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I feel like this has been discussed before, but I cannot find the thread now. Does anyone know of a solution for the 7104 readout not displaying except in "pulsed" mode when slaved to the gate (also works in manual)? Mine started doing this, and I have found very little information about it on the internet.
Thanks! Sean |
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Chuck Harris
Most 7000 series scopes that have readout seem to have a little
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switch on the readout board that selects whether the readout is sharing the display with the traces, or has its own time slot after the sweep is finished. Perhaps your switch has become intermittent? -Chuck Harris [email protected] wrote: I feel like this has been discussed before, but I cannot find the thread now. Does anyone know of a solution for the 7104 readout not displaying except in "pulsed" mode when slaved to the gate (also works in manual)? Mine started doing this, and I have found very little information about it on the internet. |
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Chuck,
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Good call; I should open it up and take a look. I'm not sure where the readout board even is on a 7104...the internal layout is *vastly* different compared to the 7904(a)! Sean On Sun, Jan 31, 2021 at 01:30 PM, Chuck Harris wrote:
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Chuck,
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Looks like mine has a more modern readout board, that contains no switch. It has a large socketed ROM where the switch would be in an older style readout system...the plot thickens... Sean On Sun, Jan 31, 2021 at 01:30 PM, Chuck Harris wrote:
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Chuck Harris
Hi Sean,
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I remember now. My 7104 spends most of its time, all dressed up, with no place to go... So, it is not one of the scopes that I am most familiar with. If you look on the front panel, you will see an outlined area that has two intensity pots (A and B), a READOUT intensity pot, and two push buttons for the readout. The one button is marked +GATE or OFF, and sets the readout to be on at the end of the GATE signal, or off. The other push button is marked "MAN", which causes the readout to be on always. Something there is probably in the wrong position, or misbehaving. Also, I keep my plugins off of AUTO on my 7104. Because of the MCP's limited life, you do not want to be wasting it with continuous readout display, or baseline display. I keep my readout in "GATE" mode, so it is off if the sweep isn't being triggered. Typically, I also keep the A and B intensity turned off when the scope is off, to avoid intensity flair during turn on. -Chuck Harris [email protected] wrote: Chuck, |
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Said switch is on the front panel of the 7104 - turn the readout pot fully clockwise into the detent at the end (PULSED position). To quote page 2-10 of the manual:
The READOUT control determines the operating mode of the Readout System. With the READOUT control set to free run (out of OFF or PULSED detent positions) the Readout System operates continuously, interrupting the crt display at random (for about 20 microseconds) in order to write each character on the crt. With the READOUT control set to the PULSED position, the Readout System operates in a triggered mode; one complete frame (up to eight words) of readout is displayed. The + GATE or EXT switch determines whether readout is displayed at the end of the + GATE or when an external signal is applied to the rear-panel GRATICULE/READOUT SINGLE SHOT input. The+ GATE switch selects whether A gate or B gate triggers the readout. HtH David |
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Chuck,
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All good advice. Personally, I guess the readouts really aren't that critical. I get used to not having any when using older scopes like my 585A! Maybe I'll just not worry about beyond checking for obvious problems (dirty or stuck switch contacts, for instance). Sean On Sun, Jan 31, 2021 at 04:07 PM, Chuck Harris wrote:
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Sean,
A friend of mine found a burned resistor and bad TO-5 metal can transistor on the Readout Board in a military version of the 7603. The R was 3.9k, the TO-5 can something like a 2n2905 or 2n3440 with an OEM number. Maybe examine / check for those parts, if that transistor loses beta over time, it may overheat the R, then self destruct causing a loss of display. Steven |
David C. Partridge