Relays, True-bypass, and stereo effects.

[343 Salty Beans]

I'll try to keep this as short as possible.

I rehoused a Digitech Digidelay to be true-bypass with a separate momentary switch for tap tempo, etc. It's not a complicated thing...this is what I did.



As you can see, the stereo jack only works as a delay out currently. The mono jack is the only one that bypasses.

A 4PDT stompswitch is certainly an interesting idea, but I've heard they're somewhat unreliable (not sure of the truth of this statement). In any case, I can get a 4PDT relay much easier, and therefore work out my stereo-output delay dreams come true.

I'm working on understanding relays right now...In the meantime, could I get input on if this is a good way to achieve my goals or if I'm just chasing dreams?

[aron]

>A 4PDT stompswitch is certainly an interesting idea, but I've heard they're somewhat unreliable

I just purchased one from Small Bear. I hope it's reliable!

[Andre]

You could also consider to use a 3PDT stompswitch and the millennium bypass.

I drew up a little schema for true bypass switching a Boss DC-2 some time ago , which could be used for your Digidelay also.



André

[Mark Hammer]

A 4PDT stompswitch is certainly an interesting idea, but I've heard they're somewhat unreliable (not sure of the truth of this statement).

I would imagine that part of the reputed "unreliability" of 4PDT stompswitches would come from older switches where the mechanical force to move 4 rocker contacts simultaneously needs to be distributed over a wider area.  The current crop of 3PDT and 4PDT switches has moved the contacts closer together such that distributing the force of a switch depression over 4 separate rocker contacts is more likely to be consistent.  Stated more simply, contemporary 4PDT switches are more likely to work better than historically earlier ones.

The other thing is what results in so-called "reliability" issues of stompswitches in the first place.  Since no one has, as yet, disputed me with empirical evidence to the contrary, I will restate my position on stompswitch reliability here yet one more time. 

The rocker contacts inside the switch are temporarily held in position during assembly by a small dab of grease.  The grease is not critical for functioning, but is merely there for the manufacturer's convenience, and I suppose to physically dampen movement so the switch feels smooth and makes a single well-defined click as opposed to a jiggling noise.  If you solder leads to the tabs quickly, you don't invite problems, but if you take too long applying heat (perhaps because either the tab or the wire is tarnished or not tinned/prepared properly, or because you decided to do them all at once), the heat from the solder tab is transferred to the rocker contact and melts that dab of grease, causing it to flow along the rocker contact inside and completely coat it.  When this happens, the rocker contact may only make intermittent electronic contact or even none at all.  Since a 4PDT has 33% more contacts to solder than a 3PDT, and double the lugs of a DPDT, it is not surprising that it would invite a greater likelihood of this grease-flow problem arising if the builder doesn't realize that heat is building up to a critical level.

What do you do?

1) When assembling, you can make a point of soldering leads to the tabs that are not in physical/electronic contact with the rocker contacts.  The rocker contact is like a see-saw, and when the common is placed in contact with one tab, that means it is physically moved out of the way of the other tab, and that's the tab you solder.  When those are done, and suitably cooled, you press the switch and solder the lugs on the other side that are now also moved out from physical/thermal contact with the rocker contact.  When those are done, or perhaps before you do them, you can solder the commons in the middle, making sure not to let the heat build up.  The grease does not liquify that instantaneously or easily, but if you are a slow solderer for any reason (e.g., a novice) then it will pay you to take a little more time and not let heat build-up be your enemy.

2) If the grease flow has already occurred, it IS possible to gently pry the tabs off the top of the switch assembly, take the switch apart, clean the rocker contacts and inside portion of the solder tabs with a Q-tip and maybe some contact cleaner, and re-assemble it.  I have rehabilitated a number of switches this way and they all work perfectly fine now.  It was the disassembly where I learned about the grease issue.

Long story short: I wouldn't worry too much about the supposed reliability or unreliability of 4PDT stompswitches, or indeed ANY stompswitches.  None of those companies could survive if they had the failure rate that the DIY community reports.  DO worry about melting the housings or about taking too long soldering, but don't worry about whether you have unwittingly purchased a "bad" switch.