20 May 2020

Octo-Curve 2 Component Analyzer.

Hello again,

This post relates to a tool I saw when I was in the consumer electronics appliance service sector decades ago. It was elegant with a posh steel case with various lit buttons and a cute little CRT tube on the left. We techs were told that it's for checking components characteristics. I thought it was a small scope for outdoor jobs. I can't remember the brand but the face panel looked approximate to a Polar T series Fault Locator or Huntron Tracker series.

In summer (meaning when it isn't raining) of 93/94, we were called for a demonstration of the aforementioned tool by a visiting sales rep of a TMI company. I was intrigued by the demo, especially amazed when he tested capacitors. Depending on the capacitor value it would display a variety of round to elliptical figures/patterns. I never knew such a fancy test could be done on a CRT based equipment. I knew from school about checking polarized caps with an analog multimeter. Nothing complex but observing the needle go up and down to indicate a pass but with that fancy tool, it looked more attractive and intelligently presented.

Long story short, our company acquired the Component Debugger (the sales rep called it). Quite awkward considering we've been using that connotation prior for everyone and everything in our dept. You know, like this bugger, that bugger, you bugger, in a joking kind of a way. Anyway soon after, I never saw any of us use the Component Debugger for trouble shooting. To be honest, at the time none of us understood how aiding it could be if it came to it. We rather had someone else have a go at it then perhaps teach us how at the end of the day. It's in our eastern culture, you know, you first, no you first, no by all means please etc.
The fact was we were all lazy and busy with incoming repairs. We were too comfortable with the presto digits of the DMM, dry tenors of the AF Gen, and revealing show on the Oscilloscope. Maybe we were too polite to the outsider (salesman) during the demo that we just nodded concurring the Component Debugger prominence foregoing procurement. Our Assistant Service Manager did one time admit buyer’s remorse. I’m sure he got questioned by people upstairs. It was not his fault. The salesman were indeed resounding in his words gymnastics and jargons. What we should have done was put both him and his debugger in a room filled of faulty electronics. Fix 5 sets with it then we'll buy and let you go or we'll beat the bugger out of you. Hehe.

Good thing it was only one unit, not 18 for each of us or I guarantee we’d gone to his office after work and beat every buggers in the hind quarters! That little debugger must’ve cost an arm and leg back then I’m sure. No joke!

It was only after I'd stumbled upon several videos on YouTube that I really understood what an invaluable test gear we had back then. It may not ever replace all I've mentioned but one more test gear is never too many. The more assessment types could be done, the more definite the analysis will be.

I am also admitting here that it took me 25 years to figure out (vaguely) what the Component Debugger was. What an idiot this writer is. Hehe.
After coming to know how expensive a dedicated Curve Tracer unit is on eBay, I decided to make one. A science fair version more or less embezzled from old electronic magazines with countless of designs online. Fairly simple but I am adding my own touches to make it snobbish and untraceable.

 Initially it must be AC powered (115V or 230V), neat, slender and trifling enough to carry or ship off. I've always liked Boss pedals so I borrowed the DD-2 theme (reverse). White font/Blue background on both front/rear panel.

Due to how minimal components were required, I could select them to be as high street as I could fork it. For longevity reason.  I designed the circuit using an online PCB software that associates with a renowned PCB fabrication company in China. The website is well-organized with real-time manufacturing updates, overall cost was affordable, and shipping was faster than quick. Their PCB build is spotless and professionally presented. Of course with anything inaugural, mistakes did happen on my end. Errors like undersized through holes, too tiny tracks, etc. You can say I was too excited to make it happen in haste. Not to worry as later I did a better revision.
 It's definitely way better than making the board myself. I had my fair share of making my own PCB with UV light then developing and acid etching it in 2009/2010. It was no easy chore. Look at the preamp example below. It's simply too ugly even to give away. Furthermore Ace Hardware stopped selling Muriatic Acid since 2012, I think. A show stopper but blessing in disguise. No more reeking the kitchen and toilet. Those whom done it would know the whiff I'm talking about.
After knowing about the two organisations, I'm more eager to expand anything PCB related. There's no valid excuse now not to clone something for myself (or others too?). Plans or shall I say drawings are in motion as we speak. I'm a one man show so do not expect things to be done overnight, but I hope to fulfil some of them if not all. Not many really, it’s just 15 years in gigabytes of stolen diagrams and ideas online. Next could be pedals, amps, or another test tool, etc.? Hey anything is possible now. 
 I presume in the finite realm of guitar world, recycling old practical electronics ideas into the market is okay, well sometimes if the parts are still obtainable. Bootlegging, hot-rodding, and giving it a prettier paintwork are common attempts by DIYer's or large private limited co. post 2000. The master is none other than you know who. I know I'm late to the party but may I join you sir? It's a rhetorical question, by the way. Pedal inflation? Yes, it’s a reality, but I chose to pretend it does not exist. Again as I said before, it’s finite. Audio processing circuit has its boundaries. Nothing really is identifiable beyond eleven except the pointer on the knobs. With components technology continuing to be smaller biennially, the cycle would still be completed and repeated within ten years or less but as each decade enters, there’ll be spawns of fresh ears searching for that elusive true drive none digital tones built by someone in a garage or room. From where I stand, at least consumers' is not finite. Globalization? Why not. So yes, enough yapping. We'll have to wait and see what happens. It's always the dollar factor. The bank balance will decide. I digress.
My Component Debugger is a prohibitive version as well. It is an external add-on gizmo to the existing oscilloscope (analog preferred) with two channels that does XY mode. I thought of naming it the Scope-Mate but changed my mind after some googling, we wouldn’t want to infuriate or infringe any entity in the Firearms sector. I do not want to be in their SIGHT (pun intended). Instead, I shall call mine the Octo-Curve 2. I don't believe it's taken. Not yet at this time. Why 2? Because number 1 and 3 are still in development.. Do you have a better name than the Octo-Curve 2? Do suggest below. The Octo-Curve connection explanation follows.

Basically, what’s on the back plugs to XY or channel 1 and 2 on the scope, what's in front plugs to the device under test? Yes! To facilitate good horizontal and vertical display, some tweaking may be needed at each volts per division rotary switch of each channel at the scope. On the Octo-Curve, the left knob is the Vari-Volt for width adjustment (12VAC to 0VAC). The 3 way Vari-Amp selector allows current steps from 1mA, 12mA, 55mA  at 12VAC. Apply V=I/R formula when playing with the Vari-Volt. By default it’s wired to 1mA, 12mA and 120mA. I've included two extra unwired current loads inside. Wire it according to requirement... All these tech talks are unexciting so let's debug some common components to see its characteristic on the scope. For this demo I'm using my shifty eyes people’s power GW Instek 20 MHz analogue oscilloscope. Of course, on Digital Oscilloscope is do able also but the display isn't going to be pleasurable nor prompt.

Video Demo Here

Thank you

10 August 2019

Fender P38J

It was left idle for 9 years as told by the owner. Bought used in mid-2000.I don't believe I've cross path with one of these.
One thing about fender instrument is they all looks the same. You need to look in the neck pocket or neck butt for clues.
This one stamped P38 or to be precise from the catalog as a P38J. I think letter 'J' stood for Japan only? My camera failed to show the real finish. It's actually greenish leading toward the dark burst outline.
There's not much work to do aside from rewiring, crackling jack replacement, setup and clean up (as best). I'm not sure whether the pickup is a real Bassline or just a cover job. Electronics look stock from factory. Good bass and Goodbye.

Thank you