Intro plus help for Medion MD33332 Now fixed

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OldLes:
Hi everybody.
I am new here, just registered. I live on the Isle of Man; amongst other things, I used to be a TV repair man, and compact disc players (20 years ago, now retired). We have "amenity sites" here, and there are many LCD tvs discarded, some with no faults (but need freeview box), some with serious faults, but many worth looking at.
Presently I have a Medion MD33332, which we used as a bedroom set, but which developed flashes on screen. Have isolated (with freezer) an IC, 1084 which is responsible. Where can I get one? Is there a circuit available? This IC is on the tuner / video / sound board. If it helps to identify, it uses a MEGMEET PSU, the same as I see here:--
http://www.shopjimmy.com/megmeet-mlt666-rev-2-8-power-supply-unit.htm
A circuit for the MD33332 would be helpful.
I have two more sets I need circuits for, but will post them later.
OldLes.

OldLes:
I notice I have had 47 views but no responses. I have just been reading through a few posts on another page (don't know my way around here yet) and I wonder if it is because I have not given enough info, so here is everything I can give.
TV is a Medion MD33332 (I presume is is something else badged as Medion?).
It has a MEGMEET PSU with number MLT666, Rev:28. 2006.126
The Main board (tuner, sound etc) is HDM9L-V 6.3. Serial No. 800302H0563F
This board carries a paper label:-- 02 07/09/21
T02H05/E001
KEY 020585
The display is a Samsung LTA320WT-L16 7Y7D17B35H
The inverter (which has 4 duplex transformers) is SS1320WA16 Rev.06
It would be useful to view a circuit, and I wish to replace the 1084 IC which I have identified by freezing as faulty so need a source. My pal found one on a board, but though it said 1084, it was rather smaller. Same size as a TIP41 for older engineers. 25 years ago I used to spend many hours advising on Grundig faults and supplying panels at a price you could afford. Now I need advice.
OldLes.

Keith:
Hi,

This type of power supply suffers from faulty capacitors, I would check the electrolytic's for high ESR. This causes high ripple / noise on the supply lines and could be causing the semiconductor to overheat.

Unfortunately, identifying some semiconductors in modern equipment can be very difficult, even if you can identify it, it can be near impossible to obtain a replacement! And schematic diagrams are as rare as rocking horse poop.

Good luck

Keith

jordan:
Medion chassis type MST9E88L MST9/MSTAR

Keith:
Hi OldLes

I have 5V and 1.8V versions in TO220 (TIP41) case on a board, can remove if you want.

Keith

AIC1084
5A Low Dropout Positive Regulator
FEATURES
Dropout Voltage 1.3V at 5A Output Current. Fast Transient Response. Extremely Tight Line and Load Regulation. Current Limiting and Thermal Protection. Adjustable Output Voltage or Fixed 1.5V, 1.8V, 2.5V, 3.3V. Standard 3-Pin Power Packages.

DESCRIPTION
The AIC1084 is a low dropout three terminal regulator with 5A output current capability. The output voltage is adjustable with the use of a resistor divider or fixed 1.5V, 1.8V, 2.5V and 3.3V. Dropout voltage is guaranteed to be at maximum of 1.4V with the maximum output current. Its low dropout voltage and fast transient response make it ideal for low voltage microprocessor applications. Current limit and thermal protection provide protection against any overload condition that would create excessive junction temperatures.

APPLICATIONS
Mother Board I/O Power Supplies. Microprocessor Power Supplies. High Current Regulator. Post Regulator for Switching Supply.

TYPICAL APPLICATION CIRCUIT
VIN 5V 3 AIC1084 1 ADJ C1 + 10µF 2 VREF VOUT 3.3V

RF1 125 + 1% C2 RF2 10µF 205 1%

VREF=VOUT -VADJ=1.25V (typ.) VOUT=VREF x (1+RF2/RF1)+ IADJ x RF2 IADJ=55µA (typ.) (1) C1 needed if device is far away from filter capacitors. (2) C2 required for stability.

Adjustable Voltage Regulator

VIN 5V

3

AIC1084-33 1

2

VOUT 3.3V

C1 + 10µF GND

+ C2 10µF

Fixed Voltage Regulator

Analog Integrations Corporation

Si-Soft Research Center 3A1, No.1, Li-Hsin Rd. I , Science Park , Hsinchu 300, Taiwan , R.O.C. TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw

DS-1084P-03

010405

1

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