Those two decoders mentioned will take a bit of sluething to determine the contact points as they aren't laid out in typical fashion.
The positive terminal for the cap can be picked up from the common lead to the LED. There "should" be a marking on the board where the LEDs are mounted to indicate this. If not, you may need to determine that as well.
There are also four black diodes on the board - two and two on opposite sides of the board. The negative to the cap will come from the banded side of an inboard diode. Again, you will need to determine which of the two diodes have their bands on the inboard side.
Once you determine the positive side of the LED, you can use that as a reference point, and using your meter set to DC, probe the banded ends of the diodes to find the negative (the decoder will obviously need to be powered up to accomplish this).
As for soldering points, there probably aren't any - unless you can follow the trace to a free pad. Normally you will have to make the solder connection right to the leg of the component. Just don't overheat the component in the process and damage it.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
Again, look at the link I posted couple or so days ago. There are pictures in the link. Might not be your decoder but you can see identify the bridge very easily.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
I tried posting in that group, but no one could help me and tell me which two terminals to solder the capacitors.
I think it is the Yahoo SoundTraxx DCC Group where some have used a 1000 ufd cap and did not use a resistor or diode. I have seen a few messages pop up in email since I belong to the group.
When it comes to DCC, belonging to a bunch of groups, forums, gives me a good cross section of DCC variables.
There will be four maybe five black diodes together. Very obvious. Look at the link I sent before.
When you take the shell off a loco, you have got to have some understanding of electronics in many cases.
Some decoders have five diodes next to each other and your meter will help you identify the full wave bridge. The largest Tantalum filter cap is next to the bridge. The positive and negative terminals are right there. Marcus shows different places some decoders have for the two places.
My question is, on the #1812, where are the bridge rectifiers, and where are the specific terminals that I need to solder to? I posed this question to the Yahoo Groups for MRC, and nothing was answered.
gatrhumpy On MRC Sound decoders like the 1812, and 1955 (both for N scale), is there a motor and sound capacitor that allows slight interruptions in motor and sound power? If so, what is the rating and voltage of said capacitor? I would like to add my own for lower chance of power and sound interruption.I understand about the warranty and possibly destroying the decoder, but I'll take my chances. I'm an engineer by trade, so this is nothing new. Just need to know where the positive and negative are of the capacitors for slight power interruptions that are on the circuit board.
On MRC Sound decoders like the 1812, and 1955 (both for N scale), is there a motor and sound capacitor that allows slight interruptions in motor and sound power? If so, what is the rating and voltage of said capacitor? I would like to add my own for lower chance of power and sound interruption.I understand about the warranty and possibly destroying the decoder, but I'll take my chances. I'm an engineer by trade, so this is nothing new. Just need to know where the positive and negative are of the capacitors for slight power interruptions that are on the circuit board.
Have not seen the article.
Capacitors have an indicator on the side that shows the negative lead.
For maximum effectiveness, connect the cap to the positive and negative terminals on the full wave bridge rectifier. That will be stay alive for motor and sound.
Some decoders have a cap for sound stay alive only.
At least 1000 ufd at 16 volts is needed.
Going to be tough for N scale. A diode and 100 ohm resistor is also needed.
Below is a link about stay alive but for HO scale.
http://www.members.optusnet.com.au/mainnorth/alive.htm