- Senco Model PP2 Meter - 8 Updates
- Seeking Opinon on EPROM Problems - 2 Updates
| Kaz Kylheku <kaz@kylheku.com>: Jan 11 05:34PM > Is it simply so I don't have to multiply by 1.414? > Be gentle. I'm new at all this and trying to learn. > Ivan Vegvary To be useful, the p-2-p meter should sample and hold the top and bottom values, and not simply measure RMS and multiply. If we measure p-2-p with a scope we get a stable trace, and then actually find the highest and lowest voltages. Note that the 1.414 factor between RMS and peak voltage only applies to a sinusoidal signal! It is incorrect for other signal shapes. For instance, a square wave's RMS is the same as peak. (Peak-to-peak is twice peak, so the factors double: p-2-p/RMS is 2.828 for sinusoidal, 2 for square.) |
| John Robertson <spam@flippers.com>: Jan 11 01:37PM -0800 On 01/10/2016 7:56 PM, Jeff Liebermann wrote: > I couldn't find a manual or schematic. I have only some bad guesses > as to what it does and how it works. At least you didn't pay any > money for it. I think it is a curve tracer of some sort. Is that a line cord soldered to the metal can of the potentiometer? Nasty. Is the line cord polarized? Did the Senco company get sued out of business by the widows? John ;-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
| Chuck <chuck@mydeja.net>: Jan 11 04:50PM -0600 On Mon, 11 Jan 2016 13:37:49 -0800, John Robertson <spam@flippers.com> wrote: >Is the line cord polarized? >Did the Senco company get sued out of business by the widows? >John ;-#)# No , it is soldered to a terminal strip tab that is embeddeded in phenolic resin paper. The tab that is soldered to the potentiometer case is also connected to the phenolic strip. There is electrical isolation between the two tabs. It was a very common c practice in the 1960s. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| John Robertson <spam@flippers.com>: Jan 11 03:24PM -0800 On 01/11/2016 2:50 PM, Chuck wrote: > case is also connected to the phenolic strip. There is electrical > isolation between the two tabs. It was a very common c practice in > the 1960s. I was wondering, the photo looked like it was soldered oddly. Thanks for clearing that up! John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
| John Heath <heathjohn2@gmail.com>: Jan 11 06:50PM -0800 On Monday, January 11, 2016 at 12:34:11 PM UTC-5, Kaz Kylheku wrote: > For instance, a square wave's RMS is the same as peak. > (Peak-to-peak is twice peak, so the factors double: p-2-p/RMS is 2.828 for > sinusoidal, 2 for square.) I have a current probe , hall effect , that claims to be true RMS. When looking at the fine print it says it is true RMS providing it is a sine wave?? If it is a sine wave then who needs a RMS mater. This is somewhat like a USB powered speakers for a computer claiming 100 watts of power. That would be 20 amps at 5 volts , extremely unlikely. In the old days they would not lie like this just to make a sale. |
| Kaz Kylheku <kaz@kylheku.com>: Jan 12 05:11AM > When looking at the fine print it says it is true RMS providing it is > a sine wave?? > If it is a sine wave then who needs a RMS mater. Someone who only has a DC meter, and wants to measure AC. In many situations we know we have a sine waves; we just want to know how big, as an RMS figure. For instance, I can stick my here handy multimeter into the wall, configured for AC, and it tells me that the line voltage is 118.7. That's an RMS (predicated on it being sinusoidal), and it is useful. If it is true RMS, and accurate, then I know that the peak voltage is 1.414 times that, or 167.9, and peak-to-peak is twice that. > This is > somewhat like a USB powered speakers for a computer claiming 100 watts > of power. That would be 20 amps at 5 volts , extremely unlikely. In But there isn't any condition under which the speakers can continuously deliver that much power without a source other than the USB port; no USB host chip provides that much current. Thus it is unconditionally a lie. > the old days they would not lie like this just to make a sale. Oh, if we pull out some old Popular Mechanics issues from, say, the 1940's, we will see all sort sof snake oil. |
| Phil Allison <pallison49@gmail.com>: Jan 11 10:45PM -0800 Ivan Vegvary wrote: > "Peak-to-Peak" meter. > For what are (were) they used? Got it for free. > Is it simply so I don't have to multiply by 1.414? ** A clue is the graphic on the front of the unit - it shows a typical sweep waveform from a TV set. TV service manuals are often full of such diagrams, accompanied by p-p voltage values. http://www.boxcarcabin.com/PhilcoPredictaSchematicBoth.jpg A service tech might need to measure the ones he finds in a set, but has not got a calibrated scope - just a basic CRT based waveform monitor. So he uses the Senco to produce a 60Hz sine wave with the same p-p height on the screen of his monitor - then measures that with a regular multimeter and multiplies the result by 2.82. A similar trick can be used when calibrating the vertical display of a scope using just a DC source and a DMM. Set the scope to DC coupled and apply a voltage to the input while monitoring same on the DMM. Most DMMs have better than 1% accuracy on DC volts so you simply adjust the scope's internal cal trimmer to match the full scale deflection ( usually 8 divs ) on the screen. Square waves can then be used to check the scope's vertical response for flatness. .... Phil |
| ggherold@gmail.com: Jan 12 08:35AM -0800 On Tuesday, January 12, 2016 at 1:45:41 AM UTC-5, Phil Allison wrote: > Most DMMs have better than 1% accuracy on DC volts so you simply adjust the scope's internal cal trimmer to match the full scale deflection ( usually 8 divs ) on the screen. > Square waves can then be used to check the scope's vertical response for flatness. > .... Phil Thanks Phil, that makes sense... I was scratching my head, wondering what this would be used for. George H. |
| "Geoffrey S. Mendelson" <gsm@mendelson.com>: Jan 11 08:04PM whit3rd wrote: > I wouldn't waste time erasing/reburning old parts (are they UV EPROMs, or flash, or EEPROM?), I'd just > program a flash replacement. The parts are cheap enough, and 'the better part of a day' is not. The 27 series EPROMs are about $1 each from Chinese vendors on eBay. These are used, erased and "tested". New ones in small quantities (yes, they are still made) are around $40 each. In my case, the $1 ones are worth the gamble, but I am not getting paid for my time and effort, and if they fail, I can just pop one out and put in a new one. If I were getting paid for my time, or selling a product, you can be sure I would buy new ones. Geoff. -- Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379 |
| whit3rd <whit3rd@gmail.com>: Jan 11 09:02PM -0800 On Monday, January 11, 2016 at 12:04:07 PM UTC-8, Geoffrey S. Mendelson wrote: > The 27 series EPROMs are about $1 each from Chinese vendors on eBay. These > are used, erased and "tested". New ones in small quantities (yes, they are > still made) are around $40 each. Electrical drop-in replacements in flash are not unavailable; 5V, 128k x 8bit Flash is under a buck a chip at DigiKey, in PLCC packages that can be mounted in a socket on an adapter to your (probably) DIP-style sockets. If there's many sizes, though, it could be awkward to adapt to some of the old parts sockets. It looks like the 32-pin DIP is still available, in 1M, 2M, 4M bit sizes. "SST39SF040-70-4C-PHE" is the 4M version. |
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