PCC QSI installation

The socket:

Hoo boy. Well a different type of socket, and Aristo violated their own specifications of the space reserved around the decoder. The socket is also a lower profile, so the legs of other decoders will not allow the decoder to seat completely.

This makes it so only the Revolution will fit and allow the bottom cover on. What a surprise. There's a set of jumper pins right under the socket that can touch the bottom of a decoder and short things out, and a small electrolytic cap there too.

The first thing to attack is the set of jumper pins. There's 5 pins on the board and the top 2 pins nearest the slide switches had a jumper on them: (between the 2 rows of socket pins, above the square orange polyswitch). The jumper is shown in the stock configuration, apparently for DC.

on the back side the pins were identified as -, DAT CLK R and +. The 2 that were jumpered stock were the - and the DAT.


Below is a picture of the socket area: note the low profile sockets. In this picture, the jumper pins have been trimmed flush with the carrier. This is the first PCC car I modified.

I modified a second PCC and bent the jumper pins over:

I put some Kapton tape over the jumpers:

OK, so now we have clearance there, the next thing to attack is the electrolytic capacitor. The electrolytic capacitor in the lower right sits above the socket so it interferes with decoders also. IT's at the bottom edge of the picture below:

Below is a closeup of the 47 microfarad, 35 volt electrolytic capacitor:


So, the capacitor needs to be reolocated. I unsoldered the cap, and soldered 2 wires long enough to get past the end of the board. See in the picture below:


This allows the cap to be placed off to the side after installation:


This also reminds me, the main board was only held in place with 2 screws, on the "switch side" of the board. I added the 2 missing screws, and also touched up bad solder joints on all 3 slide switches. Several people had electrical problems with these switches, when I resoldered them, the pads bubbled quite a bit, so I suspect a problem with bad flux or contamination on the lugs of the switches. That would also explain the electrical problems people were having. Aristo, don't go so cheap next time!


Below is a picture of a QSI installed in the socket, now you can clearly see how the non-standard socket will not accomodate the standard length pins on the QSI.


Clearly after moving the capacitor, the pins on the QSI can be trimmed. You should measure the gap and trim just slightly less than the measured gap from the end of each pin. I found the gap to be about 0.080", and laid a strip of  0.10" styrene on the plastic block on the QSI as a guide to trimming the pins. After trimming them, I used a light touch and a sanding drum to taper the tips of the cut pins just a bit.

In the picture below you can see the result:


And with that, now the stock cover on the bottom of the chassis can be installed:


Adding a speaker:

Since the speaker is inside, it helps to let the sound "out". I carved out the 2 rear windows on each side and that was sufficient. You normally cannot even notice these are cut out, I used a flash to show how close I filed the windows to the body.

Another friend just removed the window completely.

The speaker is a small 2" speaker. I found a plastic spray cap just the right diameter, and shortened it so the speaker just fit inside.

Then I ground away the corners of the circuit boards for the lights, and ground a relief into that "box" at the end of the shell:

Now the speaker nestles in as far out of sight as possible:

Weather Underground PWS KCACARLS78