126mhz Posted July 20, 2005 Share Posted July 20, 2005 A friend of mine clears out lots of Altec, JBL, Klipsch, and other professional equipment and sells it all over the world,....And sometimes I get the left overs! Today I picked up a BEAUTIFUL old Receiver, all tube, and it's an Altec Astro. Does anyone know anything about it? It needs a fuse, it's just missing and I tried both of the channels with the one fuse in it, and it works great! It says "2A 3AG only." Of course I have 1 amp, 2.5 amp and 3 amp fuses so I'll have to find a "2A 3AG" fuse. Will any 2Amp slow blow fuse work? Thanks for the help in advance. Bill Woodward Quote Link to comment Share on other sites More sharing options...
scriven Posted July 20, 2005 Share Posted July 20, 2005 Unless I am mistaken, and that has happened before, the 3AG refers to the mechanical form - 1-1/4" x 1/4" and could be ether fast or slow blow. Quote Link to comment Share on other sites More sharing options...
126mhz Posted July 20, 2005 Author Share Posted July 20, 2005 So,...am I safe to go with @amp slow blow fuses on both channels? Thanks Quote Link to comment Share on other sites More sharing options...
scriven Posted July 20, 2005 Share Posted July 20, 2005 What I am wondering, and this is a question not an implication that you are incorrect, is how do you know that they should be slow blow? Quote Link to comment Share on other sites More sharing options...
126mhz Posted July 21, 2005 Author Share Posted July 21, 2005 I'm glad you mentioned it because now that I think about it a fast blow fuse would be most safe if there is any question on an application. If anyone knows what a 2A 3AG fuse stands for exactly I'm all ears. I'll be heading for a local electronics store after work. If I'm shot down there I'll stop by a high end HiFi store to see if I can find some. Thanks again, Bill Woodward Quote Link to comment Share on other sites More sharing options...
crazytubepower Posted July 21, 2005 Share Posted July 21, 2005 Head over to the local rat shack at they will hook you up Quote Link to comment Share on other sites More sharing options...
CaptnBob Posted July 21, 2005 Share Posted July 21, 2005 The Astro is a pretty neat receiver - very "Jetsons" looking. I could be misremembering, but I think it may be a hybrid. A lot of older tube electronics use "Slo-Blo" fuses. The idea was that the amp might draw a lot of power when it's first turned on, so you don't want the fuse to pop under a momentary load. However, if a problem develops later on, and the fuse rating is exceeded for more than a second or so - like when that Bulgarian KT-88 goes unstable - then the fuse will pop and protect the amp. Quote Link to comment Share on other sites More sharing options...
scriven Posted July 21, 2005 Share Posted July 21, 2005 Is it a speaker protection fuse or is in there to protect the electronics? If they wanted a slow blow wouldn't that be indicated in the labeling? Quote Link to comment Share on other sites More sharing options...
126mhz Posted July 21, 2005 Author Share Posted July 21, 2005 It has three fuses total. Two are the 2A 3AG that I have mentioned and I'm assuming that they are one for each channel. One other fuse is a 1.5Amp fuse. Update, I bought some fuses labeled 2A 3AG and they are slow bolw fuses. I did a search and found a thread on the Altec site and this receiver cost $597.00 in 1963!!! It is a close to mint as anything could be for being made in 1963,...It's just beautiful. I fired it up and put it through a soft start circut. It sounds so nice on my LaScalas. Then I hooked it up to drive my Klipsch KP301s and the thing really rocks. Needless to say, I love it! Regards, Bill Woodward Quote Link to comment Share on other sites More sharing options...
scriven Posted July 21, 2005 Share Posted July 21, 2005 It sounds like the 2A fuses are speaker protection and are not critical to the amps functioning. Enjoy the music! Quote Link to comment Share on other sites More sharing options...
CaptnBob Posted July 22, 2005 Share Posted July 22, 2005 It does sound like the 2AG fuses are for speaker protection. Those should be fast blow - a slow blow won't melt fast enough to save your speakers. These fuses are nice to have because early solid state amps - some later ones too - could go unstable and dump the entire contents of the power supply into your speakers with a mind (and voice coil) shattering thump. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 22, 2005 Share Posted July 22, 2005 If a Slo Blo fuse is required the amplifier or schematic will usually say it. If these are speaker protection fuses most likely they are not suppose to be Slo Blo. Never install a slo blo where a fast acting fuse is the specification. Radio Shack sells both Slo Blo and fast acting they would both have the 3AG designation this is simply the size of the fuse like mentioned above. Craig Quote Link to comment Share on other sites More sharing options...
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