FW-4 rev c

[Jeffry P]

I have a FLW by Pete Hand  that has been in storage a few years and I hope the group can help me get it working up and running. The device was functional when I put it into storage.

1) What are the power requirements?

2) there is a jumper wire dangling off a pin in between the #4 and the power connector and I don't know where is supposed to attach.

3) There was another jumper wire in the box and I'm not sure where it goes.

I've attached some pics

Thank you ,

Jeffry

[5-ht]

Hi Jeffry,

Your circuit board appears to be missing U1 which is a 78L05 5V regulator in a 8-SOIC SMD package.

This design originally required a 12-18VDC external power supply (350-500ma should be sufficient, the coaxial connector is center-pin positive) but I guess one could power it with separate 5V and 12-18V power sources. The 5VDC powers the logic and the 12-18VDC the high voltage generator for the tubes.

The part number for the missing 5V regulator is LM78L05ACM-ND form Digikey and 511-L78L05ABD from Mouser.

Mark

[petehand]

Mark is correct in all respects. Sometime in the past the 78L05 regulator was removed and presumably the logic was powered externally.

I strongly recommend replacing the 78L05. The board only draws 10-20mA from 5V and using an external 5V supply is a nuisance and an unnecessary point of failure. If you have any trouble getting it going, just ask me. I seldom post here but I keep an eye on the forum.