!

Crap. Well it would be.

It keeps kicking up server errors.


I'll retry again later.

S-

[dcapper]

Re: Emerson BLC320EM9 A

Power supplies on those Emerson's are terrible. I have a 32 with a bad power supply. It's more expensive to replace the board than the tv is worth. I tried changing most of the parts on mine and still no go.

[RJARRRPCGP]

Re: Emerson BLC320EM9 A

Any "KM" caps? If any, probably xtremely out of spec! (That's an alarming trend on the forums!)

[Tedybear]

Re: Emerson BLC320EM9 A

Hi everyone.

Sorry about dropping off. We had a few issues to correct with the 62" DLP--wife complained about getting headaches and the colors just not sharp and generally yucky.

She found out why the guy stated "I took care of my baby and pulled it apart to clean it monthly". This guy must have been smoking some interesting stuff. The rear of the screen was coated with a yellowish goo crud. (I'm a former smoker, had to give it up after the heart attack a few years ago. So I know what smoke 'tar' looks like) Along with heavy dust on the mirrors and lens. I'm proud of her for figuring it out. 4 cleanings later with soap and water--and we're talking rinse and repeat... Whites are pure and crisp and the picture is 100% again. (not bad for a $30.00 DLP first generation.)


Okay Okay. Back to the POS..errr....Emerson set. The photos had major issues trying to upload. (server errors out the bazoo) So I will attempt again.

Upon measuring the main power connector from the P/S and Inverter board, I have a steady 170VDC. It does not change or waver. (pushing the power button has no effect) I ran out of time doing voltage checks, save one. The 3.3vdc line at the test points reads "1.8vdc" (Same reading with the 'test points' on the board and using the chassis ground.) Also not sure if this means anything? But when I do the 170VDC check, it's only across the B/R wire. I go to chassis ground and both lines are dead. I do a direct test--and then get the 170vdc. Not sure if that means anything?

I did find complete used boards on eBay and ShopJimmy also has them pretty cheap for the main board. (The one with all the RCA connectors) I must admit to being a bit lost here. Also the 'transistor' (I have yet to pull the number off to see exactly what it is) under the small transformer on the main board. This has the 170VDC sitting on the center terminal. (pin 2) Pins 1 and 3 show no activity.

If the issue is with the main board, would I be better off just saying 'screw it' and ordering in a known good replacement and call it a day? The P/S board is much more expensive and I did note one 'transistor' had been replaced prior. I'm good at spotting fresh looking solder that has been clearly not done at the factory. (Also they got sloppy with the white paste...)


I of course would love to see this through from the board level repair. Have to swap out my multi meter today however. I did some diode testing around the board and my meter reported a lot of 'open' diodes (to be honest...it reported ALL of them open while tested in circuit. And that would be just about impossible for ALL to fail at the same time). FR104's where the ones I was mainly testing. 50 V, 1 A, Fast Recovery Rectifier Diode is what the spec sheet states. Each one I tested in circuit read full 'open' on the test. I pulled a leg off the board just to see if something odd was going on with the circuit causing issues--it read 'open' again. So I will be changing out the meter just to be sure.

Oddly enough the meter has been acting up a bit. It's a Tenma brand meter (probably spelled it wrong). One of the higher end ones we use for work. When I did the test of the 2nd leg of the part under the small transformer--the one that read 170VDC? The meter made a couple of oddball beep sounds and then the 'beeper' was making some odd static type sounds.

I'll bring the basic Rat-Shack meter home this afternoon.

Thanks again for the help!!! If more pictures are needed, just let me know which areas to focus on. The server appears to be working normally again for pictures.

S-

[Tedybear]

Re: Emerson BLC320EM9 A

Power supplies on those Emerson's are terrible. I have a 32 with a bad power supply. It's more expensive to replace the board than the tv is worth. I tried changing most of the parts on mine and still no go.

Which symptoms where you getting with it? This poor thing doesn't show any sign of life. Not even the 2 second flash. Can't even get any readable voltage to the front panel switches either. Oh I get some 'flutters' and weak DC on some of the pins. But nothing really readable.

S-

[Tedybear]

Re: Emerson BLC320EM9 A

Bump. Need to know what's going on with this TV/Display.

Is there something about the 170VDC from the power/inverter board that I should be aware of? It's sending that 170VDC to the main board. I have to wonder about the transformer on that main board with all the diodes surrounding it. Maybe if I had a better understanding of the theory of operation I could work this one through.

S-

[Tedybear]

Re: Emerson BLC320EM9 A

Must be everyone hates working on Emerson products.

I'll put this project on the back burner. My hands where shaking badly when I was doing voltage checks and I shorted the source for the MOSFET to ground. Blew that fuse big time. And of course I replaced it? And it's blowing soon as the set is plugged in.

Sense most of the problems seem to be with the main board--and NOT the inverter power board? That's the cheapest option is to get an eBay board and just call it a day.

And just so everyone knows. I replaced the fuse with everything plugged in. Fuse blows. I remove the two wire power connector (the one with the 164VDC across the pins) and the fuse does not blow.

(Yeah...I said 170 before. The other meter is in need of replacement.)

S-

[Caleb]

Re: Emerson BLC320EM9 A

If you shorted the mosfet it will blow as many fuses as you care to feed it until the current limiting resistors go open anyway. I would check the gate circuit, you will need to replace the drive transistor as well as the mosfet. Check all the zener diodes and small signal diodes around the fet. Most commonly Ive found a shorted output diode on all but one of these funai power boards. If you can get a focused well lit picture I can circle the likely suspects for you.

Added the service manual as well below

[Tedybear]

Re: Emerson BLC320EM9 A

If you shorted the mosfet it will blow as many fuses as you care to feed it until the current limiting resistors go open anyway. I would check the gate circuit, you will need to replace the drive transistor as well as the mosfet. Check all the zener diodes and small signal diodes around the fet. Most commonly Ive found a shorted output diode on all but one of these funai power boards. If you can get a focused well lit picture I can circle the likely suspects for you.

Sounds like a plan to correct the blowing the fuse part. The first part of course is that the set has voltage to the board (164-170VDC) But does not seem to have any other voltages present, other then 1.8VDC on the 3.3VDC line. Everything else is dead. Well...it's dead now LOL. My shaky hands didn't do it any favors.

I'll post up a piccy in a bit. Just the main power 'hot' area, right?

S-

[Caleb]

Re: Emerson BLC320EM9 A

yes just a good clear pic above and below the hot section

[Caleb]

Re: Emerson BLC320EM9 A

Just a good clear pic of the hot section above and below

some numbers to start on, likely all these are toast
Q602
Q601
D604
D602
R601

[Tedybear]

Re: Emerson BLC320EM9 A

I can do more if needed. The server seems to like me this time.

S-

Thanks for the manual!! That should help a lot.

[Caleb]

Re: Emerson BLC320EM9 A

Circled in red the components likely to be blown, in yellow others you should check

[Tedybear]

Re: Emerson BLC320EM9 A

In all honesty. I've found this board all over eBay for under $30 bucks supposedly out of 'working pulls' (aka, some idiot threw their Wii-Remote at the screen)

I can smell a very light burnt smell around the mosfet that I did the booboo on.

But in all honesty. Would this be better served just to order in a different board and just call it a day? I'm thinking by the time I order in components and pay for shipping-It might just be as easy to replace that entire board.

Considering the primary problem (before the blow-up) was no juice at all....Except the 170ish VDC from the inverter board.

I can of course open up the old account at MCM, or any other recommended supply house and do part by part testing and replacement. Just wondering if in the long run--just ordering in a complete board might be the better solution.

I'll do some print work of the schematic as well. We have a laser printer at work that does a good job on fine print items.

Thanks again for all the help!!

S-

[Caleb]

Re: Emerson BLC320EM9 A

If you can find one for 30$ I would go that way. These boards can be a bear to get working. That said its good practice to track down the fault, if you keep it long enough the "new" power board will fail too.

[Tedybear]

Re: Emerson BLC320EM9 A

If you can find one for 30$ I would go that way. These boards can be a bear to get working. That said its good practice to track down the fault, if you keep it long enough the "new" power board will fail too.

Yeah, that's a point.

Before I go nuts with searching for a decent supply house. Which one has a good record around here? I've used MCM electronics in the past. (company I work for also uses them) Is there a decent company that I can work with?

(I'll probably just replace all the red parts---pretty sure that's my screwup at work.)

Just need to work through the power issue, and the schematic should help-- So far I did test all the diodes (in circuit test) and they did read good. I could tell the capacitors where charging when I was testing the diodes. It took a few moments for the readings to stabilize. Out of circuit testing is probably needed for more exact results.


Thanks again!!

S-

[Caleb]

Re: Emerson BLC320EM9 A

I get pretty much all my parts from digikey, usually about 3$ for shipping. Then mouser 7$ shipping, eBay if I can't find it anywhere else.