[justhavingfun]

I bought one of the best DIY Millett Hybrid from Thaddy (built by n_maher) recently and after the long journey to Hawaii, this amp is not powering up at all. And there is no doubt that this amp was in perfectly working condition when he shipped it to me. So something must have happened during the journey. This amp is in black Parmetal case with STEPS power supply and diamond buffer installed. The fuse in the STEPS power section area is good as far as I can tell. Can anybody out there can point me in right direction how to diagnose the power problems? So far, I have tried different power cords, different outlet, and different set of tubes with no luck, not even LEDs are light-up. Hopefully it is small thing to repair or I might have to ship it to n_maher with his approval of course.

 

[Thaddy]

For what it's worth, the amp (obviously) uses the STEPS power supply, discrete buffers, and has 3 switchable inputs and a preamp output. He also has all three sets of tubes to test, and all three were in perfect working order before the amp was sent.

justhavingfun, another thing I forgot to mention was to check for loose or broken solder joints running from the IEC -> STEPS -> amplifier board.

Guys, any help would be appreciated!

 

[[AK]Zip]

justhavingfun: please post some high resolution pictures of the amp and I will look it over.

-Alex-

 

[n_maher]

justhavingfun,

Take a few high-res pictures with the top cover off and I'll take a look at it. I can't imagine what could have happened that would make it not do anything. I'll also look over the original configuration of the amp to make sure there's nothing else it could be. If you need help hosting the pictures just shoot me a PM and I'll handle it.

NOTE: DISCONNECT THE POWER CORD BEFORE DOING ANY OF THIS!
The first thing that I would check is that all of the connections from the STEPS to the power inlet are connected correctly. If any of the three came loose I think it would exhibit the symptoms that you're describing. If the LED on the STEPS isn't even lighting we need to start there are work forward. Here's a picture of how it should look, apologies to the dial-up folks.

Nate

 

[dsavitsk]

First thing I'd check is that the nut next to the heatsink is not touching it and shorting the PS to ground.

 

[justhavingfun]

I am not sure how pictures will show up since my camera is not very good one. Hopefully it comes out good enough to see.

I did check the nut right beside the heat sink and it wasn't touching. Thanks for your input.

 

[justhavingfun]

So far, I checked all the wires for their continuity including ground wires from power supply to the MH board and they checked out ok. Also checked the power switch and it is working as it should. I am not sure what else to check since my knowledge in this regard is some what limited. I even checked the power cord and wall outlet and making sure it has proper juice. The LED from STEPS power board doesn't even lit. Could it be one of those power capacitors some how got broken?

 

[dsavitsk]

Quote:

Originally Posted by justhavingfun Could it be one of those power capacitors some how got broken?

It's not likely, and it wouldn't lead to this problem. The best thing to do would be to get a multimeter and start checking some voltages. The STEPS documentation (http://tangentsoft.net/elec/teps/) should give you a basic idea of what voltages to check on the PS. Do be careful, though, as you are dealing with live AC.

 

[justhavingfun]

I checked PS voltage with multitester according to tangentsoft website and it registers zero voltage on all the test points. I believe this STEPS power board is dead somehow. It seems like I need to get replacement power board likes of STEPS, TREAD, etc. I am going to keep try to figure out the problem but it is highly unlikely for me to find out, oh well.... I guess I need to learn how to assemble the power board or ask some other knowledgeable DIYer for me to purchase.

 

[dsavitsk]

Quote:

Originally Posted by justhavingfun I checked PS voltage with multitester according to tangentsoft website and it registers zero voltage on all the test points. I believe this STEPS power board is dead somehow.

Unlikely. At worst, there is a bad component or a bad solder joint. Are you sure the fuse is good and that it is making a good connection? Check for continuity across the fuse, and if that's okay check for AC across the power inlet and from each side of the fuse to N.

 

[matthewcarlrose]

You need to start working from the wall socket backwards with your multimeter. All the test points are post the transformer so are safe voltages, you need to test the mains AC i think your problem is there!!!...

Check the fuse, AC from the chassis socket to the steps.

Becareful and good luck!

and if you get stuck i'd be happy to come over there and help you out!

 

[Thaddy]

Thanks for the help so far guys...and justhavingfun, good luck fixing the amp! PM me if you need anything.

 

[kklee]

When checking the fuse, make sure you check with a meter rather than eye-balling it. I've had fuses that looked fine, but the fuse element was broken where it wasn't visible in the end cap.

 

[justhavingfun]

I am current at work so I will not be able to check the amp until later tonight. But last night, I checked the AC power from wall socket, fuse, and everthing else that I can think of and they all checked out ok except there is no power to amp yet???? Anyway, I will check them again tonight and report back. Thanks for all the help guys.

 

[justhavingfun]

n_maher,

Here are more pictures for you to check out. I am continuing to figuring out the problem.

Checked AC power going through the switch box and it checked out ok and all the wires going to STEPS have continuity but no power yet.