surf pi 1.2 longboard problem

[kosacid]

im just getting a high pitched sound, it used to just start up then went intermittent had to switch it of and on a few times
i think it might be the delay or some thing else i just cant work it out
test point 1

test point 2

and pin 8 of the MC14093

[kosacid]

can some one help and post a trace of pin 8 on the 4093 i don't know if its supposed to be like that should it not be -

[chevesne]

[kosacid]

some one post a scope pic of pin 8 on the 4093 im still waiting on the chips ordered a 4066 to, i cant find a scope pic of the 4093 no where on the forum

[ionut_mtb]

hello,

Did you saw this thread?
http://www.geotech1.com/forums/showt...f-PI-1-2-issue

Why do you need scope pic for pin 8? check pin 10, 11, 3, 4. is your delay working? when rotate the pot you have increase in pulse length?

[kosacid]

ok thanks, here is my problem i put the chip on a breadboard (4093) and tested the logic it works fine, i even tested it with a pot to test threshold, it switches around 1.9v, well within the range of the scope pic i posted, but pin 10 is always low on the board but not in the test so i having wtf moment, as for pin 8 i just want to make sure the right signal is going in to it and its not a power problem, this one was working fine then just slowly died on me, it used to start up fine now it just starts for a sec then a high pitch constant buzz when you turn the delay on the pot, oh and it will stay that way until i leave it for a while without power, so far i have changed every chip trimmer and main cap apart from the 4093 and 4066 they are on order

[ionut_mtb]

can some one help and post a trace of pin 8 on the 4093 i don't know if its supposed to be like that should it not be -

this is pin8 on my surf pi. it looks good!

[kosacid]

thanks for the trace yes its the same but i cant read the trace mines is +5 down to +1 is your one the same ?, when i tested the chip it should trigger but as you see i get a constant -5v on Tp1

[ionut_mtb]

thanks for the trace yes its the same but i cant read the trace mines is +5 down to +1 is your one the same ?, when i tested the chip it should trigger but as you see i get a constant -5v on Tp1

I don't know what is tp1. 5v/div mine is different.

[kosacid]

so that seems to be my problem mines is +5v and i don't know what's pulling it up its just a trimmer and resistor and a cap i must have a short some where this is before C9 and after

[ionut_mtb]

so that seems to be my problem mines is +5v and i don't know what's pulling it up its just a trimmer and resistor and a cap i must have a short some where this is before C9 and after
[ATTACH]40477[/ATTACH]
[ATTACH]40478[/ATTACH]

Is signal from 7660 and 555 oscilator syncronised? Check transistor q1. I use this schematic, and measurements are from original surf pi.

[ionut_mtb]

Pin 3 555 and pin 7 7660

[kosacid]

think i have found the problem a power track is corroded with the board being black its hard to see need to clean it up and test

[kosacid]

yes it was the problem on the main power line some how salt water got into the screen and corroded the line, note to self make a waterproof case lol

[ionut_mtb]

[ATTACH]40483[/ATTACH]
yes it was the problem on the main power line some how salt water got into the screen and corroded the line, note to self make a waterproof case lol

Great! Good that you had scope. Moisture can get inside if you swing near the sea and in time comes the trouble.