Some doubts about strange values in recapping BECKER Mexico

DaniTD

Member
2016-06-14 3:12 pm
Hi!
I'm in the proccess of recapping an old Becker car stereo from the 80s that has some problems. It takes about half an hour to be able to hear anything or regulate the volume, and the tuners are dead. Bad caps are known in this models, full of FRAKOs and ROEs. Since maybe the majority of these units have been stored for years on a basement, problems arises.


The problem I have is, I got the Becker service manual and schematics. At the end of the manual it has a complete BOM of the parts, including elko's or electrolytic capacitors. It specifies a Becker number part and capacitance for every capacitor, but not voltage.


I took a close inspection of the unit and, being a car stereo, the input filter cap and amplifier ones are rated at 16V, which is fine since a car runs on about 14V. But I see other caps in the unit with strange values (25, 35, 50 and even 63V!). I don't understand why these values since it's a 14V powered unit, with 12V and 5V regulators.


For example, the cap indicated on this image is rated at 63V and I can't understand why :confused::


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My question is, is this needed? Isn't it overrated? My doubt comes because if I follow this rule, the service manual would be useless and I would have to do a complete inventary of each capacitor, one by one, looking at the unit and there are about 65 electrolytics! Do you think of any problems of using that could arise on using 25V caps, which I think should be more that enough, or am I missing something? I know that same or bigger voltage value caps should be used, but my question is if this factory values are to be followed.


Thank you!
 
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ubergeeknz

Member
2018-08-31 12:32 pm
Unless there's something interesting going on, you'll be fine to use 25v (even 16v at a push) throughout. If there were to be higher voltages anywhere it'd be around the power amps. Very likely when built, they used whatever was on hand.

That said, if you want to do more repairs on solid state stuff in future, you may be beter off stocking up on 63v parts, as they can be used in most any application (new caps tend to be smaller than the old ones, anyway). I bought bulk in 25v parts a while back, and regret the decision as they aren't useful in a lot of applications.
 

DaniTD

Member
2016-06-14 3:12 pm
Thank you!


Strangely, caps around the amplifiers and output stage are all 16V. The strangely high value caps are mainly around the FM and AM tuning IC's. As you say today's elcos are smaller and with better characteristics than old ones. Then I suppose 25V should be a safe value for this set...
Since the main power cap is the bigger one and today elcos are smaller, I suppose I'll fit a bigger voltage cap (same capacitance), since It should work better with filtering noise and as a reservoir.


I have no interest in stocking capacitors since this is something I do as a hobby to put a rare unit on my car. I would like to build something for myself in the near future :rolleyes:.


Thanks!


Regards
 

ubergeeknz

Member
2018-08-31 12:32 pm
If you have a "shopping list", I could probably send you most of what you need for postage. I bought them by the 100's (1000 in some cases). Shoot me a direct message if you like. They're not the best capacitors out there but should be fine for the application (JACKCON sold under RS PRO brand, all rated at 25v)

If you prefer to go all out, most seem to rate Panasonic, I've also found them to be high quality and typically lower esr than competitive types. Buy from a reputable source (RS, Farnell, Digikey, Arrow etc) to ensure you're getting what you paid for.

Note that higher voltage capacitor does not necessarily mean Better performance. Often you will sacrifice either size or e.s.r. with a higher voltage part, although in most applications the main factor is a higher cost
 
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But I see other caps in the unit with strange values (25, 35, 50 and even 63V!). I don't understand why these values since it's a 14V powered unit, with 12V and 5V regulators.

It's probably a pricing decision. The higher voltages were likely available at better prices in bulk so they snapped them up.

It could also be a supply decision. Rather than stopping the line to wait for a part they brought in a higher voltage part.

25 volt parts should be just fine for most car audio.
 
1) do not replace parts at random.
You must *troubleshoot* the amplifier/radio/whatever, FIND what the problem is and focus on solving that specifically. Rinse and repeat.

2) notice your "high voltage" caps are in small values (1.5uF, etc.)
For the very same reason that ubergeeknz suggests stocking on 63V caps as a "universal" solutions, manufacturers often do the same.
I use lots of 0.47 and 1uF electrolytics, and normal stocked value is 50V.
Are , say 16V ones made? ... certainly ... "somewhere" .......
Fact is my suppliers must special order them, often in large amounts (say 1000 or more) to get manufacturer´s attention, I have to wait (sometimes a Month or more) and then they may end up costing more.
Are you getting the picture?

Now in larger values (100/470/1000/2200uF) voltage rating causes a large difference in size and cost, so you order the specific ones ... but on small values?

Unless you are VERY tight on space, you use the "larger" ones which anyway are quite small.

What Douglas Blake said, by the way :)