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N_Cook <diverse@tcp.co.uk>: Feb 05 02:11PM > Thoughts? Suggestions? I am searching for the manual from HiFi engine, but I am also hoping that someone out there may have had some experience with these beasts.   > Peter Wieck > Melrose Park, PA   Cold DVM-D of the main devices show up any disparities?

Trevor Wilson <trevor@SPAMBLOCKrageaudio.com.au>: Feb 06 09:25AM +1100 > engine, but I am also hoping that someone out there may have had some > experience with these beasts.   > Peter Wieck Melrose Park, PA   **I repaired one years ago. I have the full manual (paper version) somewhere, if you really need some of it, I may be able to scan and post. I do recall that it is a bastard of a thing to fix. Mine had (if I recall correctly) a failed output stage.   -- Trevor Wilson www.rageaudio.com.au   --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

N_Cook <diverse@tcp.co.uk>: Feb 02 02:46PM 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. 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. So far,cursory comparison, circuit looks like this one http://www.schematicsunlimited.com/o/orange/orange-rockerverb-guitar-amplifier-schematic/download/OTQ2Nw%3D%3D

N_Cook <diverse@tcp.co.uk>: Feb 04 12:10PM Definitely PbF used, but nothing obviously wrong in the way of ring cracks etc. "digital" checking of caps (with fingers) a Sanwha SD, 47uF 450 V , C16 designation ,would move like that situation of pad and pin fully soldered over so you cannot see the metal of the pin at all, but there is movement of the cap as the pin is moving fully enclosed in a PbF solder "socket". Ground back the solder on both pins to show discontinuity of metals and still no movement seen. A physical break inside the cap on one pin of 'D' anode supply to the preamp, of the R/C, B to E HT chain. I've yet to hear back from owner , how much hum there was.

"Gareth Magennis" <sound.service@btconnect.com>: Feb 05 07:04PM wrote in message news:023350fd-2984-4adb-b6ea-9eed1ab47d7d@googlegroups.com...   On Friday, February 5, 2016 at 1:43:53 PM UTC-5, Gareth Magennis wrote:     > How long does it take for manufacturers to stop using this shit?   Keep in mind that RTV silicon materials emit (contain) acetic acid (vinegar). Which attacks copper, at least. It may not be the glue itself, but the curing products reacting with the metal(s) within the system. As long as things are dry, OK. But under high humidity conditions, the salts will attract moisture, and then let the fun begin.   Peter Wieck Melrose Park, PA             I think the problem here is the heat generated inside a small speaker cabinet by the power amps. I suspect it is this heat cycling that transforms the glue into something else.     Gareth.

"Gareth Magennis" <sound.service@btconnect.com>: Feb 05 07:08PM "Gareth Magennis" wrote in message news:mn6ty.612803$wX5.241955@fx40.am4...       wrote in message news:023350fd-2984-4adb-b6ea-9eed1ab47d7d@googlegroups.com...   On Friday, February 5, 2016 at 1:43:53 PM UTC-5, Gareth Magennis wrote:     > How long does it take for manufacturers to stop using this shit?   Keep in mind that RTV silicon materials emit (contain) acetic acid (vinegar). Which attacks copper, at least. It may not be the glue itself, but the curing products reacting with the metal(s) within the system. As long as things are dry, OK. But under high humidity conditions, the salts will attract moisture, and then let the fun begin.   Peter Wieck Melrose Park, PA             I think the problem here is the heat generated inside a small speaker cabinet by the power amps. I suspect it is this heat cycling that transforms the glue into something else.     Gareth.           Could it be that some carbon compound or something else in the glue gradually migrates to the bottom of the glue pile as it constantly softens and rehardens? This would place a nice conductive layer on the PCB.       Gareth.

"Mark Zacharias" <mark_zacharias@sbcglobal.net>: Feb 04 05:16AM -0600 "John-Del" <ohger1s@aol.com> wrote in message news:78c200c3-b710-43b0-8002-8fbb178d0c17@googlegroups.com...       >When my father in law tells the story, he said that when he saw me hosing >out the TV guts in >the front yard he was thinking "oh sh$t I'm going to >have to buy a new TV tomorrow".       Same thing happened to my younger brother when our family was visiting the family of the older brother's wife.   Zenith TV died. My younger brother, who was either still in tech school or early in his career, tore the set down to bits and pieces right there on the living room floor, puzzled over it a bit, the light came on, ran down to the Zenith distributor, picked up a part, got back over there and finished the repair.   Two families (not to mention the two brothers) were sweating bullets on that one.     Mark Z.

Chuck <chuck@mydeja.net>: Feb 05 10:55AM -0600 On Thu, 4 Feb 2016 05:09:48 -0600, "Mark Zacharias"   >I was pretty confident I could fix it, but one problem kept hiding behind >the last one, and oscillation problems kinda turn my knees to jelly.   >Mark Z.   Mark,   These were the worst! I've seen 20 or more transistors blown on these amps. I admire your tenacity. The Accuphases were so much easier to repair.   --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

Bill Baxter <bbaxter455123@msn.com>: Feb 05 10:28AM -0500 I have some Vivitar 283 flashes I used several years back in lower power mode for a special application (I swapped out the thyristor for a circuit that allowed 1/16th power). The flashes were controlled as slaves (using Wein peanuts) from my main camera, a Canon Rebel at the time. The flashes performed flawlessly for the few weeks that I needed them and then stored away.   After about 5 years and recently, I brought out the flashes to use now with my Pentax KX for macrophotography and thought they would be ideal still at 1/16th power. They started off working ok again as slaves with the peanuts, but have quickly become erratic and I don't know why. Not just one, but all of them after just a couple of days of use. What's generally happening is that they won't trigger from the main flash. I suspected the peanuts and swap them out, but they still won't respond. I used contact cleaner on the peanuts themselves, then carefully inserted into the 283's, but this didn't help. Also, even if I push the ready light button on the 283's, they won't fire. Sometimes the ready light is flashing, sometimes steady but doesn't seem to matter.   I can hear the whine of the flashes, mostly steady but in some cases pulsing as the light flashes. Nothing matters though as any/ all of the flashes won't flash. I've swapped out batteries for others, used the DC to AC adapter for the flashes, and mostly they won't respond or very erratically.   Any ideas what's going on? I do notice that if I short the hot shoe terminals, nothing is happening on any of the flashes. I can sometimes get them to fire if I keep bending them, but not always.   Any help for these 283's or time for something else? I'd hate to lose all 3 of them, but none of them seem to want to work properly.

Cursitor Doom <curd@notformail.com>: Feb 04 01:59PM Hi all,   I'm now working on a different Philips scope which 'died' suddenly for no apparent reason. Here's a summary of the key points:   The smps section had power in, but nothing coming out. I checked the smps outputs for shorts/low-res. One output marked 45V was trying to feed a board with an input resistance of only 6 ohms. I located the board in question. There were several multi-pin connectors around the edge of it running off to other parts of the scope. Now it turns out the smps runs perfectly fine when *one* of these connectors is pulled from the board. With the suspect connector's plug disconnected, the aforementioned 6 ohms shoots up to about 15k and life is great. *BUT* (and here's the thing) the resistance looking into the suspect plug (which has only two wires) is several megohms. And yet this very high resistance, when plugged into the board causes such a voltage drop that the smps shuts down! How is this even possible? I keep thinking there must be something simple I've overlooked, but can't think what it might be. If anyone has experienced something similar in the past and remembers what the underlying issue was, then that could be very helpful! Thanks.

Pat <pat@nospam.us>: Feb 04 10:26AM -0500 On Thu, 4 Feb 2016 13:59:27 -0000 (UTC), Cursitor Doom >If anyone has experienced something similar in the past and remembers >what the underlying issue was, then that could be very helpful! >Thanks.   Regarding "How is this even possible?", I can think of two things. One is mechanical - plugging that 2 wire connector in causes a short near the socket. Can you unplug the other end of that cable and see if you get the result? The more likely cause is a voltage on that two wire cable turns on a transistor or some other device hard wihich then shorts the incoming line from the power supply due to a bad part somewhere else on the board. Good luck.

MJC <gravity@mjcoon.plus.com>: Feb 04 04:08PM In article <n8vlfv$7l5$1@dont-email.me>, curd@notformail.com says...   > ... *BUT* (and here's the thing) the resistance looking into the suspect plug > (which has only two wires) is several megohms. And yet this very high > resistance, when plugged into the board causes such a voltage drop that > the smps shuts down! How is this even possible?   It's rather easily possible if the current draw is non-linear with voltage. After all, the further the circuit deviates from a simple resistor the more likely this is!   Apart from brutal ideas like providing the suspect plug with a very beefy PSU and watching to see what burns up, I don't see what alternative there is apart from gradual splitting off of parts of the circuit...   Mike.

Cursitor Doom <curd@notformail.com>: Feb 04 03:42PM On Thu, 04 Feb 2016 10:26:46 -0500, Pat wrote:   > is mechanical - plugging that 2 wire connector in causes a short near > the socket. Can you unplug the other end of that cable and see if you > get the result?   Already tried and eliminated, thanks.   The more likely cause is a voltage on that two wire > cable turns on a transistor or some other device hard wihich then shorts > the incoming line from the power supply due to a bad part somewhere else > on the board. Good luck.   That's what I was wondering. If my DVM on resistance range doesn't use enough voltage to switch such a transistor or diode into conduction, then that could account for it. I'll try it again with an old-style AVO.

Cursitor Doom <curd@notformail.com>: Feb 04 04:12PM On Thu, 04 Feb 2016 16:08:38 +0000, MJC wrote:     > Mike.   "Current blasting"? It would have worked in this instance, but I've found the problem with my good old trusty AVO which confirmed my previous suspicions. People often go on about how modern DVMs are great because they don't turn on pn junctions, which is all very well, but there are odd times when that is precisely what you *do* want the meter to do! This was one of those. Thanks, guys.

Cursitor Doom <curd@notformail.com>: Feb 04 06:41PM On Thu, 04 Feb 2016 18:38:58 +0100, Reinhard Zwirner wrote:   > Would you be so kind and tell us what was wrong? Thanks in advance.   The problem was in the EHT converter section which creates 1600V from a 45V input. A BSW68 transistor in this section had fused low-resistance between C&E and was attempting to dissipate 340 watts all by itself - and it didn't even have a heatsink! :) The fact that its case had turned blue also hinted that it had been very hot. I couldn't see it on inspection initially as it was hidden by HV shielding. Now I just have to find an equivalent for it...

Cursitor Doom <curd@notformail.com>: Feb 04 09:34PM On Thu, 04 Feb 2016 12:01:02 -0800, dansabrservices wrote:   > would do.   > Check further. It may be easier to use a sub.   > Dan   Thank you for those suggestions, Dan. I've got scores of TIP BJT variants lying around in my junk box. Many years ago I had a copy of Towers' Transistor Selector which listed a good range of equivalents for a vast range of devices. I guess these days there are web sites that perform the same function, but finding one worthy of trust that produces reliable results is another matter from what I've seen so far.

Cursitor Doom <curd@notformail.com>: Feb 04 11:22PM On Thu, 04 Feb 2016 14:05:40 -0800, dansabrservices wrote:   > rather large collection of NTE parts, I use these for experiments. I > don't usually use NTE or ECG parts for a repair though. I try to use > "real" parts. It does at least give me a quick try.   Good idea. Maybe I'll look into subbing that BJT for a power MOSFET. A lot of older gear uses BJTs in situations where a MOSFET would be de rigeur nowadays. This transistor functions as a chopper switching an inductive load in this circuit and it wouldn't require much tweaking to sub it for a better device, I reckon. In fact maybe that's why the original part failed or maybe its heatsink - if it ever had one - just fell off at some point, I can't say.

"Miguel Giménez" <me@privacy.net>: Feb 02 12:10PM +0100 Hello   I'm trying to repair a dead LG 32LS570S LCD screen. The backlight work OK, all the power supply voltages are nominal and the unit turns on and off via the remote or the keypad, but there is no image. The service manual says "change the main board", but first I want to ask here if this is a known fault.   Thank you   -- Saludos Miguel Giménez

"Kenny" <me@privacy.net>: Feb 03 06:57PM "Miguel Giménez" wrote in message news:n8q2rt$1iml$1@gioia.aioe.org...   Hello   I'm trying to repair a dead LG 32LS570S LCD screen. The backlight work OK, all the power supply voltages are nominal and the unit turns on and off via the remote or the keypad, but there is no image. The service manual says "change the main board", but first I want to ask here if this is a known fault.   Thank you   -- Saludos Miguel Giménez   You didn't say if you have sound and channel change etc. Service manual's here if it helps. http://elektrotanya.com/lg_32ls570s-zb_32ls570t-zb_chassis_ld22e_mfl67360915.pdf/download.html   Kenny Cargill

"Miguel Giménez" <me@privacy.net>: Feb 04 05:25PM +0100 El 03/02/2016 a las 19:57, Kenny escribió: > You didn't say if you have sound and channel change etc.   No sound, but I don't know if the device is properly tuned (it's not mine and comes from another repeater area).   The channels may change, but I can't see the change.   I already had the service manual you pointed (thank you), but an special remote is needed for almost any test. I followed the debugging procedere until I arrived to "change main board".   Thank you.   -- Saludos Miguel Giménez

frank <frank@invalid.net>: Feb 04 10:08AM Hi all,   I've got this really old TV test signal generator to repair. I've found a very poor copy of the service manual from a well known internet site (elektrotanya). Does anyone, by chance, have a readable copy of that manual around? Thanks in advance   Frank IZ8DWF

Jeff Liebermann <jeffl@cruzio.com>: Feb 09 10:09AM -0800 On Tue, 9 Feb 2016 10:17:14 +0000, Adrian Caspersz >into the board with a meter while changing power state.   >However, the +1.5V line, is that the CPU voltage voltage? 1.298V looks >in the ballpark for the CPU in that unit.   Try watching what the ATX power good gray wire does on a working computah. There's small delay between turning on the power and when the line goes high. Normal operation is a logic high which means roughly +5VDC. +1.5V is definitely out of spec. I would venture a guess that it's really oscillation or pulsing on the power good line, which happens to average out to about +1.5V on a DVM.   Having the measured +1.5v be similar to the CPU voltage is coincidence. Recycling the above Wikipedia page: The ATX specification defines the Power-Good signal as a +5 volt (V) signal generated in the power supply when it has passed its internal self-tests and the outputs have stabilized. This normally takes between 0.1 and 0.5 seconds after the power supply is switched on. The signal is then sent to the motherboard, where it is received by the processor timer chip that controls the reset line to the processor.   Cheaper and/or lower quality power supplies do not follow the ATX specification of a separate monitoring circuit; they instead wire the power good output to one of the 5 V lines. This means the processor will never reset given bad power unless the 5 V line drops low enough to turn off the trigger, which could be too low for proper operation.   I guess the easiest test is to just replace the PS with a known good PS and see what happens. Checking the PS with a PS tester is also useful. I have a really old and crude one but am considering getting something like one of these: <https://www.google.com/search?q=atx+power+supply+tester+lcd&tbm=isch>   -- 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

"David Farber" <farberbear.unspam@aol.com>: Feb 03 10:14PM -0800 I'm servicing a Gateway GM5260. It uses an Intel DP965LV motherboard and it has Windows XP installed. It also has this habit of freezing randomly. Then you are forced to hold in the power button to shut it off. Here is the interesting part. When you power it back on after it freezes, it will ALWAYS shut down about 1 second after the power button is pressed. If you restart it second time, usually it will power up fine. Occasionally, it will take a third try to keep the power on. If the computer goes through a normal shut down, the power up process always works the first time. I've swapped the RAM, video card, and power supply, and it made no difference. The only hardware issue I can find is that in the system bios, there is a value in the hardware monitor called, +1.5V and it hovers around 1.298V. I have inspected the caps and they don't look or test bad. The CPU and motherboard temps are normal. Has anyone experienced this type of problem before?   Thanks for your replies. -- David Farber Los Osos, CA

Jon Elson <jmelson@wustl.edu>: Feb 03 03:23PM -0600 > 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 ? Actually, you could make the neon lamps, themselves, be the storage element. Connect one side of all the lamps together, and tie to B+ with one resistor. Have individual resistors to ground on each lamp. Short each individual resistor with the select pushbutton. When you press this button, all other neons will go out, and the selected one will light, and stay lit when you release the button. Now, a circuit detects which of the individual resistors has voltage across it, and selects the desired function. Definitely cheap, and will work for a while. Eventually, the neons will get far enough out of balance to cause problems.   Jon

Chuck <ch@dejanews.net>: Feb 03 04:39PM -0600 >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 ?   No It was a Large Scale CMOS chip. Maybe made by NEC. (NEC codes worked with some AOC sets.)   --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

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