Alexander Sharp tv standby Dead

Repairing a Sharp Alexander 51DXF200 TV That Stays in Standby

Initial Symptoms and Inspection

This afternoon, I received another service call to repair a Sharp television at the home of Mr. Dafid's family. The television was a Sharp Alexander 51DXF200. The complaint was that the TV would not start at all. The LED indicator remained lit continuously, and the front-panel buttons did not work. The remote control also produced no response.

As usual, I began by resoldering the components and then checking the voltages. The B+ voltage, which should normally be around 116 V, measured 150 V. The audio supply voltage was approximately 20 V, while the voltage that should have been around 7–14 V dropped when the TV was turned on. Hmm... what was going on?

This type of symptom can also be compared with the case described in Sharp Alexander TV standby and power-up failure.

Checking the 9 V Regulator Circuit

Overheating Components

I then noticed that the heatsink of the 9 V regulator IC in the 090RD1 series was extremely hot. The rectifier diode and the associated current-limiting resistor were also getting very hot. Wow, wow, wow! What else could be causing this problem?

At first, I suspected that the regulator IC was short-circuited. However, after replacing it with a new one, the same problem remained. The regulator and surrounding components continued to overheat. Hmm... what was the actual cause?

Tracing the Source of the Fault

I checked all the components connected to the regulator IC output. Eventually, I found the source of the problem in the stereo/surround circuit located near the edge of the main PCB. This circuit was mounted on a small separate board connected through a socket.

When I removed the small PCB from its socket, the TV operated normally. However, as soon as I reconnected it, the TV immediately returned to standby.

Since the fault appeared to be related to the protection circuit, the information in Sharp TV TDA93xx protection and error codes may also be useful for comparison.

Identifying the Faulty Stereo/Surround IC

Unavailable MZ-01E IC

Yes! I had finally found the source of the problem: an SMD IC marked MZ-01E. Unfortunately, this type of IC was not available on the market. I contacted the SHARP Service Centre, but they said they had no stock. Oh dear, what could I do?

Disconnecting the L3501 Connection

Finally, I decided to disconnect the L3501 connection associated with the IC VCC and then tested the TV again. Hmm... the TV powered on normally, the picture was clear, and the sound was available in mono.

For additional troubleshooting references, see Sharp TV fault analysis, which discusses other common Sharp television problems.

Repair Result

The most important thing was that Mr. Dafid's family could enjoy watching their television again. Although the sound was limited to mono, the TV operated normally and displayed a clear picture. Success to everyone!

For related service adjustments, you can also refer to the guide on Sharp TV service mode.

This article is based on my personal experience repairing a Sharp Alexander 51DXF200 television. The symptoms, troubleshooting process, faulty component, and repair results described here are based on my actual repair experience.