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gary wrote:ermmm... not quite sure what you mean by that Harry but yes I want sync added in via the voltage divider r6/r7 by applying the monostable output in via top of R6
BUT I also want you to turn RV1 completely to the left so the video input is pure black = 0v - then the cct should raise that to .8 V and the sync pulse will be added to that - i.e. it *should* go from +.8V to zero. All that means is we only have sync coming in - but it is ABSOLUTELY IMPERATIVE that RV1 be turned all the way down so we don't have any floating induced voltages floating about.
[/quote][/quote]Please remember why I am asking this - I only want ONE thing coming in at a time otherwise there is just no way to sort out the mess.
gary wrote:Ok can you run the 0v test again - but don't bother recording - but please check with the multimeter at "black level map", and also at "video out".
From the wave files it appears that you are either:
a) not getting a .8v clamp level, or
b) getting no sync
It's not possible to tell from the wave files which one it is because of the AC coupling.
BTW do you have any idea what the peak level of you monostable sync pulse is?
Edit: If it isn't too late you could also check the DC voltage (BTW all the voltages I have asked you to measure are DC voltages) at pin 3 of IC2.
gary wrote:That's good Harry - the voltages are close enough for normal operation.
I did ask you to measure at IC2 pin 3 - but I really should have asked for IC2 pin 6 anyway, could you DC measure that please?
(also what setting is your gamma switch in for interests sake? - for these tests please make sure it is in position 1 gamma = 1)
gary wrote:Ok good, Harry every thing seems fine except that you don't have any sync pulses (according to "v1 on 0.wav") - so it looks like either a sync connection error or a blown Q1.
Sorry Gary i didn't have the line pulse connected to Q1 ...
I wasn't going to change any thing but looks like i need it connected ...
I also have not got the 1meg resistor on the base of Q1 and to the positive rail connected yet .
Do you want me to do ad the resistor and sync to Q1 and do ic voltage test again ?
You might want to get the DC voltage at pin of IC2.
pin 7
10.8 volts
Harry, I thought you had a CRO - is it out of action?
gary wrote:Ok good, Harry every thing seems fine except that you don't have any sync pulses (according to "v1 on 0.wav") - so it looks like either a sync connection error or a blown Q1.
You might want to get the DC voltage at pin of IC2.
Harry, I thought you had a CRO - is it out of action?
Harry Dalek wrote:Sorry Gary i didn't have the line pulse connected to Q1 ...
Harry Dalek wrote:Oh i have my little slab of a scope .
Harry Dalek wrote:I also have not got the 1meg resistor on the base of Q1 and to the positive rail connected yet .
gary wrote: Not saying a word...
Great that will be a big help.
not positive rail see attached diagram - I think this should do it depending on the peak value of your generated sync pulses - if you had a 1m trim pot that might be better than 1m resistor - but by all means try 1m resistor - that way when you go to real sync it's all there.
BTW2 - while I think of it might be a good idea now to ensure that pin 4 of ic2 is in fact connected to ground.
Harry Dalek wrote:I didn't put it back on from the video tests as with it on theres no video out just sync..any case Whoops
Harry Dalek wrote:I hadn't been using it much as i look at your big picture scope on any NBTV .
Harry Dalek wrote:Yes gald i waited ,i have a resistor wheel handy as i recall i tried a 1 meg but i think it was a 680 ohm that worked any case i will double check it was BTW same as how you are saying to ad the sync.
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