# US Amps Merlin MD-1D help



## TwinBassDaddy (Jul 2, 2009)

Hello, 
I have a US Amps MD-1D, I got it knowing it was in need of some work. When I opened it up, no burnt outputs or exploded caps, but I've noticed a spot on the board where it's obvious a resistor and a cap should go. On the board, you can see where the legs still have a bit left on them through the solder. 

I've sent an email to US Amps, and they're more than helpful. But, the pics I have are from my phone, as my camera is on vacation with my brother. 
So, the parts that I'm looking for values are labeled on the PCB as:

Resistor : R91C

Capacitor : C92C

Thank you in advance, and AmpGuts pics where too small to make out. I thought of that too.


----------



## TwinBassDaddy (Jul 2, 2009)

Alright~~~I know SOMEBODY out there has to have this amp, and if you do could you please look at the board for me? The parts I'm looking for are on the same end as the company logo on the board. I really don't want to have to wait another week till my camera gets back.....


----------



## [email protected] (Jun 12, 2008)

Wont US Amps tell you what parts they are?


----------



## MarkZ (Dec 5, 2005)

Sorry, can't help you. Where are these components in the amp? Is there a symmetrical circuit somewhere else? (eg. is it in the amplifier sections or in a push-pull part of the power supply?) They'd very likely use the same values.


----------



## TwinBassDaddy (Jul 2, 2009)

I thought they would, I emailed Greg, and he said he needed a pic of the board. Unfortunatly, I only have the [email protected] camera on my iPhone, as my cameras on vacation with my brother. The actual part numbers on the PCB are hard to make out, but not the location. And, I sent him which parts they are on the board. I even sent the board # & build date code. I guess I'll have to wait until I get my camera back, but I don't get it. He should have a schematic of the board, or a PDF of it on his computer!?


----------



## accelerator (May 23, 2008)

I have a MD2.D, but unfortunately it's bolted into an amp rack, and would require significant effort to remove (and I *just* got everything back together last week, so I'm not really in the mood to take everything apart again). Anyway, if there are labels for a resistor and cap on the board, presumably something should go there. I'd just wait until you can send US Amps a picture of the missing components.


----------



## TwinBassDaddy (Jul 2, 2009)

MarkZ- I'm thinking that these parts are part of the DC offset,as they are not paired on the board like an output would be. Thanks though. 

Accel- I totally understand, I'd never ask or expect anyone to do that...but if you're REALLY bored some night. LOL. I'm thinking I'll just wait til I can send a pic to them. Still bugs me that US Amps can't just look at the schematic. Oh well. Thanks.


----------



## [email protected] (Jun 12, 2008)

TwinBassDaddy said:


> MarkZ- I'm thinking that these parts are part of the DC offset,as they are not paired on the board like an output would be. Thanks though.
> 
> Accel- I totally understand, I'd never ask or expect anyone to do that...but if you're REALLY bored some night. LOL. I'm thinking I'll just wait til I can send a pic to them. Still bugs me that US Amps can't just look at the schematic. Oh well. Thanks.


Have you asked for the whole schematic? I have asked acouple companies and they have provided the whole thing. Every manufacturer has them, but I know some are not willing to give them out, which is retarded, becasue if I really wanted to copy a design you could still get it done without the schematic.


----------



## audiogodz1 (Jan 5, 2010)

TwinBassDaddy said:


> Hello,
> I've noticed a spot on the board where it's obvious a resistor and a cap should go. On the board, you can see where the legs still have a bit left on them through the solder.


Sounds to me like if there is something supposed to be there it is mounted on the other side of the PCB. Of course if I had a pic it would be better. It's not really possible to disintegrate a resistor and capacitor. The cap is messy when it goes and would be shreds of paper or other materials all over and the resistor would have scorched the area it is mounted to if it burned up.


----------



## TwinBassDaddy (Jul 2, 2009)

BeatsDownLow-- I never thought of that, as like you said, a lot of companies won't give you the full schematics, I guess they're protecting their interest, but like you said, copying an amp isn't hard, and it better to have a working model over a piece of paper. I bet they don't want everyone to know how to contain the magic smoke. Thanks for the suggestion.


Audiogodz-- I believe all the components are only supposed to be on the one side of the board, you can see where the two parts were soldered, and it looks as if they were cut off. I've had an amp blow a cap, VERY messy. Looks like Rip Taylor got loose in there.


----------



## TwinBassDaddy (Jul 2, 2009)

Alright~~finally got my camera, well about 2 weeks ago, and sent better pics to Greg at US Amps. I'm not sure if you can see the pics I added here; if not let me know and I'll repost. 
Anyway, what I was told was that these parts were extra filtering for the 6V supply and are redundant and not needed for the amp to be functional. 
Strange, when I have this amp on my power supply, with no load present, I can hear a faint, distant sound; almost whining. I think this may have to do with some kind of "filtering" perhaps?
Please let me know if anyone has any input or ideas, as I'm still searching for what should be there, as I was given no answer to that question yet.


----------



## TwinBassDaddy (Jul 2, 2009)

OK.....PICS ARE ADDED FOR REALS LIKE !!!

Please any help is greatly appreciated


----------



## TwinBassDaddy (Jul 2, 2009)

AUDIOGODZ1 >>> Ive posted the pics, hope maybe you could help....


----------



## envisionelec (Dec 14, 2005)

TwinBassDaddy said:


> Alright~~finally got my camera, well about 2 weeks ago, and sent better pics to Greg at US Amps. I'm not sure if you can see the pics I added here; if not let me know and I'll repost.
> Anyway, what I was told was that these parts were extra filtering for the 6V supply and are redundant and not needed for the amp to be functional.
> Strange, when I have this amp on my power supply, with no load present, I can hear a faint, distant sound; almost whining. I think this may have to do with some kind of "filtering" perhaps?
> Please let me know if anyone has any input or ideas, as I'm still searching for what should be there, as I was given no answer to that question yet.


They know their amps best - the whining you hear likely has absolutely nothing to do with this circuit and is probably a byproduct of the amplifier design. This is common.


----------



## TwinBassDaddy (Jul 2, 2009)

I would agree that they know these amps better than anyone else, but that still doesnt help my issue. Another strange thing, if youve got the case open and your touching around where the missing pieces are, i swear, you can get a faint AM radio station, through the amp. I think this amp maybe the devil himself.....LOL

I just wish someone with the same amp could look and take a picture of theirs, then I could at least know for sure. 

I may just end up using it as a donor for parts...it has some decent caps, nice power supplies, etc.


----------



## Bain86 (Dec 19, 2014)

I have the same issue. my amp cuts out and cant figure out why? only had it ran at 1, 1.5, and 3 ohm loads so i know it wasn't my subs so i opened it up and found the same missing parts + a few fet locations are empty with no trace of ever being applied.. on the amp (the exact same as yours) resistor and cap looks like they had soldered something on the board? also under the big white logo you will see 2 empty spots labeled com1 and com2 ? is yours the same way too? also have eight (8)-IRF3710, twelve (12)STP50N06, four(4)-FMG225S and in between those i have only one(1)-KIA 7812A P438 is this all you have. i ready to exchange phone numbers and knock this issue out lol. i have had this amp for a year and bought it as is for $35 and the amp worked just kept cutting out and one day would not come back on. i later touched up some solder joints and am ready to test.. just have been waiting until a warmer day to test it. now i have to rewire my car because i undid everything thinking my timing belt jumped/ broke making my 02 sebring lxi coupe junk.. turned out to be my A/C compressor bearing. just got the car back so if you still have or know anything about this amp let me know and will work with you on any info i can help with.


----------

