MRV-T500 internal clicking noise problem

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Hi diyaudio ppl, I'm a noob here and also to repairing amps... so please excuse me and my ignorance. :) I have a few alpines that need repaired and I'm pretty sure I'm competent enough to do it so yeah. I've actually learned quite a bit from lurking around here in just the past day or so from Perry and jol50. Awesome, thank you... I'm pretty sure I could get an MRV-1000(a couple fried fets) and MRV-100M(burned ground band and a fried fet) going from what I've read. Thank you bunches!! Perhaps I could get a little guidance when I finally jump into that? It'd be soooo greatly appreciated. :rolleyes:

Anyhow, I'd like to start with this MRV-T500 I just bought on ebay advertised as 100% functional. :down: It does work indeed but it has this really loud clicking noise as soon as you power it up and every few seconds or so. If the amp is pushed it could change the frequency of the clicks or make them go away but only for a moment longer than usual. I tried this connected to a different sub and power supply and still the same thing. Though this time it started cutting out. Amp was still on but just the audio going out. At first I thought it was since it was warming up... but when it wasn't working I hardly touched it and it started again. In this location it was sitting on top the sub and exposed to more vibration than before. Stopped again, tapped it... and it started playing again. The clicking in it is actually quite loud... seems like it would have to be something physical. I felt around a bit while it was on with the cover off and it seems to be coming from the power supply.

So, I'm guessing this is just a bad connection somewhere? Bad ground? I've done a lot of searching and couldn't find a similar problem with all the clicking. Took it completely apart and looked at the back of the board and everything looked fine but I know it's sometimes hard to tell if a joint is bad visually. I own several other MRV series amps including two other mrv-t500s which were in the same location I tested this one so I'm pretty it's not me at fault. lol :p Any help or input would be greatly appreciated! Thank you and thanks again for the awesome forum! :up:
 
Sorry... "power supply" probably wasn't specific enough. Attached an image of the part that seems to be making the clicking... the big square thing whatever it is... heh :confused:
 

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Thank you for the replies Perry. :) I was about to break apart a working MRV-T500 and start comparing things with the multimeter but first I thought I'd have another look at the one with the issue and I think I found the problem... a little crack on the board. I looked over it forever before I noticed it since most of my attention was around the inductor and this was on the opposite side. Posted some pics... sorry they kinda suck. Any suggestions on how to fix? Thanks!! :spin:
 

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Yeah I was worried about the crack running. It's not visible from the other side though, buuut as you said it's coming close to another trace. The second pic of the crack is a more accurate representation of the actual line. I think it starts at the solder joint on the left side. I plan on using this in the home though where it shouldn't be very stressed so I'm hoping it will be fine as is... *crosses fingers* maybe I'll just drill it out... another good idea. Thanks again for the help guys! :)
 
Well damn, I drilled it and bridged the connection... all went smoothly... no more cutting off but it still has the clicking... :confused: grrrr heh. Seems better though... sometimes goes away completely. Also there WAS a couple other joints that looked cracked possibly. On the big round coiled thingie next to the inductor... two of them right next to each other. I dunno what I was thinking. I should have just touched them while I had the iron out and amp apart... doh... it wouldn't have hurt. I'll have to do that........
 
Went over the points on the board... still clicking. :( It seems like since I fixed the crack it will now click faster (every second)but not as violently. Though when you drive it... it will click less but then seems to be triggered by the bass hitting as it clicks immediately after. Eventually it pretty much disappears though... weird. Any ideas?
 
Yes, it sounds flawless through the speakers. Just like the others I have. Even at high volumes... and doesn't have a heat problem or anything. If anything it seems to help. When it gets warmed up the clicking pretty much disappears all together... once in a while the clicking will fade in and back out a few times and that's it. All the functions work. Though when you change the phase it will pause the clicking for a moment.
 
Yeah I was wondering if that was a possibility. Though I have two other MRV-T500s, a MRV-T501 and two more that don't work, two MRV-1000s (apart from the one mentioned earlier), and a MRV-1005 that doesn't work too... all similar if not identical and none ever did this. I was going to disregard the clicking though and call it good since it works fine... just won't be using in the application I planned to but no problem with all the amps I have lol.

That leads me to another question... the three amps I just mentioned that don't work (two mrv-t501's and a mrv-1005) all were connected to my home stereo powered using computer power supplies and left on overnight during a bad storm. No surge protector. *sighs* When it happened there was no smell or anything. They were still on and still come on with no problem but the mrv-1005 doesn't have any output at all and the mrv-t501's act indentically as they have some output but it's not consistent at all... fading in and out and sometimes seeming to surge. Any idea what could be up or be wrong with 'em? Thanks again for the help Perry...
 
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They're getting 12 volts... but I also tested the speaker terminals and they were fluctuating back and fourth quickly between 0.01 and 1.58 volts. The B+ to ground reading also fluctuates quite a bit where as it doesn't on a working amp. No fluctuations at the speaker terminals of the working amp either but instead 0.00 as I'd think it should be when it's not driving a signal.

Also, just realized that the MRV-T500 I had worked on will not stay on with out a speaker connected. It clicks of course and shuts itself off after about 5 seconds or so... then comes back on after a few more seconds. I don't think that is normal eh? heh :(
 
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