Compaq Contura 320 and 425C Repair Notes

Lots of dead floppy drives in these things. Read errors, seek errors, almost always a problem with the floppy drive itself. Send to a floppy repair facility.

Screen case can be damaged if the hinge screws come loose, so secure with loctite. Don’t disassemble the display panel assembly while it’s mounted on the unit. Remove it first, then disassemble it. Look for a screw behind the 3/20, 3/25, 4/20, 4/25 sticker (actually thin plastic) on the display panel.

No backlight - check for physical damage of the fluorescent lamp in the display. If it isn’t broken, check the DC voltage to the inverter board. If it’s present, replace the inverter board.

No brightness or contrast adjustment - clean potentiometer on the inverter board with electrical contact cleaner, check to be sure the slider controls are placed directly over the shafts on the potentiometers. Replace the inverter board if this doesn’t work.

No lights on the power button / LED assembly, unit works normally. Reseat the pin connectors. If it doesn’t work, replace the assembly. It won’t affect performance, but there is no power indicator, caps/scroll/num lock indicator or battery charge indicator.

Lots of loose KB cables and video cables - they come loose at the point where they attach to the motherboard.

Lots of broken video cables - for video noise or line problems, reseat at both ends, then replace the video cable.

The inverter board power supply cable (5 black wires) sometimes gets pinched at the hinge point - when reassembling, make sure that it’s well away from the hinge and not pinched by the case in any way.

Hard drive seek problems - almost always caused by the electronics on the bottom of the hard drive shorting on the aluminum RF shielding on the bottom of the case. It usually doesn’t damage the motherboard, but the hard drive will be damaged by this.

Won’t power on - Check the AC adapter, then replace the DC-DC converter (the module where the AC adapter connects). This is a high failure item.

Battery problems - The batteries in these things die quickly. I’ve never seen one with an original working battery - if it works, it’s been replaced with an aftermarket unit. With the AC power applied, test the output voltage at the battery terminals, both with the unit on and off. If it’s 14-17vdc, the motherboard is probably okay. Educate the user to the importance of cycling the battery (esp in the case of a NiCd battery - these units could use either NiCd or NiMH. If the unit is to be used for long periods of time on AC power, remove the battery.

On color units, the extra weight of the LCD panel, coupled with the tendency of the hinge screws to work loose, breaks screen cases. Make sure the hinge screws are tight, don’t disassemble the screen assembly while it’s on the unit, and of course, clean and lubricate the hinge points before reassembling.

The cords on the AC adapters break at the plug and at the AC module. This can cause intermittent results (the unit reboots spontaneously or when moved), or can appear to be a defective unit.