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Post by erased99 on Nov 16, 2014 20:08:35 GMT -5
Hello Sub is around 10 years old, Athena AS-P400 10" driver, 100W mossfet amp. Denon AVR 1712 receiver connected using an RCA Low Level Sub In cable. I've had a problem with this sub a few years ago, it stopped outputting any sound, if I remember correctly... I paid $100 for parts/labour, the guy might've changed a switch? I can't remember... The sub worked OK since that repair (maybe 5 years ago) until a couple of days ago when while watching a movie, it suddenly made a loud popping noise (during a bass intensive scene) and the volume dropped to barely audible. It looks like there's still power going to it, the LED is on, but I can barely hear it, even at max volume. I unplugged the sub from power for a few minutes, I switched the Low Level RCA from "sub in" to "direct in", Checked settings on my receiver, still very low sound. I removed the amp to take a look at the fuse, it looks OK... Capacitors also appear to be OK (not blown or leaking). I see some yellow spots around power and fuse connectors on the board, not sure if that is corrosion and if it'd affect the amp? My Subwoofer pictures are here: Athena PicturesAS-P400B-1 SERIAL # 0945640 The Boards revision numbers are in the pictures. I also found markings, written in pen inside amp., for a mosfet switch? (2383 100V 10A), it might've been what the guy replaced 5 years ago? All the pics are hereSpecs & info: Home Theater and SoundAthena AS-P400 Front-mounted controls Auto on/off (with dual-LED indicator) Adjustable bass level 10" injection-molded polypropylene driver (with rubber surround) 100W MOSFET amplifier Front-ported design High-level (speaker) connections Mono line-level input Direct Input to bypass crossover Internal protection circuitry Anti-clipping circuitry ManualFeatures and SpecsI have a volt meter and am handy with a soldering iron, but I need help with further testing Can anyone help with troubleshooting? Any help would be greatly appreciated! Thanks guys! |
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nashou
Unmoderated Off Topic
Tech in Training.....
Posts: 1,239 
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Post by nashou on Nov 17, 2014 11:25:14 GMT -5
one thing you can do to see if its the woofer or the amp is to play the test to tone through the Sub with the woffer not connected and put the DMM on the speaker wires
to see if there is any AC going to them. Also check for any DC as that is bad.
Mastertech would be able to help more if he can get schematics for it.
Athanasios
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Post by mastertech on Nov 17, 2014 12:15:08 GMT -5
2 basic things that need to be checked first.
1)If your Denon has another preamp output(front left or right) ty that. You need to be sure you have a good preamp signal going to the sub.
2)If you have another old speaker that you can connect in place of the sub driver that is in there now to make sure you just didn't blow the speaker out.
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Post by erased99 on Nov 17, 2014 17:48:15 GMT -5
one thing you can do to see if its the woofer or the amp is to play the test to tone through the Sub with the woffer not connected and put the DMM on the speaker wires to see if there is any AC going to them. Also check for any DC as that is bad. Mastertech would be able to help more if he can get schematics for it. Athanasios Thanks nashou I'm not an expert in audio or electronics for that matter, I know a little bit about that and have worked on both previously, but please bear with me as I'm learning!  I hooked up my portable MP3 player directly to the speaker and I could hear music, but at low volume, even with volume turned all the way up. I'm thinking it would be around the same as through headphones... Also hooked up an older boom box and the sound was MUCH louder but not as clean (sounded mono like, the bass was OK though  I'm thinking the speaker is OK? I'll try your method and report back. Thanks again for your help. |
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Post by erased99 on Nov 17, 2014 18:05:34 GMT -5
2 basic things that need to be checked first. 1)If your Denon has another preamp output(front left or right) ty that. You need to be sure you have a good preamp signal going to the sub. 2)If you have another old speaker that you can connect in place of the sub driver that is in there now to make sure you just didn't blow the speaker out. Hi mastertech As I was telling nashou I know a little bit about electronics so please bear with me as I'm learning I don't think my receiver has another preamp, I looked through the manual: Denon Manualand could only find the one for the sub. Unfortunately I don't have another speaker to test with either... Any other ideas? PS As I was telling nashou I was able to do this: I hooked up my portable MP3 player directly to the speaker and I could hear music, but at low volume, even with volume turned all the way up. I'm thinking it would be around the same as through headphones... Also hooked up an older boom box and the sound was MUCH louder but not as clean (sounded mono like, the bass was OK though Would that mean that the speaker is OK? Thanks again for your help! |
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Post by erased99 on Nov 17, 2014 18:37:44 GMT -5
one thing you can do to see if its the woofer or the amp is to play the test to tone through the Sub with the woffer not connected and put the DMM on the speaker wires to see if there is any AC going to them. Also check for any DC as that is bad. Mastertech would be able to help more if he can get schematics for it. Athanasios OK I hooked the amp to my denon like you said and played some music. I'm getting 43V DC and 94.9V AC thanks |
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Post by mastertech on Nov 17, 2014 23:28:17 GMT -5
Was that 43v DC on the wires connected to the sub speaker?
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Post by erased99 on Nov 18, 2014 4:58:08 GMT -5
Was that 43v DC on the wires connected to the sub speaker? No, the speaker was disconnected from the amp. I measured the wire that would go to the speaker. Another thing I noticed that there's current going to the speaker wire just by plugging the amp to power lines, the RCA sub line was disconnected from receiver. I was getting same voltages on AC and DC, like I stated in previous post. Thanks |
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Post by mastertech on Nov 18, 2014 10:04:21 GMT -5
Well that is not good.
I could not find a schematic for your sub so I will try to blindly walk you through it, lol. Testing for now is with unit unplugged.
There is a component on each of those heat sinks. Set your DMM to diode scale and test those components 1 at a time. Test across various legs and see it you show short, or close to short on any combination of tests.
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Post by erased99 on Nov 18, 2014 19:26:59 GMT -5
Well that is not good. I could not find a schematic for your sub so I will try to blindly walk you through it, lol. Testing for now is with unit unplugged. There is a component on each of those heat sinks. Set your DMM to diode scale and test those components 1 at a time. Test across various legs and see it you show short, or close to short on any combination of tests. Hi I'm not sure it'll help but Athena was one of the brands of API (Audio Products International), along with Energy and Mirage. API was bought by Klipsch in 2006 See here or hereI'll let you know of my diode test results in a little bit... Thanks |
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Post by erased99 on Nov 18, 2014 20:45:27 GMT -5
Well that is not good. I could not find a schematic for your sub so I will try to blindly walk you through it, lol. Testing for now is with unit unplugged. There is a component on each of those heat sinks. Set your DMM to diode scale and test those components 1 at a time. Test across various legs and see it you show short, or close to short on any combination of tests. Hello I followed this video on testing diodes: YouTubeI tested first with the probe negative to negative on diode & probe positive to positive on diode then reversed: probe-/-diode probe+/+diode reversed probe-/+diode probe+/-diode Readings: Diode# = probe, probes reversed polarity 1=461, 462 2=1336, 0 (I think this is a capacitor though, not a diode?) 3=602, 0 4=1802, 0 5=1022, 0 6=0, 0 7=0, 0 8=0, 0 9=739, 739 10=0, 0 11=0, 0 12=0, 0 13=1009, 0 14=1651, 1658 15=1647, 1653 16=599, 0 17=1680, 600 I measured everything twice to double check my readings. It appears that 11 out of 17 are bad? Here's the pic with the diodes tested, marked for reference: Diodes marked in redI also quickly checked the remaining 30 or so diodes and it appears that around 1/3 of them are bad! Am I doing this correctly? LOL |
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Post by mastertech on Nov 18, 2014 21:38:33 GMT -5
The heat sinks are the large metal plates sticking up on each side of the board. There is 1 component on each metal plate, or at least that is how it looks in your pictures. These 2 components are probably the mosfets. There should be 3 legs on each one. Test them and post you readings.
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Post by erased99 on Nov 19, 2014 1:47:53 GMT -5
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Post by mastertech on Nov 19, 2014 9:46:33 GMT -5
irf520 looks to be bad. You will need to test some surrounding parts for damage. You need to remove it before testing other parts. Also retest the mosfet after removal. Can you post a picture of the back of the board where irf520 is located?
Also a picture of the back of board for irf730's.
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Post by erased99 on Nov 19, 2014 23:09:48 GMT -5
irf520 looks to be bad. You will need to test some surrounding parts for damage. You need to remove it before testing other parts. Also retest the mosfet after removal. Can you post a picture of the back of the board where irf520 is located? Also a picture of the back of board for irf730's. Hi I removed the mosfet irf520 and tested it, it's the same: irf520 -probe to source +probe to drain 0 -probe to source +probe to gate 001 +probe to drain -probe to gate 0 Also tested diodes, capacitor, etc. around the mosfet, after removing it. Picture with numbered caps, etc., here: i1312.photobucket.com/albums/t529/no1_cdn/Athena%20AS-P400/IMG_1416A_zps1d901150.jpgI tested first with the probe negative to negative on diode & probe positive to positive on diode then reversed: probe-/-diode probe+/+diode reversed probe-/+diode probe+/-diode 1=599, 0 2=022, 022 3=1190, 1207 4=385, 0 5=385, 0 6=385, 0 7=450, 460 8=0, 0 9=0, 0 10=0, 0 Back of the board irf520 i1312.photobucket.com/albums/t529/no1_cdn/Athena%20AS-P400/IMG_1410a_zps1e2f11f4.jpgBack of the board irf730 i1312.photobucket.com/albums/t529/no1_cdn/Athena%20AS-P400/IMG_1413a_zps62b22b1e.jpgTried to get a better shot... i1312.photobucket.com/albums/t529/no1_cdn/Athena%20AS-P400/IMG_1414_zps2fe7bf5c.jpgi1312.photobucket.com/albums/t529/no1_cdn/Athena%20AS-P400/IMG_1415_zps1cdb6341.jpgThanks |
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