Regularly I seem to have to revive these kind of power supplies from studios. Common problem is heat damage, not surprising when you conider how many hours service these have to provide. Replacement modules are something like £450 so repair is worthwhile especially as the repair will upgrade them as per Chandler themselves recommend to reduce heat damage. This includes the following modifications:
- Replacement an upgrading of all power supply capacitors. Capcacitors come with a lifetime rating expressed as a maximum temperature and number of hours. Typically this will be something between 2000 and 10000 hours at 85 degrees C. This may be a long time for items that are operating for short periods of time like one hour per day but in a 9-5 environment, Mon-Friday there are 2000 hours per year. So it is no wonder that these things fry after ten years or so. However by upgrading to the highest rated parts that will fit in the box we can increase the lifetime.
- As well as improving resilience to temperature another mod recommended by Chandler is to move the power supply precision regulating transistors off from the PCB and attach to the chassis. This has the effect of reducing the temperature of the unit by about 50% so another worthwhile step.
- On some models there are some pointless internal LED and resistors that run hot and have the effect of helping to prematuely age the capacitors. This is on the MKII version of the PSU so not on all of them but it is a worthwhile modification.
- Also sometimes the power switches fail themselves and this part can be easily replaced.
Signs of wear include exceessive hum and noise.
If you open up the PSU you may well see the damaged capacitors like in the pictures below. Typically, worn capacitors will bulge up at the top and may leak oil. The ones in the picture below marked with pink dots are all clearly worn out.
The whole set should be replaced together as mixing age of components is only asking for further trouble.
Upgrade and repair is available as remote service.
