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makolber@yahoo.com: Feb 02 02:00PM -0800 On Monday, February 1, 2016 at 12:34:58 PM UTC-5, Tim R wrote:   > > red light cam?   > I'll have to drive past there on the other road. My impression was street light, not near the traffic signal.   > It's a part of town not conducive to hanging around watching for it to recur.   It seems thats were "they" like to put the red light cams.

thekmanrocks@gmail.com: Feb 02 04:51PM -0800 Dave Platt wrote: "High-pressure sodium lights exhibit a "cycling" on-and-off behavior when they reach end of life. However, when I've seen this it's been a fairly slow cycle, and didn't exhibit the sort of bright strobe-like flash you describe. "   There's a street light across from our house that cycles on and off over a period of 30-40 sec., but does it on random nights(!). We might see it do it repeatedly for one night, then do it again a week or a month later, no pattern.

Tim R <timothy42b@aol.com>: Feb 03 05:24AM -0800 > > I'll have to drive past there on the other road. My impression was street light, not near the traffic signal.   > > It's a part of town not conducive to hanging around watching for it to recur.   > It seems thats were "they" like to put the red light cams.   I got a better look yesterday. It's a street light, no camera. Besides, I see the flash when I'm stopped at a red light, so the cross traffic would have a green.   Good thinking though.

Tim R <timothy42b@aol.com>: Feb 03 05:25AM -0800 > and off over a period of 30-40 sec., but does it on random > nights(!). We might see it do it repeatedly for one night, > then do it again a week or a month later, no pattern.   Yeah, that sounds like normal failure mode. I've not seen one flash and stay lit though.

"Mark Zacharias" <mark_zacharias@sbcglobal.net>: Feb 03 06:31AM -0600 > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus   A brand new "war story".   As I am nearing the end of my career, I wonder if any one unit will be the high water mark so far as feeling the satisfaction of fixing a really tough one.   This may be it.   A Yamaha M-80 power amplifier. I've worked on a few in the past - difficult but doable.   I've always thought that "M-80" was a humorously ironic model number for an amplifier so flammable.   Initial inspection:   Burned resistors on both channels, a vented 1000uF 100v cap (one of a pair) on the main board, lots of brown glue, some green corrosion visible on component leads.   Strangely - only one output transistor was bad. I knew this was going to be a tough one but I figured I could do it - just give the customer a pretty high estimate.   Replaced those larger caps, lots of bad drivers, pre-drivers, signal transistors, several burned and corroded resistors, one bias transistor.   Replaced the one bad output and it's mate. I figured the same current ripped through both, so I wanted at least do that.   I knew the speaker relays would need service, so I took them out of order and did that job.   Bringing up on a variac, the fires were out, bias adjusted OK, but no sound. Another bad resistor.     Replaced this, but now there was a -86 volt(!) offset. Couple more bad resistors.   Each time a component replaced it was necessary to monitor bias when bringing it up.   Bring it up again, no offset but one channel oscillates. Fine. Trace down and replace the bias transistor on that channel that was breaking down. Replace it and: one channel low in gain, approximately 1/2 the other channel.   Replace a bad 3.9K 1/2 watt resistor in the feedback loop. That was easy. NOPE.   Now BOTH channels oscillate like crazy. Apparently a larger 3.9K 2W resistor was corroded and got nudged while replacing the other. Replaced that. No more oscillation. NOW:   Still no change on the gain problem.   Bad 430 ohm resistor hiding UNDER a power resistor, and not even visible until the other was removed.   Unit now repaired and functioning properly.   This thing took approximately five whole days worth of bench time.   I'm going to spend a very generous amount of time patting myself on the back for this one.     Mark Z.

N_Cook <diverse@tcp.co.uk>: Feb 02 07:33PM >> So far,cursory comparison, circuit looks like this one >> http://www.schematicsunlimited.com/o/orange/orange-rockerverb-guitar-amplifier-schematic/download/OTQ2Nw%3D%3D   > Sounds like a polarity problem with the AC input. Is there are polarity switch on this unit? Floating ground?   No polarity or ground lift options. There's always a question I forget to ask the owner. This time how prominent was the hum, like unplugging a guitar and touching the pin of the plug, or just noticeable with no signal through. I'll have to email, while I dismantle the amp.

Kaz Kylheku <330-706-9395@kylheku.com>: Feb 03 11:21AM > No PbF statements anywhere but I assume it is. > Reported as consistent intrusive mains hum with any settings of > controls, but of course with me it is perfect.   Thus, a likely hypothesis is that it is picking up some EMI in its regular location, with the regular instrument and other signal chain components that it is hooked into: stomp boxes, and their power supplies, cabling.   > Expecting a loose cap or > input socket problem, but nothing found. Before dismantling the amp, > anything to check , from access side only at the moment.   Step one is to reproduce the problem. Get the user to demonstrate it, if possible. Re-create some of the original conditions, if necessary.   You can hardly be effective in investigating a problem that isn't reproducing.   Not to mention fixing it; how can you be sure something is gone, that you never observed!   Even if you *do* reproduce a problem, doing something that apparently makes it go away isn't necessarily a proper fix. So far, one thing that makes the problem go away is to relocate the amp to your polace. See? Not a proper fix.

Kaz Kylheku <330-706-9395@kylheku.com>: Feb 03 11:23AM >> So far,cursory comparison, circuit looks like this one >> http://www.schematicsunlimited.com/o/orange/orange-rockerverb-guitar-amplifier-schematic/download/OTQ2Nw%3D%3D   > Sounds like a polarity problem with the AC input.   If it is a polarity problem, it could be in the outlet that the amp is plugged into at home.

Phil Allison <pallison49@gmail.com>: Feb 03 03:37AM -0800 Kaz Kylheku wrote:   > regular location, with the regular instrument and other signal chain > components that it is hooked into: stomp boxes, and their power > supplies, cabling.   ** Long as the amp exhibits no AC frequency hum when used alone, it has no fault.     > if possible. Re-create some of the original conditions, if necessary. > You can hardly be effective in investigating a problem that isn't > reproducing.   ** Of course, but few customers are capable of comprehending even that simple idea.     > Not to mention fixing it; how can you be sure something is gone, that > you never observed!   ** Of course, but having outlined a perceived fault customers expect it to be fixed and never return.   Only thing is to write on the invoice:   " Fault not seen, not fixed and not warrantied "       .... Phil

Phil Allison <pallison49@gmail.com>: Feb 03 03:41AM -0800 Kaz Kylheku wrote:   > > Sounds like a polarity problem with the AC input.   > If it is a polarity problem, it could be in the outlet that the amp > is plugged into at home.   ** This recent British made amp uses an AC supply ground conductor so plug polarity is irrelevant.   Been a long, long time since guitar amps were sold with no safety ground. Some mad Yankee idea, I believe.       ... Phil

jurb6006@gmail.com: Feb 02 09:03PM -0800 On Tuesday, February 2, 2016 at 9:43:21 AM UTC-5, Chuck wrote:   > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus   I am replete with useless knowledge.   Next though, I don't even know if I ever even knew this, but what would that circuit be called in a digital IC. Like in a 74XX series or something ?   Something has to momentarily cut the current to all the other neons, likewise if you tried to make this in logic, it would most likely be a bunch of bistable flip flops but with a bit different gate arrangement.   Hell, I now wonder if neons is not maybe the best way to do it even today. There is only one main dropping resistor to all of them, when you hit the switch or whatever YOUR neon pulls more current and is fired, the other ones cannot fire because of not enough voltage.   There may be a nifty way of doing this with SCRs. I just can't think of an application right now. In fact I am pretty sure I could do it with SCRs and not too many other components. But then what ? Maybe some presets for equipment where things are still set by voltages ?

Reinhard Zwirner <reinhard.zwirner@t-online.de>: Feb 02 06:21PM +0100 > Hello Graz > Mine has the same fault, Its been a fantastic tool untill it went wrong, Did you get any answers please. > Robert   I do hope that Graz has been able to find the fault in the meantime!   SCNR   Reinhard

JC <Chipbee40_SpamNo@yahoo.com>: Feb 02 04:11PM -0500 > Hello Graz > Mine has the same fault, Its been a fantastic tool untill it went wrong, Did you get any answers please. > Robert   I don't have that particular meter but on my cheapo chinese version I have twice had to replace a low value smd resistor near the input stage(open circuit). I assume this fails maybe due to me trying to measure a charged cap? Some protection? I can't remember the specifics, I try not to blow my meter up often as its inconvenient.

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