ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
For some time ago I had to replace all capacitors of a BM4000.
This Beomaster has 3 bigger caps. 2 of them are for the output stages and even a bigger one for the power supply.
The problem is that these bigger capacitors cost a lot more, because of their size (diameter).
Prices from about 25-30 euro each is quit common.
So, maybe this could be helpfull.
Another issue is that the caps inside the BM4000 are placed together in a bracket and are tightened that way. So, here's what I did.
First pic is the damage that a leaking cap can cause.
Next picture shows the different dimensions between the old and new one.
So, we start to take out the inner dielectric stuff.
Below you can see that the new one fits inside the old, but drowns...
So, I used a sheet of packaging material and started to cut..
I only used the round cutted piece and filled internally the old cap with hot glue around the new cap.
Finally the original capacitor filled with the new one in place.
It's difficult to see, but notice the bracket around the three caps. Just another several caps (orange ones etc) and trimmers to go.
BTW, this was a newer BM4000 version with 3 trimmers on each channel.
GENIUS!
Never would have thought to do that in a million years.
Very good job sir!
Beo4 'til I die!
Very much cleaner than my (accidentally) way. Wrong polarity and "lots" of voltage, inners of cap popped out with nice sound effect... Messy....
blah-blah and photographs as needed
Orava:Very much cleaner than my (accidentally) way. Wrong polarity and "lots" of voltage, inners of cap popped out with nice sound effect... Messy....
Even small electrolytics can certainly make a bad mess.
Beobuddy's idea is actually used quite often with old valve sets - modern replacements can be outright tiny compared to the old high voltage capacitors with their paper dielectrics. The downside is that you can't see that easily when the replacement starts to leak, and it might also get a bit hotter with that extra enclosure around it. But, as we can see from the size difference in this case - realized over only 30+ years or so - there's been a lot of development in recent times as well, and the modern cap will probably stay in working order quite a bit longer than the original did anyway.
--mika
I would add that the used cap is a 100Volt version.
The original one was 5000uF and 50Volt. The 100V was an afforddable one (8-9 euro) with the right diameter.
If I would have used a capacitor with the original specs, it could have been a (lot) smaller version.
The original idea was to use a replacement which could be used with the bracket.
Just to get an impression about sizes.
Down here, both has the same value, but different voltages (100V and 25V). I haven't a 50V at the moment in stock.
So compared with the original 50V version...