01-27-2012, 01:21 PM
dan mauro Wrote:Thanks Winky and Daddy for the encouragement to post a similar letter. I too am a novice at this. I have a Heath shortwave kit I built many years ago, works well, and a Philco 40-180 which works but needs at least an alignment. I haven't read anything on repair, chosing to pick your collective brains instead, since it's much easier to read a paragraph or two rather than a complete book. I understand that electrolytic caps will change over time and may need replacing but when I hear about recapping how do I determine which caps need replacement/refurbishment. Do I test them all first? Can all the caps go bad, even the micas? Do I need to test them under load or just capacitance? Where is the best place for me to start with the 40-180, should I try to realign it first or go through it cap by cap, tube by tube? Thanks for this wonderful forum and a great way to spread the knowledge you all have amassed over many years.Hi Dan,
Humbly yours, Dan
Welcome aboard! This is a great place to get started and there are many guys here that can help you out!
I'll try to answer your question. If you want your 40-180 to work the way it should, you are best off replacing all of the caps save the mica ones. Mica caps usually hold up well over the years and seldom need replacing. however, All the electrolytics and paper tubular caps should be replaced with new units. Also Philco used caps that were sealed with tar into bakelite blocks that were mounted to the chassis. If you have any in your set they should be rebuilt as well. There are detailed instructions on how to do this and it is not hard to do at all!
It's best just to replace them all and not bother with checking them! New caps aren't expensive and you can get a capapcitor kit with an assortment of the most needed values from Just Radio's for like $75 bucks. There is a link to their website on the resources page of the Phorum. I have ordered from them several times and they are great!
Also, you should also check your resistor values as well. They have a tendancy to change over the years and that will also affect how your set operates. I just finished restoring the chassis on my 1931 Philco 90 and I ended up replacing all the resistors in the set as well. After ohming them out some of them were as much as 40% past there original values!! Again, new resistors are available in kit form from Just Radio's.
Do these things first before trying to realign your set. if you try to align it first, any caps or resistors you may need to replace may change the alignment, and you will just have to do it again anyway!
You said that you are a novice at this so I would also like to recommend Bret Menassa's DVD's. I have all 5 of them and he does a great job covering the basics! I bought mine on Ebay.
Hope some of this helps, Good luck!
Kevin