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Post by ChrisK on Dec 5, 2008 20:06:30 GMT -5
The likely culprit has been identified.
In the Classic 50;
The reverb channel has a maximum current of -27 VDC/ 1,600 Ohms = -16.9 mA.
The channel select is a 12 VDC relay coil in series with 470 Ohms. Assuming that the relay coil is operated at 12 VDC, there is -15 VDC / 470 Ohms = 31 mA.
In the Classic 30;
The reverb channel has a maximum current of -36 VDC/ 1,600 Ohms = -23 mA.
The channel select is a 12 VDC relay coil in series with 1,500 Ohms. Assuming that the relay coil is operated at 12 VDC, there is -24 VDC / 1,500 Ohms = 16 mA.
The reverb currents are fairly similar.
However, it is unlikely that the same relay is operated at a current twice that in one amp vs the other (which implies an effective coil voltage that is twice that as well).
Based on a quick analysis of simultaneous linear equations, with the assumption that one resistor is 500 Ohms and the other is 1,500 Ohms, for equal coil current 22.5 VDC would be developed across the coil in both cases [27 / (X + 500) = 36 / (X + 1,500)], which is at 9 Ma. This implies a coil resistance of 2,500 Ohms, which is quite believable for a 24 VDC coil in a small relay.
For the LED being too bright at only 9 mA, it must be a very high efficiency LED.
The culprit:
The Classic 30 has an additional 10 uF cap (C55) across the channel select foot switch input. When the channel select switch is not on, this cap WILL charge to -36 VDC.
Since there is no series resistance between this cap and the foot switch, the peak discharge current from the cap can easily exceed one amp when the switch makes connection, and may be as high as 5 amps. This surge current goes thru the LED and turns it into a DE(a)D.
(Darkness Emitting Diode.)
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Post by ChrisK on Dec 5, 2008 19:04:01 GMT -5
Now, if you're willing to have the modes organized like this;
2 J-bass on
All three on
1 P-bass on
you can use a plain old LP-style selector switch.
In the J bass, both J volume pots are connected to the output jack. The tone control is also connected to the output jack.
Leave the tone control connected to the output jack.
The output jack is connected to the center terminal on the LP-style selector switch.
The common signal output connection for both J volume pots is connected to one end terminal on the LP-style selector switch.
The signal output connection for the volume pot for the P pickup is connected to the other end terminal on the LP-style selector switch.
Now, what does the "series/parallel" completely mean for the bass?
Can you post photos of the internal wiring?
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Post by ChrisK on Dec 5, 2008 18:19:50 GMT -5
Oh, you mean one of these (my Fender Stu Hamm Urge II bass);  It does not. Since M is on in all three positions, it is a plain old N/N+B/B switch with the middle volume pot always in-circuit.  Yep, it's called the Fender Stu Hamm bass above. Here's the wiring (it doesn't quite do what you are asking for, and is an active bass). www.fender.com/support/diagrams/pdf_temp1/basses/0191500A/SD0191500APg2.pdfwww.fender.com/support/diagrams/pdf_temp1/basses/0191500A/SD0191500APg4.pdfIrrelevant. Fine, we can use this. Easy to add. Yeah, this can be done, it's not optimum, but it's the only choice for a single tone control and it works out on the J pickups I presume. More detail please. I might suggest a series/parallel switch for the J bass pickups if they are not single conductor plus shield. Both modes would still be hum canceling, but the series mode might give you the J bass tone anyway. If the J pickups are single conductor plus shield, I have a design that could put them in parallel, in series with the P pickup. Yep, this will use a DP3T ON-ON-ON switch. What does the "series/parallel" completely mean. |
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Post by ChrisK on Dec 5, 2008 17:52:27 GMT -5
Why, isn't this your amp and not his now? They likely have different currents flowing thru their foot switch circuits. Remember, this foot switch design was for your specific amp. All bets are off when another amp (of unknown circuitry and values) is used. There is a series resistor or relay coil in the amp that forms the major total circuit current limitation value. Sheet 1, lower right-hand corner. www.prowessamplifiers.com/schematics/misc/Peavey_Classic_50.htmlSheet 1, left side middle www.prowessamplifiers.com/schematics/misc/Peavey_Classic_30.htmlRemember, this foot switch design was for your specific amp. Looking at the two schematics linked above, one will clearly see that the internal circuitry AND VOLTAGES are different for the two amps. Mechanical foot switches won't care, but electronic circuitry (a.k.a. LEDs and balancing resistors) WILL. All bets are off when another amp (of unknown circuitry and values) is used. In this case we are putting a current shunting resistor in parallel with the LED to bypass some of the current in order to reduce the brightness. The higher the value of the parallel resistance, the less the value of bypassed current. The lower the value of the parallel resistance, the greater the value of bypassed current. Assuming that the LED has a constant voltage drop of about 1.8 VDC, a 180 Ohm resistor will have 10 mA flowing thru it. This means that whatever the current flowing thru the LED is, it will be 10 mA less. However, if the current flowing thru a small resistor value is insufficient to generate a voltage drop at least equal to the LED ON voltage drop, no light will be emitted. It's a balancing act in that you are adjusting the bypass current for illumination at a lower desired level. The total circuit current needs to remain constant to effect proper amp operation. And yes, this is indeed how you calculate two resistances in parallel. R1xR2R1+R2 For two or more resistances in parallel, it's; 1/(1/R1 + 1/R2 + ..... 1/Rn) |
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Post by ChrisK on Dec 4, 2008 20:14:55 GMT -5
There have been three pickup guitars with three volume pots. Some early Epiphone and Gibson's come to mind. There have been three volume SGs and LPs.
I have seen home-built ones with this.
Yes, this is why the Strat has two tone controls (neck, middle) and not three (one on the bridge). The high frequency response of the early amps was dismal, and one needed all the brightness one could muster from the bridge pickup.
Not really. With the info above, and the volume control placed real near the bridge pickup (pinky swells, anyone) based on voice of the customer (well, some of the customers back then), the two tones gave one fixed (bridge) and two adjustable (neck, middle) tone settings for that there 3-way switch that was used (the 5-way didn't "notch" its way onto the scene until the 60's).
This is exactly why the tone cap is shared (ain't never was more than one pickup on at a time).
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Post by ChrisK on Dec 4, 2008 19:17:58 GMT -5
You want them to "glow"" not "go" (away). LEDs are really crappy diodes (they glow after all). They have a very poor reverse voltage rating. I suspect that if it isn't an over current issue, it's that a reverse voltage more than perhaps 5 VDC is being applied. BTW, are the internal circuits of the Classic 50 and Classic 30 the same? |
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Post by ChrisK on Dec 4, 2008 19:09:06 GMT -5
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Post by ChrisK on Dec 4, 2008 13:07:56 GMT -5
Ooooooooh Kay, WTF is  Is it good or bad? Is there a hint of oak and nuttiness too? ;D ;D ;D |
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Post by ChrisK on Dec 4, 2008 12:58:26 GMT -5
Yeah, we use them there neat words in the modern software/embedded world. You know, like taxonomy, coercion, enumeration, heterogeneous, framework, use case, encapsulation (a specific instantiation of a thing or group of things, sometimes in an actual real thing). Then there are words like homomorphic, which is a real word and related to mathematics theory (i.e. the four color theorem), but try explaining that to the company VPN IT Nazi's when you get caught trying to surf a web site while doing research on homomorphic behaviours. ;D   |
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Post by ChrisK on Dec 4, 2008 12:42:14 GMT -5
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Post by ChrisK on Dec 4, 2008 12:10:42 GMT -5
I'm sorry to have confused you with my reference to the star ground point, but based on am you confused me.  The green wires are the signal return/ground path to the output jack. The red wires are the signal output path to the output jack. Note that no wire from the neck pickup is directly connected to the green path. A good place for the star ground point (where the bridge/string ground wire, the control cavity shielding (if used), the pickup shield wires, the ground wire to the output jack, and the signal return/ground path all merge/connect might be the terminal on the bridge volume pot where the green wires are connected. I rarely show the grounding methodology in a pickup switching/wiring scheme since there are various methods used, and there would have to be a version done for each, for each scheme. While both are important, they are rarely entwined and hence, are separate. I also presume that you've identified which pot element correlates to each concentric shaft.  |
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Post by ChrisK on Dec 3, 2008 19:36:27 GMT -5
If this link doesn't work (select the free online tool fret position calculator at the bottom), www.stewmac.com/shop/Bridges,_tailpieces/Electric_guitar_tremolos/Wilkinson_Gotoh_VS-100N_Tremolo.html Go to the StewMac Bridge position calculatorGo to " Bridges, tailpieces" Go to "Electric guitar Tremolos" Go to " Wilkinson/Gotoh VS-100N Tremolo" Go to "free online tool fret position calculator" |
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Post by ChrisK on Dec 3, 2008 19:22:11 GMT -5
Scary, isn't it? If you give a man a fish, you feed him for a meal. If you teach a man to fish.....(you can get rid of him for a whole weekend). ;D ;D |
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Post by ChrisK on Dec 3, 2008 19:15:07 GMT -5
Wiring diagrams are great if one wants to see how it's implemented (external view/plumbing/instantiation). For simple things these are fine.
Schematics are required to "see" the logic flow and theory behind the design, and to see how it can be transposed(concept).
I speak schematic, wiring diagrams are just local dialects.
In this case, enough theory was dispensed (sans schematics) such that all "saw" the solution.
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Post by ChrisK on Dec 3, 2008 19:06:50 GMT -5
NO.
Since you are using series and series out-of-phase on the neck pickup, the shield for the neck pickup cannot be connected to the same point as the "not" wire from the neck pickup.
Connect the shields to the star ground point. Connect the "hot" and "not" wires as shown in my diagram.
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Post by ChrisK on Dec 3, 2008 18:53:08 GMT -5
Why, my (ground) work here is done! |
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Post by ChrisK on Dec 2, 2008 18:25:47 GMT -5
Good. Great. That's ok, I do. Actually, both pickups are wired in series with the hot wire of the top one going to the volume pot and the return wire of the bottom one going to ground. Without the switch, both pickups are always on. The switch will have one end terminal connected to the volume pot, and the other end terminal connected to ground. The center terminal will be connected to the connection between the two pickups. In the center position, nothing is connected. When switched to either end position, one or the other pickup is shorted. This is perfectly safe and will have no detrimental effect (as it didn't have in the original guitar). Ok, you can always add it with a push pull pot later. Series Out-of-Phase is an interesting sound whereas Parallel Out-of-Phase is weak and very thin sounding unless a 1/2 Out-of-Phase capacitor is used (which I would have included had you wanted a phase switch). Ok, I'm traveling tonight so I won't look at this until sometime tomorrow at the earliest. I will include the phase switch design anyway, it can always be not wired. |
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Post by ChrisK on Dec 2, 2008 16:17:36 GMT -5
Were the original pickups on the 1457 selected in series? If so, that original switch may well be a SPDT (center OFF) as ash mentions, and it can then be reused. For a simple test, set the switch to the middle (both pickups on) position. Measure the resistance from the center terminal to each side terminal. If it is very near zero (perhaps 5 Ohms or less) to both end terminals, it is for parallel selection (SPDT center ON), and if it is over 1K or so to both end terminals, it is for series selection (SPDT center OFF). (Make sure that the volume controls are all the way up for this test.) As ash mentions, there will be some little loss of treble from shunting across that unused coil, but you mention that you really liked the way that it sounded as it is, so if it is a shorting switch (SPDT center OFF) it should sound nearly identical to the way that you like. Well, it will be different since you are using different pickups. You may want to take the approach of implementing the new wiring using the original pickups to verify things, and then just change the pickups. Check this out, we're almost there. Now, let me further complicate things. If you want to keep things stock looking, push pull pots can be used for the master volume and master tone. The original switch that might select the pickups in parallel (or the new one that you show that likely does) could be used to select the pickups in parallel. The master tone push pull switch could reverse the phase of one pickup. The master volume push pull switch could do an overriding series selection regardless of the LP-style selector switch. The 1457 would appear to be stock, but have two "stealth" switches for a total of four modes and six pickup combinations. |
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Post by ChrisK on Dec 2, 2008 11:26:28 GMT -5
Ground loops within a passive guitar are generally a misnomer.
The only time that a ground loop has any effect is if significant current passes thru the loop such that it generates an offset or error voltage that causes errors or noise relative to the signal of interest.
Most currents within a passive guitar are quite small and any internal ground loops are small as well.
A ground loop might also act as an antenna for EMI.
If star grounding practices are followed, there usually will not be issues from grounding (shielding is another topic).
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Post by ChrisK on Dec 2, 2008 11:13:29 GMT -5
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Post by ChrisK on Dec 1, 2008 23:29:18 GMT -5
To do phase reversal, a DPDT ON-ON switch must be used. You show a SPDT. Do you have a DPDT switch? This is only possible if the pickups have opposite magnetic polarity. If the string facing sides of the pickups attract, they are opposite. If they repel, they are not and hum cancellation will not be possible. Are your pickups of opposite magnetic polarity? You show a typical three-terminal LP-style SP3T center-ON switch. This cannot be used for series. You will need a DP3T ON-ON-ON mini-toggle switch or a 3 pickup LP-style switch (which is also a DP3T ON-ON-ON switch). |
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Post by ChrisK on Dec 1, 2008 17:03:30 GMT -5
Well, my avoidance of eating or cell use while driving may be related to the prevalence of manual transmissions in my cars for many years, but even with Blue-tooth, I don't talk and drive. My last company car (in my last company) was a Mitsubishi 3000 VR4. It had those kilometer thingies on the speedometer too. When in Germany, I often drove the autobahn at 160 mph, but then, I wasn't using a go-kart either. I still have my card from the Michael Schumacher driving school, although I haven't been there for over 4 years (talk about fun go-karts). While driving tests are prety much a joke in the U.S., we insisted that both of our children practice with a learner's permit for a year until they were 17 before we let them test for their license. |
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Post by ChrisK on Dec 1, 2008 16:44:12 GMT -5
FYI, an analog(ue) multimeter only uses the battery on the Ohms ranges (to bias the resistor under test). As a result, the meter on the DC voltage ranges CAN be used to test the battery.
I vote for a bad battery or bad leads.
Good, there is enough difference between the pickups that they can be discerned later if wiring issues arise.
The shield is a separate connection. Both coil leads are isolated from the shield. We can do series and out of phase with no issues.
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Post by ChrisK on Nov 30, 2008 21:04:14 GMT -5
Hold On!
I created a test thread in E&W.
I linked to said thread in a new thread in E&W.
I moved the test thread to a different category.
When I clicked on the link to the test thread, it went to the "moved" message.
When I deleted the "moved" message, the link was "not found"
For every moved thread that someone has previously linked to in any given post, if that thread is moved, the link will go to the moved message. If that message is deleted, the link in the post will go nowhere.
This will destroy the reference to the thread in the post, and possibly make logical/continuity dead ends.
Links are absolute, and hence broken if the target is moved.
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Post by ChrisK on Nov 30, 2008 11:25:03 GMT -5
There was more than one reason why I had you measure the resistance of the pickups. You could attached you multi-meter to the output jack on the guitar and measure the resistance for the different switch positions. Make sure that all volume and tone pots are at "10" or maximum on. First start with guitar parallel and only the bridge MB selected. Try the different positions of the push pull pots that select the various momma-bucker coil sets. Either two-coil set in binary parallel will be about 13K Ohms. The two of these in binary series will be about 26K. The two of these in binary parallel will be about 6K5. Record your results, for the state of the switches (up vs down) and resistance. There will be four measurements. You should hear slight tonal differences between either two-coil set (Wh vs Nh). This is how you can later confirm that you have either one selectable (since the coils area all so similar in resistance, measurement can't help). Now select only the neck, also in guitar parallel mode, You should read about 16K Ohms. Record the result. Now set the bridge pickups for both on in binary parallel. This should be 6K5 Ohms. While still in guitar parallel mode, select both the neck and middle. You should read about 4K6 Ohms. Now select guitar series mode, You should read about 22K5 Ohms. HTH |
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Post by ChrisK on Nov 29, 2008 20:58:07 GMT -5
GeBabel GeFooey! Happy GeBirthday!  |
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Post by ChrisK on Nov 29, 2008 20:53:15 GMT -5
The "A" box is one pickup (or structure). The "B" box is the other pickup (or structure).
In the "Take 1" section "E" in "Fun With Toggles & Push-Pull Switches", when in series mode, "A"'s volume pot functions as an adjustable series shunt across "A". In essence it gradually shunts out or reduces to zero "A's" contribution in the series mode.
"B"'s volume pot functions as an adjustable master volume for the entire series chain.
So, "A" is shunt-able, "B" is not. You can control the contribution of "A", but not "B".
Choose as you wish (what "A" and "B" stand for). I would likely put the series/parallel switch on the pot that I wanted to be the master volume in series mode.
In parallel mode, both volumes function as normal. Note that the pickups are connect to the wipers on their volume pots and the CW lug goes to the LP toggle switch
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Post by ChrisK on Nov 29, 2008 20:05:14 GMT -5
newey, The 0221B that you linked to is not a black switch. The "B" indicates nothing other than it's the next toggle switch in their listing. There is a 0221A (3PDT) and 0221 (SP3T center-off). Yes. The poles are as follows: 1. One to disconnect the bridge pickup red/white center tap. 2. One to disconnect the bridge pickup green wire and connect it to ground. 3. One to disconnect the bridge pickup black wire and connect it to #4 below. 4. One to disconnect the output jack hot wire from the 3-way switch and connect it to #3 above. Try www.mouser.com they may have them. If you can only find chrome plated switches, try using a short length of black heat-shrink tubing over the flattened bat. It will not come off easily. You could then use the black nut and washer that you already have (it the threads are the same, there is the US standard of 1/4"-40 and a metric version) It is my preference to use switches rated 0.4 VA maximum for guitar signals since these switches are rated for dry contact use. This means that no minimum (or wetting) current is required. In order to meet this rating, the internal contacts are gold plated. The 0.4 VA rating (usually at 28 VDC max) is to ensure that the gold plating is not burned off. Since most of these switches have the gold plating over silver, once the rating is exceeded, they become power switches as below. The switch that you linked is a 6Amp power switch. It has silver contacts. Since this is a power switch, for long-term reliable use it should switch a minimum current of at least 50 or 100 mA. This current level is not possible with the extremely weak signals that come from a passive guitar pickup, which develop a maximum current of perhaps 0.25 to 0.5 mA, 100 times less at least. If there wasn't a difference, they wouldn't make the gold plated ones! I know this from working as an OEM electrical/electronics design engineer for 30+ years. Virtually all mini-toggle switches sold by guitar parts suppliers are power switches and not low signal level switches. They usually work, but they're not guaranteed to. Silver plated lever and rotary switches work well since the contacts have a wiping action as they slide across each other, which removes the oxide (until the plating is worn off). Silver oxidizes, gold doesn't |
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Post by ChrisK on Nov 28, 2008 1:17:19 GMT -5
Ummm, no. It's not an issue of IQ.
It's an issue of consideration for others. After all, they're the center of the universe.
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Post by ChrisK on Nov 28, 2008 1:13:26 GMT -5
Wow, it was all that I could do to walk on the cobblestones in London in the summer.
The entire road is a speed bump.
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