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"pfjw@aol.com" <pfjw@aol.com>: Dec 14 08:50AM -0800 a) Assume nothing. b) The nose knows. c) The complexity of the problem is in inverse proportion to the symptoms displayed. d) That one problem has been found and fixed does not imply that all problems have been either found or fixed. f) First cause may be intermittent. What is observed may be secondary.   Peter Wieck Melrose Park, PA

Cydrome Leader <presence@MUNGEpanix.com>: Dec 14 06:02PM >> 1. Assume nothing.   >> Perhaps we can assemble a list of golden rules....   > First analysis instrument to use on removing the case cover - your nose   smell test is good.   check power, fuses, probe around for expected voltages. For example if there's any sort of linear regulator check output, input, check voltages on ICs. I deal with old stuff so there's always some 7400 series logic so +5 is expected to be all over the place.   Look for burned parts, puffy caps, probe anything in areas with heat-discolored circit boards, check and resolder and suspect joints by parts that warms up. Diode check is a great feature on DMMS.   If you're dealing with suspect dried up caps, just solder a new one on the solder side of the board and see if that helps at all. I like to add parts on the bottom of the board, get things working then position parts where they belong if all good.   If these things appear OK, then you have to narrow the problem down and dig around into what the circuit should do vs. what's happening.   For intermittent problems tap the hell of boards, cable assemblies etc. Check power supply voltages with the device cold AND after it warms up.   Just came across a machine that would crash fairly often, The problem appears to be a mix of loose sensor and power connectors, a power supply that drops voltage as it warms up, plus a dead cooling fan in the electronics section. Just to keep things interesting, nothing warms up that much with the service panels removed.

N_Cook <diverse@tcp.co.uk>: Dec 14 06:08PM On 14/12/2015 18:02, Cydrome Leader wrote:   There is problem with "twizzling" for intermittant soder joint failure, if it is a PbF board. Its too easy to temporarily "fix" a failed joint. I start with light touching stuff with a bird feather, while switched on. Then firmer twizzling. Then hot air or freezer spray. Then if I auapect a PbF failure ,an adapted engraver tool with a shaped nylon bolt in place of the engraving tip, to rattle the board, listening on headphones , if an audio amp.

Cydrome Leader <presence@MUNGEpanix.com>: Dec 14 08:43PM > Then if I auapect a PbF failure ,an adapted engraver tool with a shaped > nylon bolt in place of the engraving tip, to rattle the board, listening > on headphones , if an audio amp.   I'm pleased to say I don't really deal with PbF stuff. How often do you find bad joints that looked OK (well, as good as PbF looks) and did have weird cracking or separating from the part lead?   Do you do repairs with real solder or that fake tin stuff?

Jon Elson <jmelson@wustl.edu>: Dec 14 03:07PM -0600 Cursitor Doom wrote:   > troubleshooting? I'll kick off by suggesting:   > 1. Assume nothing.   > Perhaps we can assemble a list of golden rules.... Well, usually that is a very good rule, and saves time chasing what you THINK the problem must be, when in fact it is something novel you haven't seen before.   But, then, I have repaired a few thing recently, where past experience told me what the most likely failure was, and that was the correct thing to fix.   Jon

Phil Allison <pallison49@gmail.com>: Dec 14 04:45PM -0800 Cursitor Doom wrote: > troubleshooting? I'll kick off by suggesting:   > 1. Assume nothing.   > Perhaps we can assemble a list of golden rules....   ** Troubleshooting is like a maze, there are many starting points and blind alleys to negotiate on your the way to the goal.   Unfamiliar equipment requires a more cautious approach than familiar items.   Always observe the fault carefully *before* starting disassembly and find out what functions work and what do not.   Owner's descriptions are often misleading or fail to mention important issues, but you still need to find out what prompted that description.   Bench tests need to simulate actual use or worst case use, but beware of simulating abuse.   When stuck on a problem, take a break and start over a day or so later.         .... Phil

whit3rd <whit3rd@gmail.com>: Dec 14 09:10PM -0800 On Monday, December 14, 2015 at 6:07:52 AM UTC-8, Cursitor Doom wrote: > Anyone care to share their experience on the correct approach to > troubleshooting?   Make a block diagram. It may only be a mental picture, but it's an important step toward tracking a symptom down.   I taught a class of technicians once, from a local factory... the block-diagram-exercise got them talking amongst themselves more productively than any other lesson.

"Mark Zacharias" <mark_zacharias@sbcglobal.net>: Dec 15 06:17AM -0600 This thread, to me, represents the best of what newsgroups like this are for.   1. The aforementioned "assume nothing". (probably should have been ALL CAPS)   2. Correlate stated or observed malfunction with: a.) Visual inspection and yes, often smell checks. b.) Power supply checks. c.) Again, check for mechanically intermittent connections.   3. Don't assume too much from DC voltage checks with a multimeter. A 'scope can often give you the best "eyes" into what the circuit is actually doing.   Nevertheless, a good multimeter can give really great information interpreting voltage drops, finding leaky or shorted nodes, bias issues, etc.   Too many people just start off re-capping for example, assuming this fixes almost everything. I'm sick to death of hearing this from customers who have been on the internet.   Another thread here, I see...   Mark Z.

Ken <Ken@invalid.com>: Dec 15 06:24AM -0600 Phil Allison wrote:   > .... Phil   "When stuck on a problem, take a break and start over a day or so later." I cannot tell you how many problems I solved while doing that. Sometimes getting just getting away from the problem allows clearer thought.

N_Cook <diverse@tcp.co.uk>: Dec 15 12:33PM On 15/12/2015 12:24, Ken wrote: > later." I cannot tell you how many problems I solved while doing that. > Sometimes getting just getting away from the problem allows clearer > thought.   Posting a query to some "social media" may not ellicit the solution but some suggesting will often set you thinking in a different train. Its so easy to decide in your own mind that the problem must be in some particular narrow area and you totally overlook a completely valid alternative area.

N_Cook <diverse@tcp.co.uk>: Dec 14 05:54PM On 13/12/2015 14:43, Adrian Tuddenham wrote: > be flouted. The only time you would need a reversing turntable is if > you needed to play it backwards to recover a lost turn because of a > jumped groove.   Found a pulley to give +0.5% of 50 RPM, so within normal mains f variation. I intend to record on minidisc as stereo from a magnetic pickup. At this stage not playing around with the EQ of the phono amp, any recommendations for setting the normal domestic amp bass and treble controls for this first (only?) recording . After a second or 2 at inner and outer posistions to check antiskating weight and stylus weight is ok

adrian@poppyrecords.invalid.invalid (Adrian Tuddenham): Dec 14 06:13PM N_Cook <diverse@tcp.co.uk> wrote:       > I intend to record on minidisc...   No, No, NO!!!   Record in the highest possible uncompressed quality. This may be the only surviving recording and you don't want to screw up the sound wih the artefacts of Minidisc or any other compression format.   Even with a high bit-rate digital format, it is best to put right everything that can be done in the analogue domain before digitising it; once digital artefacts have been created by digital equalisation or speed changes, they can never be undone.     -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk

N_Cook <diverse@tcp.co.uk>: Dec 15 09:57AM On 14/12/2015 18:13, Adrian Tuddenham wrote: > everything that can be done in the analogue domain before digitising it; > once digital artefacts have been created by digital equalisation or > speed changes, they can never be undone.   I could certainly take the 1V "L & R" audio feeds to other recorders, but the only analogue recorder I have is an ordinary domestic cassette recorder of dubious quality other than it works, no 30 IPS R-R recorder, plus wav file on a laptop?

adrian@poppyrecords.invalid.invalid (Adrian Tuddenham): Dec 15 11:53AM > but the only analogue recorder I have is an ordinary domestic cassette > recorder of dubious quality other than it works, no 30 IPS R-R recorder, > plus wav file on a laptop?   Stereo WAV file on a laptop is your best option. If you were able to equalise it and get the speed exactly right before digitising it, you could used 16-bit 44.1k sampling, but if you intend doing any digital manipulation, a higher resolution is preferable to keep the artefacts to a minimum.   If you know what format your processing software needs, record in that format to avoid the artefacts of conversion - but it is better to eliminate all that nonsense by getting the analogue signal right in the first place.     -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk

O <X@NOWHERE.COM>: Dec 14 09:22PM -0800 Replacing an APC UPS battery pair labeled CP1290 12V 9AH. The unit has two confusing labels: on front is XS1500 and on back is BX1500. Was this a transition unit, insides BX1500?   Need recommendations of battery brand and type. Battery type includes high temperature batteries. Is this a better battery overall?   Buying batteries from Amazon.   Batteries in the unit are swollen and cracked but not leaking.   They are fastened together with a cable coming out between the to batteries that are mechanically packaged top to top.   Not sure if I can easily get apart and reuse that mechanical setup. Suggestions please.   --- news://freenews.netfront.net/ - complaints: news@netfront.net ---

Bruce Esquibel <bje@ripco.com>: Dec 15 11:48AM > Suggestions please.   Run, do not walk, to the nearest trash bin and toss that thing out, all of it, the batts, ups, everything.   Those things are total junk.   I bought around 10 of those (apc xs1500/bx1500) back when they came out (2005?) and none of them are still around.   Half of them, when the time came to do something (like supply backup power), arc'ed like a lighting strike, released the magic smoke and went dead.   The others that didn't have that feature, ate batteries like candy, I don't think any lasted 2 years. As you noticed, there are two batteries taped together and are somewhat bonded by a plastic frame and more tape.   There is nothing special about the batteries, like you, I replaced/rebuilt the carrier with ones from amazon (and a few from Microcenter) but like the originals, the lifespan was incredibly short.   I ran across a web site a while back where someone analyzed that series and discovered its the self-test killing the unit off. Instead of running the self-test every week to 10 days, that test runs every 24 to 36 hours and those short tests, after just a year, already killed off 50% of the usable life. After 14 months, the battery is practically useless (at 35%) and pretty much DOA at 18 months.   Add in the fact that the battery pack is wedged into a metal chamber with little to no air flow, it's just not a well designed ups.   http://www.pcliquidations.com/p15050-apc-back-ups-xs   If you look at the picture, on the front where the red APC letters are, that is actually a door that slides down. I think those were the first consumer level ups's that had "user replaceable batteries" and they designed the cabinet for safety when being replaced (thus the metal battery chamber).   Those batteries are $35-$40 each and what I'm saying is, that ups is not worth the $70-$80 and your time to rebuild the pack assembly. It's probably not going to work when you need it anyways.   Piece of shit.   -bruce bje@ripco.com

"Gareth Magennis" <sound.service@btconnect.com>: Dec 14 07:43PM "Phil Allison" wrote in message news:22272735-e7a9-4080-b4d2-8c88646a60cf@googlegroups.com...   Gareth Magennis wrote:     > Come on Phil, give us a clue, I'm stuck here.   ** Most times I've seen such a problem, it was due to lack of shielding between the output valve plate wiring and input signal wiring. Maybe a shielded signal wire really isn't or the plate wires need to be twisted, tidied and pushed against the chassis.   Everything in the JCM600 is crammed together making unwanted coupling more likely.   Other times it has been due to high resistance grounds on pots or jacks - or because some fool decided to put the OT next to the inputs jacks.     .... Phil           Yep, the plate wiring wasn't tidy or hard on the chassis, and one of the PCB interconnects was way too close. (Some cable ties had not been replaced)   All is good now, thanks.     Gareth.

Phil Allison <pallison49@gmail.com>: Dec 14 05:30PM -0800 Gareth Magennis wrote:     > Yep, the plate wiring wasn't tidy or hard on the chassis, and one of the PCB > interconnects was way too close. (Some cable ties had not been replaced)   ** Found this pic of the insides of one:   http://gitaradiy.pl/uploads/2_974_JCM600_6.jpg   The OT is on the far left ( right behind the input jacks ) and primary wires run next to all the pre-amp valve wiring on their way to the valve sockets on the right. That is a *really* poor layout for a valve guitar amp and sitting duck for oscillation.   Be worthwhile twisting the three primary wires and moving them further back.     .... Phil

"Gareth Magennis" <sound.service@btconnect.com>: Dec 15 09:32AM "Phil Allison" wrote in message news:8a7973ba-0515-40cb-888d-2450e7ada015@googlegroups.com...   Gareth Magennis wrote:     > Yep, the plate wiring wasn't tidy or hard on the chassis, and one of the > PCB > interconnects was way too close. (Some cable ties had not been replaced)   ** Found this pic of the insides of one:   http://gitaradiy.pl/uploads/2_974_JCM600_6.jpg   The OT is on the far left ( right behind the input jacks ) and primary wires run next to all the pre-amp valve wiring on their way to the valve sockets on the right.   That is a *really* poor layout for a valve guitar amp and sitting duck for oscillation.   Be worthwhile twisting the three primary wires and moving them further back.     .... Phil         The multitude of grey interconnects are not actually screened cable, just a signal wire lying beside an earth wire. I don't know what level of protection that actually offers.       Cheers,     Gareth.

amdx <nojunk@knology.net>: Dec 14 10:58AM -0600 On 12/14/2015 9:15 AM, Phil Hobbs wrote:   > I wouldn't be 21 again on a bet.   > Cheers   > Phil Hobbs   On the other hand, a recent comic had an old man and a young child, the child ask, "Grampa, how old are you?" Grampa replied, "I'm 89 years old, and I don't recommend it!" Mikek

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Dec 14 12:09PM -0500 On 12/14/2015 11:58 AM, amdx wrote: > the child ask, "Grampa, how old are you?" > Grampa replied, "I'm 89 years old, and I don't recommend it!" > Mikek   It's true, being really old is no fun either.   http://dilbert.com/strip/2008-01-30   But then I'm a Christian, so I don't have to hang on with my fingernails.   Cheers   Phil Hobbs   -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics   160 North State Road #203 Briarcliff Manor NY 10510   hobbs at electrooptical dot net http://electrooptical.net

Cydrome Leader <presence@MUNGEpanix.com>: Dec 14 08:45PM > The next day I found the SABA turned on with the MUTE activated (the radio was selected so the FM display etc was all lit, but no sound). Since I never used to use the MUTE button and I was the only one at home to use that thing I was quite surprised. I unmuted it and turned it off, all appeared to work correctly. The same day in the evening the same again, that made it obvious it was not me. In the next few days the same kept happening at random times but never when I was there, and because it would turn on with the mute set I could not hear when it happened.   > Finally one day it was off, I went to the kitchen and when I came back it was on and muted again, so I guessed a relation had to exist. Turned it off and went to the kitchen again - no joy. Repeated a few times and surprise - again on and muted. Some more experiments revealed that switching off the kitchen light sometimes would cause the SABA to turn on and activate the mute at the same time.   > The kitchen light consists of two 36W fluorescent tubes, apparently the inductive kick at turn off found its way into the SABA digital controls. They were two rooms apart, so not exactly next to the kitchen switch or lights. The issue did not reoccur after I plugged the printer back.   Ha!   Was noise filtering on the always on printer was somehow supressing the interference?

"Gareth Magennis" <sound.service@btconnect.com>: Dec 14 08:57PM "Phil Hobbs" wrote in message news:99idndpGh9yHQPPLnZ2dnUU7-W-dnZ2d@supernews.com...   On 12/14/2015 10:08 AM, MJC wrote:   > If only one could "turn the clock" back and recapture one's long-gone > youth that way...   > Mike.   I wouldn't be 21 again on a bet.   Cheers   Phil Hobbs           Youth is wasted on the young.   Being young again with an old mind though .......       Gareth.       Gareth.

Jeff Liebermann <jeffl@cruzio.com>: Dec 14 10:02PM -0800 About 3 weeks ago, I was blessed by the addition of a Samsung Syncmaster 243T 24" 1920x1200 LCD monitor to my repair backlog. It had been sitting around the donors office for a year or two, so nobody could recall why it was retired. I plug it in and it appears that everything is working. I have two similar LCD monitors at home for running my flight simulator. A third monitor would make a start on a wrap around cockpit window view. (actually 4 is about right).   So, I take home the monitor, being careful not to bash in the screen like I did the last monitor I took home by planting the groceries dead center in the middle of the panel. It arrive safely, I plug it in, and nothing works. No power, no pilot light, no messages, no nothing.   I'm not exactly equipped at home to fix monitors, so I drag it back to the office where it sat around for a few days. I plug it, and everything works normally. I check for intermittents by beating on the monitor, but nothing happens.   At this point, a sane and rational person would tear the monitor apart, look for problems, probe around with a volts-guesser, determine the culprit, and fix it. Nope. I'm out of bench space and have no room to work on a big monitor. So, I drag the monitor home again, and once again, it's dead on arrival. So, I drag it back to the office for the 3rd time, where it once again works perfectly.   This would be a good time to guess the cause (although I haven't really revealed enough info to make a proper deduction).   I still haven't ripped it apart to see what's going on, but I do have a good guess what's wrong. It probably has the usual bulging capacitor problem in the power supply. I keep the office at 72F (22C) to keep the customers happy. At home, I prefer something around 65F (18C). The workbench, where I do my testing is not very well heated, and is probably colder. Outside temperature is now about 43F (6C).   Bulging electrolytics are detected by measuring the ESR, which increases as they leak. Heating the caps lowers the ESR back down. Cooling the caps raises the ESR back up. Incidentally, this is why some devices run merrily when warm, but won't turn on when allowed to cool off. The Samsung monitor is likely teetering between working when warm, and not running when cold.   I'll disclose what was really wrong after I fix it, probably next year.   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann <jeffl@cruzio.com>: Dec 14 10:30PM -0800 One of the advantages of my office location is that it's very centrally located. Within about 500ft is the intersection of 3 freeways, the main drag into Santa Cruz city, and smaller roads leading directly to nearby cities. All roads lead to my office, which is both a benefit and a problem. Besides making it easier for my customers to drop in, it also attracts a motley assortment of people that just happen to be driving by my dead end street, and just happen to in the mood for trashing my day with inane conversation.   One memorable day, I had 4 of these visitors perched on benches and chairs (I only have two chairs in the office to make sure they're not very comfortable). I was working on replacing some caps in an ATX power supply. Of course, I wasn't paying attention and accidentally soldered the caps in backwards. With the cover off, I plugged in the power supply, and continued the discussion with my visitors. Suddenly, several of the caps decided this would be a excellent time to explode and launch oily confetti all over the office. Everyone, except me, dived for cover under or behind tables and boxes. I just continued talking as if everything was perfectly normal and nothing unusual had happened. The visitors soon made a rather hasty exit. Oddly, they must have told their friends, because my office was free of unwanted visitors for at least a week or two.     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

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