Memphis 16-ST500d Repair help

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi, this is my first post to this forum and I'm here because I have questions reguarding my amp and how I should go about repairing it. I have had it since new so for about 5years now. for 4 years the gain has been touchy. The gain control just spins and doesnt have a stop at full like it used to. It used to work when I found the right spot in the gain. but now it is not constant at all. I think i have narrowed the problem to the gain pots or at least that is where im going to start but i am having an impossible time figuring out where to get replacements for them. Any help would be awesome. THanks, Clay
 
Hi Clay
I think that you are asking about the small pcb mounted pot's that are inside the case of your car amp. It should be possible to find replacement parts. You could 1) Contact the manufacturer and inquire about service information like schematics and parts lists as well as parts avaiablity. 2) If you are brave, take it apart and look for the value like 10K 25K - that sort of notation. 3) Take the cover off and take the best picture you can and post it here. Someone may be able to help. 4)Take the part out of the circut and measure the value with an ohmeter and look on parts suppliers web sites ie. Digikey Mouser. or heaven for bid, and I hate to even mention the name but Rat Shack still sells a few pot's.
If all else fails there is no doubt a combination of fixed resistors that will allow reliable operation but at a fixed level.
 
Thank you for your reply, I am talking about the pots you mentioned. and i must be either brave or stupid because i already have it completely apart. I am just trying to find the specs i need to look for in replacement pots to get this part fixed and confirm that it is the problem
 
I Am An Idiot, on the left side(looking at it as if you were going to adjust it) of each potentiometer there is number. There are 3 pots. two big and one little. The two bigger ones are for the gain and the LPF, the small one appears to be for the SUBSONIC FILTER(i know nothing about this). The two large ones have a number on the side that reads 15C503X4GD, and the small one has a number that reads, B203X2ED. On back of each pot there is what appears to be a brand and it reads
K.I.E. When inspection the amp and all the electronics i see scoring of anykind. By this i mean no places that look burned up or anything like that. Ill connections seem to be good and the original factory fuses are still there and not blown. I feel like the problem has to be the pots. I would rather be able to replace them rather than hard wire it to be at a constant power. this amp comes with a remote gain controller which i have if there is anything i could do with that, like bypass the onboard gain or something. thanks for your time, any help will be greatly appreciated.
 

Attachments

  • photo 226.jpg
    photo 226.jpg
    77.4 KB · Views: 136
I think the small pot is the gain. The others are for filters.

If I'm not mistaken, the pot is being used as a simple voltage divider. If that's the case, the value isn't critical.

Some of Rockford's gain pots (bd1000?) are almost identical but are 5k ohms. Some of SoundStream's pots (VGA series amps) are similar but I'm not sure about the shaft. I think they use 50k gain pots. The Rockford would require that you change a 1k ohm resistor (between the pot and the secondary ground) to ~220 ohms to restore the original range. The SS pot may work well enough with the rest of the components as they are.

In the 1000, only half of the pot is being used (the rear half). this means you can use virtually any 20k pot to test your amp (you don't need a stereo pot - if the 500 and 1000 use the same design).
 
your very right perry, the small pot is the gain, i had the plate that has their labels upside down when i held it up to the board. I think that the LPF and the SS were fine when it quit so im thinking maybe i can get away with just replacing the gain pot. But that brings me to where i am now. What do I replace it with.
 
Clay
Those are pretty special pots. Sound like the only one you really need is the gain pot. The manufactures web site dosen't offer much encouragement by way of service support. One other possibility is finding a local shop that repairs the brand, and walk in and ask for the service manager. Sometimes you can convince them to order the part for you.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.