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#1
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ADA Stereo Delay repair advice needed
I have the STD-1 with a problem. When I turn it on the lights come on
and then about 10-15 seconds later the lights fade out. At that point the input light just flashes about 120 times a minute (yes I counted). I tried replacing the main two caps right after the powersupply but no luck. Any idea on what this could be and if not does anyone know of a place that would specialize in this kind of thing? I already emailed Analogman and am awaiting response. Thanks Jesse |
#2
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Jesse Skeens wrote:
I have the STD-1 with a problem. When I turn it on the lights come on and then about 10-15 seconds later the lights fade out. At that point the input light just flashes about 120 times a minute (yes I counted). I tried replacing the main two caps right after the powersupply but no luck. More likely it's one of the smaller decoupling caps. One of the tantalums is failing into a short when it heats up. You can try using freezone on them individually and seeing which one cures it. If you are VERY careful you can start cold and individually heat the tantalums up with a soldering iron until you find the guilty one. Or you can shotgun all of them. Could also be a cold solder joint, but if it's thermally related, the tantalums are a very popular failure. If you have any chips that are in sockets, pull them out and reseat them too. That's another source of thermal issues, although a less popular one. Any idea on what this could be and if not does anyone know of a place that would specialize in this kind of thing? I already emailed Analogman and am awaiting response. This stuff is easy to work on. Your neighborhood TV repair can deal with it. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#3
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More likely it's one of the smaller decoupling caps. One of the tantalums
is failing into a short when it heats up. You can try using freezone on them individually and seeing which one cures it. If you are VERY careful you can start cold and individually heat the tantalums up with a soldering iron until you find the guilty one. Or you can shotgun all of them. Scott, I looked up Freezone but didn't find anything, is that the correct spelling? I assume this is some kind of freon I can spray on the cap to keep it cool? As far as taking it to a TV repair place do they need schematics or anything special like that? Jesse |
#4
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Jesse Skeens wrote:
More likely it's one of the smaller decoupling caps. One of the tantalums is failing into a short when it heats up. You can try using freezone on them individually and seeing which one cures it. If you are VERY careful you can start cold and individually heat the tantalums up with a soldering iron until you find the guilty one. Or you can shotgun all of them. I looked up Freezone but didn't find anything, is that the correct spelling? I assume this is some kind of freon I can spray on the cap to keep it cool? It's a kind of spray that cools things down _abnormally_ so that you can find things that fail when they freeze or get hot. I don't know if Freezone brand is still around, but I am sure GC Electronics sells something like it, and your local electronics parts place probably carries it. As far as taking it to a TV repair place do they need schematics or anything special like that? It would probably help, but the fact that it's temperature related and it's on the digital side might be enough. If you're paying time and materials for work, you will invariably wind up paying less if you provide complete documentation, though. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#5
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Look at www.newark.com enter freeze in the search box.... to see what
Scott had in mind.... However the first thing you should do is look for the ....warmest component... other than the pass transistor or regulator in the power supply..... Although tantalums are one suspect, they are not the only one..... cmos logic chips are another suspect.... If you have a board layout you can use a milivolt meter to find the problem.... measure the voltage drop in a couple of inches of circuit board trace on the power supply distribution lines (an ammeter with the resistance of the circuit board trace as the shunt).... when you get to the place in the distribution line with no drop you have passed the shorted point. Regards: Eric "Jesse Skeens" wrote in message om... More likely it's one of the smaller decoupling caps. One of the tantalums is failing into a short when it heats up. You can try using freezone on them individually and seeing which one cures it. If you are VERY careful you can start cold and individually heat the tantalums up with a soldering iron until you find the guilty one. Or you can shotgun all of them. Scott, I looked up Freezone but didn't find anything, is that the correct spelling? I assume this is some kind of freon I can spray on the cap to keep it cool? As far as taking it to a TV repair place do they need schematics or anything special like that? Jesse |
#6
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(Jesse Skeens) wrote in message . com...
I looked up Freezone but didn't find anything, is that the correct spelling? I assume this is some kind of freon I can spray on the cap to keep it cool? As far as taking it to a TV repair place do they need schematics or anything special like that? Jesse All the documentation and schematics for the STD-1 can be found he http://www.adadepot.com/adagear/gear.../ADA-STD-1.htm Those are definitely cool sounding units. A lot of fun to play around with. And apparently they're somewhat rare because I've seen more than one of them sell for over $400 on eBay within the past couple of years. Do you have the version with 1/4" inputs/outputs, or is yours XLR? I think the XLR ("studio") version is the _very_ rare one. |
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