Understanding Transistor Replacement, Substitution and Information Is Very Important For a Electronic Repairer

ECG Philips Guide Book

Finding transistor replacement can take you hours if you don’t know the right method to do it. Searching the right transistor for substitution is a skill, if you replace wrong specifications of transistor into the equipment; it may burn in less than couples of seconds.

Substitute with the correct part number, the equipment will work for a long time and sometimes the substitute transistor will even work better than the original part number. A new model of a product usually used latest part number in the circuit. If this latest product has a transistor burnt, you may face difficulty of getting the original part number because the transistor is so new and cannot be found in the market or from your electronic supplier.

Your only option is to find the transistor replacement or substitution. You have to refer to a transistor cross reference book such as the famous Philips ECG semiconductors master guide or any other information that you think can help you to find the near replacement. Searching the internet and visiting technical forum may also help you to get an answer.

Up-to-date world's transistor diodes, thyristors & ic's guide book

For your info, not all transistor guide book provides the correct information but at least you have some reference data for you to refer. Choosing the right transistor parameters or specifications for the equipment you repair will avoid callbacks from your customers. Callbacks or repeated repairs due to wrong transistor replacement will cost you extra money and a waste of time.

Understanding the transistor data will definetely helps you to find the right and correct part number for substitution. Below are some important transistor specifications or parameter that you should follow in order to get the nearest replacement.

The maximum collector-to-base voltage (VCBO) – The substitution part number should have a VCBO rating equal to or higher than the original one.

The maximum collector-to-emitter voltage (VCEO) – The substitution part number should have a VCEO rating equal to or higher than the original one

The maximum emitter-to-base voltage (VEBO) – The substitution part number should have a VEBO rating equal to or greater than the original one.

The maximum collector current (IC) – The substitution part number should be able to handle as much (or more) collector current as the original one.

The Power dissipation (PD Watts) – The substitution part should be able to dissipate as much (or more) power as the original one.

The Gain (hfe) – The substitution should have a gain equal to or better than the original and it should be as close to the original parameter as possible.

The Gain-bandwidth (ft) – The substitution should have a transition frequency equal to or faster than the original and it should be as close to the original parameter as possible.

Above is a table of application requirement and important specification that you can use for guidelines when comes to transistor replacement. Remember, the replacement transistor should not run hot and if problem still present, try another substitution number or find the original part number if you can. Do not overlook that the surrounding components also may caused the transistor to run hot even if original number is used.

For instance, in the case of repairing Monitor, the horizontal output transistor (HOT) always burnt in few hours to few days time, if you did not check the surrounding components such as the electrolytic capacitor connected to the supply pin of horizontal driver transformer. Understanding transistor replacement is very important and considered“must” knowledge to you if you want to be successful in repairing any electronic equipment.

Monitor Horizontal Driver Circuit