Knight Audio Technologies Ltd. Deacy - Style Amplifier Kit Build Instructions

Transcription

1 Knight Audio Technologies Ltd Deacy - Style Amplifier Kit Build Instructions

2 Introduction Firstly, thank you for purchasing this amplifier kit. We have designed this amplifier based on the Mullard 1960 s schematic known to many, but have in addition, modified the values of the components to bring that design closer in tone and performance to the actual Deacy Amplifier. We have also developed a pair of transformers (sold separately) that ensure this circuit performs as closely as possible to our design. Other transformers may be used if required. A range of other components that complement this amplifier are also sold separately. These include a twin cone loudspeaker, a Sapele veneered MDF/Chipboard bookshelf speaker cabinet and a Direct Record board for Direct connection to a mixing desk and headphone listening. Let s not also forget the KAT DABS (Deacy Amp Battery Simulator) unit, that will power your Deacy-Style Amplifier Kit and save you money on pricey Batteries! We very much hope you enjoy building this kit! Where to start; Start by checking off all the items in the kit by comparing it to the list below. If you have any items missing, please contact your KAT dealer and have your Deacy - Style Amp Kit and the missing component details to hand. Please do not start building the Kit until you have all the components in place.

3 1a. Kit Check List (Amp Kit) Amplifier Board Resistors Circuit Colour code/description Qty Ref 47K R1 Yellow/Violet/Orange/Gold 1 12K R2 Brown/Red/Orange/Gold 1 3K9 R3 Orange/White/Red/Gold 1 2K2 R4 Red/Red/Red/Gold 1 2K2 R5 Red/Red/Red/Gold 68K R6 Blue/Grey/Orange/Gold 1 12K R7 Brown/Red/Orange/Gold 1 330R R8 Orange/Orange/Brown/Gold 1 560R R9 Green/Blue/Brown/Gold 1 2K2 R10 Red/Red/Red/Gold 1 39R R11 Orange/White/Black/Gold 1 560K R12 Green/Blue/Yellow/Gold 1 4R7 R13 Yellow/Violet/Gold/Gold 1 120R R14 Brown/Red/Brown/Gold 1 Capacitors Circuit Colour code/description Qty Ref 2.2uF C1 Black 2u2 63Vdc 1 330uF C2 Black 330u 25Vdc 1 2.2uF C3 Black 2u2 63Vdc 1 47uF C4 Black 47u 63Vdc 1 100uF C5 Black 100u 63Vdc 1 220nF C6 Yellow block cap 220n 1 330uF C7 Black 330u 25Vdc 1 Semiconductors Circuit Colour code/description Qty Ref AC125 Q1 Silver can transistor AC125 1 AC126 Q2 Silver can transistor AC126 1 AC128 Q3 Silver can transistor AC128 1 AC128 Q4 Silver can transistor AC128 1 Hardware Circuit Colour code/description Qty Ref Heat-sinks HSK Multi-Finned spring loaded Heat-sinks 2 PCB PCB Screen Printed AMP PCB 1 ¼ Jack Socket SKT1 3 pole jack socket 1 PP9 Battery Clip LD1 PP9 battery clip/lead 1 Hook-up wire Wire Black/Brown/Red/Orange/Yellow/Green/Blue/Violet/Grey/White/Pink 1 ea 1b. Diagrams and Instructions Diagrams Description Qty Instruction Booklet A4 Booklet 1 Amplifier Schematic A4 Drawing 1

4 Building The Amplifier Assembly 2. Loading the Resistors Firstly, sort out the resistors. Make sure you have the right values, check them with a multi-meter if you are not totally sure of the colour codes. The resistors need their leads dressing, so gently place a 1/8 blade screwdriver shaft against the lead and away from the body of the resistor and wrap the lead 90 degrees around the screwdriver shaft. Do the same on the other side so that both leads head downwards in the same direction and measure approximately 13mm between them. Do this to all the resistors. Next, pick up the PCB and insert the resistors into their respective locations. Try to mount the resistors so that all the tolerance bands (gold) are either pointing towards the top or right hand side of the board (with the Fryer Sound logo at the top). As you place each resistor in its respective holes, gently bend the leads apart on the track side of the board just enough to hold their position and stop them falling out again. Once you have all the resistors loaded, place the board face down onto a soft surface and carefully solder each lead in place. Do not apply too much solder. Ensure that the finished joint has a concave web of solder surrounding the lead. A convex web shows that you have too much solder on the joint. Once all the leads have been soldered, they can be trimmed back to within 1mm of the joint using a sharp pair of side cutters. Take care not to bridge adjacent tracks with excess solder. 3. Loading the capacitors: Most of these are polarity conscious, so care should be taken when orientating the devices. Start with the smallest capacitor, C6. This is the small yellow block capacitor and it resides just above the output transformer T2. Place this in its holes and gently, as with the resistors, bend the legs apart so as to retain the device. Solder this in place now and trim the leads accordingly. Make sure that the capacitor is seated squarely on the top surface of the PCB.

5 Now load the electrolytic capacitors one by one. PLEASE NOTE THAT THESE ARE POLARISED DEVICES AND MUST BE LOADED IN THE CORRECT ORIENTATION. You will note that the capacitors have a silver band with minus signs running up one side of their bodies. This is the negative leg of the capacitor meaning the other leg is the positive. This POSITIVE leg needs to be inserted in the holes in the PCB marked with a +. Again, ensure each capacitor in turn is seated properly, and then solder them in place. BE CAREFULL WHEN SOLDERING THE 2.2UF CAPACITORS AS THE TRACKS ARE VERY CLOSE AND CAN EASILY BE SHORTED WITH AN OVER-LOADED SOLDER JOINT. With the Resistors and Capacitors now loaded, it is a good time just to check that you have all the components in the right place and in the correct orientation. From here onwards, it will become more difficult to make changes as the board becomes more densely populated. 4. Loading the Transformers: It is now time to load the largest components on the board. The two transformers (available separately) have been labelled T1 and T2 respectively. T1 is the driver or interstage transformer, T2 is the push-pull output transformer. Care has to be taken to ensure both transformers are mounted in the right positions and in the correct orientation. Load one transformer at a time, hold it in place making sure it is seated properly against the PCB, the solder the pins. These will not require cutting afterwards. Do the same for the second transformer.

6 5. Loading the Semiconductors: INITIAL NOTES AND WARNINGS: GERMANIUM TRANSISTORS ARE EXCEPTIONALLY DELICATE DEVICES AND CAN BE DESTROYED WITH BOTH EXCESSIVE AMOUNTS OF HEAT OR STATIC ELECTRICITY. Start with Q1 (AC125). Insert the transistor legs into the holes in the PCB. Note the orientation of the device and compare it to the screen printed guide on the PCB surface. Carefully push the device to within about 10mm of the board. In other words, there is 10mm of lead showing between the transistor and the top of the PCB. Again, check the orientation of the transistor prior to the next stage. To solder the device, choose the first lead. Wrap a rubber band around the handles of a small pair of snipe nosed pliers and attach these to the first lead between the board and the transistor. The rubber band will hold the pliers in place as a heat-sink and stop the heat from the soldering iron from damaging the device. Now solder the lead track-side. Repeat this for the other two leads and then for the other three transistors. 6. Mounting the Heat-sinks: Transistors Q3 and Q4 require heat-sinks to be fitted. If they are not fitted, the transistors will over-heat during loud continuous playing and almost certainly be damaged due to thermal runaway if the battery is not disconnected in time. To fit these, open them up by placing a pair of snipe nose pliers in the centre space and gently prising them apart. Slip the heat-sinks over the body of the transistors making sure you do not push too hard and bending the legs. The board is now populated and ready for connections.

7 7. Installing Inter-Connecting Wires: We would recommend the following colour codes be used for the inter-connects. Battery Speaker Input Jack (+ Red, - Black) (+ Blue, - White) (Signal + Yellow, Ground Green) Strip the leads back by 6mm, twist and tin them with the soldering iron. Make sure that any excess solder is removed otherwise the wires will not fit through the PCB holes. Push each wire in turn, bare end first through their respective holes from the component side of the PCB. Carefully solder the wires track-side. Trim as per the resistors. ENSURE THE BATTERY + AND BATTERY PADS ARE CONNECTED TO THE RED AND BLACK LEADS RESPECTIVELY. Connect the Speaker to the amp board and the jack to the input leads. 8. Congratulations, we are now ready to test! IF YOU HAVE ONE, CONNECT A MULTIMETER AS A CURRENT MEASURING DEVICE IN SERIES WITH THE BATTERY + LEAD (RED). Adjust the multi-meter so that its range will read up to 1 amp DC. Connect the battery and quickly read the meter. You should be drawing around 12 14mA. If it s significantly higher, firstly disconnect the battery quickly! Then check that you have: 1. Installed the all transistors the right way round and in the correct locations. 2. Installed the correct value resistors in R10 and R11 positions. 3. Installed the correct transformers in their respective locations. 4. Not got any solder bridges or splashes anywhere on the board. Once you have found the problem, you should find the current drops to the stated level.

8 If you do not have access to a multi-meter, turn the unit on and keep your fingers on all the transistor cans for a minute or so. None of the transistors should get warm whilst the amplifier is in quiescent or Idle mode. There should also be a faint hiss from the speaker. If any of the transistor cans start getting warm, disconnect the battery quickly! Then check the items listed above. Once you have found the problem, you should find that all transistors run cool under No-Signal conditions. If you dab your finger on the yellow connection of the input jack, you should hear a loud buzz. 9. Fault Finding: The amplifier is now ready to mount in your cabinet. All the components in these kits have been pre-tested by KAT Ltd. We would advise that you build this kit as per the instructions and schematics as any deviation from the designed circuit may result in irreparable damage to some of the components. If your amplifier does not work first time, it will almost definitely be caused by one of the following: Wrong component in a location (All components) Wrong component orientation (capacitors/transistors) Dry solder joint Solder bridge (across two adjacent tracks, Check in particular, C1 and C3) Damaged transistor due to over-heating or wrong orientation. Polarity of battery connections We wish you many hours of enjoyment building this kit and hope that the resulting amplifier will add a versatile and great sounding addition to your set-up. Cheers, Nigel Knight Knight Audio Technologies Ltd.