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MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CHIP KIT ASSEMBLY & REPAIR KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith 0409 662 794. keith.rippon<at>gmail.com VINTAGE RADIO REPAIRS: electrical mechanical fitter with 36 years ex­ p erience and extensive knowledge of valve and transistor radios. Professional and reliable repairs. All workmanship guaranteed. $10 inspection fee plus charges for parts and labour as required. Labour fees $35 p/h. Pensioner discounts available on application. Contact Alan on 0425 122 415 or email bigal radioshack<at>gmail.com DAVE THOMPSON (the Serviceman from SILICON CHIP) is available to help you with kit assembly, project troubleshooting, general electronics and custom design work. No job too small. Based in Christchurch, NZ but service available Australia/NZ wide. Email dave<at> davethompson.co.nz Where do you get those HARD-TO-GET PARTS? Where possible, the SILICON CHIP On-Line Shop stocks hard-to-get project parts, along with PCBs, programmed micros, panels and all the other bits and pieces to enable you to complete your SILICON CHIP project. KEEP YOUR COPIES OF SILICON CHIP AS GOOD AS THE DAY THEY WERE BORN! SILICON CHIP ONLY 95 On-Line SHOP $ 1P6LUS p&p A superb-looking SILICON CHIP binder will keep your magazines in pristine condition. * Holds up to 14 issues * Heavy duty vinyl * Easy wire inserts ORDER NOW AT www.siliconchip.com.au/shop www.siliconchip.com.au/shop FOR SALE PCB MANUFACTURE: single to multi­ layer. Bare board tested. One-offs to any quantity. 48 hour service. Artwork design. Excellent prices. Check out our specials: www.ldelectronics.com.au tronixlabs.com - Australia’s best value for hobbyist and enthusiast electronics from adafruit, DFRobot, Freetronics, Raspberry Pi, Genuino and more, with same-day shipping. LEDs, BRAND NAME and generic LEDs. Heatsinks, fans, LED drivers, power supplies, LED ribbon, kits, components, hardware, EL wire. www.ledsales.com.au PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone 0434 781 191. sesame<at>sesame.com.au www.sesame.com.au ADVERTISING IN MARKET CENTRE Classified Ad Rates: $32.00 for up to 20 words plus 95 cents for each additional word. Display ads in Market Centre (minimum 2cm deep, maximum 10cm deep): $82.50 per column centimetre per insertion. All prices include GST. Closing date: 5 weeks prior to month of sale. To book, email the text to silicon<at>siliconchip.com.au and include your name, address & credit card details, or phone Glyn (02) 9939 3295 or 0431 792 293. I recognise that you probably can’t give detailed assistance in troubleshooting this type of problem with individual projects. However, it would be appreciated if you could verify that the batch of programmed PIC16F877As you have in stock for the SemTest project are all OK. I can then move on to look at other possible causes knowing that the micro is unlikely to be the problem. (K. B., Hobart, Tas) • There have been one or two constructors of the SemTest unit who have reported much the same problem and siliconchip.com.au as far as we're aware, their problems were all found to be caused by poor connections between the IDC connectors and the ribbon cables. Not in the solder joints between the connectors and the PCBs but inside the crimped part of the connectors, where each fork at the rear of a contact hasn't made reliable contact with the wire inside the ribbon. We don’t believe there have been any problems caused by the PIC16F877A micros purchased from the Silicon Chip Shop. So we suggest you use a scope (if you have access to one) to check that all of the signals from the micro to the LCD are getting through. The most important signals in this case are the RS and EN signals, which emerge from pins 9 and 8 of the micro and should be reaching pins 4 and 6 of the LCD. If either of these signals is not getting through, this would certainly result in no display. These signals are sent to the LCD very soon after power up, to provide the initial greeting display. So it’s fairly easy to monitor them at this time. We hope this helps you to track down the cause of your problem. SC March 2017  103