MTD3055 transister burned out?

You can apparently replace the MTD3055E with the STD12N06 Power-MOSFET. This is the modern-day replacement for it with identical pinouts. Another standard replacement component is NTD2955. An equivalent is the 2SK1623L.

The STD12N06 datasheet can be found here.

Q11/Q12 transistor issues

On the main lynx circuit board, Q12 appears to crop up all over the web regarding 'dead lynxes'. It's actually Q11 on Lynx 1's, and Q12 on Lynx 2's. The part number is sometimes 222 M(Motorola) T3055EL.

Q12 on the Lynx 2 board

If you have a Lynx that won't power up when you press the power button (not even the power LED lighting up), this transistor could have failed. To test, you can short one side of this transistor (can't remember which side) to GND and the unit should power up.

Another thing to try: take a wire and connect the headphone ground (middle pin) to the battery minus. If the Lynx starts up the MOS transistor Q12 is broken. Replace it and all should be good. If this 'wire trick' doesn't help, don't bother replacing Q12 - it won't help.

 

DC power jack

This is another problem area on both Lynx 1 and Lynx 2. Typically, the pin inside the jack that connects to the PCB breaks off. With this problem you'll just need to measure for the input voltage of your AC adapter across C-39 (less the diode voltage drop). You just need power connected to the power connector on the PCB to do this test - no need to connect anything to the other connectors: the speaker, LCD, buttons, backlight, or even a game cartridge. Also remember to remove the batteries first. When the unit is on there will be about 5 Volts across C-41. If you need to replace the jack it is part #CB102242 for the LYNX 2 & #CB101842 for theLYNX 1 through BEST ELECTRONICS. A dab of hot melt glue should be placed on each side of the jack after it is replaced (and as preventive maintenance) to keep it from "jiggling" which seems to be the cause of the pin breakage.

No Sound / Very low sound

A previous owner may very well have plugged in the DC adapter into the headphone jack. This 9V is enough to fry or badly damage the speaker. To test, plug in some earphones. If you get good sound, the speaker is damaged - replace it with a new 40mm speaker. If you want a really loud one, get an 8 ohm, or for a more silent one get a 16 ohm one. The stock speaker is 16 ohm, 0.2W.

Touchpad buttons don't work

If you get no response from the touchpad, you'll need to dismantle the Lynx and clean the button pad from the inside.