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
Hi all!
I recenently purchased a used Beomaster 1900 (Type 2903) receiver. I am now in the process of recapping it to get rid of the quite noticable humming.
Since I have no experience in repairing hifi components, I bought the recap kit from the beoparts shop to make my life easier.
After dismantling the amplifier, I noted that one of the two large reservoir caps had leaked. The reservoir caps were not part of the aforementioned recap kit, so I now have to find an adequate replacement myself. Which brings me to my main question:
I am totally overwhelmed which ones to buy. The original Wilcon caps were rated 5000 uF at 35V. It doesn't say much more on the tin and I can't find the full specs anywhere. I only found one blog article where a specific replacement cap was mentioned (link), but this one is no longer manufactured.
Looking at sites like mouser, there many more specs that seem relevant like
- rated Temperature
- max ripple current
- some caps are classified as "audio grade" but most of them are "general purpose"
The price ranges also varies widely (between 4-80 EUR). I would like to buy caps that are rated for at least 2000 hours.
Regarding capacitance: There are not many caps with exactly 5000 uF. Some people suggest getting 6800 uF instead, while others say you should go for 4700 uF because the larger caps could draw too much current when turning on the amplifier.
Could anybody point me to specific cap that they have used in the past (or would use)? I'd be very grateful for any help.
Thanks,
Tom
Choose 4700uF for capacitance.Choose 35V, 40v or even 50V (but not higher) for the voltage rating.Stay away from low-ESR types.Check that the physical size fitsand both you and your Beomaster will be fine.
Martin
Martin,
thank you so much for your help!
I just ordered two Vishay 2222 056 57472 caps which seem to meet all of the specs you mentioned. I can't wait to have my Beomaster working again.
Have a nice weekend!
Except the data-sheet says Low ESR...
https://www.vishay.com/docs/28340/056057psmsi.pdf2nd line.
Risk of selfoscillation.Been there, hence my note.
Hi Martin!
Now I'm slightly more confused. When I researched the cap, I referred to this datasheet, which is for the same cap series but older (anno 2005). Unlike the newer datasheet, it doesn't mention low ESR anywhere, despite having the same ESR values listed as in the newer datasheet.
I also checked the caps from the 058 series (datasheet), which were explicitly labeled as "low ESR". So I went for the 056 series.
It seems like the manufacturer has changed their definition of "low ESR" over the course of time.
The 056 series cap in the 25x30mm case size has an ESR of 82 mOhm at 100khz (4700uF, 40V). This is the case size I ordered.
The same 056 series cap in the 22x40mm case size has about half the ESR (49 mOhm).
So my question: What ESR values should I be looking at to be considered "not low ESR" ?
Sorry for being overly curious, but I just want to make sure that I put in the proper caps before I go through the long process of reassembling the 1900.
Cheers,
Cheap general purpose (black) Nichicons will more than likely suit.
Thanks!
I've now picked the Nichicon LGU1V472MELA. I hope these will be fine.
Have a great weekend!
I am happy to report that the recap was successful. Now the old lady sound like it's 1976 again :-)
Thanks to Martin and fkatze for your support!
Hi Martin, what happens if you use the wrong capacitor ?
The Beomaster was constructed with the type of components that were used in production in mind.If you change a component to one of a different type, you will often get a malfunction - like if you replace the front panel incandescent lamps with LEDs or a wrong type of lamps, the related functions will no longer work as intended.
If you fit low-ESR capacitors or high-HFE transistors in the output stage, there will be a risk of self-oscillation.If you fit low-ESR capacitors for the power supply filters, the same can happen - and you will place more stress on the rectifier, because of the very low impedance of the capacitors at power up (when charging begins).Do both and you are almost guaranteed to blow something - either the output stage or your tweeters.
We had this (small) example not to long ago:
https://archivedforum2.beoworld.org/forums/t/41585.aspx
I see, does this also cause the popping sound when turning on ?
No.It's normal for Beomaster 1900/2400 to produce a small thump sound when going out of standby.It's from the amplifiers being powered up (no speaker relay in these Beomasters).
Ok, thank you Martin