[DanRotigel]

Hi all,

Here are my symptoms:

31v AC between tp 1 and 2
40v DC between tp 3 and 5
5.7v DC between tp 4 and 5

If I adjust vset, the output voltage varies very little and can go down to 5.6. The LED is glowing happily and the PS doesn't seem hot at all.

Obviously its the 5.7v DC that is off-I was expecting 28 or so! Here are the parts I used:

Transformer is a Amveco 70052k
R1=1/4w 1M ohm
R2=1/4w 100 ohm
R3=1/4w 100 ohm
R4=1/2w 2K ohm
R5=1/4w 2.2K ohm

Can anybody help me out?

cheers,
dan r.

 

[blueworm]

Is the tantalum cap C7 correctly orientated?

 

[Teerawit]

Quote:

Originally Posted by blueworm Is the tantalum cap C7 correctly orientated?

Shouldn't it have blown up already if it were reverse-oriented?

 

[dsavitsk]

Quote:

Originally Posted by Teerawit Shouldn't it have blown up already if it were reverse-oriented?

Not necessarilly. They take a while to blow from reverse voltage.

 

[kin0kin]

1) make sure you did not reverise R3 and R4
2) make sure you populated the pot properly
3) make sure the diodes are not reversed

usually it is one of these three problems.

 

[blueworm]

Quote:

Originally Posted by dsavitsk Not necessarilly. They take a while to blow from reverse voltage.

here

 

[DanRotigel]

Yep, it was the tantalum cap! I'd like to dedicate my first hour of listening (its connected to a millet and 125 grados) to Blueworm! Many thanks.


32v AC between tp 1 and 2
42v DC between tp 3 and 5
28v DC between tp 4 and 5

The amp was probably on for half an hour of testing before I switched the cap back to what it should be. Have I friend any components? Is it safe to try it on my millet?

cheers,
dan r.

 

[blueworm]

The only component that would have suffered is the actual tantalum which in any case is optional.
Change it if you are a little paranoid, otherwise enjoy.

 

[DanRotigel]

Ok, I plugged the PS into the millet, and flipped the switch. the LED on the STEPS dimmed briefly, but the LED on the millet didn't come on! The tp's on the PS have much the same values as before, even with the milllet switched 'on.'

I unplugged the millet and plugged it back into the wallwart. Everything seems well, so whats the deal? The millet has been up and running for a year or so now, so its a 'known-good' at this point i think. Any thoughts?

cheers,
dan r.

 

[Teerawit]

Did you hook up the Vout from the STEPS into the V+ power input pad?

Did the Millett's LED come on after you plugged the wallwart back in?

 

[DanRotigel]

Teerawit,

I have a power cable with a plug on the end running from the STEPS to the millet. On the STEPS, the wire with the ------- mark on it is soldered to the ground on the board, the wire with the writing on it is soldered to the vout. The other end plugs into the stock connector on the millet. Is this incorrect?

The LED on the millet is on while using the wall wart; the amp is working and i'm listening to it now.

Any ideas?

cheers,
dan r.

 

[n_maher]

Dan,

Simply check that the power plug from the STEPS and the wallwart are both wired the same. One might be center pin positive the other negative. Use your DMM to make sure that measuring the output of each cable plug yields the same sign (+ vs. -) voltage reading. That's the only thing that I can think of that would cause what you are describing. Never trust the cable markings and whatnot.

Nate

 

[DanRotigel]

Got it!

The polarity was reversed between the wall-wart and the STEPS. I re-soldered the line on the steps and it sounds great. I can't wait to put this thing in a decent box, thanks all!


cheers,
dan r.