Surf PI Constant Beep - No Detection

[jabemer]

Hello everyone, Did you fix your problem ? I do have the same problem, i cannot adjust the offset to 0v, i got 4.4v and continuous beep, i did my board from a picture of internet .

[kenny444]

Hello jabemer, Just to qualify, all my IC's are in sockets so allowing easy removal, replacement and version improvements. Check your IC's are in the right place and with correct orientation, check you have not got 5534 in a 555 socket, with the board solder side up and a jewelers loop (big magnifiation eye glass) check for shorts (solder bridges), then check all your pot wiring and the pots too (some of my new pots were faulty). There is a list of voltage on this forum somewhere which you may find helpful, sadly I do not know where it is. Working through it logically you will get there, make notes and keep records. A wrong or faulty component can cause a big headache, Best Wishes

[jabemer]

thanks for response i keep looking and post results

[kenny444]

I think the answer was the 5534, but do check all solder joints, which way round and in the right socket.

[Qiaozhi]

Very often, in various threads (usually associated with either Surf-PI or Baracuda) there are suggestions for fixing a non-working design, that range from eye-balling the PCB, checking component values, checking component orientation etc., but many of these lead to a non-result. This "debugging" methodology is haphazard at best, and basically amounts to guessing. Sometimes you can get away with it, but most times it will only end in frustration.

The first thing you should always check is the power supply voltages, and you can do this with a humble voltmeter. After that - there's no substitute for conducting proper repair procedures using an oscilloscope. Without a scope, it's like trying to navigate a maze while blindfolded. You should logically check the various parts of the design (assuming it's a PI) as follows:

1) TX oscillator
2) TX transmitter
3) Preamp
4) Sample generator circuits
5) Sampling integrators
6) Later integrator stages
7) Audio amp

If you don't have a scope, then find a friend who has one. Or better still; buy your own. Although sometimes you can get away with building a kit without using a scope, it's basically asking for trouble. Also, you can learn so much more by studying the waveforms and actually understanding how the design works, rather than following a "monkey-see monkey-do" set of instructions.

[jabemer]

hello again, i did some voltage readings that i saw on another post should i post here or start a new thread?

[jabemer]

This is what i got on the voltage readings;
U1 pin 8, +11.76
U2 pin 7, + 5.00
U2 pin 4, + .93
U3 pin 8, + 5.00
U3 pin 4, - 4.40
U4 pin14,+ 5.00
U4 pin 7, - 4.40
U7 pin14,+ 5.00
U7 pin 7, - 4.40
U6 pin 5, - 2.19

[jabemer]

I replace the 1nf capacitors and is working now