Hello,
Attached is a pic of the board inside my Steve Sank modified Parasound HCA-1000A. I am currently recapping the four large filter caps located in the center and am cleaning the PCB from their electrolyte leakage. It eluded me, but I found another electrolytic cap, which I have circled here in red, which has also leaked some electrolyte onto the board but no bulging at the top at all. It's a 25V 1000uf cap. As you can see the amp is laid out "dual mono" if you will, with a few parts not mirrored on each side and this part is one of them. It's located near that Omron relay. Anyone know what the function of this cap is and if I should swap it out? Wondering how silly it would be if I tried to get by not changing it. Any help would be appreciated. Thanks.
Attached is a pic of the board inside my Steve Sank modified Parasound HCA-1000A. I am currently recapping the four large filter caps located in the center and am cleaning the PCB from their electrolyte leakage. It eluded me, but I found another electrolytic cap, which I have circled here in red, which has also leaked some electrolyte onto the board but no bulging at the top at all. It's a 25V 1000uf cap. As you can see the amp is laid out "dual mono" if you will, with a few parts not mirrored on each side and this part is one of them. It's located near that Omron relay. Anyone know what the function of this cap is and if I should swap it out? Wondering how silly it would be if I tried to get by not changing it. Any help would be appreciated. Thanks.
Attachments
I change amp caps when the power drops off the rating, or the sound gets weird. Usually well before they leak. I've only seen one or two leaky ones in the ~400 caps I've changed since 2008 when I quit work. Power I measure on the speaker terminal with an analog VOM, right below clipping. P=(V^2)/Z where Z is speaker impedance. Usually Z=~1.3*R where R is speaker resistance.
Cap could have something to do with the protection relay, of which there is usually only 1.
The only source I've found of 3000-10000 hour service life caps is national distributors. Those are the caps that will last more than a year if your amp is on 12 hours a day ( which my main amp usually is). So the freight on the box is $8 (newark) to $14 (mouser). (Your location may vary) I don't save much by not buying a $.35 cap. So I tend to buy them all, then change them 2 at a time between audible tests. If the amp got worse, I know right where I made a bad solder joint.
Do what you want, but cleaning up a corrosive mess is not my idea of a fun job. Which I had do to the ST70 after a bargain cap I got from Stereo Cost Cutters, leaked and shorted the 3rd time I turned it on.
Hint, the service life can be seen in the selector table of newark & digikey. mouser makes you read the datasheet on every part number. Alliedelec only sells 1000 hour caps, the kind the pro repair shops use so you will be a repeat customer in a year or two.
Not likely the relay cap is run very hard, you might get away with not changing it. If you don't, date all the ones you do with a sharpie so that you know where the problems will be the next time you take the cover off.
BTW, the organ I put 77 new caps on in 2009-10, I just turn it on & play it. Just like when it was new. Not broken all the time like an appliance with time fuses left installed. (dried up rubber caps).
Cap could have something to do with the protection relay, of which there is usually only 1.
The only source I've found of 3000-10000 hour service life caps is national distributors. Those are the caps that will last more than a year if your amp is on 12 hours a day ( which my main amp usually is). So the freight on the box is $8 (newark) to $14 (mouser). (Your location may vary) I don't save much by not buying a $.35 cap. So I tend to buy them all, then change them 2 at a time between audible tests. If the amp got worse, I know right where I made a bad solder joint.
Do what you want, but cleaning up a corrosive mess is not my idea of a fun job. Which I had do to the ST70 after a bargain cap I got from Stereo Cost Cutters, leaked and shorted the 3rd time I turned it on.
Hint, the service life can be seen in the selector table of newark & digikey. mouser makes you read the datasheet on every part number. Alliedelec only sells 1000 hour caps, the kind the pro repair shops use so you will be a repeat customer in a year or two.
Not likely the relay cap is run very hard, you might get away with not changing it. If you don't, date all the ones you do with a sharpie so that you know where the problems will be the next time you take the cover off.
BTW, the organ I put 77 new caps on in 2009-10, I just turn it on & play it. Just like when it was new. Not broken all the time like an appliance with time fuses left installed. (dried up rubber caps).
The brown goo around that cap and also where the large caps used to be looks a lot more like glue to me, than it resembles electrolyte. LArge caps are often glued onto boards to help prevent them vibrating and cracking their solder.
As to the function or red circle cap, my guess is it is the power supply for the relay nearby. Note the little bridge rectifier next to it and the fuse. I'd suspect one of the nearby connectors carries AC in from the transformer. SOme serious cobble work down either side of the big hole.
As to the function or red circle cap, my guess is it is the power supply for the relay nearby. Note the little bridge rectifier next to it and the fuse. I'd suspect one of the nearby connectors carries AC in from the transformer. SOme serious cobble work down either side of the big hole.
Very poor quality of work on this "mod". If a capacitor is actually leaking, then it must be replaced.
Thanks, guys, for the replies. I appreciate it. Good information. I figured that cap was maybe part of the supply for the relay. That may very well be glue where the big caps were! Indeed. Upon inspection just now it appears that is in fact what it is as I don't see any discharge coming out of the cap at all. But, those caps were about 20 years old so a recap will be good.
Interesting the cobbled mod work. Ha ha. Does it look like it? Have to say I'm not an expert. I bought this amp from someone in its modded state several years ago. It's a great sounding amp. I had heard of Steve Sank and apparently he did the mod. I didn't think the work looked too bad really but you guys are experts. I was told these were the mods:
• Copper RCA's and binding posts
• Matched output drivers
• Sonicaps throughout
• Sand resistors replaced with metal film resistors
• Mur series ultra fast diodes replaced original bridge rectifiers
• Cryo treated 6/9's copper wire.
• Disabled features are: bridge mode, loop output jacks removed, and level controls removed
Interesting the cobbled mod work. Ha ha. Does it look like it? Have to say I'm not an expert. I bought this amp from someone in its modded state several years ago. It's a great sounding amp. I had heard of Steve Sank and apparently he did the mod. I didn't think the work looked too bad really but you guys are experts. I was told these were the mods:
• Copper RCA's and binding posts
• Matched output drivers
• Sonicaps throughout
• Sand resistors replaced with metal film resistors
• Mur series ultra fast diodes replaced original bridge rectifiers
• Cryo treated 6/9's copper wire.
• Disabled features are: bridge mode, loop output jacks removed, and level controls removed
None of those mods look weird, except the special copper wire. Ultra fast diodes can cause RF noise @ 120 hz that ordinary slow recovery diodes won't. Make sure the mod guy put .01 to .1 uf disk caps across the output of the bridge made of UF diodes. Or more fiddly, those caps series a 50 to 500 ohm resistor to make a super sophisticated "snubber".
Yes, the brown stuff is hot melt glue. Cap leakage dries white and is crusty. Cap slime eats copper over time & has to be washed off with water, alcohol, maybe detergent water. Gentle scrubbing with paper towel is my prescription. Final water rinse to remove all chemicals.
20 years is about max on rubber sealed caps even in industrial quality PA amps. 27 years on an Allen organ that the factory repairman says "never needs electrolytic caps". Yeah, tell that to the meter that measured 2 watts out of a 100 watt amp. I was asked to quit posting on organforum because the factory guy is expert & my meter is wrong. Meanwhile after 3 years & 17 e-caps the 100 w amp puts out 100 watts.
Yes, the brown stuff is hot melt glue. Cap leakage dries white and is crusty. Cap slime eats copper over time & has to be washed off with water, alcohol, maybe detergent water. Gentle scrubbing with paper towel is my prescription. Final water rinse to remove all chemicals.
20 years is about max on rubber sealed caps even in industrial quality PA amps. 27 years on an Allen organ that the factory repairman says "never needs electrolytic caps". Yeah, tell that to the meter that measured 2 watts out of a 100 watt amp. I was asked to quit posting on organforum because the factory guy is expert & my meter is wrong. Meanwhile after 3 years & 17 e-caps the 100 w amp puts out 100 watts.
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LOok at the two bridge rectifiers and four fuses. Below the two outer fuses, see the TO220 transistors with their legs all bent so the holes might work, plus resistors and caps soldered to other parts in mid air. That is the cobble I am talking about.
And the three film resistors twisted together to make ballasts for the output transistors looks pretty amateur to me. Just my opinion.
And the three film resistors twisted together to make ballasts for the output transistors looks pretty amateur to me. Just my opinion.