View Full Version : My mistake of not testing AMP now SOL
04-28-2005, 12:24 AM
I had bought an Alpine MRV-t301 view (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=5753846622&ssPageName=STRK:MEWN:IT) to match my mrv-t501 that was running my 6x9's. Upon arrival I visually inspected it and looked all good, but by its settings, it obviously was running a single sub. Well just now I FINALLY hook it up to my front speakers in my car and within 3 seconds the amp's fuse sparked and broke. Fuck. Replaced it, set gain to minimum, tried again and it stays on but sounds distorted. Also the sound doesn't change volume if I adjust the gain control. Distorted meaning bass is garbled, volume varies without touching any controls, speakers will occasionally shut off. I was using speaker level inputs but I checked it with line-in inputs to no advantage. So I assume it's fried. I take it apart, everything looks "alright" except some brown spots on the circuit board near some bigger solder points. I'm not sure what else to look for (I'll take a pic of the board if necessary) is there any other way to test and diagnose what the problem is on this amp? I'm more than likely screwed on this since it's been a while. Also I'm interested in recommendations for a 4-ch amp under $200 with EXCELLENT sound quality/clarity and good power to run a pair of alpine 6x9's and pioneer 6.5's. Thanky..
04-28-2005, 02:11 AM
heard of depth charge? made by memphis, it's their cost-efficient lineup. since memphis doesn't believe in on-line sales, you would either have to find a local memphis dealer or find one on ebay.
anywho memphis used to have problems with channel failure, but i've heard since their earliest amps this has been resolved. i paid right around 200 for a two channel amp that ran two memphis studio 10s quite well.
that'd be my recommendation
04-28-2005, 08:28 AM
Do you have a multimeter with diode check function?
If so, try that on each MOSFET and each output transistor. Check the voltage drop (in diode check mode) between each of the 3 pins. In no circumstance should it read 0.00V. If so, switch it to ohms mode and see if you also get near 0-ohms. If you do, there's a short.
On a completely dead amp, almost always there's at least 1 blown MOSFET transistor or output transistor. Some I've seen have multiple blown output AND MOSFET transistors. Occasionally a bad MOSFET transistor will take out a driver transistor (these are the smaller ones physically connected to the MOSFETs).
Since yours isn't completely dead, it's probably going to be a little more difficult to track down.
04-28-2005, 10:51 AM
I assume the MOSFET transistors are the black square units that are screwed down to the heat sink body, there was at least 4 of them. Let me check my multimeter. Sucks too cause the occasion that it didn't distort it sounded real good :lol: thanks
04-28-2005, 02:46 PM
a good 4ch-amp under a $100 is the pyramid 75wX4, thats what Im using in my car to power all four speakers, although if you buy this amp, you will need a filter. but I think it was about $80 and Ive had it for not quite a yr with no probs at all
04-28-2005, 02:54 PM
Yep, black square things about 1/2" wide screwed down to the heatsink would be the MOSFETs. They'll probably be near the transformer. The bigger black things about 3/4" wide also screwed down to the heatsink are usually the output transistors.
04-28-2005, 09:45 PM
ok hang on :lol: I think I got it working, and it wasn't the amps fault. Will explain in a couple hours when I finish!
04-28-2005, 11:05 PM
Ok the amp is again in and it appears to be working. My problem turned out to be one of the terminals of the front speakers were grounding onto the door frame :? So fixed that. How did I know? I bought this here (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4950&item=5770051452&rd=1&ssPageName=WDVW) for like $85 brand new on clearance/discount at my job. Wired THIS up and the same shit occured for the front half. To make a long story short the pair of Alpine amps are back in (MRV-t301 fronts MRV-t501 rears) the fronts still sound a little distorted with the bass though, and the power LED doesn't light up like it's supposed to, so maybe it's fried NOW or always was fried? And call me crazy but the Jensen amp (made by Audiovox) actually sounded pretty good! What to do now....
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