sci.electronics.repair@googlegroups.com

Google Groups

jurb6006@gmail.com: Apr 26 10:22AM -0700 Does anyone know anything about these ? I know the basics but there are details missing from the print, LIKE THE PINOUT of the CRT !   I can see though (thank you Drs Budrous and Stewart) so I can see the thicker wires, those are pretty much at cathode potential, -500 volts. I can also find the deflection plates and with the centering make the DC voltages equal, still no display.   Unless there's something I missed I need to get into the grid and focus voltages and if those are all there, the CRT is bad ?   From what I hear you would need a SWAT team and a bunch of automatic weapons to get a replacement CRT. Even people with experience on these things, how many receivers had built in scopes ? I saw one in another brand once but can't remember what it was, maybe a Kenwood ? Other than that only Marantz and then even very few models.   I got the other problems fixed, it had a fault on the one power amp board and a bad transistor on the tone amp board which is by the way stuck to the chassis with double sided foam tape ! For what they charged fro these things, foam tape ? And you should see the PITA it is to remove, I was thinking "This board it gonna break", but it didn't.   What you really need is a Fein cutter with an L shaped blade. (they are normally used to cut windshields out of cars)   Anyway, thanks in advance for anything useful on this matter. It makes a big difference in the value of the unit.

JC <Chipbee40_SpamNo@yahoo.com>: Apr 26 02:06PM -0400 > I got the other problems fixed, it had a fault on the one power amp board and a bad transistor on the tone amp board which is by the way stuck to the chassis with double sided foam tape ! For what they charged fro these things, foam tape ? And you should see the PITA it is to remove, I was thinking "This board it gonna break", but it didn't.   > What you really need is a Fein cutter with an L shaped blade. (they are normally used to cut windshields out of cars)   > Anyway, thanks in advance for anything useful on this matter. It makes a big difference in the value of the unit.   Pinouts here :   https://www.radiomuseum.org/tubes/tube_g3-11gj.html   replacement here (bit spendy) :   Ebay item no 254200412600

dplatt@coop.radagast.org (Dave Platt): Apr 26 02:45PM -0700 In article <65b4af8a-0653-49c7-b9ea-5599fd271ffd@googlegroups.com>, >Does anyone know anything about these ? I know the basics but there are details missing from the print, >LIKE THE PINOUT of the CRT !   The service manual is available at HiFiEngine.com (free registration required to download). The scope-module schematic is on page 62 of the original and the tube ponout is given.   The scope V901 is "CRT with 13-pin Nixie base", Marantz part number 337-1000. According to one article I read elsewhere, it's originally a Siemens D3-II GJ.   After all of these years, I wouldn't be surprised if the cathode were worn out (low emission) or the CRT has become gassy.   >From what I hear you would need a SWAT team and a bunch of automatic weapons to get a replacement CRT.   From what I read, it's well beyond that now... you'd need the services of at least four demigods, and several falling asteroids to blast one loose. They're probably mostly in the hands of owners of Marantz receivers in that series, being preserved against a Time Of Need.   >Even people with experience on these things, how many receivers had built in scopes ? I saw one in another >brand once but can't remember what it was, maybe a Kenwood ? Other than that only Marantz and then even >very few models.   Some Macintosh tuners had scopes. Mac seems to have used a more common/popular tube variety (a 3RP series), for which there are still some used-but-good tubes available and even a few Chinese-build clones.   >Anyway, thanks in advance for anything useful on this matter. It makes a big difference in the value of the unit.   One guy who wrote, said that he'd sold a Model 19, and had also sold a new-old-stock replacement CRT he had for it. He got more for the CRT than for the receiver.   I've been dealing with a slightly similar problem myself... I bought a CTS service monitor whose scope is working-but-dim. Fortunately it has a 3RP CRT (like the Cushman and Macintosh systems do) and I have a local source for a used tube (and there are online sources as well).   I was thinking of trying to cons up a solid-state replacement. I think one could probably be made by using a Raspberry Pi or similar processor as a core, hooked to a reasonably fast (audio-speed) two-channel SPI-based ADC which would sample the horizontal and vertical deflection voltages (suitably attenuated and centered of course). The Pi would capture the data, and then draw it to a 2" color LCD.

tabbypurr@gmail.com: Apr 26 04:32PM -0700 On Friday, 26 April 2019 22:45:21 UTC+1, Dave Platt wrote: > vertical deflection voltages (suitably attenuated and centered of > course). The Pi would capture the data, and then draw it to a 2" > color LCD.   shango66 on youtube does some good explanations re CRT emission problem fixing. Though I don't remember him discussing EHT boosting.     NT

John Robertson <spam@flippers.com>: Apr 26 05:48PM -0700 >> color LCD.   > shango66 on youtube does some good explanations re CRT emission problem fixing. Though I don't remember him discussing EHT boosting.   > NT   Aren't you going to run the risk of X-Ray production if the EHT is increased beyond a reasonable point? The link below says 5KV and up can produce X-Rays:   https://www.nde-ed.org/EducationResources/HighSchool/Radiography/xraygenerators.htm   We have a problem in my industry with 13" colour tubes being over driven by ignorant people using the wrong HV transformer (from 19" monitors) and getting the tube into the soft X-ray range...   John :-#(#

Trevor Wilson <trevor@rageaudio.com.au>: Apr 27 11:59AM +1000 On 27/04/2019 10:48 am, John Robertson wrote: > by ignorant people using the wrong HV transformer (from 19" monitors) > and getting the tube into the soft X-ray range...   > John :-#(#   **I've had the odd X-ray and, being an inquisitive chap, I usually examine the equipment as best as I am able. I've never found an X-ray machine that operates below 75kV. I recall reading some years ago that X-rays begin to be a problem at around 20kV. That said, I would imagine a small tube like the one fitted to the Model 19 (which I also own, BTW) would operate on a potential of around -500 Volts or so. WAY lower than 5kV.   -- Trevor Wilson www.rageaudio.com.au   --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

John Robertson <spam@flippers.com>: Apr 26 10:46PM -0700 On 2019/04/26 6:59 p.m., Trevor Wilson wrote: > a small tube like the one fitted to the Model 19 (which I also own, BTW) > would operate on a potential of around -500 Volts or so. WAY lower than > 5kV.   I wish you were right about 75KV being the minimum voltage to generate X-rays, but the article suggested otherwise. I'd agree that anything under 1000V is likely to do anything other than shock you - I've found nothing so far to challenge that assumption.   The problem with video game repairs with using a 19" flyback on a 13" tube is the tube is then working at upwards of 25KV, which the specs on the tube say is dangerous. The maximum safe voltage for these 13" tubes was around 20KV.   An interesting paper on 6BK4 tubes being driven (60KV) to give off X-Rays, but it appears they would also generate X-Rays at voltages found in colour TVs:   http://www.belljar.net/xray.htm   Later 6KB4 tubes had leaded glass it seems.   Well, that is enough time spent on X-Ray production for now. sure looks like under 1KV is quite safe, and over 20KV it gets interesting.   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."

pallison49@gmail.com: Apr 26 11:02PM -0700 John Robertson wrote:   > Later 6KB4 tubes had leaded glass it seems.   > Well, that is enough time spent on X-Ray production for now. sure looks > like under 1KV is quite safe, and over 20KV it gets interesting.   ** Monochrome CRTs and monitors operated with HT voltages in the range of 16 to 20kV and were made with plain glass while colour CRTs operated at voltages about 5 or 6kV higher and were made with thick leaded glass at the face.   The reason was X-ray generation.   However, seeing small kids sitting less than a metre from colour CRT screens always made me cringe.       .... Phil

Lucifer <LuciferMorningstar@bigpond.com>: Apr 27 05:01PM +1000 On Sat, 27 Apr 2019 11:59:49 +1000, Trevor Wilson >a small tube like the one fitted to the Model 19 (which I also own, BTW) >would operate on a potential of around -500 Volts or so. WAY lower than >5kV.   I had an HF modem with a built in scope for tuning. I still have a 20" colour TV with a CRT, and a 5" colour portable TV with a CRT.

Trevor Wilson <trevor@rageaudio.com.au>: Apr 27 07:35PM +1000 On 27/04/2019 3:46 pm, John Robertson wrote: >> lower than 5kV.   > I wish you were right about 75KV being the minimum voltage to generate > X-rays,   **Read what I wrote. Particularly this point:   "I recall reading some years ago that X-rays begin to be a problem at around 20kV."     but the article suggested otherwise. I'd agree that anything > under 1000V is likely to do anything other than shock you - I've found > nothing so far to challenge that assumption.   **I've never heard of any issues surrounding X-ray production at potentials as low as 5kV. And at the several hundred Volts on a Model 19 tube, there is zero chance of a problem.   > tube is the tube is then working at upwards of 25KV, which the specs on > the tube say is dangerous. The maximum safe voltage for these 13" tubes > was around 20KV.   **Sure. Colour picture tubes are a known source of X-rays.     > Later 6KB4 tubes had leaded glass it seems.   > Well, that is enough time spent on X-Ray production for now. sure looks > like under 1KV is quite safe, and over 20KV it gets interesting.   **Which is pretty much what I said.     -- Trevor Wilson www.rageaudio.com.au   --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

tabbypurr@gmail.com: Apr 27 05:38AM -0700 On Saturday, 27 April 2019 01:48:25 UTC+1, John Robertson wrote: > by ignorant people using the wrong HV transformer (from 19" monitors) > and getting the tube into the soft X-ray range...   > John :-#(#   I guess it's largely been answered :) Depends what voltage you're running at, how much boost & how much leeway you have with xray production. I would not consider EHT boosting until other options were exhausted. A 500v tube is not an issue though.   Medical x-rays use much higher voltages so the rays are harder, ie penetrate more.     NT

Chuck <ch@dejanews.net>: Apr 26 11:51AM -0500 On Thu, 25 Apr 2019 11:09:09 -0700, Bill Martin <wwm@wwmartin.net> wrote:     >Where does the model 2230 fall in this lineup? I still have one of >those, bought in about 1970, I think...still worked last time I powered >it on...several years ago.   It is a pretty decent receiver. It wasn't made by Marantz in the U.S.. It was manufactured by Standard Radio in Japan.

jurb6006@gmail.com: Apr 26 10:05AM -0700 >"**The 2230 is old school Marantz. Very nicely laid out, easy to service and TO3 output devices. Should last a very, very long time. The smaller receivers of the time used plastic pack output devices and were significantly less reliable than those (like the 2230) that employed TO3 output devices. "   Just don't break the dial string. You said way back you had trouble with cassette decks ? Well I got one trouble and that is dial stringing. I wish there was a guy around I could just pay to do it.

"pfjw@aol.com" <peterwieck33@gmail.com>: Apr 26 11:00AM -0700 > Just don't break the dial string. You said way back you had trouble with cassette decks ? Well I got one trouble and that is dial stringing. I wish there was a guy around I could just pay to do it.     Invest in a couple of small hemostats, some curved suture needles (coarse) and a couple of dental picks. Buy a box of small springs from McMaster-Carr, and you will find your life to be much easier. That, and some Dacron fishing line of the correct gauge (does not stretch and holds very tight knots very well) - simple.   Peter Wieck Melrose Park, PA

John-Del <ohger1s@gmail.com>: Apr 26 11:40AM -0700 > >"**The 2230 is old school Marantz. Very nicely laid out, easy to service and TO3 output devices. Should last a very, very long time. The smaller receivers of the time used plastic pack output devices and were significantly less reliable than those (like the 2230) that employed TO3 output devices. "   > Just don't break the dial string. You said way back you had trouble with cassette decks ? Well I got one trouble and that is dial stringing. I wish there was a guy around I could just pay to do it.     My dad hated dial cord stringing. When he got married in the 1940s and opened up a radio repair shop, he had my mom string up radios which she did with no trouble at all. She could also knit, sew, crochet, and make ravioli so good that you would cry.   I just restrung one of those "Crosley" radio/phono/cd abominations and it looks like it was designed wrong. One of the pulleys was on the far side of the main tuner pulley and very close to it. There was no way that would have worked easily with the dial cord pulled over the top of the main pulley in the opposite direction. It didn't even function as a back tension pulley to keep the lateral pull on the tuner even. I shortened the dial cord leaving the odd pulley out and it worked easily and smoothly and in the correct direction with only two turns on the tuning shaft.

Trevor Wilson <trevor@rageaudio.com.au>: Apr 27 06:47AM +1000 >> "**The 2230 is old school Marantz. Very nicely laid out, easy to service and TO3 output devices. Should last a very, very long time. The smaller receivers of the time used plastic pack output devices and were significantly less reliable than those (like the 2230) that employed TO3 output devices."   > Just don't break the dial string. You said way back you had trouble with cassette decks ? Well I got one trouble and that is dial stringing. I wish there was a guy around I could just pay to do it.   **I broke a few in the early days. Once bitten, twice shy. I haven't damaged one since. PITA to repair.   -- Trevor Wilson www.rageaudio.com.au   --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

"malua mada!" <fritzo2ster@gmail.com>: Apr 26 12:34PM -0700 The COM port is for a remote display or to stack another unit for increased punch. Get a car battery and jumper cables, connect DC. Expect a spark. If the unit is silent find a on/off pushbutton switch . If it ticks it is in search mode. If it hums it is ON. Good luck

Jeff Liebermann <jeffl@cruzio.com>: Apr 26 10:41AM -0700 On Thu, 25 Apr 2019 11:39:06 -0500, Sem Jansen >of those college textbooks are even close to the practical use hands on >SAMS and Forest Mims type which we all used to read a few decades ago for >all our hardware designs.   Are you looking for a book on designing analog integrated circuits, or a book on using analog integrated circuits in some kind of device? Forrest Mims III wrote mostly about circuit design, not integrated circuit design.   >Do you know of a hands on technician type of analog ic design book?   Only one book? It would be difficult to cram all things analog into one book. Art of Electronics III is the best I can suggest for everything under one cover. <https://artofelectronics.net> Be wary of counterfeit copies.   Also see books by Jim Williams and Bob Dobkin: <https://www.amazon.com/Analog-Circuit-Design-Applications-Solutions/dp/0123851858/> <https://www.amazon.com/Analog-Circuit-Design-Immersion-Black/dp/0123978882/> <https://www.amazon.com/Analog-Circuit-Design-Three-Collection/dp/0128000015/>   Also, you might consider asking the same question in sci.electronics.design.   -- 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

You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com.