05-09-2016, 02:35 PM
Let's start with an easy one. the 6800uF smoothers will be fine.
Not sure which zeners you're referring to. If it's the pair of 30V parts just after the main smoothers then the 330R resistors need to be at least 2W rated. It says 3W on the schematic. I'd probably use 5W wirewound, spaced off the PC. If the 30V rails aren't loaded the zeners will be taking (55-30)/330 = 0.076A. Hence they will be disspating 30V * 0.076A or 2.27W. Use 5W zeners, again spaced off the PCB. Such as these which are cheaper than I expected: http://cpc.farnell.com/on-semiconductor/...dp/SC07189
There are other zeners on the schematic. If they need replacing we'll need to asses them on their merits. For example Z1 and Z2 will be carrying at most (55-15)/3k3 = 12mA and hence will disspate 180mW at most. Hence any zeners will do here. The 3k3 resistors are also carrying up to 12mA and will dissipate a touch under 0.5W. Use 1W parts to be safe.
Polyester caps of that vintage should be OK unless mechanically damaged.
Not sure which zeners you're referring to. If it's the pair of 30V parts just after the main smoothers then the 330R resistors need to be at least 2W rated. It says 3W on the schematic. I'd probably use 5W wirewound, spaced off the PC. If the 30V rails aren't loaded the zeners will be taking (55-30)/330 = 0.076A. Hence they will be disspating 30V * 0.076A or 2.27W. Use 5W zeners, again spaced off the PCB. Such as these which are cheaper than I expected: http://cpc.farnell.com/on-semiconductor/...dp/SC07189
There are other zeners on the schematic. If they need replacing we'll need to asses them on their merits. For example Z1 and Z2 will be carrying at most (55-15)/3k3 = 12mA and hence will disspate 180mW at most. Hence any zeners will do here. The 3k3 resistors are also carrying up to 12mA and will dissipate a touch under 0.5W. Use 1W parts to be safe.
Polyester caps of that vintage should be OK unless mechanically damaged.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
