CB Re-caping

[Philomath]

Hi there folks, I hope you are all well. I have a Capacitor question. I'm not a tech, Just a tinkerer.
I plan on re-caping my Cobra 148gtl and my Uniden Washington. Upon reading the capacitor list for these radios, I see that the Cobra has around 12x .47uf capacitors with 4 different voltages ranging from 10 to 50 volts and other values with different voltages.
My question is.
Can I just simplify the parts list by just using all 35volts or higher for all capacitors?
Thanks in advance for any advice.
Best regards to all,
Walt.

 

[MKwrench]

Thats what I do. I just order 10 to 50 or so of each at a time from Mouser as needed. Some get used more than others. It helps keep my storage bin space to a minimum. Keep in mind that some are rated for 50v.
Also 0.47uf is as small as I have ever ordered, I havnt seen much difference using them where a 0.1uf or 0.22uf electrolytic would go, these are usualy for passing audio or, absorbung the "Pop" spike in a switched circuit. Youll be fine

 

[tramd]

Or you could just buy a complete kit from a place like Klondike Mikes.

 

[MKwrench]

Or you could just buy a complete kit from a place like Klondike Mikes.

Heck yeah, These are great if you're focusing on one radio at a time and bringing back original performance and quality.

But, if you want to experiment with different enhancements or characteristics in the radio or just have multiple radios to go through, bulk is a better option. Just so you have the stuff on hand.

For now ordering from Mike will be the best option.

The most important things now are:
"Time" , Don't rush, double check before and after each cap, you shouldn't have to pull or twist. A little wiggle while heating will tell you if you're on the right one...
"Good smaller tip soldering iron"
, I picked one up for around $30, you don't have to go crazy on features, but picking a known brand name is a plus. It will last for years.
" Iron resting spot" , you'll be focused on the repair using both hands, and the iron needs to be in a handy, known, accessable spot.
"Desoldering Tools"
I recommend the solder remover kit from (please forgive me) Harbor Freight, it's only about $13 and comes with 3 solder remover pumps and 2 rolls of solder wick. The pumps can be disassembled and cleaned too. I still use the one I got years ago.
Once you get the feel for it, you'll want to upgrade tools and, find more radios to repair.....
Get to it, and tell us how it comes out!

 

[Night Stalker10]

Hi there folks, I hope you are all well. I have a Capacitor question. I'm not a tech, Just a tinkerer.
I plan on re-caping my Cobra 148gtl and my Uniden Washington. Upon reading the capacitor list for these radios, I see that the Cobra has around 12x .47uf capacitors with 4 different voltages ranging from 10 to 50 volts and other values with different voltages.
My question is.
Can I just simplify the parts list by just using all 35volts or higher for all capacitors?
Thanks in advance for any advice.
Best regards to all,
Walt.

There are two pieces of advice I could give you. When you get ready to replace the electrolytic caps, take a black marker (or any color) and put a mark or dot on the top of the cap towards the front of the cap that's facing towards the front of the radio. Do this to every cap before you start to de-solder them. That way when you install the new cap, you can use the old cap with the mark to verify which hole in the pcb is for the negative lead. Sometimes the pcb hole has the positive polarity mis-marked. I've also found a 1uf 50v cap with the positive lead to ground on a radio, and that's the way it was intended from the factory. Even though it looked like I was installing the new cap wrong, but with the mark on the old cap, I knew it was correct. Plus once your done recapping, you can check every capacitor and if you find one with the mark on it, you know you missed that one.

Always replace the electrolytic cap with the same value. If it's 470uf, then install another 470uf. You can always go higher in voltage rating, but be aware that the higher the voltage rating, the larger the cap might be physically. Sometimes due to the tight fitting of parts, you can't replace a 16v cap with a 35v, because the 35v is physically to big to fit.

 

[9C1Driver]

Klondike Mikes - Electrolytic capacitor kits

Quality electrolytic capacitor replacement kits for vintage radios, CB and HAM transceivers, scanners, and other classic electronics. Restore your Cobra, Realistic, Midland, Uniden, Kenwood, Icom, Yaesu, Bose, RadioShack, Uniden, GE, President & more. **klondikemike**

klondikemikescapkits.com

He is also a forum member.

 

[brandon7861]

I too agree that higher voltage rating caps are just fine.

I have tried to research reasons not to use higher voltage caps on a few occasions and I have only found one reason.

A change in ESR can affect signal phase and filter zero frequency and potentially cause instability in circuits that were designed around caps with higher ESR values. A higher voltage rating means thicker dielectric, and that means more foil to achieve the same capacitance, but the increase in foil area usually reduces ESR. So higher voltage caps have lower ESR. I suppose the increase in foil length may increase the parasitic inductance a little too.

If you recap an old SMPS, be careful. In a CB radio, I don't think it matters at all.

 

[AudioShockwav]

Klondike Mikes - Electrolytic capacitor kits

Quality electrolytic capacitor replacement kits for vintage radios, CB and HAM transceivers, scanners, and other classic electronics. Restore your Cobra, Realistic, Midland, Uniden, Kenwood, Icom, Yaesu, Bose, RadioShack, Uniden, GE, President & more. **klondikemike**

klondikemikescapkits.com

He is also a forum member.

Second on Mike, he does the footwork of logging all the values and putting the kits together for you.

73
Jeff

 

[doffo]

Even before I returned here, I bought a couple kits off Klondike Mike to recap a couple of my TRC-465 radios back in 2019.

 

[Philomath]

Thanks for the advice folks. I have a soldering station and a de-soldering station and I've been soldering stuff for 60 years, so fear not my friends.
You have essentially answered my question.

After farther research I see that the need for specified voltages is a physical size thing to make sure that they fit in a given space, higher voltage usually means bigger, a feature for those who wish to build teetsy weetsy stuff.
However, 40 years down the track components have gotten smaller. with a 40 or so year old radio it shouldn't be a problem. I'll go with the higher voltage caps and make sure that they fit.

I have looked at Klondike Mike's stuff and it's good stuff. but exchange rate and shipping is price prohibitive. So I'll buy local here in Aus where I can and as you guys suggested, I'll probably buy bulk.

 

[nomadradio]

The very first caps to fail from age alone are frequently the ones rated for six or ten Volts. Around here we call that the "Ten Volt Blues". Manufacturing techniques have shrunk the size many radial caps found in a 45 or 60 year-old radio. We don't stock but one or two caps with a voltage rating below 25. The higher the voltage rating, the lower the cap's internal leakage current. You'll see a 50-Volt factory part in some 12-Volt circuits. This is usually to minimize that leakage in senstitive circuits. Odds are the higher-voltage rated cap won't be bigger than the original. Might last longer.

Dern shame about the cost of a ride from Canada to Oz. Mike sticks to the reputable name-brand caps. Just be skeptical of chinesium parts from fleabay.

Just resist the temptation to remove more than one at a time. Reduces the error rate to replace one before removing the next.

73

 

[Smokinone]

When I recap, I check value of the old cap coming out, and the new cap going in. More time consuming, but interesting to see the degradation of the older cap, and QC being what it is, I don't put a bad one back in...just my $0.02 worth.

 

[Cable Guy]

I do a 1 for 1, verifying the value printed on the old cap.
Long ago, I caused more work for myself by just dropping the new caps in and soldering up. I don't like taking chances anymore, so I hold the new cap leads to the grounded bus bar at the bench for a few seconds before putting them in to drain away any residual potential. I have fried stuff by putting a charged capacitor in a circuit. I imagine it may have a much greater voltage than the circuit can handle due to static. You could just short the leads together and zero out the potential, but that zero is not necessarily at ground potential. I could be wrong, my understanding is hit and miss, but in this instance (low voltage, low capacity capacitors), it never hurts to discharge the capacitors before installing them.

Mike's is the only place I order cap kits from. I wish he did more than what he does, like game console cap kits. If you go that route and order from Mike, you don't have to worry about voltage ratings, and going up in voltage is good.

 

[saturated]

This is really great stuff Im gonna make a list the ten commandments of re-capping and I don't have to look further than this thread