There is a silver pin that fits into the periphery of the timer. I think this trips the smaller dial to rotate. If the sprinkler is set to go off at 4am, where should I place this silver pin for it to work properly

If zones are not advancing, then 1) Clock motor is not rotating dial > replace clock motor, 2) on-off trippers are worn down > replace trippers, 3) or the day skipper is set to skip all days and all skipper pins are pushed down, 4) or sprinkler valve is bad.

The sprinkler timer dial rotates each 24 hours. The trippers cause sprinkler head to turn on zone 1 for example. Zone 1 waters until the dial rotates to part of dial with no tripper. Without a tripper on the dial, the timer turns off circuit to sprinkler. At this point, the sprinkler valve mechanically advances to zone 2 and waits for timer to turn off again. The timer does not advance sprinkler to next zone > the sprinkler valve is designed to advance each time circuit turns off. The timer just turns on and off. When next tripper rotates around, the timer turn on the circuit and zone 2 begins to water.
http://waterheatertimer.org/pdf/How-to-Set-and-Troubleshoot-Intermatic-sprinkler-timer.pdf

The silver pin inserted at 12midnight position is for advancing the day skipper wheel.
Open following link for parts and resources:
http://waterheatertimer.org/Intermatic-trippers-and-parts.html#sprinkler

The silver pin is put into timer dial at 12 midnight to advance the day skipper wheel each time dial rotates.
Open following link for Intermatic sprinkler/irrigation timer resources:
http://waterheatertimer.org/Intermatic-trippers-and-parts.html#sprinkler

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You posted under Intermatic T100R (R for raintight) series timer.

Add a comment if you have different timer.
http://waterheatertimer.org/How-to-troubleshoot-Intermatic-timer.html
http://waterheatertimer.org/Intermatic-trippers-and-parts.html#sprinkler

To set timer, lift and rotate dial clockwise until current time on dial lines up with silver pointer.
If dial is lagging or falling behind, then replace clock motor.

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You posted under Grasslin in-wall mechanical timer.

Instructions for this timer are nearly identical to GE
http://waterheatertimer.org/GE-timers-and-manuals.html#15070

First, the timer has to be wired correctly, so review wiring instructions shown on link above.
Next, the pins have to be set, so read instructions and look at image of pins shown on link above.
Last, the timer switch has to me set. I believe timer switch is moved all the way right for timer program to operate.

To check operation, manually rotate dial clockwise to watch lights turn on-off.
This will tell you exactly how to set pins and switch.
To set current time, rotate dial clockwise until current time lines up with arrowhead located on inner dial.
Dial rotates as time passes, and pins trip a lever that opens and closes switch to your lights.

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R88 series timers at Intermatic.
Click on model number to see manual:
http://www.intermatic.com/products/timers/mechanical%20time%20switches/sprinkler%20irrigation%20timers.aspx

Add a comment if you have different timer

At fixya, we're not supposed to copy-paste from manual, but manual says information clearly.
If timer has the day-skipper wheel located lower left of large yellow dial:
Not every timer has day-skipper wheel, in which case timer works same for each day.
TO SKIP DAYS: Turn black skipper wheel COUNTER-CLOCKWISE
until today's day is in front of "14" arrow. Press pins DOWN on days
of NO watering. The skipper wheel must have all pins UP for daily
watering.

Additional instructions:
1. TO SET FIRST ZONE: For watering, push gold pin into slot on yellow
dial at desired ON time. For each 12 minutes of additional watering
add one pin WITHOUT skipping a slot.
2. TO CHANGE ZONES: Leave one blank slot on yellow dial after ON
line (gold pin), and valve will automatically advance to next zone.
3. TO SET ADDITIONAL ZONES: Repeat steps 1 and 2. REMEMBER
to leave blank space between zones
4. TO SET TIME OF DAY: Turn yellow dial CLOCKWISE, until correct
line is at end of silver time pointer. Do NOT turn silver pointer.
5. TO SKIP DAYS: Turn black skipper wheel COUNTER-CLOCKWISE
until today's day is in front of "14" arrow. Press pins DOWN on days
of NO watering. The skipper wheel must have all pins UP for daily
watering.
6. PUT SELECTOR SWITCH IN AUTO: This switch can be used to turn
the system ON or OFF for manual operation without affecting the set
program.

http://www.intermatic.com/~/media/files/intermatic/products/instructions/timers/t8845pv%20-%20english.ashx

The timer is used to power a low-voltage sprinkler solenoid valve.
A solenoid is an electrical switch that opens and closes a gas line or water line.

The yellow wires go to your sprinkler system solenoid valve.
The solenoid is the valve that turns water on-and-off.

The 120Volt electric cable that runs the timer connects to the Line and Neutral terminals.
Black to Line terminal, white to neutral terminal

The clock repeats each 24 hours.
Lift and rotate dial until current time lines up with silver pointer

The skipper wheel has pins >> press pin down for each day you do not want watering
Rotate skipper wheel counterclockwise until current day lines up with 14 arrow

Put tripper pins on yellow dial
Each pin represents 12 minutes of watering
To water for 48 minutes, put in 4 consecutive pins
Put pins on wheel at the time you want watering to take place.
To water twice a day, put pins at two different times, and do not put any pins between those times.

Paragon 4000 series timers are traditional electro-mechanical timers.
The dial rotates around like a clock as time passes
Black and silver tripper pins on attached to outer edge of dial.
Black tripper is Off
Silver tripper is ON
The tripper pins encounter a lever.
The On tripper pushes lever one direction, the Off tripper pushes lever opposite direction
Click manual override to switch lights by hand

To set current time, lift and rotate dial until current time lines up with black pointer.
Set your trippers on the dial next to the On and Off times you want.
Set silver tripper at 5:oo
Set black tripper at 11:oo
Minimum set time is 1 hour

Paragon 4000 series

If this is not the correct timer, answer back with a description and I'll check my files

http://waterheatertimer.org/pdf/1103INSTALLOP.pdf


This is probably very similar to your timer.
The Tork 1100 series is electro-mechanical timer.
Lift and rotate dial to set current time.
Line up current time with the word Time located to lower right of dial.
The trippers are black and silver.
I think the black is OFF and silver is ON
Clock motor rotates dial as time passes.
Trippers contact a lever.
Off tripper pushes lever one way.
On tripper pushes lever other way.
The manual override clicks back and forth as trippers move lever.
To check function of timer, click manual override
Common problems:
1) Clock motor is not rotating dial
2) Trippers get stuck on lever and can't move lever because timer is dirty or worn out, or clock motor is bad.
3) Trippers are worn down and won't trip the lever.

Replacement of these timers is simple
Check out the functions and problems and then answer this post and I will help more if needed

http://waterheatertimer.org/Intermatic-trippers-and-parts.html#sprinkler
http://waterheatertimer.org/images/R8806P101C-timer-778.jpg

1) The silver pin goes at 12 midnight on large yellow dial. This pin advances the skipper wheel each day.
2) Turn yellow dial clockwise until current time lines up with silver pointer.
3) Rotate skipper wheel counter-clockwise until today's day (Monday) is in front of 14 arrow.
4) To skip a day of watering, the skipper pin is pushed down for that day. So you want to push down Monday and Tuesday.
For watering, the skipper pins is up for that day. So you want The skipper pin up for Tuesday.
5) The brass trippers are inserted on yellow wheel. Each brass tripper represents 12 minutes of watering for example. So if you want to water for 1/2 hour, then put two consecutive pins on the yellow timer wheel. For 1 hour, put 4 consecutive pins.

The silver pointer arm is supposed to be stationary.
Part is not sold separately.
T100 series, the stationary pointer is pointed at 6:00 position.
Sprinkler timers, the pointer points at 7:00 position.
To set timer, rotate dial until current time lines up with stationary pointer.
Open following link for troubleshoot checklist
http://waterheatertimer.org/How-to-troubleshoot-Intermatic-timer.html