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MARKET CENTRE Advertise your product or services here in Silicon Chip KIT ASSEMBLY & REPAIR FOR SALE 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, New Zealand, but service available Australia/NZ wide. Email dave<at>davethompson.co.nz LEDsales KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith: 0409 662 794 keith.rippon<at>gmail.com FOR SALE LEDs and accessories for the DIY enthusiast LEDs, BRAND NAME AND GENERIC LEDs. Heatsinks, LED drivers, power supplies, LED ribbon, kits, components, hardware. For a full list of the parts we sell, please visit www.ledsales.com.au PMD WAY offers (almost) everything for the electronics enthusiast – with full warranty, technical support and free delivery worldwide. Visit pmdway.com to get started. Lazer Security For Quality That Counts... QUALITY COMPONENTS AT GREAT PRICES. Check out the latest deals this month. SMD parts and more. Go to www.lazer.com.au PCB PRODUCTION PCB MANUFACTURE: single to multilayer. Bare board tested. One-offs to any quantity. 48 hour service. Artwork design. Excellent prices. Check out our specials: www.ldelectronics.com.au ADVERTISING IN MARKET CENTRE Classified Ad Rates: $32.00 for up to 20 words (punctuation not charged) plus $1.20 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 (02) 9939 3295. (January-March 2017; siliconchip.au/ Series/308) using Altronics K5157 kits. I have a few questions that would help to clarify assembly in my head. 1. The heatsink drilling details show the central KSC2690A/TTC004B transistor 5mm lower than the two other transistors on either side. That appears different from the photos of the finished module, where all three middle transistors are mounted at the same height (30mm from the bottom of the heatsink). Should they all be level at 30mm from the bottom of the heatsink? 2. I am going to mount the clipping LEDs on the front panel. Can I use any 5mm red LEDs for this? I have some bezels that fit 5mm LEDs handy. Or is there a particular LED I should use? 3. The transformers I am going to use are Ferguson PF4361/1 200VA siliconchip.com.au 35-0-35/15-0-15 transformers from a very old ETI Series 5000 kit. I have built two power supplies and will use one transformer for each SC200 Amplifier board and power supply board. Based on your previous emails, I think these should be okay to use. My speakers are 4W Magneplanars. 4. Under “Final Assembly”, regarding mounting the transistors to the heatsink, it says, “Once the soldering is completed, trim the leads and remove the two supports near the heatsink, as these are no longer required; the transistors should be mounted to the chassis via the heatsink only, otherwise, thermal cycling could crack their solder joints.” I take it that means to remove the two plastic PCB standoffs near TP1 & TP2 but retain the other two standoffs at the front/input edge of the amp Australia's electronics magazine board. Will they still allow thermal cycling to occur safely? Thanks for all your support so far with my project. (S. W., via email) ● Our answers to your questions: 1. The heatsink drilling has been purposefully kept compatible with the Ultra-LD Mk.2, Mk3 & Mk.4 amplifiers, which used larger transistors except the middle one, even though the extra height is not needed for those two transistors on the SC200. That was to allow existing heatsinks to be reused. You could certainly drill them all at the same (lower) height, as we did on our prototype. 2. Most LEDs should be suitable, but we suggest you test how bright they are at 1mA by powering them from a DC supply with a fixed resistor, eg, a 3kW series resistor for a 5V supply or a 10kW series resistor for a 12V supply. July 2024  103