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PP-18 Turret board assembly




Your PP-18 kit contains a turret board, already staked with turrets for you to add and solder your kit's board-based components. Click here to open a page with detailed photos of the layout of the components on this board.
      The top picture shows the components soldered in position. The bottom photo is annotated with component numbers (C1, R4, etc). Before starting, read the whole of this page first - for advice on mounting components, etc.

Where to start?

Some parts of the board are quite tightly packed with components, whereas other areas have lots of space. To make sure you've got space to work and easy access for your soldering iron, it's worth adding a few components and links first:
* Add the short link (as shown in the dotted outline below) to the board first, soldering it to the side of the two turrets leaving the turret holes available for other components/wires.



* Add R17 in the same way (shown below); this makes it easier to mount other component leads



* There's a set of four resistors and two capacitors near the centre of the board (shown right) that are rather fiddly to add. It's best to do them early and solder them in place so that they don't get jogged about when you add other components.

Turret board soldering tips
* Do a 'dry run' before you start to solder. Line up all of the components in their correct order, from left to right. This helps you spot missing components and helps to avoid mistakes that could make you have to desolder components to start again.
* Even if you can read resistor colour codes easily, it's easy to make mistakes in poor light. Use your multimeter to check the resistance value, just in case. (Note: +/- 5% is normal tolerance.)
* Check twice and cut once! Extending a component lead that you've mistakenly trimmed too short is a pain, so double-check that you've got the correct component before cutting the lead to size.
* Trim the component leads so that there's just 3mm or so inside the turret. Once again, this makes it easier to desolder and remove the component if you make a mistake (or if you want to alter components to tweak your amp's tone).
* Aim for solder joints that are shiny and gently domed. Solder should 'flow' around the component leads and turret surface - almost seamlessly.
* If a solder joint looks 'lumpy' or dull, you may have a poor joint, which can cause the amp not to work (or even to work intermittently - a tricky problem to debug). If in doubt, resolder the joint.
* If a turret's top hole is crowded, making it difficult to fit another lead, don't worry - use the side of the turret. There are side-ridges for this purpose - wrap the new lead around the turret's side and solder it in position.


Resistor notes

Make sure to use the larger resistors - which are rated at 2W or 3W - in the appropriate position. For example, there are four 100k resistors, one of which is substantially thicker than the other three. The smaller ones are R4, R10 and R11 - all are plate resistors for the ECC83 valves (two are shown left). The larger one is R18 (on the right), a bleed resistor which has a higher power rating because it connects directly across the high voltage supply, and dissipates a lot more energy.


Polarity notes

Some of the components - five of the capacitors and four diodes - have a polarity that you need to follow. On the capacitors, the polarity is indicated by an arrow or chevron with a minus (-) symbol which points at the negative lead. For the PP-18, mount the following capacitors so that their negative lead is towards the bottom edge of the turret board: C1, C9, C10, C11 and C12.
      In addition, the four diodes (D1 - D4) must also be soldered the correct way around. Follow the example shown in the component layout diagram, paying close attention to the orientation of the grey-silver bands at one end of each diode.


Side-mounted components

It's best to mount most of the components using the holes in the top of the turrets. However, it will be easier to connect some wires at a later stage if you side mount some of the components: R17 (described above) and D1 - D4 (shown right).


Ground and other connections

As you place components on the board, there are three short connections to add at the same time (shown in dotted red lines in the annotated photo on the right). Use some of the uninsulated wire to directly connect:
* the positive end of C1 and R5
* the turrets at the top ends of R10 and R11
* the turret where D3 and D4 meet to the turret at the bottom edge of the boards
      Finally, solder two ground bus wires and one power supply wire, using the annotated photo shown right as your guide. The first ground bus wire connects turrets A-E, and the second connects turrets F-K. These two wires will connect all of these components to ground once the wiring is complete. Last of all, connect turrets L-N along the top of the board. In the next section you will add the wiring.
      Note: At this stage, you will have some unused resistors, capacitors and turrets. This is normal.



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