Tesoro/Laser B2 help needed please

[ash]

Just wondering if anyone can tell me which is the trimmer for the coil please. I know on the Golden Sabre Plus,it used to be on the same side as the coil fitting,but not sure if it's still on the same side on this model.
Plus is the other trimmer for the threshold tone,or the disc setting. I'm looking to fit an external threshold control to this model.
Any help with either would be great

[Rov]

same side as the drive front end Mos.to coil.balance tx n rx.as to the other trimmer fire it up you soon know if its threshold,from response.mark it first so you can go back to the preset if wrong.I havent got this circuit so just making conclusions.

[ash]

Many thanks for the help Rov

[ash]

You were right about the trimmer for the coil.
Coil now trimmed in. Plus the other trimmer was the threshold.

[Rov]

Nice to hear Ash!Glad the unit is performing for you.
btw what coil have you got matched with it?
Rov

[ash]

It was fitted with the smaller 7" widescan that came with the unit when new,but have now just fitted the 8" x 9" web coil for a little more depth. Have also got it super tuned now as well.

[Pete B1]

tesoro/laser b2

Hi, I have a non working Laser b2 made by Tesoro. The problem is, i think, that voltage polarity is reversed somewhere .Measuring voltages at coil chassis plug i have -7v at pin 1 when it should be +5v? I would welcome suggestions on likely components to check, the pcb being smd isn't the easiest to check.

pin1 -7v
pin2 -9v
pin3 +4v
pin4 -7v
pin 5 ground

thank you for any help, Pete

[Skippy]

I know nothing about this machine, but... I see a voltage inverter chip, the '7660 which I assume works with two of the large electrolytic capacitors. Check out the correct operation of this circuit block - the caps may have dried out/ failed.

[Pete B1]

Thanks Skippy, the caps check out so i think i'll change that 7660 and go from there.

Cheers, Pete.

[Skippy]

The 7660 is unlikely to fail. Verify it is functioning correctly first, as changing it will be difficult. Check all the usual mechanical parts - switches, connectors, pots, that are high failure rate items.

[mario]

Have you tried checking the polarity of your diodes?

It sounds like one of them may be shorted.

[Pete B1]

Many thanks Mario, turns out that it is one of the diodes.