Ironsounds Traveler 18w New Build Problems

[Zarrir]

Hi there! I´ve just built a PCB based 18w clone from Ironsounds, as per the schematics bellow. New tubes, new power transformer (290PAZ Hammond).It was a clean build but i am running into newbie problems.
Before installing the tubes i measured Heater and high voltage tabs and got  114VAC(!!!) and 258VAC respectively. I then lifted the heater ct wiring from ground and got 3VAC on each heater pad.
Tubes installed, I am getting negative voltage(-33VDC) at Red B+ (TP4 on the schematics). I should be reading +370VDC there!
Frustrated. Any ideas? Maybe bad diodes?

[sluckey]

I'd say either your meter is whacky or the amp ain't wired right.

[Zarrir]

Hi Sluckey! All components on the PCB double checked. No sound from speakers. Maybe a faulty PCB?

[sluckey]

Your voltage readings are very crazy. I'd say either your meter is whacky or the amp ain't wired right.

Let's see some pics.

[John]

Put fresh battery in your meter first (easiest to try). Then make sure your diodes are installed with polarity correct. Like Sluckey says if your meter is right, something is wired (or installed) wrong.

[Zarrir]

Pictures. Will fetch a new battery for meter. Forgot to mention something important: When i first powered it up, i had forgotten to ground the PCB and got a blown fuse. Maybe something else was ruined?

[sluckey]

Your PT wire colors don't seem to match the schematic?

[John]

Double check the diodes coming off your 2 red wires. It seems that not all the bands would be pointing the same way on a PCB; the few I've seen had 2 diodes going one way, and 2 the other due to how the traces are. But, maybe they have the traces different on your board than what I'm thinking?

[Zarrir]

Sluckey, this is a Brazilian copy of the Hammond. Exactly same specs, only the center taps are different colours. Center tap for the heaters is blue and center tap for the HV is black. John, diodes are correctly assembled on the board. Even the picture on the build manual shows them pointing that way.  I have recharged my meter´s battery. Will take some measurements now. I am concerned to have first powered it up without connecting the GROUND pad of the PCB to star ground. A fuse blew up and i am afraid something else went belly up. When i power it up now with the dim bulb tester, the bulb does not even light up.
Well, i am actually getting NO voltage (0 volts) at TP4 (B+), TP5, TP6 (HVA), TP3 points on the schematics above. Tubes installed. Stuck now.

[Zarrir]

EARLY MORNING UPDATE: Picked up a new multimeter at a friend´s.  HV pad = 285v   Heaters pads = 3.2v each, no tubes installed. Sluckey you were dead right. My multimeter went belly up.  Tubes installed, no voltage at B+.  Removed PCB and resoldered all four diodes. Removed Standby switch from the circuit, it was shocking me like hell. VOILA!!!  370VDC at B+  and sound from the speakers. Seems like a VERY nice amp for the price, extremely quiet and superb cleans.  Thanks everyone. Your replies are what keep newbies from giving up.

[John]

Your standby should NOT be shocking you, sounds like a (dangerously) bad switch. But, you don't need it anyway. Glad you got it sorted out! And, I learned something new too about those diodes, there is no "standard" for the pcb and how they are laid out.


Side note: If your SB was shocking you, it means it was feeding voltage to ground, so I'm surprised your light bulb limiter didn't glow brightly.

[Zarrir]

Thank you John.  it was shocking me from the inside wiring. It looked as if HV couldn´t pass through the diodes and decided to run offboard through the Standby pads...