While diagnosing a RAM failure in my more sickly GRiDCase 1520 I noticed an unpleasant odour coming from the rear of the machine. Pretty soon it started behaving erraticly, rebooting at random. It's capacitors again — this time in the DC-DC converter module. Time to break out the soldering iron!
Extracting the DC-DC converter requires opening up the computer. It was immediately obvious that at least one large capacitor had leaked: underneath the DC-DC converter a brownish liquid was pooling. It also coated the lower half of the converter PCB :-(
DC-DC Converter Overview
The DC-DC converter takes the DC input to the system (16.24V from battery/PSU bay or 9-20V from external barrel connector). It converts this to the various voltages required for the rest of the system.
There are multiple models for the GRiDCase 1500-series DC-DC Converter:
- LCD-115, GRiD part number 104144-00. Used with the two LCD display options. Provides −15, +5, and +12 DC outputs plus switchable 100VAC.
- PLASMA-116, GRiD part number 104145-00. Used with the two plasma display options. Provides −15, +5, +12, and +33V DC outputs.
The machine I'm repairing here had an LCD display.
Removing the Capacitors
The capacitors I removed and their values were:
I managed to source replacements that met the capacitance; met or slightly exceeded the voltage and temperature rating; and were physically the same size or smaller.