Greetings, I found some caps with bulging tops in my Harman Kardon AVR-240 and am not having any luck finding exact replacements so unless anyone knows where I can find these I guess I need to know what my options are for suitable replacements. I have read some who say that the voltage ratings must be adhered to very strictly and yet others who are using ones with voltage ratings far outside the originals both ways but mostly higher. Anyway a bit of clarity on that would also be much appreciated as, although this one is an AVR, I think I'm going to start buying vintage stereo receivers and trying them out to see which ones sound the best with each pair of my speakers until I find a sweet spot and I know that most of them in my price range will probably need at the very least some caps replaced. This one is a guinea pig, its a backup for my backup system lol. It was working and I had it in my bedroom with 4 older JBL speakers until I found a deal I couldn't resist on the rest of the JBLs that match the ones I have and when I went to pick them up, the lady handed me an extra box and said that it was a freebie. I was in a bit of a rush so I didn't question her or bother to see what it was at the time. Considering the JBLs were still in factory sealed boxes, I was assuming that it was what the box was from and sure enough, when I got home and started breaking into boxes, she had given me a shiny new Harman Kardon AVR 347 along with all the speakers including a second subwoofer that wasn't listed in the ad. I called her to see if it was a mistake and she said, "nope, you can keep it all" She said that it was her husbands system that he had bought for a man cave that he never even started and she was taking over the unused space for her fitness room and she just wanted it all out. So that is now my new one for my room and decided to open this old beast up and see what she looks like under the hood. Abit dirty but other than that and these 4 bulging caps, all looks pretty good.
The tops bulging is normal when plastic warms up and cools down multiple times.
Nothing to worry about and expected to happen.
The only time to worry is when they vent and that is from the connector end, not the top, in this type of capacitor. The only time they vent from the top is when there is a cut made into the aluminium can and then, they are always uncovered. They do not have a plastic cover on them in that case.
Put them back, they are fine.
Nothing to worry about and expected to happen.
The only time to worry is when they vent and that is from the connector end, not the top, in this type of capacitor. The only time they vent from the top is when there is a cut made into the aluminium can and then, they are always uncovered. They do not have a plastic cover on them in that case.
Put them back, they are fine.
Wow, that's the first time I've heard anyone say that! Anyway, cool. That saves me some money, looks like around $60 to $80 minus shipping and taxes for similarly rated ones but the only ones I could find that were identically rated were larger sized. I have a multi meter but it doesn't have a capacitence setting. I know there are several ways to test them so I'll try a couple before I do. Now I'm kicking myself in the rear for removing them. Thanks a bunch.
OK, I see what you're saying now. All the smaller ones have "x" shaped cuts in the aluminum tops. None of those are bulging or open. Now, that brown gooey stuff that was all around the bottom of these... That's not from these, correct? It's some type of adhesive? And do I need to re-apply something there? Because I cleaned as much as I could from the board.
Sorry, and 1 more question. There were little white squares of "paper" between the resistors and the heat sync and some of them disintegrated while I was separating the board in order to clean in between them. What should I use when I re-assemble it? I have conductive silicone for use between motherboard CPUs and their heat syncs but not sure if that's the right thing to use here...
@RayD8r , I hoestly think that you're over-obsessing and overthinking all this audio stuff.
If I were you, I'd stay out of the equipment until something is not right.
Sound like you're putting the cart before the horse.
And even then, you'll need to learn at least some basic electronics servicing techniques.
Avoid those internet self-appraised internet guru's who insist that others mess around with "recapping" for no good reason. - that crap's gotten way out of hand and rediculous, if not dangerous to novices who don't know better.
This is advice from a 45+ year professional service tech - ME.
If I were you, I'd stay out of the equipment until something is not right.
Sound like you're putting the cart before the horse.
And even then, you'll need to learn at least some basic electronics servicing techniques.
Avoid those internet self-appraised internet guru's who insist that others mess around with "recapping" for no good reason. - that crap's gotten way out of hand and rediculous, if not dangerous to novices who don't know better.
This is advice from a 45+ year professional service tech - ME.
AVNTKER Double Sided Thermal Tape 25mm/1inch x 66 Feet Super Strong Adhesive Non Conductive Heatsink Sticky Tape for CPU, GPU, SSD Drive, HDD, VGA, PCB, LED Strips, 3D Printer, Raspberry Pi Radiator https://a.co/d/6hsvwWA
I'm at work but I'll post pics of the resistors when I get home
Those are TRANSISTORS!
Not REsistors!
PROPER terminology is mandatory in discussing electronics.
You've made a mess of things now, and re-installing all those TRANsistors with undamaged or new insulating pads and fresh heatsink thermal paste is going to be a big hassle because of potential alignment issues due to your lack of understanding about these things. (over-flexing connecting leads, torque of mounting bolts, etc.)
Sorry, I'm out of here.
Not REsistors!
PROPER terminology is mandatory in discussing electronics.
You've made a mess of things now, and re-installing all those TRANsistors with undamaged or new insulating pads and fresh heatsink thermal paste is going to be a big hassle because of potential alignment issues due to your lack of understanding about these things. (over-flexing connecting leads, torque of mounting bolts, etc.)
Sorry, I'm out of here.
I assume you are referring to my comment about conductive silicone.
I meant thermal conductive silicone, sorry if that sounded like I meant electrically conductive. I have it from swapping out a CPU on my mobo that didn't come with a heat sink so I had to use the one from the oem and I also used it to fix a couple of red ringed x-box 360s for my kid.
Wow what a dick. It's an old AVR that I don't even care about. I'll throw the entire stupid thing in the recycle bin for all I care. I didn't know I needed a degree to try and learn about Audio equipment. We aren't all born with them. It seems I have picked the wrong place to ask for advice. And FYI when I looked them up by the numbers that are printed on them, Google gave me results for resistors, that's the only reason I was calling them that!
If you have a multi meter, switch to the low Ohm position and measure metal of the transistor to heat sink. The resistance should be very high or completely open. With so many transistors, it is quite easy to make a short with one. The surface of the heat sink seems coated with elox, this does not conduct electricity, so connect one pole of the multimeter to something like the mounting traverse made from steel, then touch the transistor metal. From the pictures it looks fine so far.
PS there are little cirquit boards with a black transistors, two small resistors, a small black capacitor and a grey/ white trimmer. Do not touch the trimmer, it adjusts the idle current and is set by the factory. The only have to get adjusted if transistors are changed.
The tape you linked to should be fine for the task.
The tape you linked to should be fine for the task.