This is a very simple build. I only have a few tips and things to look out for. I do recommend following these steps due to the diode/transistor relationship. 1. Install the three ceramic caps. If you are supplying your own IC opamp, make sure to read the note at the very bottom of this document regarding C3. 2. Install the IC socket. Make sure the half circle in the socket is aligned to the half circle in the silkscreen. As a tip, after installing I use a cut off lead from a small cap or resistor and my needle nose pliers to prep each of the holes in the IC socket. This will make the initial install of the IC easier and will give you less chance of bending the IC s leads over. 3. Install all four resistors. For vertical resistors, I bend the lead at the top of the resistor around my smallest jewelers screwdriver. That way it doesn t get bent at the body and the lead has a nice round shape to it with no kinks. The circles in the silk designate where each R s body should go. 4. Install the transistors. Make sure they are in their proper places and that the print on their bodies is facing the correct way. These parts are not interchangeable and cannot be turned around. I alternate soldering so I don t heat the parts more than necessary. Make sure they are aligned straight and don t look all sloppy and what not. Check for solder bridges after clipping the leads. Page 1 of 7
5. Cut the supplied blue heat shrink tubing into two pieces that are 5/16 (8mm) long. You will have a very small piece of scrap left over. I chose blue because it sounds a little more neutral than black or red.! Slip these 2pc of heat shrink over the transistors as shown. 6. Bend the four diode leads in the same manor as the resistors. Two will have their anode end toward the bend and two will have their cathode end (black band) toward the bend. Page 2 of 7
7. Insert all four diodes into their proper positions. Remember, the cathode end (the end with the black band) will go into the hole that the arrow is pointing to. The body for each diode will go up against the body of their respective transistor. The body will be inside the heat shrink and the bent lead will be on the outside. 8. Make sure the heat shrink is sitting on the PCB and that all four diodes are down against the heat shrink. Partially activate the heat shrink to hold the diodes in place. Page 3 of 7
9. Flip the PCB over and solder the four diode leads that are closest to the transistors. Adjust the diodes so that their bodies are up against the transistor bodies. 10. Fully activate both pieces of heat shrink tubing. 11. Finish soldering the four diodes. 12. Install the two 47µF caps. 13. I install the Mill-Max pins last. I start with the bottom of the PCB up. Using the small pointed tip of my iron, I lift the pin and apply the smallest bit of solder, which basically just holds the pin in place. Excessive solder running down the pin can be an issue. 14. After lightly soldering all the pins from the bottom, I insert the assembly into place on a PCB that uses sockets. This will hold the amp and pins in their proper position while soldering all the pins from the top of the PCB. Page 4 of 7
15. The final step is to install the IC into the socket. There is typically a dot indicating pin #1 and/or a small half circle in the IC s body. Make sure those indicating marks go toward the half circle in the IC socket and the silkscreen. Make sure all 8 pins of the IC are started into the socket properly before you press the IC in firmly. And that s a wrap folks!! Page 5 of 7
Resistors 2 R1 3K3.25W 1% MF Xicon R4 2 R2 3R9.5W 5% CF Xicon R3 Diodes 4 D1 1N914 Rectifier Fairchild D2 D3 D4 Capacitors 2 C1 47µF, 25V Radial, Electrolytic Nichicon C2 2 C4.1µF, 50V XR7 Ceramic BC C5 1* C3 22pF, 50V C0G Ceramic BC Transistors 1 Q1 BD140-16 PNP-BJT Fairchild 1 Q2 BD139-16 NPN-BJT Fairchild Operational Amplifiers 1 A1 Single, DIP8 5534 Compatible?? Miscellaneous 1 A1 DIP8 Socket Gold over Nickel Mill-Max 6 ****.04" PCB Pins Gold over Nickel Mill-Max 1 **** PCB CAPI BB2521 Rev A.1 capi-gear.com 1 Q1 & Q2.75 x.375 3:1 Heat Shrink *C3 is connected between pins 5 and 8 of A1. This compensation cap is required for a 5534 IC. The LME49710 has no connection between these pins so it makes no difference if it is installed or not. Check the datasheet if you use a different IC to see if the cap should be removed or installed. Page 6 of 7
Copyright Notice This assembly manual, including but not limited to all text, photographs and diagrams, is the intellectual property of Classic Audio Products of IL, Inc. Reproduction or re-publication by any means whatsoever, whether electronic, mechanical or electro-mechanical, is strictly prohibited under International Copyright laws. The sole purpose for this document is to aid in the assembly of the BB2521 Hybrid Opamp kit offered by Classic Audio Products of IL, Inc. Commercial use is prohibited. Page 7 of 7