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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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can i connect an LCD VGA monitor in place of a crt?
i am trying to repair a video slot machine. the monitor image is not correct. the image is shifted to the left and cut off. there is a black vertical bar, about 15% of the screen size in the right 3/4 of the screen . to the right of that is the beginning of the image that is shifted to the left. i took the monitor to a repair shop, and he says the monitor/chassis is ok. i'm not too sure about that. a different mpu in the slot has the same result. its a tatung VT-1440S monitor, VGA . i would like to hook up a desktop vga monitor.
i posted an image from the slot schematics he http://s408.photobucket.com/user/mho...GA%20interface is it possible to hook up the LCD monitor to test the machine? i made a cable with a female db-15 and individual pins on the other end. thanks much mike |
#3
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can i connect an LCD VGA monitor in place of a crt?
On Sat, 27 Aug 2016 18:47:02 -0700 (PDT), wrote:
is it possible to hook up the LCD monitor to test the machine? Yes. It should work. I do that all the time for old CNC machines that basically have a PC inside as a controller. Just be careful how you wire the video cable or adapter. You can get a rebuild kit for your Tatung VT-1440S at: http://www.ebay.com/itm/Tatung-VS-14428-VT-1440S-Cap-Kit-Get-Well-Kit-for-Monitor-Repair-/200889563465 $16 total. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#4
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can i connect an LCD VGA monitor in place of a crt?
On Saturday, August 27, 2016 at 11:31:14 PM UTC-4, Jeff Liebermann wrote:
On Sat, 27 Aug 2016 18:47:02 -0700 (PDT), wrote: is it possible to hook up the LCD monitor to test the machine? Yes. It should work. I do that all the time for old CNC machines that basically have a PC inside as a controller. Just be careful how you wire the video cable or adapter. You can get a rebuild kit for your Tatung VT-1440S at: http://www.ebay.com/itm/Tatung-VS-14428-VT-1440S-Cap-Kit-Get-Well-Kit-for-Monitor-Repair-/200889563465 $16 total. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 i need to know what pins to use and not use. thanks |
#5
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can i connect an LCD VGA monitor in place of a crt?
On Sun, 28 Aug 2016 06:39:42 -0700 (PDT), wrote:
On Saturday, August 27, 2016 at 11:31:14 PM UTC-4, Jeff Liebermann wrote: On Sat, 27 Aug 2016 18:47:02 -0700 (PDT), wrote: is it possible to hook up the LCD monitor to test the machine? Yes. It should work. I do that all the time for old CNC machines that basically have a PC inside as a controller. Just be careful how you wire the video cable or adapter. You can get a rebuild kit for your Tatung VT-1440S at: http://www.ebay.com/itm/Tatung-VS-14428-VT-1440S-Cap-Kit-Get-Well-Kit-for-Monitor-Repair-/200889563465 $16 total. i need to know what pins to use and not use. thanks Why, when you can easily fix the existing monitor? Well, you have a schematic of the interface, so that should be easy. http://i408.photobucket.com/albums/pp163/mhooker32/VGA%20interface/monitor%20wiring_zpseldutpwd.png Ok, I'll try to connect the dots. I'll guess(tm) that you have a matching 19 pin connector for the monitor and need to attach a DE15 connector to go to your random VGA replacement Monitor. If so, do NOT connect anything to pins 14 thru 19 on the monitor cable end because those are involved in supplying power to the monitor. Monitor DE15 (VGA) 1 Blue 3 (BL video) 2 Red 1 (RD video) 3 Green 2 (GN video) 4 HSYNC 13 (horizontal sync) 5 Red Gnd 6 (red shield ground) 6 Blue Gnd 8 (blue shield ground) 7 Green Gnd 7 (green shield ground) 8 Digital Rtn 10 (digital ground) 9 VSYNC 14 (vertical sync) 10 Touch Rcv (see note 1) 11 Touch Xmit (see note 1) 12 GND 5 and shield gnd 13 GND 5 and shield gnd Notes: 1. The game machine obviously requires a touch screen input to operate. While the VGA monitor will show something, there is an unknown as to how a random VGA montitor is going to produce the required and unknown touch screen signals. In any case, the wires from Monitor pins 10 and 11 do NOT go to the random VGA monitor. 2. I'm not sure about the various grounds on the VGA connector pins 6, 10, and shield. I'll need to tear apart a VGA cable to see how it's done. I don't have one handy, so you get to do that yourself. 3. Notice that many of the wires are shielded. You can build the adapter without using shielded cables. It will work, but probably show some noise and smearing. Good enough for a first test and you probably won't notice on a small monitor. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#6
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can i connect an LCD VGA monitor in place of a crt?
On Sunday, August 28, 2016 at 1:38:14 PM UTC-4, Jeff Liebermann wrote:
On Sun, 28 Aug 2016 06:39:42 -0700 (PDT), wrote: On Saturday, August 27, 2016 at 11:31:14 PM UTC-4, Jeff Liebermann wrote: On Sat, 27 Aug 2016 18:47:02 -0700 (PDT), wrote: is it possible to hook up the LCD monitor to test the machine? Yes. It should work. I do that all the time for old CNC machines that basically have a PC inside as a controller. Just be careful how you wire the video cable or adapter. You can get a rebuild kit for your Tatung VT-1440S at: http://www.ebay.com/itm/Tatung-VS-14428-VT-1440S-Cap-Kit-Get-Well-Kit-for-Monitor-Repair-/200889563465 $16 total. i need to know what pins to use and not use. thanks Why, when you can easily fix the existing monitor? Well, you have a schematic of the interface, so that should be easy. http://i408.photobucket.com/albums/pp163/mhooker32/VGA%20interface/monitor%20wiring_zpseldutpwd.png Ok, I'll try to connect the dots. I'll guess(tm) that you have a matching 19 pin connector for the monitor and need to attach a DE15 connector to go to your random VGA replacement Monitor. If so, do NOT connect anything to pins 14 thru 19 on the monitor cable end because those are involved in supplying power to the monitor. Monitor DE15 (VGA) 1 Blue 3 (BL video) 2 Red 1 (RD video) 3 Green 2 (GN video) 4 HSYNC 13 (horizontal sync) 5 Red Gnd 6 (red shield ground) 6 Blue Gnd 8 (blue shield ground) 7 Green Gnd 7 (green shield ground) 8 Digital Rtn 10 (digital ground) 9 VSYNC 14 (vertical sync) 10 Touch Rcv (see note 1) 11 Touch Xmit (see note 1) 12 GND 5 and shield gnd 13 GND 5 and shield gnd Notes: 1. The game machine obviously requires a touch screen input to operate. While the VGA monitor will show something, there is an unknown as to how a random VGA montitor is going to produce the required and unknown touch screen signals. In any case, the wires from Monitor pins 10 and 11 do NOT go to the random VGA monitor. 2. I'm not sure about the various grounds on the VGA connector pins 6, 10, and shield. I'll need to tear apart a VGA cable to see how it's done. I don't have one handy, so you get to do that yourself. 3. Notice that many of the wires are shielded. You can build the adapter without using shielded cables. It will work, but probably show some noise and smearing. Good enough for a first test and you probably won't notice on a small monitor. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 the touchscreen is an overlay on the front of the crt. i dont want to attempt to repair the monitor until i know all the other functions of the machine work. it can be operated with buttons if the touchscreen isnt there. thanks much |
#7
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can i connect an LCD VGA monitor in place of a crt?
On Saturday, August 27, 2016 at 6:47:06 PM UTC-7, wrote:
i am trying to repair a video slot machine. the monitor image is not correct. the image is shifted to the left and cut off. there is a black vertical bar, about 15% of the screen size in the right 3/4 of the screen . to the right of that is the beginning of the image that is shifted to the left. So, the video system is probably sending bad timing signals? This sounds like a screen format miscommunication issue. VGA uses three pins to send screen capability data from the monitor to the video card, and that info determines whether you get 640x480 or 1280 x 800, or whatever. Older VGA uses different schemes, just to make things interesting. Screen mispositioning often just means a bad video cable. I've seen it happen with DVI, too. |
#8
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can i connect an LCD VGA monitor in place of a crt?
whit3rd wrote:
VGA uses three pins to send screen capability data from the monitor to the video card The original monitor seems NOT to be connected by VGA, it's possible the slot machine will just assume the CRT is the correct one to display whatever signals it outputs, rather than looking at EDID data the way a PC would. |
#9
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can i connect an LCD VGA monitor in place of a crt?
On Monday, August 29, 2016 at 2:18:30 AM UTC-4, Andy Burns wrote:
whit3rd wrote: VGA uses three pins to send screen capability data from the monitor to the video card The original monitor seems NOT to be connected by VGA, it's possible the slot machine will just assume the CRT is the correct one to display whatever signals it outputs, rather than looking at EDID data the way a PC would. will that affect what i'm trying to do? |
#10
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can i connect an LCD VGA monitor in place of a crt?
On Monday, August 29, 2016 at 9:11:28 AM UTC-4, wrote:
On Monday, August 29, 2016 at 2:18:30 AM UTC-4, Andy Burns wrote: whit3rd wrote: VGA uses three pins to send screen capability data from the monitor to the video card The original monitor seems NOT to be connected by VGA, it's possible the slot machine will just assume the CRT is the correct one to display whatever signals it outputs, rather than looking at EDID data the way a PC would. will that affect what i'm trying to do? i made up the cable as per jeff's chart, and the lcd monitor displayed a very nice image. now i can go thru the machine and test all its functions. with the image on the original monitor as described above, do you think a cap kit will do the trick? thanks |
#11
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can i connect an LCD VGA monitor in place of a crt?
wrote in message ... i am trying to repair a video slot machine. the monitor image is not correct. the image is shifted to the left and cut off. there is a black vertical bar, about 15% of the screen size in the right 3/4 of the screen . to the right of that is the beginning of the image that is shifted to the left. i took the monitor to a repair shop, and he says the monitor/chassis is ok. i'm not too sure about that. a different mpu in the slot has the same result. its a tatung VT-1440S monitor, VGA . i would like to hook up a desktop vga monitor. i posted an image from the slot schematics he http://s408.photobucket.com/user/mho...GA%20interface It sounds like a phasing problem - its a simple fault to fix, but not simple to find the part. Usually; the phase is sampled from a winding on the horizontal transformer. There's usually a high resistor in series with that signal on its way to the horizontal oscillator. If that's in a chip - its usually easy to trace the path to the transformer. Another possibility is the scan energy recovery system, the left to centre part of the scan is driven by recovered energy - the horizontal transistor drives from centre to RHS, the energy is recovered at the end of that. A fault there usually causes cramping (horizontal linearity) but early onset faults can distort the waveform back to the phase discriminator. |
#12
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can i connect an LCD VGA monitor in place of a crt?
On Monday, August 29, 2016 at 6:11:28 AM UTC-7, wrote:
On Monday, August 29, 2016 at 2:18:30 AM UTC-4, Andy Burns wrote: whit3rd wrote: VGA uses three pins to send screen capability data from the monitor to the video card The original monitor seems NOT to be connected by VGA, it's possible the slot machine will just assume the CRT is the correct one to display whatever signals it outputs, rather than looking at EDID data the way a PC would. will that affect what i'm trying to do? Maybe; the video MODE information never gets confused when the ID pins are read, but if those AREN'T in use, the video output and the sync signals might be misinterpreted as the entirely wrong sync rate, or resolution. The description of the picture being offcenter of the screen does sound like a mode mismatch between monitor and video 'card'. So, the monitor walks the picture off the left screen edge at 5 milliseconds, but the picture isn't completely sent until 8 milliseconds. The monitor just decided on the wrong horizontal sweep rate. In the early days of multisync monitors, Apple and IBM and third parties all did the timing according to whims. Adaptation was a BIG issue. |
#13
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can i connect an LCD VGA monitor in place of a crt?
On Mon, 29 Aug 2016 10:03:35 -0700 (PDT), wrote:
i made up the cable as per jeff's chart, and the lcd monitor displayed a very nice image. now i can go thru the machine and test all its functions. Very good. with the image on the original monitor as described above, do you think a cap kit will do the trick? Of course, why else would I suggest it? I haven't fixed CRT monitor for at least 6 years. I didn't even know that there were re-cap kits available for CRT monitors. However, if it's anything like LCD monitors, replacing the caps will usually do the trick. Electrolytics don't last forever. You might need to look into replacing the flyback if you can't get any hi-V and the rest of the horizontal sweep circuitry seems to be ok. Hard to tell from here. Also, CRT's are potentially dangerous and can zap you without much provocation. Attach a clip lead to a big INSULATED screwdriver, ground the lead to the frame, and discharge the CRT tube before diving into the circuitry. Remember, you have but one life to give to your profession. thanks Never thank me before it's working. Bad luck and all that. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#14
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can i connect an LCD VGA monitor in place of a crt?
On Saturday, August 27, 2016 at 9:47:06 PM UTC-4, wrote:
i am trying to repair a video slot machine. the monitor image is not correct. the image is shifted to the left and cut off. there is a black vertical bar, about 15% of the screen size in the right 3/4 of the screen . to the right of that is the beginning of the image that is shifted to the left. i took the monitor to a repair shop, and he says the monitor/chassis is ok.. i'm not too sure about that. a different mpu in the slot has the same result. its a tatung VT-1440S monitor, VGA . i would like to hook up a desktop vga monitor. i posted an image from the slot schematics he http://s408.photobucket.com/user/mho...GA%20interface is it possible to hook up the LCD monitor to test the machine? i made a cable with a female db-15 and individual pins on the other end. thanks much mike When my buddy was in the vending business, I repaired several hundred of his monitors, many just like this one. I seem to recall a horiz phase adjustment on the main board. Sometimes just tweaking this pot would lock in the picture. If the board has never been recapped, it's time to do this. Go to Digikey and select low ESR high hour caps (I prefer Panasonic) and shotgun the board. |
#15
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can i connect an LCD VGA monitor in place of a crt?
wrote in message ... On Saturday, August 27, 2016 at 9:47:06 PM UTC-4, wrote: i am trying to repair a video slot machine. the monitor image is not correct. the image is shifted to the left and cut off. there is a black vertical bar, about 15% of the screen size in the right 3/4 of the screen . to the right of that is the beginning of the image that is shifted to the left. i took the monitor to a repair shop, and he says the monitor/chassis is ok. i'm not too sure about that. a different mpu in the slot has the same result. its a tatung VT-1440S monitor, VGA . i would like to hook up a desktop vga monitor. i posted an image from the slot schematics he http://s408.photobucket.com/user/mho...GA%20interface is it possible to hook up the LCD monitor to test the machine? i made a cable with a female db-15 and individual pins on the other end. thanks much mike When my buddy was in the vending business, I repaired several hundred of his monitors, many just like this one. I seem to recall a horiz phase adjustment on the main board. Sometimes just tweaking this pot would lock in the picture. The phase comparator compares the sync with a pulse from a winding on the horizontal transformer. Its fed by a high value resistor - going high or open is a very common fault. |
#16
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can i connect an LCD VGA monitor in place of a crt?
On Thu, 1 Sep 2016 19:24:18 +0100, "Ian Field"
wrote: wrote in message ... On Saturday, August 27, 2016 at 9:47:06 PM UTC-4, wrote: i am trying to repair a video slot machine. the monitor image is not correct. the image is shifted to the left and cut off. there is a black vertical bar, about 15% of the screen size in the right 3/4 of the screen . to the right of that is the beginning of the image that is shifted to the left. i took the monitor to a repair shop, and he says the monitor/chassis is ok. i'm not too sure about that. a different mpu in the slot has the same result. its a tatung VT-1440S monitor, VGA . i would like to hook up a desktop vga monitor. i posted an image from the slot schematics he http://s408.photobucket.com/user/mho...GA%20interface is it possible to hook up the LCD monitor to test the machine? i made a cable with a female db-15 and individual pins on the other end. thanks much mike When my buddy was in the vending business, I repaired several hundred of his monitors, many just like this one. I seem to recall a horiz phase adjustment on the main board. Sometimes just tweaking this pot would lock in the picture. The phase comparator compares the sync with a pulse from a winding on the horizontal transformer. Its fed by a high value resistor - going high or open is a very common fault. This happens very rarely but I've seen a cap to ground open on this line which causes the picture to shift. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
#17
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can i connect an LCD VGA monitor in place of a crt?
"Chuck" wrote in message ... On Thu, 1 Sep 2016 19:24:18 +0100, "Ian Field" wrote: wrote in message ... On Saturday, August 27, 2016 at 9:47:06 PM UTC-4, wrote: i am trying to repair a video slot machine. the monitor image is not correct. the image is shifted to the left and cut off. there is a black vertical bar, about 15% of the screen size in the right 3/4 of the screen . to the right of that is the beginning of the image that is shifted to the left. i took the monitor to a repair shop, and he says the monitor/chassis is ok. i'm not too sure about that. a different mpu in the slot has the same result. its a tatung VT-1440S monitor, VGA . i would like to hook up a desktop vga monitor. i posted an image from the slot schematics he http://s408.photobucket.com/user/mho...GA%20interface is it possible to hook up the LCD monitor to test the machine? i made a cable with a female db-15 and individual pins on the other end. thanks much mike When my buddy was in the vending business, I repaired several hundred of his monitors, many just like this one. I seem to recall a horiz phase adjustment on the main board. Sometimes just tweaking this pot would lock in the picture. The phase comparator compares the sync with a pulse from a winding on the horizontal transformer. Its fed by a high value resistor - going high or open is a very common fault. This happens very rarely but I've seen a cap to ground open on this line which causes the picture to shift. It was common enough on TVs, and I've seen it on a few VGA monitors. With some TV makes/models - it made it onto the stock fault list. |
#18
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can i connect an LCD VGA monitor in place of a crt?
On Thursday, September 1, 2016 at 5:04:11 PM UTC-4, Ian Field wrote:
"Chuck" wrote in message ... On Thu, 1 Sep 2016 19:24:18 +0100, "Ian Field" wrote: wrote in message ... On Saturday, August 27, 2016 at 9:47:06 PM UTC-4, wrote: i am trying to repair a video slot machine. the monitor image is not correct. the image is shifted to the left and cut off. there is a black vertical bar, about 15% of the screen size in the right 3/4 of the screen . to the right of that is the beginning of the image that is shifted to the left. i took the monitor to a repair shop, and he says the monitor/chassis is ok. i'm not too sure about that. a different mpu in the slot has the same result. its a tatung VT-1440S monitor, VGA . i would like to hook up a desktop vga monitor. i posted an image from the slot schematics he http://s408.photobucket.com/user/mho...GA%20interface is it possible to hook up the LCD monitor to test the machine? i made a cable with a female db-15 and individual pins on the other end. thanks much mike When my buddy was in the vending business, I repaired several hundred of his monitors, many just like this one. I seem to recall a horiz phase adjustment on the main board. Sometimes just tweaking this pot would lock in the picture. The phase comparator compares the sync with a pulse from a winding on the horizontal transformer. Its fed by a high value resistor - going high or open is a very common fault. This happens very rarely but I've seen a cap to ground open on this line which causes the picture to shift. It was common enough on TVs, and I've seen it on a few VGA monitors. With some TV makes/models - it made it onto the stock fault list. cap kit did the trick, nice image now. way in the corner of the board was a leaker you couldnt see until it was pulled. thanks to all for your help |
#19
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can i connect an LCD VGA monitor in place of a crt?
wrote in message ... On Thursday, September 1, 2016 at 5:04:11 PM UTC-4, Ian Field wrote: "Chuck" wrote in message ... On Thu, 1 Sep 2016 19:24:18 +0100, "Ian Field" wrote: wrote in message ... On Saturday, August 27, 2016 at 9:47:06 PM UTC-4, wrote: i am trying to repair a video slot machine. the monitor image is not correct. the image is shifted to the left and cut off. there is a black vertical bar, about 15% of the screen size in the right 3/4 of the screen . to the right of that is the beginning of the image that is shifted to the left. i took the monitor to a repair shop, and he says the monitor/chassis is ok. i'm not too sure about that. a different mpu in the slot has the same result. its a tatung VT-1440S monitor, VGA . i would like to hook up a desktop vga monitor. i posted an image from the slot schematics he http://s408.photobucket.com/user/mho...GA%20interface is it possible to hook up the LCD monitor to test the machine? i made a cable with a female db-15 and individual pins on the other end. thanks much mike When my buddy was in the vending business, I repaired several hundred of his monitors, many just like this one. I seem to recall a horiz phase adjustment on the main board. Sometimes just tweaking this pot would lock in the picture. The phase comparator compares the sync with a pulse from a winding on the horizontal transformer. Its fed by a high value resistor - going high or open is a very common fault. This happens very rarely but I've seen a cap to ground open on this line which causes the picture to shift. It was common enough on TVs, and I've seen it on a few VGA monitors. With some TV makes/models - it made it onto the stock fault list. cap kit did the trick, nice image now. way in the corner of the board was a leaker you couldnt see until it was pulled. thanks to all for your help On old gear - some engineers do a cap kit anyway before getting down to fault finding (if there is any). If the fault persists, there's a much greater level of confidence when you have to roll your sleeves up and hunt the elusive part. |
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