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
Just about to recap two pairs of Penta 1s and have four pcb 14 and four pcb 15s to compare.
They are all in beautiful condition with no leaking capacitors or burned-out resistors - which makes me wonder if it it even worth recapping - is there a scientific way to test them?
Surprisingly, the electrolytics are all marked bipolar but they appear to be randomly soldered on the boards. There are three different configurations for board 14 and also three for board 15, even though they all have the same marking: 14 is labelled 8006028F and 15 is 8006027F. The capacitors are labelled ROE (Roederstein?) and have a band at one end. I vaguely remember some issues with this in a previous post but can't find it
So, simple question - are these bipolars not polar!? And, suggestions please on what or if I replace them with?
Cheers, and here's wishing a very Happy B&O New Year
Paul
Bipolar means it doesn't matter which way you solder it in.
I find it difficult to source bipolars that big at the regular electronics suppliers, so searching for audio component suppliers is often useful.
/ Johan
Even if they are bipolar, they are still rolled from conductor foils, and the roll has both an outer & inner end. That's why they are marked, because that does matter in some applications for reasons that are not related to polarity.
For a speaker crossover, the difference is a practical zero. A perfectionist (or somebody with an Asperger's diagnosis) will still connect them all in the same way
As Johan says, regular component suppliers might not have them, but any DIY speaker shop should be able to help you (except for the 27uF caps, which are quite rare - you will probably need to use two caps in parallel for that). Or make it easy for yourself and get the whole kit from Dillen.
The parameter that goes bad in them is ESR, and you need a specialized instrument to test that. These speakers are all so old now that it is rather safe to assume that a recap (with the more affordable regular bipolar caps instead of anything "audiophile") will be worth it in every case, especially if you have the filter boards on the desk already.
--mika
Thanks for the replies guys. Should have known about bipolars, but we live and learn.
Interestingly, despite the Penta 1 label of 6602 on the powered pair and 6611 on the passive speakers, these both seem to have Penta 2 boards with the 6621 set up, so the caps are pretty standard as follows (spot newbie descriptions!):
Will see if Dillen can do a kit for these.
Cheers, Paul
General rule of thumb - when dealing with speakers, bipolars are preferred.
Nichicon ES are quite affordable, and recognized as the best of the Bipolar electrolytics, before you start getting into exotic film caps.
Those MMK / MKT caps (and most/all of the small values you didn't identify as bipolars already) are plastic foil capacitors. There's no need to replace them unless they are visibly damaged, they don't age at all.
And fit nothing less than 100V components.At max the Penta amplifiers can output close to 100Vac (!)
Martin
Thanks to all for the very helpful comments.
Bit of a shame about the 100V rule - large MKP or even MKT seem really expensive so I was planning on trying Nichicon DB, GB for the 68uF capacitors but these max at 50V. Any suggestions on the best compromise between price and performance for the 22, 27 and 68uf sizes at 100V? (Example costs for 68 alone: 3 in each penta; 4-6 to do; cheapest MKP about £15; = £180 to £270 just for these caps)
Cheers,
PS Got the list sightly wrong too - board 15 C1 is 27uf not 22 as my ailing eyesight (and hopeful bank balance) said