MPS 2240 Problems

soth · Post by **soth** » Sat Nov 10, 2007 4:51 pm

Hey guys, need some help here

. My mps2240 is having some problems. Here is what it's doing or not doing whichever way you want to look at it

The green light will come on and start blinking. It usually blinks 4 times really fast and then blink 1 time normal. I've not checked everything thorough yet. I need to see what the basics to test first, I might have already done that and then try to narrow it down from there.

I've unplugged rca's and speaker wire. The same things happen. It is showing i've got around 14.4 volts. It appears the board isn't getting the power to it from the power block I guess.

No leds are showing either. No thermal, no overload. Just a green blinking light and I can hear some sort of sound whenever it blinks.

I've replaced the caps before this happened and i've inspected the board top/bottom. I cannot see anything where it's blown and I was very careful re-assembling the board to the chassis again.

Any ideas?

Kevin

1moreamp · Post by **1moreamp** » Sat Nov 10, 2007 5:17 pm

Blown channel and the blinking is caused by power supply ramping up then shutting down on fault detection...C

soth · Post by **soth** » Sat Nov 10, 2007 5:26 pm

Hmmm, that doesn't sound good at all. Is this something that is fixable?

1moreamp · Post by **1moreamp** » Sat Nov 10, 2007 8:12 pm

soth wrote:Hmmm, that doesn't sound good at all. Is this something that is fixable?

Of course, you have all sorts of options . Call PG for a RMA and flat rate of like $110.00 + shipping as per this link:
http://web.archive.org/web/200708141400 ... trate.html
, PM Doc Fosgate to see if he is busy. And or tech it out yourself.

I am not taking on any extra work between here and next month sometime. I have shipment deadlines to clear my bench and shelves by no later than the 21st of November.
The rest of the month is packing , moving, unpacking, and what not, hence my not listing myself as available in your options. Sorry mang my life be shot for a few weeks or more...You will be in great hands with PG or Doc.....C

soth · Post by **soth** » Sat Nov 10, 2007 9:20 pm

Thanks for the info Cecil. Not sure what i'll do right now. I may try and tech it out myself since the funds are low atm. Luckily my current position at work lets me do whatever I want on a daily basis for the most part.

Looks like i'm going to start googling and reading, reading, reading and see what happens.

LOL, at this point i'm about ready just to sell the d*m things, but as long as I can find some info and some examples i'll feel otherwise

Thanks,

Kevin

nico boom · Post by **nico boom** » Sat Nov 10, 2007 10:03 pm

Just wanted to share that I've had EXACTLY the same problem after replacing the caps for the first time.
A very small piece of aluminium [from screwing the end-screws out] became trapped under one of the sil-pads.
It had pinched thru the silpad, causing the fet to short-cicuit to the heatsink.
After disassembling, and finding this fault, I cleaned the heatsink areas very carefully, and used compressed air to remove any further particles; problem solved.
Hope you have the same problem; checking is easy.
GOOD LUCK!.

soth · Post by **soth** » Sun Nov 11, 2007 9:49 am

This morning when I took the amp apart again I noticed a few very tiny metal pieces (very, very tiny) stuck to the padding on the chassis where the board goes to. I cleaned all that off, but noticed that on one of the fets,transistors labeled (Toshiba 25A1302) there padding had wore off the chassis. All the other ones have the red/brown padding still intact.

Could this be a problem?

Thanks,

Kevin

nico boom · Post by **nico boom** » Sun Nov 11, 2007 11:00 am

I'm no expert for sure, but I do know that all sil-pads must be like new; in fact I always replace them when doing the caps.
They get older, and stick to the board like a gasket; they are relativly cheap, and isolation as well as heat-dissipation is very important!
I would put power to the board very shortly, before mounting it again in the heatsink, to check if the power-up problem is gone.
If it is, I'd mount the board with all sil-pads renewed!
[be sure to clean every fet very carefully before mounting ]

That's my simple view; hope it helps you bro.
nico

marko · Post by **marko** » Sun Nov 11, 2007 11:17 am

sounds like you blew one of the outputs then, i did exactly the same after a cap change, one tiny sliver of speaker wire shrting an output out, went with a right old pop too

soth · Post by **soth** » Sun Nov 11, 2007 4:33 pm

Well actually I just looked at the fets wrong. It's not missing any, but the others are stuck to the chassis while that one is stuck to the back of the fet. I'm going to clean all the fets tomorrow probably. You just use alcohol and q-tips I assume?

Marko, I did the same thing on my 2125. Exactly the same thing, a small piece of metal shaving from the chasis (screwing the end plate back on) fell in there and I didn't know it and Pop, the irfp044 fet blew. I'm in the process of fixing that. Luckily nothing was seriously damaged.

As for the 2240, there was never a pop or anything.

Thanks so far for all the help guys.

Kevin

soth · Post by **soth** » Tue Nov 13, 2007 6:31 pm

Quick update: Cleaned off the chasis, blew everything out, applied artic silver thermal grease on the smaller fets that dont have the pads on them. Cleaned off the pads and fixed the protective bottom sheet. It had a small hole in it.

I checked all fets/transistors along the chasis. Granted they are still in the board and connected to the chasis (does it matter if they are connected to the chassis?). They have have pretty high values and they seem consistent.

I've not tested it yet, will do that tomorrow.

Is there anything else I can quickly check before hooking it up?

1moreamp · Post by **1moreamp** » Tue Nov 13, 2007 6:45 pm

Try and use a small drill bit to clean off the thread areas of all the screws by chamfering each drill hole just a bit to flush and threads that might be getting pulled to the surface when tightening the install hardware.

I have a current and voltage controlled power supply, so I can set current limits where i want. If you can find and use one of these you can actually test the amp out of its case. Just limit max current to 3 to 5 amperes Max.

Working on any amp requires this most basic of tools and the variable current and voltage is a God send for out of case testing.

Also then you could tell me the current draw when it cycles thru its on off thing its doing. the current draw outside the case should be about 1 ampere, maybe a little more at 12 volts DC.
The amp can stand to be out of the case for a short while but don't leave it on for too long as it will have problem with the sink attached doing its job, and don't test with music into speakers. I don't need that info and neither do you right now.
Your checking for a short to the case < not a uncommon issue with these on reassembly>
I add fiberglass underneath all the MS amps I work on, especially under the power supply section. I have spare stock from my buddy that makes boards for a living. Its way better than the plastic PG used as it cannot be melted or punched thru by component leads.

PM me back with what you get and lets get you square...C

soth · Post by **soth** » Tue Nov 13, 2007 7:14 pm

Thanks C, I'll try and get that info tomorrow night if all possible. It did seem as though the bolts were not going in like they should. It just didn't go in smooth and at a few points it sounded like a squeeky sound.

Yeah, at this point only thing that i'll be hooking up is just the power to see if it works, just like you said, no speakers needed

Gnight C and all!

Kevin

1moreamp · Post by **1moreamp** » Tue Nov 13, 2007 7:29 pm

OOHHH no Sqeeky the screws please, stop and clean the threads and if possible just a touch of nickel or copper anti seize on all the threads.

Extreme case here:
Try and match the threads to a set of flat bottom fluted taps, and do a thread chase, and then a chamfer of the outside lip areas of all the mounting holes. Then make sure all are clean and clear of thread debris.

If need be take the sink to a local machine shop and have then clean, chase, and chafer all the mounting holes. If not you will most certainly snap off a screw, and then you will really be screwed so to speak.

I have seen this before and you really need to back step and follow through with some machine touch ups so the reassembly will go smooth and easy.

I really have been where you are right now and my hindsight is speaking loudly, so forgive me if I sound like a broken record....A broken screw is worse though...C

soth · Post by **soth** » Sun Jan 06, 2008 4:49 pm

Well I got around to fiddling with my 2240 again. Decided just to take a break from it for a bit.

Hooking it up to a battery pack inside the case and outside produces the same result. When i'm checking the rail voltage the f2 fuse looks fine. It's around 12-14 or something around there. The f3 fuse is 0. I'm guessing I need to trace it back and see where it's not getting any voltage from.

Good day all.