IMPORTANT errata and notes
Posted: Tue Jun 18, 2013 1:33 am
Current Issues wrote:These apply to some batches of coils that we shipped recently. They will be updated frequently.
- BEFORE POWER TESTING: for some kits, the secondary in your kit is wound to be in tune with 5 primary turns, not 6. You should wind your primary with 5 turns to avoid IGBT failures (measure the secondary resistance first - under 228 ohms means you should use 5 turns).
- The newest chassis (shipped on or after 12/5/2013) are a tight fit - on some of them you might need to gently tap the pieces with a rubber mallet to get them together. On the bright side, you shouldn't need any glue.
Older Issues wrote:These apply to older batches of kits.
- If your kit came with gold-colored thermal paste, be careful when applying it. We've heard reports that it is somewhat conductive, and if it makes contact with both the tab of the IGBT and the heatsink, your coil may fail. You're probably better off not using it - the sil-pad will deform to fill gaps, and acts much like thermal paste.
General notes wrote:
- Tuning. Some secondaries were manufactured with too few turns of wire, resulting in a higher resonant frequency than intended. If your secondary measures under 228 ohms, you will need to remove one turn from the primary, leaving five turns, to match the resonant frequencies of primary and secondary.
- We recommend adding some more coats of varnish to your secondary coil. Minwax brand polyurethane works well.
- Use the manual available at onetesla.com/downloads for the most up-to-date version, and check back every once in a while for updates.
- When transporting the coil, be careful not to place too much stress on the heatsink; when shipping completed units without supporting the heatsink, the IGBT leads have snapped. We did not solder or bolt the heatsink to the board in order to make IGBT replacement easier.
- The chassis pieces are asymmetric. In particular, the hole for the terminal block should line up with the terminal block on the board; if it doesn’t, flip pieces around until it does. The interrupter chassis is also slightly asymmetric; if it doesn’t fit, don’t force it. While installing the interrupter board into the chassis, removing the collar on the optical transmitter may help.
Specific issues with early kits wrote:
- Kits shipped before late August did not have thermal reliefs on the ground plane, as we wanted to minimize inductance. We realized that it’s probably more important to avoid cold solder joints from poor soldering instead, so we have since added thermal relief. If you have an early version of the board, use extra heat to solder these pads. Try two soldering irons simultaneously.
- The first kits had three identical 100K resistors. Though they look like 1/4W, they are all rated for 1/2W. After realizing how confusing this was, we included three of the 1/2W resistors and quickly ordered more in a larger form factor to make it clear which were which.
- The value of R6 is 560 ohms. A 470 ohm resistor would work too, but we included 560 ohms in the kits.
- C5-C7 are 220uF. 100uF would work too, but we included 220uF capacitors in the kits.
- We didn’t include information on how to position the breakout point in manuals version 1.3.0 and 1.3.1. Please refer to the latest manual on our downloads page for instructions on positioning the breakout point. The coil is very sensitive to its positioning, so this is an important step for good performance.
- We found out that the green LEDs we initially ordered were manufactured backwards; the flat side should go opposite the flat side of the silkscreen drawing. In fact, to be safe, you should look closely at the internal structure of each LED to determine its polarity.
- If you have slightly too little GDT wire than you need to wind the number of turns in the manual, that's OK. Fewer turns work as well.
- If you have four twisted wires in the GDT wire bundle, remove one wire. For a while we cut up ethernet cable for the wires inside, but this was inconvenient as there are two twisted