Re: QCX microprocessor startup
开云体育Hi Cap,No need the for game over thinking.... Man designed it, well HAN's designed it.? ;-) Man built it = you. Man / you used it, even if it was only for a short time. It's a positive thing that it did work, it proves you are 99.9% there. EVERYTHING is repairable, just some are easier than others. Plenty of times engineers walk away & grab a coffee, or other stimulant of choice.... (You would be VERY unlikely to find the problem to be with a new component, there something called infant mortality in electronic components. Some findings are true. Much not, but used by people who don't understand the big picture and use it for their own end's. WAY OFF TOPIC....) FACT:- one reason SMD's came about, was to enable machines assemble PCB's cheaply, quickly & RELIABLY. They are our friends...... Quickly back to IC1 You have reported the supply volts as 3.5. All OK. I didn't spot you have reported the check on the 27MHz Osc? measure on a scope the crystal leadout, dangle a wire from the ant jack of a RX and listen for 27MHz, failing that, DVM and it should measure close to half supply volts. Seeing it on a scope is the best check. To move on to the next step, are the MCU & Synth talking? I2C bus on IC1 pins 4 & 5 The best place to measure is at their connection to the pull-up resistors R3 & R4 I have not got a QCX to measure first hand, and report what it looks like & scope settings. It will be a digital waveform, so expect a voltage swing close to 0-5v. Is there anything, a quick burst, or a train of data on both pins? If not, is at the MCU end, IC2 pins 27 & 28 RE:- photo's, It's not a personal attack, Han's did find poor SMD machine soldering on one kit, out of 2500? Sometimes it just takes a fresh set of eye's to spot something, If you have a camera phone, or better still a DSLR many have a macro function and with correct lighting you can get good images of PCB's. (Some of us HAVE to use them daily, to inspect soldering on SMD's after middle age..... When I started and had good eye sight, it was valves & components mounted on tag strip, and used a 120w solder gun. Now I have tired eyes, the 'biggest' components are less than 1 inch square and have +120 legs. That's progress...) if you want to, perhaps buddy up with an Elmer or find somebody at a local club that does his own construction to take a fresh look at it. The thing to do is not to do anything you may regret later, one of my beef's is when you take on a job from another engineer who has damaged the PCB tracks, or worse still deliberately cuts tracks to isolate an area of circuit for "fault finding"... Until we find out what's wrong, don't warm up the soldering iron yet. Every one has talents and weaknesses, You probably never met me on the air sending CW. If you do, it will be machine sent....?? :-[ Alan
On 01/02/2018 04:04, CAP ALLEN wrote:
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Alan de G1FXB