MS2125 Inspection, Service, Recommendations

[JayGold]

Found a seller with an original gray MS2125, he states the amp has been repaired by the previous owner and operates fine. The gold colored kapton tape lining the heatsink under the fets is a dead giveaway that the circuit board was removed. He's not knowledgeable enough to verify what components have actually been swapped.

He sent me some pics (not very clear photos) and I'm trying to determine if I should purchase with intentions of:
1) it works as stated, clean up and use it for my front components at 4 ohms stereo
2) test amp and swap out any components/caps/etc. which look questionable
3) walk away from this all together

Assist me on this one guys:

[nico boom]

I'll try to give you some hints as what I look for first of all when looking at a MS amp;
-if possible, always have the amp hooked up to power and check if it's playing fine with all led's lit on the board and only the green led lit at the front. [had one that played fine with one clipping-led lit...]
-look closely at the speaker- and powerconnectors for any cracks.
-check wether all screws are there in the sink plus connectors etc.
-check for rust outside AND INSIDE the amp; grey ones do suffer from rust even on the inside sometimes.
-inspect the solderings of the fets for signs of bad repair-work.
-look for burn-marks, or the smell of a burned board.
-never mind looking at the input-caps; REPLACE THOSE!
-usually repairs are done under the board, so expect to find some wires, or small components there when you recap the amp; when in doubt post some pics of these repairs.
-turn both pots back and forth while powered and connected to speakers for any cracking, indicating the pots need to be replaced.
Depending on price, a grey one is always a real treasure to find when in good condition.....
-think about wether you are able to change the caps [PLUS SILPADS!] etc. yourself, or that you have to pay someone for it.
I hope you will be able to buy it for a good price, recap- and clean it; you'll be able to use it for MANY years to come!

[JayGold]

I'll try to give you some hints as what I look for first of all when looking at a MS amp;
-if possible, always have the amp hooked up to power and check if it's playing fine with all led's lit on the board and only the green led lit at the front. [had one that played fine with one clipping-led lit...]
-look closely at the speaker- and powerconnectors for any cracks.
-check wether all screws are there in the sink plus connectors etc.
-check for rust outside AND INSIDE the amp; grey ones do suffer from rust even on the inside sometimes.
-inspect the solderings of the fets for signs of bad repair-work.
-look for burn-marks, or the smell of a burned board.
-never mind looking at the input-caps; REPLACE THOSE!
-usually repairs are done under the board, so expect to find some wires, or small components there when you recap the amp; when in doubt post some pics of these repairs.
-turn both pots back and forth while powered and connected to speakers for any cracking, indicating the pots need to be replaced.
Depending on price, a grey one is always a real treasure to find when in good condition.....
-think about wether you are able to change the caps [PLUS SILPADS!] etc. yourself, or that you have to pay someone for it.
I hope you will be able to buy it for a good price, recap- and clean it; you'll be able to use it for MANY years to come!

This helps me out, unfortunately I'm in Chicago and the amp is on the West coast.

If in fact I do go for it...who on this site is a repair technician located in the US which I can send the amp to for updating/repair?

[mhyde71]

i would check with eric d. I know he can...but he may be able to shed some light on whether or not he has time or desire to given he just landed full time gig as of late

[JayGold]

i would check with eric d. I know he can...but he may be able to shed some light on whether or not he has time or desire to given he just landed full time gig as of late

I'm already ahead of you, unfortunately he's tied down like you stated.

Anyone else?

[valeks1]

The yellow tape acts as an insulator. However, I’m not sure why it was installed seeing as the original seal pads are still in place. The tape isn’t good because it decreases thermal conductivity (reduces the transfer of heat from output XSTR's/MOSFET's to heatsink).
If you buy that amplifier, might be a good idea to remove the tape and replace any damaged seal pads. Looks like left channel power supply MOSFET’s was replaced. Other than that the amplifier looks fine, although I can’t say the same about the pictures.

[JayGold]

The yellow tape acts as an insulator. However, I’m not sure why it was installed seeing as the original seal pads are still in place. The tape isn’t good because it decreases thermal conductivity (reduces the transfer of heat from output XSTR's/MOSFET's to heatsink).
If you buy that amplifier, might be a good idea to remove the tape and replace any damaged seal pads. Looks like left channel power supply MOSFET’s was replaced. Other than that the amplifier looks fine, although I can’t say the same about the pictures.

Seller told me the Toshiba fets #2SA302 3-pairs have been replaced. Now I'm concerned that the replaced Mosfets could be fakes. With no clear image, it's very difficult to tell.

[The Golden One]

im not sure if they made fake toshibas or not but i have heard that some of the mosfets for the zpa amps have had some reproduced that are fakes. and they where said to not spec out the same and sometimes they would burn up. but like i said im not sure if they made fake toshibas but maybe someone else may know for sure.

[JayGold]

Thanks for the help guys, but I backed out of this one due to the seller becoming hasty with me requesting clear pictures of the fets. He claimed to have over 10 years experience in used car audio, sorry but that's not convincing enough to sell me an amp with no known history of what has been repaired and why. So I'm still looking for a MS2125, perhaps the 10th Ann TA on eBay will pan out.

[JayGold]

More questions....

What is the current asking price for most used (8/10 cosmetically and original guts) original gray colored MS2125's today?

What version of these had the (2) RCA's on the same end cap side?

Example:

[rolandk]

Thanks for the help guys, but I backed out of this one due to the seller becoming hasty with me requesting clear pictures of the fets. He claimed to have over 10 years experience in used car audio, sorry but that's not convincing enough to sell me an amp with no known history of what has been repaired and why. So I'm still looking for a MS2125, perhaps the 10th Ann TA on eBay will pan out.

Hate to say it, but you are better off passing on this one. Bare minimum before the amp even gets powered up the circuit board needs to be removed, kapton tape removed and thrown away, input caps need to be replaced, 99% chance the oem insulators will need to be replaced, then when you put it back together hope to christ that all the oem screws, washers and heatsink threads are in serviceable condition.

And the Toshiba 2SA1302 is not a power supply FET, its an output transistor (the green ones in your pics). PS FET's are IRFP044.

[JayGold]

Hate to say it, but you are better off passing on this one. Bare minimum before the amp even gets powered up the circuit board needs to be removed, kapton tape removed and thrown away, input caps need to be replaced, 99% chance the oem insulators will need to be replaced, then when you put it back together hope to christ that all the oem screws, washers and heatsink threads are in serviceable condition.

And the Toshiba 2SA1302 is not a power supply FET, its an output transistor (the green ones in your pics). PS FET's are IRFP044.

Thanks for the lesson. I did pass this on this one, the seller stated a local buyer was interested.