Mechanical connection of new capacitors - Vintage Audio Recapping - Page 1
Forum section: electronics / beginners

author: riffmaker
author_rank: Newbie
timestamp: March 05, 2019, 08:47:43 am
content: Hi All,I am currently recapping a vintage audio receiver (Harman Kardon TA600) and I changed the main power capacitors by new ones. I anticipated the fact that the diameter of the new ones would be smaller, and I used a kind of foam to compensate. But unfortunately the negative pin of the old capacitors was connected to a metal part (also common ground for many other boards), see picture attached.The problem is that with new capacitors, the spacing between pins is different and does not fit with the metal ground part (see picture attached). I know that it wouldn't be very clean, but do you think that I could solder a wire (large section) between the capacitor pin and the metal ground part ? Same question for the positive pin and the diode bridge ?Thank you for your helpPierre

author: xwarp
author_rank: Frequent Contributor
timestamp: March 05, 2019, 10:08:46 am
content: It's kind of hard to tell from the picture, so I could be wrong, but I'd make sure the polarity of the cap, (orientation), is correct.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: March 05, 2019, 03:40:05 pm
content: The answer to your question is "yes", you can connect the new capacitors to the old wiring and ground point with short bits of wire of appropriate diameter. Do it carefully and neatly and if possible use some kind of insulating sleeve, like bits of insulation stripped off of larger wiring, to cover bare wiring. If you don't have a lot of experience soldering, practice on some scrap wire before doing it inside the chassis.But do makesurethat you have the polarity of the capacitors the right way around. On the new electrolytics the NEGATIVE side will be indicated by a stripe along the body. On the old capacitors it appears that the POSITIVE side is marked with a red dot on the terminal itself (check to make sure). Inspect old and new caps carefully to be sure about the negative and positive terminal orientations and be sure that you connect the new ones correctly.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: March 05, 2019, 03:43:50 pm
content: Actually it looks to me like no additional wire is really necessary. Some careful work with small needlenose pliers can connect the ground bus and the diode bridge to their respective terminals on the caps for soldering, and there is enough slack in the other wiring to connect them also without splices or jumpers. I think.Just be sure the caps are in the right way round.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 06, 2019, 01:51:19 am
content: The original wiring looks pretty much like a bodge anyway, so you may even be able to improve upon it!With the new caps, mechanical rigidity is king--- make sure they can't "wobble around".Only then, approach the wiring of the ground connection back to the chassis.Make sure the connecting wires (if you are using the original ones) & the chassis connection are really clean,(I would use a stiff brush & IPA or similar).When you make the ground connection, use liquid resin flux & a large enough tip to heat the connection up quickly.By the the way, I would be seriously tempted to send that diode bridge "to rectifier heaven".It probably has, at worst, been subject to considerable overload, & at least, covered in conductive/corrosive "gunk".PS :- looking at the second pic again, you seem to have already done a good job with the cleanup.Maybe scrape some of the remaking brown discolouration off?

author: riffmaker
author_rank: Newbie
timestamp: March 06, 2019, 01:46:16 pm
content: Hi All,Thank you for the answers.I will surely buy a new copper rodd and redo the entire ground connection.@vk6zgo : Yes I already cleaned some parts of the chassis connection with IPA. What would be the benefit to use liquid resin flux ? Not enough to just use the solder ?

author: vk6zgo
author_rank: Super Contributor
timestamp: March 07, 2019, 12:07:49 am
content: Quote from: riffmaker on March 06, 2019, 01:46:16 pmYes, it should be good, it's just that I have found it easier to get good, clean, large joints using LRF.