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bitrex <bitrex@de.lete.earthlink.net>: May 10 05:07PM -0400 > ( There are two R78s in the drawing... so it can't have been proofread > or checked very carefully.)   > RL   I believe it's a common supply, yes.   Here's the full schematic:   < http://experimentalistsanonymous.com/diy/Schematics/Full%20Synth s%20Drum%20Synths%20and%20Misc%20Synth/BOSS%20DR-55.gif>   The output from the "Schmitt trigger" is used to activate the "CE" line of the cmos SRAM IC in "write" mode. I can't see any other connection from the output to the input that affects its operation.   The purpose of the diode/RC network hanging off pin 6 of the 4011 flip flop is unclear to me.   --     ----Android NewsGroup Reader---- http://usenet.sinaapp.com/

legg <legg@nospam.magma.ca>: May 11 10:12AM -0500 On Tue, 10 May 2016 17:07:46 -0400 (EDT), bitrex >> or checked very carefully.)   >> RL   >I believe it's a common supply, yes.   Viewing the larger drawing, there are two types of skyhook supply arrow indicators. One is solid arrow off of C13, the other is skinny arrow off of C48.   -The skinny connection is a switched contact (input socket plus volume control S8 on VR2) to a ~6V battery pile, running most control logic. -The solid connection is a filtered skinny supply running to analog signal sections. While the TC5501 (IC1) runs from skinny-minus-a-diode-drop on C39, the rest of the control circuit runs on the unreduced skinny rail. This means that input signals to IC1 can (potentially) exceed it's VCC pin. This includes some direct switched contacts on S3 and some CMOS drive outputs (~600R) of IC2 and IC3 - not good. The rest are resistive pull-ups of 10K or greater - not an issue. It would not be easy to predict what response to expect from IC1, when inder the infuence of or subsequent to the application of >VCC voltages on the affected pins. Supposedly it has worked as expected since 1980, until it didn't. Any idea when this (didn't) was? > line of the cmos SRAM IC in "write" mode. I can't see any other > connection from the output to the input that affects its > operation.   Changing state of the Q15 collector node in the "write" mode is also expected to produce a R/W pulse on IC1 input pin 20. Expect this is negative-going from about 3/4 of logic supply.     >The purpose of the diode/RC network hanging off pin 6 of the 4011 > flip flop is unclear to me.   There is nothing in this circuit that could hold Q15 collector low, externally in "write" mode; the CE2 line of IC1 and the E line of IC2.   In "write' mode the clock and FF circuitry are effectively out of the action. Q15 can only respond to button presses, directly and in real time. No latching should be expected, as drawn.   RL

bitrex <bitrex@de.lete.earthlink.net>: May 11 10:25AM -0400 > action. Q15 can only respond to button presses, directly and in real > time. No latching should be expected, as drawn.   > RL   Good question when it stopped working. I grabbed it off eBay for around $30...vintage ones in good condition often sell for hundreds as techno/electronic musicians often fetishize this old stuff. Check out what the big brother of this box from a few years later, the TR-808, sells for on the vintage market sometime...   This one was in bad shape, looked like it had been sitting in a wet basement for years and had water/rust damage. Only a small corner of the PCB was corroded fortunely, though there were a couple obviously lifted traces which I jumpered.   It also had quite a few failed parts...IC 4011 was shot, the FET in the accent control was dead, the switches were frozen and needed to be freed, and the contacts in the push buttons were worn out and needed to be replaced.   It is essentially functioning normally now in "play" mode, but I can't write patterns due to the RAM not being advanced/written correctly by that circuitry at the bottom. When one tries to use the buttons to advance the steps the box just lets out a blast of noise.   Here is the quote from the service manual about that section:   " 3 SCHIMITT TRIGGER (Q15, 17, 18) This circuit functions in WRITE mode only. The collector of Q15 goes H when either the START switch S5 or the STOP switch S6 is turned ON, and goes to L when the switch set to ON is turned OFF."     --     ----Android NewsGroup Reader---- http://usenet.sinaapp.com/

bitrex <bitrex@de.lete.earthlink.net>: May 11 10:26AM -0400 >> action. Q15 can only respond to button presses, directly and in real >> time. No latching should be expected, as drawn.   >> RL   Also all electrolytic caps were replaced.   --     ----Android NewsGroup Reader---- http://usenet.sinaapp.com/

"pfjw@aol.com" <pfjw@aol.com>: May 11 05:47AM -0700 All:   I will be leaving tomorrow morning for the XXXIV Kutztown Radio Show in Kutztown (Berks County), PA, less than an hour from Allentown, three from NYC and two from Philadelphia.   http://www.dvhrc.com/kutztown.html   Tomorrow is mostly a set-up day, and non-club members and non-registered dealers may pay a small fee to get onto the site if they wish to buy or sell.   Go over some of the pictures - there is an ever-increasing number of audio items at the show, some very high end indeed, as well as the obvious thousands of radios. One of the advantages of an event such as this is that one may kick the tires, smell the roses and so forth. eBay offers no such opportunities.   But, as an added incentive to attend - and first-come-first-serve - I will be bringing a fully operational soldering gun kit - useful for making chassis ground connections at least - free to the first individual who comes to the Clinic table (at the Club Table) and asks for it. The _ONLY_ expectation on my part would be that the individual posts in the group where he/she read this offer. I have only one (1) such item.   Peter Wieck Melrose Park, PA

Tim R <timothy42b@aol.com>: May 10 01:18PM -0700 > yeah !   > https://goo.gl/rPQFwR   > Q5 is: how to label wires that is of what material n print substance ?   Yeah. Use what the pros do. They carry little sheets of material made for the purpose.   Some stupid questions are easily googled. Used the term "wire marker."   There are thousands of sites like this: http://www.cableorganizer.com/cable-identification/

Micky <NONONObobbyburns1111@gmail.com>: May 11 03:08AM -0400 > https://goo.gl/rPQFwR   > Q5 is: how to label wires that is of what material n print substance ?   > is there a preferred tape and ink ?   I'm no pro but on occasion I've used white vinyl electrical tape and a black permanent marker. But usually I use nothing and then wonder which is which a couple years later.

"Ian Field" <gangprobing.alien@ntlworld.com>: May 10 08:24PM +0100 <jurb6006@gmail.com> wrote in message news:170ce20b-a17f-498b-bb5f-2de133bd94cd@googlegroups.com... > they took a torch to it and heated it up first and then it was definitely > affected by microwaves. Before that I never knew glass becomes conductive > at high temperatures.   Most types of glass are lossy enough at microwave to not need any such preparation.   Once I put a TV valve (tube) in the microwave, the glass glowed red and became plastic, it wrapped around the internal structure like cling film.   My coffee mug is glass - I have to tuck the handle into a corner when I heat a cup of water, otherwise the handle gets hot and burns my hand.   The alumina ceramic on a spark plug is also lossy enough to get red hot.

Tim R <timothy42b@aol.com>: May 10 01:15PM -0700 On Tuesday, May 10, 2016 at 3:24:00 PM UTC-4, Ian Field wrote:     > The alumina ceramic on a spark plug is also lossy enough to get red hot.   I believe you, but............how do you know? It's darned hard to get the ceramic off the steel part before I put it in the microwave.

"Ian Field" <gangprobing.alien@ntlworld.com>: May 10 10:05PM +0100 "Tim R" <timothy42b@aol.com> wrote in message news:1c6d4622-6924-4192-9167-768a8d0f46de@googlegroups.com...   >> The alumina ceramic on a spark plug is also lossy enough to get red hot.   > I believe you, but............how do you know? It's darned hard to get > the ceramic off the steel part before I put it in the microwave.   I was cleaning the plugs - they wouldn't have been much use if I'd removed the metal bit.   If you leave a plug overnight in an industrial strength ultrasonic cleaner, it loosens the compacted powder seal - put it in an engine and the seal will blow out within a mile.   If I want the metal shell to make a 2-stroke TDC measure, I just grind off the rolled down lip and dig the seal out with a small screwdriver.

N_Cook <diverse@tcp.co.uk>: May 10 06:17PM +0100 > They might also be nickle, like the stuff used for connecting cells > together in battery packs. > Eric   I always thought that was stainless steel as was the casing. My hot air gun has survived hundreds of extra hours of use, by crimping the broken ends of the heater wire with bits of that strip, would nickel survive that?

"pfjw@aol.com" <pfjw@aol.com>: May 10 11:19AM -0700 > They might also be nickle, like the stuff used for connecting cells > together in battery packs. > Eric   Probably not. Nickle is not hard enough to stand up to the heating. It will anneal to a very soft state, even with the stiffener/vibration damper attached.   It is used for the links you describe because it spot-welds very well, and is a much better conductor than steel, and it also takes stress better than copper.

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