Dediced to check the SSG's body and shutter contacts for resistance and functioning. Thanks to those supplying links to wiring diagrams, it's easy to do.

With no batteries installed, connected the ohmeter between body connectors A and B then pressed the red camera switch button. Continuity happened, but resistance seemed to vary a bit depending on the angle and force that button was pressed at. This may indicate some contact surface corrosion. It may get better if I push it enough to break away the corrosion and make bare, clean metal contact.

With the meter plugged into body connectors A and C, cocking the shutter (set to 1/2 sec.) then tripping it manually, the meter needle jumped. Good; the shutter and all the camera contacts were good. Tried it again at different shutter speeds and the needle didn't jump. Tried 1/2 second and no jumping. Took the lens board out then cleaned its contacts as well as the camera standard's contacts with a pencil's rubber eraser. Contacts went from dull grey to shiny chrome bright. Retested and all's well everywhere.

My batteries haven't arrived yet so I can't test the camera's battery-capacitor functions dynamically as seen by the ohmeter. Continuity seems good between all points I can get at. But I think the camera's wiring diagram I got may have two connectors labeled backwards, A and B; or, I don't understand it in the first place.


Until the batteries arrive (next week), could I connect five 9V batteries in series then apply their combined 45 volts to the camera's connectors?

If so, I could then check the solenoid's function as well as everything dynamically as a total system.

Bart
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Socket layout on the camera body front to rear- B A C.

C (rear of socket)- connects to red contact top left of lens board opening.
A (center contact? of socket) connects to white contact at top right of lens board opening and top solenoid connector (lower right rear of front standard). To battery + (point X) 30 ohms (solenoid)
B (front of socket?) to Battery socket(-)- 2.83K ohms; battery socket (+) capacitor charge/discharge depending on lead polarity.

A>B infinity once capacitors have charged (depends on lead polarity) 0 ohms when switch is pushed

Battery socket + to - capacitor action switch unpressed; 2.87K ohms switch depressed.

Solenoid 30 ohms measured across contacts at rear of front standard.

45PSS wrote:

Socket layout on the camera body front to rear- B A C.

Ah ha!. The pinout's are reversed on the drawing. They must have left out the note explaining the A B C sequence doesn't match their physical location.

Your readings all over pretty much match what I got. I may well redraw that diagram with the pinouts laid out as they appear on the right side bottom of the frame. Then post it here so others will get correct information.

Thanks 45PSS, you're worth your weight in sheet film of your favorite make, type and size. Now I'm ready to measure how much torque the lens hood takes to cock the shutter.

Best wishes,

Bart

It's very common for pin layout on paper to follow function while actual physical position is different. In this case the common lead is in the center with the flash and remote trip leads either side.

Quote:

you're worth your weight in sheet film of your favorite make, type and size

That's a little over 200 pounds of film.

45PSS wrote:

Solenoid 30 ohms measured across contacts at rear of front standard.

This is good to know. I didn't meter this for a low resistance value. I probably checked it with the ohmeter set to a higher scale, noted continuity then went on to other points.

Solenoid in this shutter measures 29.9 ohms across the two straps on the front standard; close enough for me.

Can I connect five 9 volt batteries in series to the battery posts to check everything dynamically? Or will they pump too much current through the camera wires? My batteries won't be here 'till my wife brings 'em back from Las vegas late next week.

Bart

The 9V batteries may not provide enough current to operate the solenoid. Batteries in series are limited to the current capacity of 1 battery. 5 9V in series will provide 45V. The new 22.5V batteries will provide 46V to 47V when first installed.

The solenoid is in the front standard not the shutter.

If I read the schematic correctly, the solenoid is powered by dumping the charge in the capacitors through it, not by battery current so the 9v batteries in series should work the solenoid if the capacitors are in good condition. It just might take a little longer to charge them if the current rating of the 9v batteries is less than that of the 22.5 ones.

C. Henry

9 volt batteries have 625 mAh current capacity. The Eveready 412 batteries for the SSG have 140 mAh. 'Twould be over 4 times as much current. I don't know if the electric parts and paths could handle that much. People have burned up stuff pumping too much current through them.

I'm not now sure I want to take the chance. I'll wait until next week when I get the batteries.

Yes, those cap's work much like those in radar transmitters I used to work on. About 6 cubic feet of huge capacitors stored up 5 megawatts of power to dump in the transmitter to get 1 megawatt out. I was surprised to see such a 45 VDC circuit in an "old" press camera to pulse the solenoid. I imagine that solenoid's much like the external ones often seen connected to those old camera's shutters.

Bart

The camera will only draw the current it needs. If a component is defective then it would draw higher current up to the supply capacity. Full current draw of the battery capacity will run the batteries down long before any damage to the camera will occur.

Again, if I read the schematic correctly that 2.7 K (2,700) ohm resister is in series with the battery. Unless that resistor is partially or completely shorted it will limit the current from any battery connected to the camera's battery terminals.
In this case the battery current is limited to about 17 MA, 45 V divided by 2,700 ohms = 0.0166666 Amps of current. The resistor can be checked by measuring the resistance between the "-" battery terminal and the "B" terminal on the body socket.
I assume that Graflex probably used standard commercial electric components which may have a 10% tolerance above or below the stated rating. 2,430 ohms to 2970 ohms in this case.

C. Henry

Its a 20% resistor and as that vintage carbon resistor goes bad it increases. A resistor has 3 or 4 color bands starting at one end of the resistor. The first 3 are the resistance value in ohms, the 4th if present is the tolerance if less than 20%, no band is 20%. 2700*.2=540 2700+540=3240
2700 red violet red.
mah is mil amps for 1 hour that the source battery will provide. As C Henry points out even a direct short in the capacitors, diode, or solenoid will not cause enough current draw to damage anything even if the supply were capable of suppling 1 amp or more. A voltage source higher than 50V will damage the capacitors. A fresh set of batteries providing 52V is nothing to be concerned about, 60V would be.
http://www.csgnetwork.com/resistcolcalc.html

Well then, looks like I can hook up my 9 volt batteries then connect them to the SSG's battery terminals. Thanks for your combined assurance.

Bart

45PSS wrote:

Quote: you're worth your weight in sheet film of your favorite make, type and size That's a little over 200 pounds of film.

That's a little over 24,348 sheets of 4x5 film.

Quotes: That's a little over 200 pounds of film & That's a little over 24,348 sheets of 4x5 film.

Is this before or after processing?????