>Considering in my experience, the number one killer of everything was the LV
>design. What seems to happen is that during power on/off, one of the zener
>diodes will explode and then take out the rest of the circuit.
>
>If you look at one version of the schematic they have a good size capacitor
>directly across the zener diodes No current protection what so ever.
There's
>enough current in that capacitor to take out the diode during a quick
discharge.
>Or it looked like if one channel of the power supply discharge/charged faster
>than the other, the imbalance could cause havoc. Later they added a
resistor in
>series with the zener to keep it from dying, only to greatly reduce
regulation
>(and raising the output voltage from 25 to 27)
Interresting you should mention this. When you install a new LV PCB you
will be able to visually see this happening. With the LV2000 installed,
when you turn the game off, the positive LED stays on longer than the
negative LED. i.e., -- the negative supply discharges faster.
>
>I like the idea, are the TVS's fast enough to protect the transistors?
>
>-Zonn
I believe so. I will look in to this.
-Anders.
-----------------------------------------
| Anders Knudsen
| ASIC Design Engineer
| Adaptec, Inc., Boulder Technology Center
| anders_knudsen@btc.adaptec.com
| http://www.adaptec.com
=========================================
Received on Wed Jan 14 15:39:18 1998
This archive was generated by hypermail 2.1.8 : Fri Aug 01 2003 - 00:31:06 EDT