|Posted by: Terry
Hoover on 09/18/04
Note: Terry will rebuild your Power PakContact him at his email address ([email protected])
I found a capacitor that very closely resembles the original in physical and electrical characteristics. The original was rated for 0.05microfarad [mfd] @ 330VAC and the replacement I found is 0.047mfd @ 630VAC (2000Vdc) but that’s close enough. Higher voltage tolerance is always better in a capacitor. It’s Newark stock #48F3940. (has been replaced with #66k5388. Both seem to have the same values and it appears that the replacement was because of the Rohs directive ( restriction of hazardous substance).) (update thanks to: sailpanel on 4/21/08)
It’s round with axial leads and almost the exact physical dimensions. Very pricey for a capacitor @ $2.29 each.
Our caps measure L=1.438 & d=0.532. The replacement I found is L=1.339 & d=0.591.
It’s also a film cap like the originals but in a more modern casing without the wax.
I also found two types of replacements for the transistor. One is virtually an exact replacement in physical and electrical characteristics but rather expensive at about $15 each. It’s a true Germanium PNP transistor like the original.
(NTE121 - Newark Stock #29C4423)
The other also has the correct physical characteristics but the electrical characteristics are slightly different. It’s still a PNP but is a cheaper silicone transistor. It will function perfectly well and is about $5 each. (NTE219 -Newark stock #29C8652)
I prefer the NTE121. The 219 has a lower current gain than the 121 and some of the voltage parameters on the 121 are more robust.
The following are replacement resistors that most closely resembled the originals in style, color, physical dimensions, and electrical characteristics. A resistor is a resistor, so Radio Shack and other electronics outlets (even Newark) will most likely have perfectly acceptable replacements for less money. Just give them the resistance and wattage and take your pick. As I said, this info is primarily for the purists.
Even though resistors seldom go bad, at 35 year old it’s very likely they shifted values somewhat. If I have to repair a power pack, I also replace the resistors just so I don’t have to worry about it later.
For the 1.5ohm @ 5 watt resistor I found an exact replacement in physical as well as electrical characteristics. It is a true wire-wound resistor in a white ceramic fire proof rectangular case, just like the originals. There are many other perfectly functional styles of fire proof resistors but they do not have the same “look”.
It is Newark stock #33C8895 and sells for $.040 each (expensive for a resistor).
For the 1.5K ohm ½ watt resistor I found Newark stock #84N2195 @ $0.07 each. It is slightly smaller than the original but is a carbon resistor like the original. It also has the resistance code bands like the original. Many of the newer resistor styles do not have the bands and are not carbon.
Finally, for the 50 ohm one watt wire-wound resistor I found Newark stock #02F1195 @ $1.31 each. Definitely expensive for a power resistor, but this one closely resembles the original in physical dimensions. It does not have the exposed wires like the original but it is a true wire-wound (with a brown ceramic coating) and it’s the closest I could find.