Volume Control -- Revisited

[pfurman]

For these purposes, any cheap soldering iron will do the trick. Just something with a small tip on it.

Thx Tulsa. Do you put anything underneath the volume control while you're soldering the wire to it, in case anything drips down? I don't wanna sound like a nervous nellie here, but I try to head off problems at the pass whenever possible.

[Tulsa]

It's generally not going to be necessary. Solder cools very quickly. Just use the tip to heat up the point at which you want the solder to adhere to, generally just a few seconds of the tip touching it, then apply the solder while the tip is still there. It will quickly melt, pull the solder away and move the tip around to make sure you have the solder where you want it. Then pull the tip away. A few seconds later it should be cool to the touch.

[v3550]

I've never soldered anything before, but I imagine it's not rocket science. Any recommendations as far as what type of soldering gun to get? Something pretty basic at Radio Shack? Any precautions that you've learned from experience? TIA.

Here are some tips that may help you:
http://www.mediacollege.com/misc/solder/

[websherpa]

It's generally not going to be necessary. Solder cools very quickly. Just use the tip to heat up the point at which you want the solder to adhere to, generally just a few seconds of the tip touching it, then apply the solder while the tip is still there. It will quickly melt, pull the solder away and move the tip around to make sure you have the solder where you want it. Then pull the tip away. A few seconds later it should be cool to the touch.

A good soldering iron and quality tips go a long, long way to making soldering a dream (hint, they don't sell them at Radio Shack (The Source CC)). But you can get away with a decent pencil soldering iron in a pinch (soldering guns are overkill for this kind of thing. Make sure you "tin" the tip first (pre-melt a little solder on it, then roll wipe it in a wet soldering sponge). touch the tip to both the items you want to solder, preferably on the side furthest away from the component or wire sheathing so as to give them a fighting chance. Touch the solder to the item opposite where you have applied the iron (say on the on the other side of the wire), the solder should flow (use thin rosin core solder, silver solder works best for audio applications, but not necessary). What you want to see is the solder flow onto the wire and also flow smoothly onto the larger item you are soldering to (it usually takes longer to heat). A good solder joint will boil away most of the rosin flux (which cleans the metal), and forms a kind of hat ^ shape up the wire and down onto the connecting surface and starts to flatten out on the larger surface (concave up the wire) so it's not a ball of solder. If you have a ball (convex up the wire) then you have a bad solder joint that might not adhere. Often the joint is shiny too, bad solder joints tend to be hazy.

Practice on something unimportnat first. Once you see the "magic" it gets easier and repeatable.

Hope that helps.

[websherpa]

Oh, as Tulsa says, pull the solder away first, then tthe iron (otherwise the solder may stick). You should NOT have to move the solder around with the tip of the soldering iron, that's a no, no (sorry Tulsa). Any movement in the joint has to be discouraged so that the joint has a chance to cool. Movement causes fissures and poor solder joints. A "third hand" (it's an appliance with clips that holds the item to be soldered steady) comes in handy for anything but the roughest wire splices (which are the very easiest solder joints).

[pfurman]

Oh, as Tulsa says, pull the solder away first, then tthe iron (otherwise the solder may stick). You should NOT have to move the solder around with the tip of the soldering iron, that's a no, no (sorry Tulsa). Any movement in the joint has to be discouraged so that the joint has a chance to cool. Movement causes fissures and poor solder joints. A "third hand" (it's an appliance with clips that holds the item to be soldered steady) comes in handy for anything but the roughest wire splices (which are the very easiest solder joints).

Thank you for this and your previous post. I'll give it another shot probably in a day or so, once my ego has healed a little bit more.

[pfurman]

With regard to pots, since pots come in different wattages (generally, 1/4 and 1/2) and different ohm ratings (500 to 1Mb), is there one general combination that works best in pachislo machines? (Say, 1/4W, 100k ohm, or 1/2W 1MB ohm).

Also, on machines we've gotten from Milt in which he's installed vol controllers, the knobs have to be turned counter-clockwise to increase volume, and clockwise to decrease volume (essentially, backward of normal operation). He only uses two of the three terminal leads on his pots (the center/wiper lead, and the left lead, when looking directly at the B501 marking). I remember reading somewhere that using different wiring configurations with these types of pots increases performance and eliminates the backward rotation as far as increasing/decreasing volume is concerned. Any thoughts/input on this as far as how would the wiring need to be changed?

For example, the instructions that come with Milt's pots advise finding the positive wire for each speaker, cutting it, attaching the end that now goes directly to/from the speaker to the center lead on the pot, and attaching the wire going to/from the amp to the left lead. Nothing happens with the negative wire from the speaker. I saw a diagram that I think showed the ground wires from the speakers being routed to that third terminal on the pot (the one that's not used in Milt's setup), along with the comment that using that setup fixed the reverse issue and gave a smoother overall volume increase/decrease curve.

Note: It looks like Gaku used a 500 ohm B (linear taper, and not 500k, just 500) on Mojouh's top two speakers, and an unmarked pot on the bigger bottom speaker. Only two lead terminals on the pots were used, but they work correctly as far as which way to turn them to increase/decrease the volume. The volume, however, does not increase/decrease very smoothly; you have to turn the knob at least 50% before you hear any change at all.

[cwstnsko]

I would normally look for 500 or 1K ohm pots with the 1/2 watt preferred to the 1/4 watt.

On the pots that are using only 2 poles, by leaving the center wire alone and moving the outside wire to the opposite side, it should reverse the direction the knob turns to get louder. One thing to keep in mind is that if it's audio taper pot, this may affect the adjustablity and make it very sensitive. On a linear pot, it's shouldn't matter.

The only place I'd use a different pot would be on the piezo tweeters in some Sammy machines. They need much more resistance to affect the volume. I'd use a 2.5k or 5k ohm pot for those.

The only volume mod I've done that has good, smoothly adjustable range is the L-Pads I got from Parts Express. Definetly a higher quality volume mod, but more $$. I treat all of the pots as a set it and forget it type of adjustment. The L-Pads, I mount through the front panel to the token tray area so they can be adjusted on the fly.

[websherpa]

Even with the L-Pads installed on my Hanabi Hyakkei I find that they only have a narrow range (there is a lot of travel with not much volume adjust, then a very quick slope toward the quiet end). THese are the same L-Pads (15w) as Parts Express (cheapy chinese ones I beleive - couldn't afford the NA ones). Do people expreience the same with their L-Pads?

Any ideas from electronic gurus on how to make the volume adjustment more continuous or linear? (I've tried hiking the machine's volume adjust switch to the max, doesn't make a huge difference, I think.)

[pfurman]

I would normally look for 500 or 1K ohm pots with the 1/2 watt preferred to the 1/4 watt.

On the pots that are using only 2 poles, by leaving the center wire alone and moving the outside wire to the opposite side, it should reverse the direction the knob turns to get louder. One thing to keep in mind is that if it's audio taper pot, this may affect the adjustablity and make it very sensitive. On a linear pot, it's shouldn't matter.

The only place I'd use a different pot would be on the piezo tweeters in some Sammy machines. They need much more resistance to affect the volume. I'd use a 2.5k or 5k ohm pot for those.

The only volume mod I've done that has good, smoothly adjustable range is the L-Pads I got from Parts Express. Definetly a higher quality volume mod, but more $$. I treat all of the pots as a set it and forget it type of adjustment. The L-Pads, I mount through the front panel to the token tray area so they can be adjusted on the fly.

1. So are you suggesting liner instead of audio pots? 2. When you say 500 or 1K ohm (with the exception of the Sammy's), are you saying it doesn't make much difference, 500 or 1K? And, would you stay away from 100K's?

[cwstnsko]

For most pachislos, the 500 will give you the best range of adjustability. The 1K should give an OK range of adjustment, but anything bigger will likely get really sensitive. I would think the 100K pot would be almost impossible to adjust, all or nothing. My concern with the audio taper pots would be that the taper is desiged to modify the input in a logrithmic manner, and we are modifying the output. I think the logrithmic taper will only be correct for one orientation of the pot, and that might be the orientation that has the knob turning the opposite of what we are used to.

I'll have to look at the machines I have L-pads on, I may have used a resistor network in conjunction with the L-pad to get the range that I have.

[pfurman]

For most pachislos, the 500 will give you the best range of adjustability. The 1K should give an OK range of adjustment, but anything bigger will likely get really sensitive. I would think the 100K pot would be almost impossible to adjust, all or nothing. My concern with the audio taper pots would be that the taper is desiged to modify the input in a logrithmic manner, and we are modifying the output. I think the logrithmic taper will only be correct for one orientation of the pot, and that might be the orientation that has the knob turning the opposite of what we are used to.

I'll have to look at the machines I have L-pads on, I may have used a resistor network in conjunction with the L-pad to get the range that I have.

OK, cool. Because I found a site that has pretty much the full range of pots, and the 1/2 watt, 500 ohm linear taper pots are only $1.90. (The 1/2 watt, 500 ohm audio taper pots are $2.75. I don't care about the 85 cents; just that I can now order the right thing.)

http://www.oselectronics.com/ose_p74.htm

So I'm gonna order some and see how that works out. (I'll still keep trying to get the hang of soldering, but in the meantime I would like at least one viable alternative that I know I can do.)

[pfurman]

OK, guys....I finally have a photo of the Syscom volume controllers with the lead wires soldered to them. All that needs to be done now is patch each one to the positive speaker wires in any non-Sammy machine. (There are special Syscom volume controllers for Sammy machines.) NOTE: Even though the solders on each end look sort of dull in the photo, they're actually very shiny. (Otherwise they could be cold solders, but they're not.)

http://img379.imageshack.us/img379/2...soldered7j.jpg

[websherpa]

Thanks for this pfurman, it answers a question I had about whether the pots were being used like rheostats (using only two of the three leads) or all three (two leads are tied together, and the third one is used as well). Thank you.

[Tulsa]

That's actually a very nice looking solder job. Very nice indeed.

[arbycoffee]

yes, better than me i think

[ssdcinc]

Nice job on the soldering, see and you had your doubt's!!

looks like you used flux, paste i hope, since acid is no good for
the electronics.

keep up the good work!!!

OK, guys....I finally have a photo of the Syscom volume controllers with the lead wires soldered to them. All that needs to be done now is patch each one to the positive speaker wires in any non-Sammy machine. (There are special Syscom volume controllers for Sammy machines.) NOTE: Even though the solders on each end look sort of dull in the photo, they're actually very shiny. (Otherwise they could be cold solders, but they're not.)

http://img379.imageshack.us/img379/2...soldered7j.jpg

[Lddrizzt]

definately neater than I can do!

[pfurman]

That's actually a very nice looking solder job. Very nice indeed.

It was definitely my best pair! (Well, of volume controls, that is.)

[pfurman]

General note: I went through 3 soldering irons (finally got it going with a Weller WP30, and the flat tip, instead of the pencil tip), lots of vol controls that looked a lot uglier than these two, and lots of desoldering practice too. But I stuck with it, until I finally found my way of doing it that worked best for me. And of course, all the help everyone here offered was a major help. A big THANK YOU to all the great Pachitalk members!! (And of course, a big thanks to bf too...he was VERY supportive. He even tried a couple himself.)