Need help identifying 8 pin DIP used in Plasma PS PLEASE.

On Mon, 18 May 2009 01:19:48 -0700 (PDT), jango2 put finger to keyboard and composed:

The FA551x parts don't match your pinout discoveries, so I wouldn't use them. I just cited them for comparison purposes.

It would have helped me a great deal to have known that ...

I don't understand why a 60V audio frequency power transistor would be used on the primary side of a high frequency switchmode PSU.

I notice that the mains rating of this TV is AC 110-240V (50/60Hz), so maybe it uses active PFC to boost the voltage on the bulk capacitor to around 380V. AIUI, this would require a high voltage power transistor/MOSFET to switch a coil on and off during each mains half-cycle. The transistor/MOSFET would only need to be rated for low frequency use. The FA5522N part doesn't seem to have enough pins to implement APFC, so I would expect that there must be another IC in the PSU.

Is there any chance you could upload a photo of the PSU to a file sharing service?

BTW, you can determine the switchmode frequency by monitoring the anode of any rectifier diode on the secondary winding. You don't need to risk probing on the primary side.

- Franc Zabkar

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....

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"I don't understand why a 60V audio frequency power transistor would be used on the primary side of a high frequency switchmode PSU." Feedback winding on hot side of transformer drives the collector of

2SD2012 via a series diode (pf value cap across), emitter of the transistor feeds supply to pin 6 of mystery ic (which is vcc of FA5516/7/8 too) base-emitter resistor 2k2 ohms, emitter to ground reverse biased diode, another reverse biased diode across C-E. A common base config transistor acting as a voltage regulator?

"The FA551x parts don't match your pinout discoveries, so I wouldn't use them. I just cited them for comparison purposes." They do only if you're looking at the FA5516/7/8 pdf and not the FA551X datasheet. I see a perfect match. No discrepancies.

"The FA5522N part doesn't seem to have enough pins to implement APFC, so I would expect that there must be another IC in the PSU." Bang on! The plot thickens, guess what?, A Fuji FA5502P/M power factor correction IC mounted on a small glass epoxy pcb labelled PCPF0159 with a Murata logo on it. Only this time they didnt remove the FE logo on the ic. PFC achieved by that and two 2SK3528 and a huge transformer shaped inductor.

"BTW, you can determine the switchmode frequency by monitoring the

The oscillator totally whacked out of sync, hence the irritating buzz. :(

3 images uploaded to PF7437L.jpg

Thanks Franc,

On Mon, 18 May 2009 06:30:31 -0700 (PDT), jango2 put finger to keyboard and composed:

I think so, but there would have to be a zener diode connected to the base. See your Vestel plasma TV circuit (page 65). I still don't see why you need a 3A power transistor to supply this IC, though.

BTW, in an earlier post it appeared that you were saying that the emitter of the 2SD2012 was connected to the current sense input on pin

1. Are you sure pin 3 is not sensing the MOSFET current?

Yes, you're right ... if pin 3 is sensing the current in the MOSFET. I also thought that pin 1 may not have matched. It appears that the only difference between the FA5516/7/8 parts is their switching frequency

-- 130kHz/100kHz/60kHz. I wonder what is different about the FA5522? Frequency? Supply voltage?

In any case, the FA5516/7/8 parts don't seem to be any easier to find.

Searching here ...

... finds a US supplier for the FA5522N but the minimum order is $300. Maybe if you begged ...

Alternatively a broker named Patrick Cheung used to offer parts in single quantities to members of the sci.electronics community:

Hindsight is a wonderful thing.

This URL could have saved us a lot of grief:

The OP blames C102 (101, 2kV) for the "whole tragedy", so it might be worth checking/replacing.

I thought you still had a good TV to take measurements from.

More photos:

In future may I suggest that you post direct links to your photos. That way we don't have to suffer the ads and banners.

- Franc Zabkar

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Hi Franc, BTW, in an earlier post it appeared that you were saying that the

Sorry pin 6 of the ic connects to pin 3 of the vertcal pcb, my bad , i got confused.

Alternatively a broker named Patrick Cheung used to offer parts in

It's quite tough deciphering that page, it's all in chinese....I just posted requirement on hobid. Rather uncanny that a bloke in Russia was working on the same model at the same time and scratching his head about the same ic.... Will post individual links for pics in future, thx for the pointer. The working set was delivered , cant use that for any kind of reference now. Thanks for all the help Franc, You're an asset to this forum and planet :) Cheers!

FA5522N-A2-TE1 Would this be the same part? Nothing showed up on the townt website. Have posted requests everywhere including usbid. I'm not quitting easy. I will see this through.

On Fri, 22 May 2009 03:38:29 -0700 (PDT), jango2 put finger to keyboard and composed:

I don't know.

FWIW, suppliers also list the FA5518N-A2-TE1 part.

- Franc Zabkar

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On Fri, 22 May 2009 03:38:29 -0700 (PDT), jango2 put finger to keyboard and composed:

Try emailing him directly:

patrick.cheung at towntarget dot com dot hk

- Franc Zabkar

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On Fri, 22 May 2009 03:38:29 -0700 (PDT), jango2 put finger to keyboard and composed:

I notice that B&D Enterprises stock some FA55xx parts. Maybe they could order the FA5522N part for you ???

FWIW, here is a "Fuji AC-DC IC Series brochure":

... and a Fuji SMPS devices brochure:

There are FA5530/5531/5532 and FA5540/5541/5542 parts. They are described as quasi-resonant ICs.

Here is a spec sheet for the FA5530/31/32 parts:

Here is an app note for the FA5540/41/42:

The FA5532 and FA5542 are spec'ed for 120kHz/130kHz operation. Therefore I suspect that the FA5522 is also a 120kHz/130kHz part.

FWIW the FA5520 is a 5-pin IC:

The FA553x parts specify "linearly changed frequency at light load", whereas the FA554x parts specify "intermittent switching at light load".

This is Fuji's datasheet site:

FWIW the FA5542 part is listed as still available. Maybe it would be worth a gamble ???

The FA557x parts may be worth a look, too:

You might also like to search for ...

FA5502 filetype:pdf

Maybe you will find a service manual for a device that uses this APFC IC in conjunction with another Fuji part.

I'm no expert, but it seems to me that you need to find out whether the FA5522 is "current mode" or "quasi-resonant". The difference appears to be that pin 1 is either CS (soft start/latch-mode stop) or ZCD (zero current detect). Maybe you should do some tracing around that pin and consult the application examples.

- Franc Zabkar

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