21-03-2019, 11:23 PM
(This post was last modified: 21-03-2019, 11:24 PM by Murphyv310.)
(20-03-2019, 08:28 AM)Old Sparky Wrote: With all due respect, Sam, in this case, I would change all the waxies in a DAC90/90A. They'ra all likely to be leaky, and on the 90/90a being mounted on a tagboard are easy to get at and replace. I have a 90A in my 'roundtuit' pile, so will be replacing the caps. in that. I will however re-iterate the advice often given to newcomers, which is to change one cap. at a time, and check your work as you go. Another tip would be to snip out old components, leaving as much lead as possible, then solder the new item's leads to that, rather than try to untwist & remove the old component's leads completely. More time-consuming and can lead to broken tags as well!
Hi.
Well although you "can" replace all the wax caps there are some that can be safely left in place with no detriment to the set or performance. The capacitors in question would be those across cathode resistors in the Frequency changer and IF amplifier. You can of course replace everything if you wish but wax caps will not be an issue in some sections of the set. You rightly see that bunging mains across a leaky filter cap will give some interesting results and of course the audio coupling capacitor to G1 of UL41 should be replaced as a matter of course. I also agree pin 4 of the UL41 should NOT be used as an anchor pin.
I also have to say joining a new component to a "stub" of wire is poor practice, there should be a mechanical joint that is then soldered, I'd not consider doing a "repair" or restoration like that. I use a good quality solder vacuum sucker and braid to remove excess solder, then it is easy enough to unravel the wire from the tag strip or valve base and then feed in the new component.
