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MS-2125 Amp fuses question
Posted: Sat Nov 06, 2010 1:08 pm
by gothpunk4christ
I received this amp from a friend who said it didn't work. It looks like the main issue is that 2 fuses need to be replaced/installed. I've done a few searches and haven't been able to find a schematic.
Here's a picture of it and the 2 fuses I need are on the far right side. They are the larger fuses, not the smaller ones.
MS-2125
Posted: Sat Nov 06, 2010 2:14 pm
by ttocs
are the diods between them burned up or have they been replaced?
Posted: Sat Nov 06, 2010 2:16 pm
by gothpunk4christ
I'm not sure. Those Zener diodes, it appears to just be rosin.
Posted: Sat Nov 06, 2010 2:20 pm
by joerg
The fuses are 40 Amps

Posted: Sat Nov 06, 2010 2:21 pm
by gothpunk4christ
joerg wrote:The fuses are 40 Amps

Awesome. 120V?
Posted: Sat Nov 06, 2010 2:25 pm
by valeks1
AGU Type 40A. If you need I think I have.
Posted: Sat Nov 06, 2010 2:27 pm
by gothpunk4christ
valeks1 wrote:AGU Type 40A. If you need I think I have.
Ah, well I appreciate it! I have several resources though I should be able to find something. If I have any trouble getting them I'll give you a holler!
Posted: Sat Nov 06, 2010 3:25 pm
by gothpunk4christ
32VAC it appears.
Posted: Sat Nov 06, 2010 3:52 pm
by oldschoolfan
Sure looks like someone dumped some solder on those diodes. Caps look original too.
Posted: Sat Nov 06, 2010 3:57 pm
by gothpunk4christ
oldschoolfan wrote:Sure looks like someone dumped some solder on those diodes. Caps look original too.
Yeah I really don't know any of the history behind this amp. Guy said it worked for a while in his truck but then it stopped and he got another amp. I'm gonna go back over a lot of the board and clean up what looks to have been spilled (same method I fix all those water damaged iPhones with) and keep tracing voltages over the board to see what else I can figure out.
I haven't used much of my electronics knowledge in quite some time but I still remember enough to break something worse.

Posted: Sat Nov 06, 2010 5:16 pm
by oldschoolfan
It is always strongly suggested by most on this site to replace the input caps if they are original. They have a bad history of leaking, whether or not you can see leakage, so they need to be replaced to prevent a fire in your car. Not trying to scare you, just very important preventive maintenance. If you look around there are a ton a threads here about it, some great pics of damage that can result as well.
Here is an offsite link of a repair a regular on this site did, very informative.
http://www.soundbuggy.com/Eric/Car%20Au ... index.html
Posted: Sat Nov 06, 2010 5:26 pm
by gothpunk4christ
Hey I really appreciate all the information. I haven't measured the zener diodes yet to see if they are still good or not.
I imagine I'll need to keep the same capacitance or is there a suggested replacement, and that's only for the front capacitors, not the larger blue ones?
Posted: Sat Nov 06, 2010 6:21 pm
by ttocs
no the big ones are the ones you need to worry about. I have an amp I am repairing now that a cap blew up on and they take part of the board with them when they go.
Posted: Sat Nov 06, 2010 6:23 pm
by gothpunk4christ
ttocs wrote:no the big ones are the ones you need to worry about. I have an amp I am repairing now that a cap blew up on and they take part of the board with them when they go.
Ah, so I should just probably replace all of them then? lol. The images from the link above made me under the impression that the larger ones were ok.
Posted: Sat Nov 06, 2010 6:30 pm
by oldschoolfan
Usually the larger blue caps, the rail caps, are fine and don't need replacement. The twelve for the power supply are the ones you need to do for sure. The current caps available for the power supply that match the original specs are about a third the height of the originals. For this reason you can get caps that are the same size dimensionally as the originals but with higher capacitance. You can change these to higher capacitance without issue, you just wouldn't want to go lower than original specs. Originals are 16 volts and 2200 micro farads.
Read through this thread, it has some of the caps listed that are commonly used for this preventive maintenance.
http://phoenixphorum.com/ms-capacitor-r ... t9930.html
Posted: Sat Nov 06, 2010 6:32 pm
by gothpunk4christ
Awesome. I tried doing a search but I have a bad habbit about not typing the exact words I need to get legitimate and useful results.
I'll dig thru that forum asap, I'm really enjoying the poeple here on this forum too lol. Useful and informative, and quite nice as well.

Posted: Sat Nov 06, 2010 6:37 pm
by oldschoolfan
Glad to hear it, welcome.
Posted: Sat Nov 06, 2010 7:56 pm
by ttocs
if yer gonna replace some caps why wouldn't you do them all?
Posted: Sun Nov 07, 2010 3:35 pm
by Thunderdome
mmm

Posted: Sun Nov 07, 2010 7:30 pm
by gothpunk4christ
ttocs wrote:if yer gonna replace some caps why wouldn't you do them all?
Good point, but I'm one of those "if it aint broke don't fix it" kind of people.
Or in this case "if it's not bound to break soon, only fix what will go out soon"
I may have to see about it though.
Posted: Sun Nov 07, 2010 8:15 pm
by gothpunk4christ
On further inspection, and a taste test, it looks like the spill that I was noticing on the board, is actually the capacitors leaking... I'm currently going over it with some isopropyl, seeing what I can clean off (its taken off quite a bit)
I am wondering though, there's a connector for a fan... has anyone tried installing one on this amp? I wanna see pictures!
..... and no I didn't actually taste the stuff.

Posted: Sun Nov 07, 2010 8:34 pm
by gothpunk4christ
Looks like someone previously attempted repair on this amp and did a shoddy job at it. Most of the transistors on the side are unscrewed and looks like a couple of them are even broken. Bah.
Posted: Sun Nov 07, 2010 9:05 pm
by ttocs
that was unfortnatly what I suspected with the bad solder job on the resistors.
Posted: Sun Nov 07, 2010 9:59 pm
by gridracer
I might have some parts for you I have a ms2125 parts board. show pics of what you need. Or you can send it to valeks1 he used to be a pg repair tech and probably can refresh it like new. Alo drfosgate on here does repairs.