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Will replace 7406 and see what gives.
Thanks, will be in touch.
I tried to send photo of counter to show you what it looked like,but i cant seem to work out how to incert it.
rog
Click on 'Go Advanced' tab .... next to 'quick reply' tab.
Click on paper clip icon at top.
Scroll down to see what specific file types are accepted ... jpeg ... or whatever.
Save photo as designated file in a convenient location....i.e. desktop
Click 'browse' tab in upper part of window, and find the saved file.
Then 'upload' the file.
You should see the file listed ...
If you don't have the correct type of file .... it will fail to upload and post.
There are probably several other ways to do this .....
I see that there are maximum file size limits for the different file types...
The 12 pin on (7473) is high, there is a high on pin 9 (7460), so pin 8 (7460) is low, dont i need a low on pin 12 (7473)?.The other thing is there is no pulse on pin 5 (7473), i'm begining to wonder if the (7473) is no good, all though i've just replaced it.
I think i will fit ic sockets this soldering ic in is no fun.
rog
Pin 12 on IC4 needs to go low.
However, there might be more than one cause to look at.
Pin 14 of IC4 needs to switch on and off, as a result of TR2 switching on and off, when the start button is pushed ....
Pin 1 on IC4 is the clock pulse pin, and needs to change state in accordance with the output of TR1 .... taken from its emitter ...input to pin 9 of IC2.
The clock pulse is generated when the slotted brass wheel is turned.
Check to see if pin 2 (marked 'clear') of IC4 is high ...It looks like pin 2 is supposed to toggle between high and low, as the count progresses.
I am curious about pin 1 of IC2. It is held high by a resistor and a capacitor.
You should get a high for pin 2, constant, no change.
If you have checked pin 5 of IC4, and you are not getting a clock pulse to this component, then the contact terminals of the decade switch might be oxidized or dirty .... not letting the signal get through. Use a little electronic contact cleaner spray on the decade switch, and operate the switch back an forth a few times to clean the switch contacts.
The use of sockets should be okay ... for convenience.
Pin 1 ic4 changes state with clock pulse.
Pin 2 ic4 remains high all the time.
Pin 1 ic2 is high no change.
I am getting a pulse from pin 5 ic4 all be it very slow.
Pin 14 ic4 goes high when start button is pressed, but there is no change to pin 12 or 13 ic4.
I have not changed anything else yet, i still suspect ic4 though.
I will give you all pin readings from all ic's later tonight.
rog
Pin 1 ic2 is high.
Pin 6 ic2 toggle's.
Pin 8 ic4 toggle's.
I cant quite understand how the j k flip flop works,from what i can gather if, in this case pin 3 k is tied to 0 volts and pin 14 j is held low, and there is no clock,and clear is low,output from Q pin12 should be low and pin Q 13 should be high,it just does'nt seem to work.i am getting all the right readings,low on pin3, low on pin 14, low on pin 2, and no clock.any idea's.
rog
If pin 2 is low, it would have priority ....bringing pin 12, Q, low, and pin 13, Q*, high.
The J and K inputs, switched by the clock pulse, would be superseded by the reset.
Maybe the 7473 is defective ....
You might try de-soldering the current 7473 and soldering in its place an IC socket ... just for convenience .... until you get the problem resolved. There is a version of an IC socket called a 'machined pin' socket, which is a little better made, a little sturdier construction .... if you can get one.
Another tip ... I always use a liquid solder flux ... the resinous liquid type... sometimes there is a small brush in the bottle cap ... just brush a little onto the work area ... even when de-soldering something.
The flux seems to make the solder flow a little better.
It would probably be a good idea to use some alcohol or other solvent to clean the solder side after using the flux though ... since the flux is very sticky when it dries.
Have now replaced ic7473, and solinoid works, but !!!! pin 13 ic4 is still low,pin 12 no reading, pin 2 high,and stays high pin 1 is getting a pulse.
Have just checked voltage on pin 12 and it's 0.976 volts.
Just cant make head or tail of it
If pin 12 is 0.976 volts .... that is low .... which is inverted at pin 8 of IC6, and should turn on the solenoid.
Pin 2 should not stay high. It should toggle as the count progresses.
What is the voltage drop between pin 12 of IC6 and the +5 V bus?
Is R3, the 1k resistor, warm to the touch?
Check pin 5 of IC4 again to see if you are getting a clock pulse.
Check the 0.033 µF capacitor, C2, between pin 4 and 11 of IC4, to see if it is shorted out.
Pin 2 does not change it stays high,
Voltage drop between pin 12 ic6 is 1.2 volts.
There is no pulse on pin 5 ic4 and the capacitor is ok.
The only thing that gets warm is ic4 and it gets quite warm.
I am going to make a circuit to check these 7473 chips, i still think they are no good.The trouble is getting some more, it seems like they are like gold dust, (stupid expression)
will be in touch.
rog
It is necessary to have a toggle .... clock ...pulse on pin 5 of IC4.
This clock pulse originates at the rotary switch of the decade counter.
Try removing IC4 ... the 7473 .... from the circuit, and checking pin 5 for a clock or toggling pulse.
If you don't detect a pulse signal at pin 5, that points to something wrong with IC202, the SN 7442, or possibly one of the 7493 or other divider components.
Maybe there is something mechanically wrong with the rotary switch of the decade divider. ... Sometimes rotary switches have a metallic flex arm that contacts the various metal tabs .... Maybe the flex arm has become bent .... and is not exerting sufficient pressure onto the contact pins.
Have removed 7473 pin 5 toggles no problem.
Here are voltages from 7473 socket ic out.
Pin 1 150mv..(2) 5.0v..(3) o.ov..(4) 5.0v..(5) 5.ov..(6) 1.7v..(7) 5.0v..(8)..1.7v..(9) 120mv..(10) 5.0v..(11) 1.5mv..(12) 1.7v..(13) 16mv..(14) 27mv.
I used some contact cleaner on switch and it seems ok.
Its a shame you dont live closer i would pass it over. Give me a diesel injection pump any day.
rog
It may be that the SN7473, IC4, is defective somehow.
Another question, though:
With IC4 removed from the circuit, can you test pin 14 of IC4, on the circuit board?
Pin 14 is controlled by TR2 being on or off.
If you ground the base of TR2 with a jumper wire, then pin 14 of IC4 should switch from low to high.
The TR2 base pin is designated as pin 14, on the edge of the Single Shot Board.
If you don't see pin 14 of IC4 switch, when you ground the base pin, then maybe something is wrong with TR2.
Also, it would be useful to know if relay RL601 is working .... making good contact... as it grounds the base of TR2.
Pin 14 switches from low to high by grounding base of TR2, it also changes state when start switch is pressed, so i assume RL601 is fine.
How does the clock pulse get to other IC's if IC4 is'nt in the circuit?
I made up a circuit to try the 7473IC and it does seem to work as it should do, mind you the other 2 i had were no good, i took the readings from the function table on the data sheet.
Why is pin 2 on the socket of IC4 high when first switched on, i would have thought it should be low so as to reset every thing?.
rog
Pin 2 should not be high when first switched on.
However, resistor R2 and capacitor C1 form a time constant of about 0.1 seconds.
This means that within 0.2 to about 0.4 seconds, pin 2 should have switched from a low back to a high.
Even so, this short interval with pin 2 at a low state should be sufficient to 'clear' the 7473 of IC4, and bring pin 12 low, initiating the startup sequence.
Have you actually measured the capacitance of C1 with a capacitance meter?
It would be reassuring to know that its value was in fact something around
22 µF.
The SN 7413 is a specially designated nand gate, which is supposed to be able to switch states when the input is a slow rising ramp, as in the case of the R2 and C1 time constant.
I'm not certain that you can catch the startup change of state of IC2 using only a DMM. If you had an oscilloscope you would have a better chance of observing what is actually going on.
If you don't have a scope, then maybe you could replace C1 with a known good 22 µF electrolytic capacitor. Remember to put the + lead of the capacitor in the correct orientation on the board.
As far as the clock pulses for the 7473s, they are generated independently, at different locations on the board, and don't require the 7473s to be in place.
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