Leaderboard

Fed some hummingbirds (with 1 part organic cane sugar : 4 parts water) , in Sonoma.

Good afternoon Yountville But first we'd like to thank our sponsors, Sotherby's International Realty, so don't forget to rush out and buy a house after the concert. Now some classic rock, with The Fog City Swampers (And the good people of Yountville) Who were also moved to dance by the end. .

Hello Sonoma ! Swing daddy! , With the Alpha Rhythm Kings. They moved one couple enough to leave their blanket and dance.

I bet everybody knew this was coming but we've been moving fast and the board is taking shape. If it's not clear from the photo then this is a massive slab, 16" x 12", so quite a bit bigger then the production version. It will be built like the BHSE with the board mounted to the top of the chassis, with the tubes sticking out of the top and the components on the bottom. Massive heatsinks are needed to keep this beast cool and a single angle bracket is used on each side of the board to connect all the parts together and make assembly just a bit easier. To honor the Stax legacy the following will be printed on the board: "With the utmost respect and admiration for Dr. Takeshi Hayashi, a living legend". For those who don't know, Dr. Hayashi is the designer of the T2 and also the son of the Stax founder. Without his great vision and talents we wouldn't have the quality of phones/amps we have today. We will keep you updated as the project moves forward.

Once again this year I'm prepping to ride a century in support of the Kelly Brush Foundation. Between Zwifting as required by the rainiest spring in history, the MTBs, and getting outside as much as possible this summer I'm piling on the miles in preparation this year and should in proper form before the event. Once again this year it'll be an in-person ride up in VT, with friends mostly coming from near-by so we should have a strong crew of 8 with some riding the 50 and most doing the full 100 miles. For me this is the 12th century that I've done in support of either Northeast Passage or Kelly Brush and I'm hoping the recent trend of good weather continues. So the mission remains the same, I'm trying to raise a bunch of money again this year with a goal of $3,000. As usual, all of the donations are tax deductible and maybe some legislation will get passed this year to make that more meaningful but really, I'm hoping the motivation isn't just to get a write off. So for those that are interested, here's the link to my personal fund raising page - Nate's Fundraising Page. Any donation large or small is very much appreciated. A bit about KBF - they are a non-profit organization dedicated to assisting individuals with spinal cord injuries in finding ways to get out and enjoy an active lifestyle. For me, this is a cause close to my heart. I love the outdoors and the freedom to explore it in a variety of ways and have worked with organizations like the KBF for the last twenty years to help others do the same. Last year's crew with Kelly at the starting line.

It's dropped another 7% if anyone is interested. Mine just arrived today. Sounds good.

I wonder if the somewhat small tab set in the dado is a possible point of failure. If it is plywood that is probably less important but I still might want a pocket screw or two into the cleat on each end. It looks like you already glued it in so maybe just drill a pilot hole at an angle and put a screw on each end to add strength so all the weight isn't hanging on the tabs and the glue joint. 🤷🏻‍♂️

The one cleat should be plenty. Just make sure it's secured with screws every 6" or so.

Donation in. I thought this was coming around pretty soon. cheers

I chipping in a bit

When in Yountville* *(With apologies to Thomas Keller)

Dunn....

Bonus track from recent slightly expanded edition:

That's kind of what I was trying to evoke, thank you for picking up on that.

Exactly my reaction to some of his previous work -- a bit too religious, to the point impossible to ignore (Jesus Christ the Exorcist, etc.), but the music's so great, I listen to it anyway.

gcc -I. -c all_above.c -o working_amp.exec

The unofficial mostly modern T2 troubleshooting and verification guide. Weclome, this guide covers the mostly modern T2 which has the following schematic: The gerbers for the amp can be found here: https://drive.google.com/drive/folders/1r3g2TAtBUaBdiMorTWX7yYgeJ7maQbYW and the gerbers are staxt2nc3fdh7.zip The guide is intended for both pre-power on verification of an amp build, verification of voltages on power on and general troubleshooting. All tests are performed using a Brymen BM869s and peak DCA75. Using a different multimeter may effect the results slightly but you should still get similar behaviours and ball-park figures. Transistor and Diode Location Section 1. Build verification with no valves installed and no wires/volume control connected to the amp All of these checks can be performed with a multimeter from the top side of the amp board leds Checks. All 3 leds on each channel should read about 0.55V voltage drop in forward bias (multimeter + terminal/red lead connected to led + and multimeter - terminal black lead connected to led -) and open circuit in reverse bias (swap the probes around) when tested with a multimeter in diode check mode. The leds will not light from the diode test due t the current draw if the components around them. The exact forward voltage drop will depend upon the characteristics of the red led but anything significantly different here indicates a problem. 0 voltage drop in both directions indicates a short across the led or the components it connected to. check for solder bridges and failed short transistors. 0L indicates in both directions means the led has dry solder joints or is blown. using a multimeter in resistance mode check the leds D23 close to the -360VDC psu input. In forward bias expect around 4M ohms. With the probes reversed you should get open circuit. D24 is the led closest to the octal socket for the EL34 and should read about 1.8M in forward bias and about 1.9M in reverse. D1 is between in the 9 pin sockets but close to the heatsinks. This should read about 1.5M in both directions. Readings in both directions of a few hundred K ohms or lower indicate the led may have been leaky or a transistor it is connected to has gone short circuit or a solder bridge. Input terminal checks With the multimeter in resistance mode and the - terminal connected to the amp ground, and the positive terminal connected to the + input of the amp you should get about 340K and the same for the - input. Naturally expect the same results for the other channel. If significantly different suspect incorrect resistors for R94, R7 (positive input). Or R95, R8 on the - input. Output terminal checks With the multimeter in resistance mode and the - terminal connected to the amp ground, and the positive terminal connected to the + output of the amp you should get about 0.5M and the same for the - output. Naturally expect the same results for the other channel. Valve Socket Checks. With the multimeter in resistance mode and the - terminal connected to the amp ground, and the positive terminal expect the following resistances for both EL34s: (socket viewed from the top of the amp). (note the 0.5M reading may start lower and quickly ram up and the small capacitors in the circuit are charged by the multimeter). For the 6922s (socket viewed from the top of the amp) Diode Checks of transistors Note it is possible for a transistor to fail in such a way it has very little gain but still has a diode drop and so diode checking transistors is not a foolproof measure of a transistors health. But 0V drop when not expected indicates a short etc. Diode checks KSA1156 checks Q1, Q2, Q3 two of the ksa1156s (Q2 and A3) measure the same in diode mode the centre one (Q1) differs slightly. All combinations of probes and pins on a transistor result in open circuit unless otherwise shown otherwise: + indicates positive multimeter probe attached, - indicates negative multimeter probe attached n/c indicates no probe attachment. Note: for the other channel EACH KSA1156 is rotated 180 degrees about the y (vertical) axis. Peak DCA in circuit testing Q1-3 The peak DCA 75 identifies all 3 transistors as PNP silicon. The centre with a hfe or around 28 and the other two with slightly higher hfe of 30 to 31. This test is reliable, anything significantly different indicates a problem. Note it is easier to do these tests from the underside although you can hook up the dca proe hooks to something like a sensepeek weighted self standing spring loaded probe tip assembly and test easily from the top (https://sensepeek.com/pcbite-20 Diode check and Peak DCA 75 for Q23P FJPF2145 This is reliably identified as a NPN with hfe 26 and is part of the virtual battery connected to the + output side of the channel. NOTE: It has a mirror image pinout compared to the ksa1156s. Diode check and peak DCA 75 check for Q5 2SK216 This is reliably identified as a N channel mosfet with body diode and has a transconductance of 23.3mA/V. Although not part of the virtual battery it is directly connected to it. WANRING This transistor has a live mounting tab and must be fully insulated from the heatsink. A resistance check from the metal tab to the heatsink it is mounted on absolutely must read open circuit. Diode measurement for this transistor does not show a stable reading. In this case dec indicates a reading that decreases over time. The next two transistors in the heatsink row are Q23N and Q4 which perform exactly the same role and are exactly the same type of transistors as Q23P and Q5 respectively and should measure about the same I got 28mA/V for the Q4 so expect a little variance here). NOTE: on the other channel the order of the 2SK216 and FJPF2145 are reversed. Diode check and peak DCA 75 check for Q35 and Q36 FJPF2145 These are the current providers (driven by Q34) for a 10mA constant current source that feeds the input 6922s. The job is equally divided between them and they should measure the same. The DCA75 reliably identifies them as NPN silicon hfe 25-26 Diode check and peak DCA 75 check for Q15 and Q10 (10M90S) These are identified out of circuit by the dca75 as N channel depletion mosfets. However, in this circuit they provide anode current and are wired in such a way the DCA75 can not identify them and reports no component. The DCA75 should not report any shorts and the metal mounting tab is live and absolutely must be insulated from the heatsink they are mounted on. Q15 and Q10 are identically configured and should measure the same. The gate and cathodes are connected together with resistors totalling only 400ohms so the diode drop voltages will be lower than for the other transistors also unlike the other transistors all combination of probes will result in a voltage drop. The voltage drop should be the same in the forward and reverse directions. Diode check and peak DCA 75 check for Q28 and Q29 (KSA1156) These are identified out of circuit by the dca75 as PNP silicon. However in this circuit they are wired in such a way the DCA75 can not identify them and reports no component. Each should measure the same. Diode check and peak DCA 75 check for Q26 and Q27 (2SK216) These transistors do not produce stable diode voltage drops. Diode check and peak DCA 75 check for Q25 and Q24 (2SJ79) These transistors are not easy to get a stable reading on. Diode and peak dca75 Check Balance servo Q37 - Q40 (MPSA06) 4 of the MPSA06es have their collectors and bases shorted together and so can be considered to only have two pins as far as diode checking concerned. NOTE for any transistor with shorted pins only two dca75 probes were used (one to the shorted pins and the other to the non shorted pin) to avoid the dca just reporting probes shorted. Understandably ni this case the dca75 can not identify the component as a transistor and instead reports a 9.87V zener. All other transistors are correctly identified and hfe provided. Diode and peak dca75 Check Virtual Battery Q16 - Q18 (STN9360) and Q20 (MPSA06) the other virtual battery in the channel (just to the left) should measure similarly and is identically laid out. Q20 pt 1 has collector and base shorted. All 4 stn9360 should diode measure similarly. NOTE for any transistor with shorted pins only two dca75 probes were used (one to the shorted pins and the other to the non shorted pin) to avoid the dca just reporting probes shorted. Understandably ni this case the dca75 can not identify the component as a transistor and instead reports a 10V zener. All other transistors are correctly identified and hfe provided. The stn9360 are pnp and the remaining non shorted mpsa06 as npn Diode and peak dca75 check Q30 and Q31 (FJPF2145) Each transistor provides a separate 5mA current source and are directly connected to the virtual battery. With the led D24 across their base and emitter. Each is identically configured and should read the same. Dca75 reliably identifies both transistors as npn both hfe 18 Diode and peak dca75 check Q32 (on seperate small heatsink) and Q33 (FJPF2145) this forms a 20mA current source which is controlled by Rv5 and sets the DC offset. DCA75 reliably identifies both transistors as npn both with hfe 26 Diode and peak dca75 check Q34 (FJPF2145) Q34 provides control for Q35 and Q36 which creates a 10mA current source. The dca75 says no component detected. <<< IN PROGRESS >>> #include <usual_disclaimer.h> #include <usual_high voltage_warnings.h>

The difference is absolutely helical heads vs. standard planar knives. Plus, they send the best straight grained Sapele to the USA, because that's where the best woodworkers are! 😝

OOF. Found the first real casualty of moving today: That's a bootleg house remix of Air's "All I Need" that is now utterly destroyed. The bootleg mix is not on YT, of course. I don't really buy vinyl anymore (I own ~2K records and don't use them for DJing) but this is one I'm going to make a point to replace. Hopefully Discogs (bless its heart) doesn't block the sale of it on their marketplace.