Roctron Silver Dragon Stopped Working ?

[gtrplayr1976]

I only know to ask this because I have done the same thing... don't feel bad. We are human and easily overlook the simple things. Hopefully, that'll fix it.

Connected this FS to my variac set at 13V ,and she works , but hums badly. Could be this black wire that was broken ,and I have no idea where it broke from. Looks like a ground , but grounding to the chassis makes no difference. It's connected to one side of LED3 that shows to ground. Any ideas ?

[g1]

Is Led3 working without that wire connected? It looks to be the 'power on' led.
Prime suspects for hum would be components that could have been damaged from the use of the wrong supply, like caps or diodes in the supply area.

[gtrplayr1976]

Is Led3 working without that wire connected? It looks to be the 'power on' led.
Prime suspects for hum would be components that could have been damaged from the use of the wrong supply, like caps or diodes in the supply area.

I just checked ,and the LED does work without the wire connected.

[g1]

So then that black wire was used to ground something using the same ground the LED3 is attached to.
Pretty tough to figure out without a very careful visual inspection, unless someone has posted gut shots on the net.
Can you post some pics of the guts?

[gtrplayr1976]

So then that black wire was used to ground something using the same ground the LED3 is attached to.
Pretty tough to figure out without a very careful visual inspection, unless someone has posted gut shots on the net.
Can you post some pics of the guts?

I have searched up ,and down for gut shots. I have a few at the beginning of the thread.

[gtrplayr1976]

So then that black wire was used to ground something using the same ground the LED3 is attached to.
Pretty tough to figure out without a very careful visual inspection, unless someone has posted gut shots on the net.
Can you post some pics of the guts?

Just noticed something off with the schematic. R38 is missing. Not sure if it was a change, or someone broke it off.

[gtrplayr1976]

Well that seems to have been a change. I also see other strange changes like resistors in places where caps would be according to the board ,and schematic. This is a strange animal.

[Enzo]

"Missing" parts are common in gear, they are just changes. If you ever look at the drawings for some product where you have all ten revisions, you usually find just such changes.

Frankly, the hum could be from using the variac. For reasons discussed in the widowmaker thread, you might have the neutral side as your hot.

[gtrplayr1976]

"Missing" parts are common in gear, they are just changes. If you ever look at the drawings for some product where you have all ten revisions, you usually find just such changes.

Frankly, the hum could be from using the variac. For reasons discussed in the widowmaker thread, you might have the neutral side as your hot.

Yes sir. That's what I figured after I started looking at the board ,and the schematic.

I'm pretty certain I have the neutral ,and hot correct. I'm using a polarized plug ,and the end of an old adapter. Would be nice to have the actual power supply.

[Enzo]

Simple test: Set up the unit as you described. Don't connect it to an amp, just the power connection. Now measure for AC voltage between the chassis of the unit and earth ground somewhere, like the center screw of a wall outlet. If you see a few volts, you have the variac backwards.

You can find a 12vAC adaptor at Radio Shack or places like Best Buy.

In my shop I had a collection of power adaptors, so I could always have a proper supply for anything. I always tell people to bring their supplies with them, but so many do not.

[gtrplayr1976]

Simple test: Set up the unit as you described. Don't connect it to an amp, just the power connection. Now measure for AC voltage between the chassis of the unit and earth ground somewhere, like the center screw of a wall outlet. If you see a few volts, you have the variac backwards.

You can find a 12vAC adaptor at Radio Shack or places like Best Buy.

In my shop I had a collection of power adaptors, so I could always have a proper supply for anything. I always tell people to bring their supplies with them, but so many do not.

I will give that a try. Thanks Enzo !

[g1]

The black wire that is disconnected, is it the one in your pic that goes to the tube board bracket?
If so, it looks like on the schematic it goes to a ground at the AC adapter jack.
The green/yel wire lug should go to a chassis screw to ground the chassis.

[gtrplayr1976]

The black wire that is disconnected, is it the one in your pic that goes to the tube board bracket?
If so, it looks like on the schematic it goes to a ground at the AC adapter jack.
The green/yel wire lug should go to a chassis screw to ground the chassis.

Yes, that's the wire. It isn't long enough to go to the AC adapter jack unless it's connected to a pad on the board that goes to the jack. The yellow/green has a ring on it that goes to one of the foot switches ,and is the chassis ground.

[gtrplayr1976]

Simple test: Set up the unit as you described. Don't connect it to an amp, just the power connection. Now measure for AC voltage between the chassis of the unit and earth ground somewhere, like the center screw of a wall outlet. If you see a few volts, you have the variac backwards.

You can find a 12vAC adaptor at Radio Shack or places like Best Buy.

In my shop I had a collection of power adaptors, so I could always have a proper supply for anything. I always tell people to bring their supplies with them, but so many do not.

I could only see about half a volt.

[gtrplayr1976]

The black wire that is disconnected, is it the one in your pic that goes to the tube board bracket?
If so, it looks like on the schematic it goes to a ground at the AC adapter jack.
The green/yel wire lug should go to a chassis screw to ground the chassis.

If you look at the pictures above , the blue wire is the tube ground. This black one has me baffled. No gut shots of others anywhere to be found.