Easyvibe, cleaning pcbs, wah pot, and trimpot/parts sourcing questions

[joelap]

Couple of short answer questions:
1) On the easyvibe, I have four optocouplers, but which side does the positive end of LED go into?  I know where the LDR and LED goes, but which hole does the positive end of the LED belong?  My board doesnt have markings for + and -, or square/circle designations.

2) I got this PCB a year ago and finally got the parts.  Anyways, the person who made it for me told me to clean it first.  I disregarded the advice thinking it'd be fine after a year of sitting.  Well, the solder isn't adhereing to the copper traces very well at all    How can I clean the PCB so the solder sticks better?  Is it as simple as scuffing up with some very fine steel wool?

3) I've been using the cermet box style trimpots for a while now, but have seen some of you guys' builds with those circular style ones.  In one of my courses I used a trimpot that was circular disc-shaped.  In the middle it had a phillips head insert, but the whole top of the trimpot turned, so it was able to be adjusted by hand.  I was wondering if any of you knew of the mouser part number for that style of trimpot, or one of the other circular ones that lay flat?  The boxes take up too much room.  I'd prefer to find that exact one that moved by hand, but so far I'm not having much luck.  Any of you ever see that one?

4) Wah Pots:  I've got a fulltone pot right now, but I'd like to try something with a little more modern sweep.  How is the dunlop Hot Potz?

5) Final question: Regarding capacitors.  I have been using the green xicon caps for a while now, but I have been plagued by their size at times.  I got a couple of box caps that fit pretty nicely in pedals.  I'm not going to ask if there's a difference in sound between cap types... so I'll ask a similar but different question: Is there any advantage to using one type of cap over another, save for the obvious differences in tighter tolerances?  Do you have a preferential cap that is cheap, small, yet effective?  I had a bunch of .1uf yellow box caps that went into a lot of boss pedals I once modded and I thought they were great, considering their size and price.

Thanks!

[Andre]

1. If you take a look at the layout, look for R18 right next to the trimpot.
    One side of R18 connects to the trimpot, the other side connects to the anode of the LED.
    The anode is the longest of the 2 wires of the LED.

2. For cleaning I normally  use acetone or 96 % alcohol, but I think you can use fine steel wool too,
    and yes you should have listened better to the person who made it for you.

The rest of the questions I will have to leave to others I'm afraid.

André

[Andre]

Joe,

I forgot to mention that all 4 optocouplers have the same orientation.

André

[Meanderthal]

 #3- I get scores of the kind of trimpots you described by salvaging them from old tvs and stereos. Free.