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Jeff Liebermann <jeffl@cruzio.com>: Jul 06 09:44AM -0700 On Thu, 6 Jul 2017 07:15:39 -0000 (UTC), frank <frank@invalid.net> wrote:   >I'll try to make a test setup with constant current on a GDT and try >to measure the frequency of the oscillation. >Frank   Could I trouble you to disclose the maker and model of the gas discharge transient suppressor that you're testing, and the model number of the Heathkit curve tracer? I don't have a curve tracer but I do have a high voltage variable power supply that I can manually sweep to see if there are any negative resistance regions.   The manufacturers of gas discharge tubes should have something on the gas discharge tubes and negative resistance. <http://www.littelfuse.com/~/media/electronics/product_catalogs/littelfuse_gdt_catalog.pdf.pdf> Yep, the graph looks much like a neon lamp. The tube triggers at 75 to 600VDC, and rapidly drops to 15VDC.   I have a different guess(tm). When the gas discharge tube conducts, it effectively shorts the terminals of the device. I don't think your Heathkit curve tracer will not like a short circuit. It should have some kind of short circuit or overcurrent protection circuit which I would guess(tm) is doing the oscillating. Insert a large value resistor in series with the gas discharge tube and try again.   -- 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>: Jul 06 10:00AM -0700 On Thu, 6 Jul 2017 09:51:44 -0400, Phil Hobbs   >No, it's a coupled plasma/surface effect. It's really cool. It peaks >down around a few tenths of a millitorr, but it's still appreciable at >higher pressures.   According to Wikipedia: <https://en.wikipedia.org/wiki/Incandescent_light_bulb> the gas pressure in a common light bulb is about 70 kPa or 525 torr. That's quite a bit higher than a few tenths of a millitorr.   >The light bulb thing was discovered by somebody turning on an >incandescent lamp and wiping out his reception.   I don't quite believe it. In the early daze of light bulb research, it was wrongly assumed that a better vacuum produced a better light bulb. So, early light bulbs had a fairly high vacuum, which might explain the RF interference, except that radio hadn't really become common at the time. Eventually, someone figure out that it was the water in the glass that was killing the filaments. Once the water was baked out of the glass, subsequent light bulbs had a much lower vacuum.   >I don't know if the pressure in the transient suppressor is low enough >for Barkhausen--if not, it's probably the neon bulb oscillation as >others have said.   I don't think that the ceramic gas discharge tubes have a vacuum. More like they are under pressure in order to lower the conduction current. However, I'm guessing and don't have time to look it up right now.     -- 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

frank <frank@invalid.net>: Jul 06 06:25PM >>Frank   > Could I trouble you to disclose the maker and model of the gas > discharge transient suppressor that you're testing, and the model   I don't know, I've pulled them out of a scrap PCB. They are marked as 201M TM4M (on two separate lines). 201 might be the discharge voltage which is in good agreement on what I see on the curve tracer.   > number of the Heathkit curve tracer? I don't have a curve tracer but > I do have a high voltage variable power supply that I can manually > sweep to see if there are any negative resistance regions.   it's IT-3121, connected to an HP-1801A/180AR as display.   > some kind of short circuit or overcurrent protection circuit which I > would guess(tm) is doing the oscillating. Insert a large value > resistor in series with the gas discharge tube and try again.   series resistor was already selected to limit the current peak value, it's a knob on the curve tracer. I've tried going from 5K to 50K and oscillation remains, of course peak current varies. Using 100K as series resistor doesn't make the tube ignite at all. Max voltage value on this curve tracer is around 240V. Do you mean I should add an external resistor? I believe it would just go in series with the internal one. Indeed these tubes are meant to adsorb transients, so once fired, their impedance could become very low, that would explain what I'm seeing. Frank

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Jul 06 03:21PM -0400 On 07/06/2017 01:00 PM, Jeff Liebermann wrote: > it was wrongly assumed that a better vacuum produced a better light > bulb. So, early light bulbs had a fairly high vacuum, which might > explain the RF interference,   How exactly, if not Barkhausen? Hot wires don't produce a lot of RF IME.   > water in the glass that was killing the filaments. Once the water > was baked out of the glass, subsequent light bulbs had a much lower > vacuum.   If you read my original post, I pointed out that it was only the old fashioned evacuated bulbs that showed the effect, not the modern argon ones. > More like they are under pressure in order to lower the conduction > current. However, I'm guessing and don't have time to look it up > right now.   You don't want to reduce the conduction current in a gas suppressor tube, though, do you? My guess is that they'd be a torr or two, to get lower breakover voltage, which is on the high side for Barkhausen, for sure.   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

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Jul 06 03:23PM -0400 On 07/06/2017 12:12 PM, frank wrote:   > I do have one (of course, I'd say). My radio reception (hamradio bands) has > never been disturbed by incandescent lights though (and it's about > the only electric thing that doesn't make any RF nowadays).   Right, the argon-filled ones don't show the effect--the gas pressure is much too high. If the transient suppressor has that much gas in it, it definitely won't be Barkhausen oscillation.   > In the next days (as I find time) I'll try to run the transient suppressor > with a small dc current and see if it oscillates (and at what frequency).   I'll be interested in the results.   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

ggherold@gmail.com: Jul 06 01:02PM -0700 On Thursday, July 6, 2017 at 9:51:54 AM UTC-4, Phil Hobbs wrote: > higher pressures.   > The light bulb thing was discovered by somebody turning on an > incandescent lamp and wiping out his reception.   Huh, OK... Get any sort of link? B-K tube, https://en.wikipedia.org/wiki/Barkhausen%E2%80%93Kurz_tube sounds like a delay... like a reflex klystron.   Is it a surface plasmon thing? https://en.wikipedia.org/wiki/Surface_plasmon_resonance   Back to Frank, Can you do an I-V (at DC) to see if there is negative resistance. (i've never looked at a negative resistance so I don't really know if I'm asking the right question.)   George H.

Jeff Liebermann <jeffl@cruzio.com>: Jul 06 09:51PM -0700 On Thu, 6 Jul 2017 15:21:48 -0400, Phil Hobbs >> bulb. So, early light bulbs had a fairly high vacuum, which might >> explain the RF interference,   >How exactly, if not Barkhausen? Hot wires don't produce a lot of RF IME.   All that I know is that someone allegedly turned on a light bulb which produced enough RF to wipe out their radio reception. My point was that until 1916, when Irving Langmuir invented the gas filled light bulb at GE, light bulbs were made with a sufficiently high vacuum to produce Barkhausen noises. The light would also need a tungsten filament, which was introduced in 1908. So, if the bulb really did produce noise, it would have to have been manufactured between 1908 and 1916. The Barkhausen effect was discovered in 1919, so the person flipping the light switch would have needed a pre-1916 light bulb, in order to call the noise Barkhausen Effect by running the test after 1919.   Meanwhile the radio receivers of that era were crude at best consisting of coheres, magnetic detectors, cat whiskers, liquid diodes, and early triodes. Regular entertainment broadcasting didn't begin until 1922. Therefore, whatever was being broadcast between 1908 and 1916 would probable have been amateur radio or military signals. The receive technology lurched forward rapidly, but I suspect there was nothing worth listening to until the 1930's by which time all the light bulbs would probably have been gas filled.   If not Barkhousen noise, the light switch could have caused an arc somewhere in the light circuit. It could have turned on something else in the circuit, such as a carbon arc lamp, which generates enough RF noise to clobber even the most deaf receivers of the day.   I'm also having problems believing that the weak paramagnetism of tungsten, can generate enough RF to be heard on the presumably AM LF (low frequency) receiver of the day. Also, I don't see why a high vacuum is required since there are several YouTube videos demonstrating the effect at 1 atm. <https://www.youtube.com/watch?v=H7nJi5episc> <https://www.youtube.com/watch?v=YLycGnOCqLc>   So, do I wrap some wire around an incandescent light bulb and feed it to my spectrum analyzer? Or, is this a waste of time with modern gas filled light bulbs?   >> vacuum.   >If you read my original post, I pointed out that it was only the old >fashioned evacuated bulbs that showed the effect, not the modern argon ones.   I read that, which is why I'm questioning the timing. At the time when there were radio receivers sensitive enough to hear Barkhousen Effect noises, the light bulbs were all gas filled. Well, I guess the person flipping the switch might have been using an antique light bulb: <http://www.centennialbulb.org>     >You don't want to reduce the conduction current in a gas suppressor >tube, though, do you? My guess is that they'd be a torr or two, to get >lower breakover voltage, which is on the high side for Barkhausen, for sure.   I wish I could xray the ceramic GDT and measure the spark gap spacing. My guess(tm) is that it's fairly wide at perhaps 1 mm, something similar to a common NE-2 neon lamp. I wouldn't need to have a hard vacuum in order to get a lower breakdown voltage when neon breaks down so easily. So, if I don't need a vacuum, and want plenty of ionized neon atoms to provide conduction, I would pressurize the tube with as much neon gas as I could cram into the package.     -- 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>: Jul 06 10:21PM -0700 On Thu, 6 Jul 2017 18:25:31 -0000 (UTC), frank <frank@invalid.net> wrote:   >They are marked as 201M TM4M (on two separate lines). >201 might be the discharge voltage which is in good agreement on what I see >on the curve tracer.   I tried to identify the manufactory from the part numbers supplied. Nothing. I would agree that 201 might mean 200V discharge voltage.   I found one in my junk box inscribed Joslyn M-3 2204-44. I also couldn't find any specs on that device. I was going to try it on my hi-v power supply, but ran into 2 problem. The power supply is dead for no obvious reason. My workbench is currently being used to test my latest Harbor Freight purchase, a 1x30" belt sander suitable for sharpening all my dull kitchen knives. That's a priority project.   >> I do have a high voltage variable power supply that I can manually >> sweep to see if there are any negative resistance regions.   >it's IT-3121, connected to an HP-1801A/180AR as display.   Schematic and operating instructions at: <http://www.vintage-radio.info/download.php?id=225>   On Pg 62 of the operations manual, it shows various display anomalies. Some are loops which look something like your photo. They suggest using the LOOP control to reduce the effect or lower the power supply voltage. You've probably already tried this, but I thought I would mention it anyway.   >series resistor was already selected to limit the current peak value, it's >a knob on the curve tracer.   Yep. Resistor values from 0 to 1M. Aim towards the higher values here.   >I've tried going from 5K to 50K and oscillation remains, of course peak >current varies. Using 100K as series resistor doesn't make the tube ignite >at all. Max voltage value on this curve tracer is around 240V.   You might be too close to the conduction threshold on the tube. Hard to tell without specifications. If the device appears to fail to fire at high series resistances, it might have fired, dropped the voltage to about 15v across the tube, and stayed there. Grab a DVM and measure the voltage across the device. My guess(tm) is that it's about 15v and holding.   For fun, put a capacitor (300v or high) across the tube with a high series resistance and see if you can get it to oscillate as a relaxation oscillator.   For additional entertainment, replace the tube with a common NE-2 neon lamp and see if it does the same thing.   >Do you mean I should add an external resistor? I believe it would just go >in series with the internal one.   No. I didn't realize that there was a series resistor in the curve tracer. This switchable resistor should be sufficient.   >Indeed these tubes are meant to adsorb transients, so once fired, their >impedance could become very low, that would explain what I'm seeing.   Yep. Good luck.   -- 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

frank <frank@invalid.net>: Jul 07 07:02AM > negative resistance. (i've never looked at a negative > resistance so I don't really know if I'm asking the right > question.)   well yes, I could do that probably. I have a 300V DC source but it's not variable. I could try with resistor dividers and measure a few points.   Frank

"Ian Field" <gangprobing.alien1@virginmedia.com>: Jul 06 08:44PM +0100 Someone on one of these groups suggested a very good service manual site, but I never find it because the link to open the document is obscure.   The PSU is the worst I've seen that didn't already go bang!   Changed all the bulged electrolytics and ESR tested all the others - but I think I got one mixed up putting it back. The service manual would be quite handy.   Or I could just fire it up and see how loud the bang is....................   Thanks for any help.

N_Cook <diverse@tcp.co.uk>: Jul 07 07:45AM +0100 On 06/07/2017 20:44, Ian Field wrote: > quite handy.   > Or I could just fire it up and see how loud the bang is....................   > Thanks for any help.   1 second fire-up, followed by scanning with IR thermometer?

Jeroni Paul <JERONI.PAUL@terra.es>: Jul 06 11:47AM -0700 > https://na.suzohapp.com/pdf/service_pdfs/support/visionpro/49-1329-vp2_schematic.pdf   > B+ is 12v3, 12V and 24V good. i was thinking yoke, but they ohm out good, and look like brand new. no physical damage. looks like a few transistors are after the vertical ic, i'm looking at them now. not real good at following this schematic, so any help is appreciated.   > thanks   In the yoke there are two coils for vertical and two for horizontal connected in series or parallel depending on the design, if in parallel one coil connection could be broken. The coils are connected together in the solder posts on the yoke, you may check there if some wire looks loose.

mhooker32@gmail.com: Jul 06 12:32PM -0700 On Thursday, July 6, 2017 at 2:47:59 PM UTC-4, Jeroni Paul wrote:   > > B+ is 12v3, 12V and 24V good. i was thinking yoke, but they ohm out good, and look like brand new. no physical damage. looks like a few transistors are after the vertical ic, i'm looking at them now. not real good at following this schematic, so any help is appreciated.   > > thanks   > In the yoke there are two coils for vertical and two for horizontal connected in series or parallel depending on the design, if in parallel one coil connection could be broken. The coils are connected together in the solder posts on the yoke, you may check there if some wire looks loose.   thats a great idea, i didnt know the coils were doubled up. i will check that for sure tonite. i was thinking of inverting the image, there are solder pads for an inverted header on the chassis board, and see what the image does. that would tell me if its the yoke or a chassis issue. does that make sense?   thanks much

John-Del <ohger1s@gmail.com>: Jul 06 12:58PM -0700 > https://na.suzohapp.com/pdf/service_pdfs/support/visionpro/49-1329-vp2_manual.pdf   > https://na.suzohapp.com/pdf/service_pdfs/support/visionpro/49-1329-vp2_schematic.pdf   > B+ is 12v3, 12V and 24V good. i was thinking yoke, but they ohm out good, and look like brand new. no physical damage.   Not saying the yoke is the problem, but a single turn shorted to an adjacent turn will not change the resistance reading on your dmm, but a single shorted turn will totally collapse the magnetic field of the coil.   A ringer is the best instrument to check for shorted turns.

mhooker32@gmail.com: Jul 06 02:18PM -0700 On Thursday, July 6, 2017 at 3:58:22 PM UTC-4, John-Del wrote:   > > B+ is 12v3, 12V and 24V good. i was thinking yoke, but they ohm out good, and look like brand new. no physical damage.   > Not saying the yoke is the problem, but a single turn shorted to an adjacent turn will not change the resistance reading on your dmm, but a single shorted turn will totally collapse the magnetic field of the coil.   > A ringer is the best instrument to check for shorted turns.   not sure what a ringer is, but im pretty sure i dont have one. you mean like a tone generator, and you move it around the yoke ?

"Ian Field" <gangprobing.alien1@virginmedia.com>: Jul 06 10:21PM +0100 "John Robertson" <spam@flippers.com> wrote in message news:9vOdneJtZoCTHsHEnZ2dnUU7-WXNnZ2d@giganews.com... > (typically the lower of the two on schematics) is the one at fault.   > The vertical drive is just a very slow audio amp, apply audio amp service > methods.   Not quite - it has flyback boost and tailored feedback for linearity.   Either of those can cause similar symptoms.

"Ian Field" <gangprobing.alien1@virginmedia.com>: Jul 06 10:22PM +0100 <mhooker32@gmail.com> wrote in message news:c5b3309f-f414-4936-bd35-fc7cacbc7c60@googlegroups.com...   >> thanks much   > just got done replacing the vertical IC, la7833. no change in the image. > no better, no worse.   There might be a flyback diode lurking nearby - it could've gone leaky.

"Ian Field" <gangprobing.alien1@virginmedia.com>: Jul 06 10:26PM +0100 "John-Del" <ohger1s@gmail.com> wrote in message news:514af99a-2f1b-41a7-8a6b-dc0dea0292ca@googlegroups.com... > adjacent turn will not change the resistance reading on your dmm, but a > single shorted turn will totally collapse the magnetic field of the coil.   > A ringer is the best instrument to check for shorted turns.   DSE did one, but I don't think the kit is available anymore.   The schematic is floating about and there's no unobtanium in the parts list.

John-Del <ohger1s@gmail.com>: Jul 06 02:36PM -0700 > > Not saying the yoke is the problem, but a single turn shorted to an adjacent turn will not change the resistance reading on your dmm, but a single shorted turn will totally collapse the magnetic field of the coil.   > > A ringer is the best instrument to check for shorted turns.   > not sure what a ringer is, but im pretty sure i dont have one. you mean like a tone generator, and you move it around the yoke ?   A dedicated instrument that checks inductors for shorted turns by injecting a waveform and counting the "rings" (like echos). A shorted coil won't ring or will ring very low. In the old days, several companies made "flyback" testers that would check flybacks and yokes for shorted turns. I have a Sencore LC75 that has a ringing feature and it works well.   Another way of checking the yoke out of the circuit can be done with a scope. If you can identify and electrically separate the two halves of the vertical yoke, you can connect each section to the calibration output jack of your scope and monitor the resulting waveform of each. Unless the top section shorted to the bottom, you can be pretty confident you have one good section and one bad. If the waveform on one of the sections is severely distorted compared to the other, it's a yoke issue. If both waveforms look the same, the yoke is most likely good.

John Robertson <spam@flippers.com>: Jul 06 02:53PM -0700 On 2017/07/06 2:26 PM, Ian Field wrote:   > DSE did one, but I don't think the kit is available anymore.   > The schematic is floating about and there's no unobtanium in the parts > list.   The old DS ringer was designed by Bob Parker and was best for checking flybacks (LOPTs), not much use on yokes I'm afraid. The kit is now made by Anatek (we carry it on Flippers), but you would be better off with an inductance meter - split the vertical windings and each side should be identical.   John :-#)#   -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."

John Robertson <spam@flippers.com>: Jul 06 02:54PM -0700 On 2017/07/06 2:22 PM, Ian Field wrote:   >> just got done replacing the vertical IC, la7833. no change in the >> image. no better, no worse.   > There might be a flyback diode lurking nearby - it could've gone leaky.   Flyback diode won't affect the vertical deflection. You will lose the HOT though if that diode is open. Nowadays they are part of the HOT though.   John :-#)#   -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."

rickman <gnuarm@gmail.com>: Jul 06 11:20PM -0400 >>> thanks   >> In the yoke there are two coils for vertical and two for horizontal connected in series or parallel depending on the design, if in parallel one coil connection could be broken. The coils are connected together in the solder posts on the yoke, you may check there if some wire looks loose.   > thats a great idea, i didnt know the coils were doubled up. i will check that for sure tonite. i was thinking of inverting the image, there are solder pads for an inverted header on the chassis board, and see what the image does. that would tell me if its the yoke or a chassis issue. does that make sense?   I don't get why your idea is not good. If you can flip the drive signal polarity the image will invert. If the problem is in the drive circuitry the half that is working will swap with the half that loses drive. If the problem is in the yoke the image will invert, but the problem won't. No need for fancy testers or widgets. Or maybe there is something I don't understand about this?   --   Rick C

John Robertson <spam@flippers.com>: Jul 06 09:48PM -0700 On 2017/07/06 8:20 PM, rickman wrote: > drive. If the problem is in the yoke the image will invert, but the > problem won't. No need for fancy testers or widgets. Or maybe there is > something I don't understand about this?   Great point Rick, that would indeed be a good test to see if the yoke is linear or not.   John :-#)#   -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."

mhooker32@gmail.com: Jul 06 10:04PM -0700 On Friday, July 7, 2017 at 12:48:26 AM UTC-4, John Robertson wrote: > (604)872-5757 (Pinballs, Jukes, Video Games) > www.flippers.com > "Old pinballers never die, they just flip out."   i soldered a header into the reverse position on the chassis, and gave it a try. it did the same thing as before, just inverted. now the bottom half of the screen has an image that compresses toward the center, a total collapse on the center, and no image in the upper half of the screen. does that rule out a yoke problem?   thanks

"megamusic" <nema@nema.com>: Jul 07 04:51AM +0200 <jeff.panasuk@cfl.rr.com> wrote in message news:45234dd2-55fe-4efa-a90d-39a920cf2af9@googlegroups.com... > storage but every 4 months or so, when I see it and think about it, I fire > it up. Hate to trash this old tv. >Kind of part of the family now. Has > anyone ever heard of this before?   MN14834HH is processor, check oscillator (pins 36/37) and reset voltage (pin 39). Replace resistor RO125 and DO110 (on pin 6).

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