Recapping older radios

[ExitThirteen]

I suppose I had a poor choice of words in my post.

Perhaps I should explain further.

When I said my audio was crisper, I was told by several people that my audio was "fuller", "bolder", "crisper" than it was previous.

The RX audio is brighter, but it's also a fuller sound as well, more robust.

The clarifier (to me) seems to be a bit more linear when sliding.

I buy Nichicon capacitors in bulk. Total bill to recap my Madison was around 8-10 bucks. But KALR 7570 said it best, "An ounce of prevention is worth a pound of cure."

I saw this thread and decided to take the plunge on my Madison, just to see if there were any benefits, and there was indeed benefits to recapping the radio. Was it necessary? Eh, probably not, it worked satisfactory before, even tho there were a few caps that were questionable. Did it improve the radio? Absolutely. It was something for me to try.

~Cheers~

 

[Captain Kilowatt]

There are tech's out there that have actual experience working on these radio's for the last 30-40 years and don't necessarily know all the theoretical this or that.

Sharing their experience with the community, there is a known history of failures and recommend replacements. As Edmund Burke stated, "Those who don't know history are destined to repeat it." I prefer to heed the warning.

I have probably replaced a few thousand capacitors in my lifetime, most of which were in circuits that detected audio control tones or in audio circuits in general. It has been my experience that the value had to drop significantly before any noticeable difference in sensitivity was concerned or audio quality affected. It is also my experience that those who claim lots of experiance and little background theory to back it up are the same ones that are the fast talkers and shikesters at a lot truck stops. You know the ones, they get irate when you dare question their decision.

 

[Lil'Yeshua]

What about replacing caps with bigger ones? One radio repair/customizer I know of does that as upgrades to their customer's radios.

 

[Captain Kilowatt]

In almost all cases there is nothing wrong with doing that. Tbere may be no change in performance in most cases but there is nothing wrong with doing it.

 

[The Mad Scientist]

Ok, I am curious here. After reading through this thread I keep hearing about "performance". From what I have read and experenced the majority of these "capicitor replacements" are being done as a preventive measure and not for "better performance" as in the prevention of the "ten volt blues" which is a legit and well documented issue. I understand what you are getting at Captian k., But it is a good school of thought to be a why not? instead of a why? in these cases. It is always better to take a proactive step no matter how small one thinks it may be to help keep the equiptment that uses those ten volt electrolitic capicitors running smooth for the foreseeable future instead of "waiting" for something to happen. Replacement of these capicitors is a viable step in preventive maintainance and has nothing to do with "performance".

Now on the other hand equiptment that uses other types of capicitors and equiptment that has a good reputation for long life the individual opinions will vary.

 

[Lil'Yeshua]

My 959 came with 25 volt caps.

 

[Lil'Yeshua]

I read somewhere that the voltage could be turned up from 13.8 to 14.5 volts thus the need to change out the lower voltage caps for a higher voltage. This was in reference to upgrading some transistors. The Galaxy tech told me that the MOSFET 959's were already upgraded.

 

[Robb]

The caps I replaced were a necessity; not a performance option. They had failed outright. Showing almost no capacitance and even began to show a very low resistance value. IOW - 'shorted'. The circuit that these caps were in were heating up other parts in that circuit. I thought it was odd these failures occurred in various places; not where one would expect great loads placed upon them - either.

There had been caps - just a decade ago - that were defective by design. There were allegations and proofs of industrial sabotage that created this situation. You can read about it on Wikipedia if one wants to take the time. Many consumer electronic products were affected including any radio that was mfd in that time period.

The large number of failures of aluminum electrolytic capacitors with liquid electrolytes are based on millions of faulty capacitors produced in the years 1999 to 2007 by some (but not all) Taiwanese manufacturers[16] whose products started failing prematurely after only a few months of operation. Many of the capacitors had a life span specification (load life) of 2000 hours at 105°C. With a lower average internal temperature of 45°C on a printed circuit board and a ripple current within the data sheet specifications, these capacitors should have a life expectancy of about 18 years of continuous operation. With respect to this life span expectation, a failure after 1.5 to 2 years is very premature.

http://en.wikipedia.org/wiki/Capacitor_plague

I had recently repaired a computer monitor that had failed caps. Fixed it with new caps. Bought a new monitor in the mean time to replace it. But recently it had also failed. More like a five year time span here - BTW. Still - Unbelievable! Soooo, I replaced the caps and it is working once again. Now I have two monitors; one is now a backup. Venturing a guess here; these cap failures are due to 1) planned obsolescence and 2) the switching power supplies used are underrated and fail due to continuous strain. Or both. Or even a third option: cheap/low-grade caps that cannot handle the ripple might have been re-branded and sold as a higher grade. IOW - counterfeits!

Mouser sells cap kits for monitors if you need them . . .

 

[RADIOOMAN]

Never mind..... I was looking for the article and overlooked the link you have show in your post.

 

[Grinder74]

I just fixed a President Jackson by replacing 2 large caps that were leaking and one .22uf in the final circuit. I have another radio with the same issues the jackson had and will check out it's caps at the final.

 

[15minigrass]

But if it is broke; then you must fix it.
Right?

When you replaced the caps in a non-working radio that is more than 25 years old, the caps were of dubious quality to begin with, then test all of the caps you took out and found 25% of them were bad; then you don't question why.

I now have three more working +25 year old radios than I did after I recapped them.
A SuperStar 360FM, 3900, and a Uniden/President Grant.

There were bad caps, OK caps, and failing caps; that is all there was to it.

Did you do all the work yourself? I have a uniden grant gray fac here that I think needs to be recapped. When I lower the deadkey/am power, it squeals but when I bring up the am power, it stops squealing but modulation is stil scratchy. Now itndeadkeys 9-10'watts and swing 12+ watts.. If you do these kinds of repaired please lmk how much. Aloha James.....

 

[Klondike Mike]

I just fixed a President Jackson by replacing 2 large caps that were leaking and one .22uf in the final circuit. I have another radio with the same issues the jackson had and will check out it's caps at the final.

Unnecessary. They were probably still within spec. Unless there's smoke coming from out back of the unit, you've wasted your time and money.

 

[Mudfoot]

Unnecessary. They were probably still within spec. Unless there's smoke coming from out back of the unit, you've wasted your time and money.

Lol, are you ex quality control supervisor?

 

[Captain Kilowatt]

Leaking caps ARE bad and need to be replaced.

Robb I know the case you spoke of regarding the bad run of caps. Industry insiders say jt was not sabotage persay but rather poor quality bootleg parts from China. It seems a parts manufacturer cut corners and used substandard chemicals to make bootleg parts. We had about two dozen computers that started to die because of that. Parts were traced to that issue.

As for replacing caps because of the ten volts blues as someone called, fine. I never argue about upgrading due to piss poor borderline design. I just see no point in replacing parts with similar rated parts just because. That is what I have been contending all along.

 

[Robb]

Did you do all the work yourself? I have a uniden grant gray fac here that I think needs to be recapped. When I lower the deadkey/am power, it squeals but when I bring up the am power, it stops squealing but modulation is stil scratchy. Now itndeadkeys 9-10'watts and swing 12+ watts.. If you do these kinds of repaired please lmk how much. Aloha James.....

Sounds like more issues than just a cap kit - IMO . . .

Putting a cap kit in will take some time. I turned down a couple of local operators when asked to recap their radios. It is time consuming and tedious. Just buy a kit from Klondike Mike and DIY. Requires a decent soldering iron, a solder sucker, and use lead solder. Oh yeah; an old pair of toe clippers to remove the excess leads after the new caps are soldered in place. Must be patient and willing to the job right the first time. One more thing, use a strong flashlight for finding/tracking the traces for each cap. Makes for easy removal/replacement when locating the parts on the board. Make sure the polarity of the cap is correct before you solder it in place - or they may explode/pop!