2-1176 Bulb Help

Hoping someone can help me with a somewhat odd predicament I'm in.

I had someone build me a 2-1176 clone using some of the designs and parts from this forum.  Unit works and sounds great, no issues there.  At the time the builder did not have the proper 12v bulbs in stock and the part was on backorder for a loooong time so I had the unit shipped to me for the time being and figured I'd install the bulb myself sometime down the road. Unfortunately I never received a schematic, and I'm unable to reach the original builder any more to get further help.  This is almost a year latter.

Long story short, can someone help guide a total newbie wire this bulb up.  Seems so silly to ask as its only a light but I don't want to fry anything.  I'm pretty handy with a soldering iron though.

He did leave me instructions of how to wire up the bulb before he sent the unit, but like I said, I'm totally clueless to this stuff unfortunately. Here's what he provided.

"There are about a hundred ways to wire the pilot light, but the easiest/safest would be to use a 12v bulb and wire it directly to the negative rail on the power supply which is -10v. -10v to one side and power supply return to the other."


Anyways, I've attached a photo of the build, but if someone could be so kind to try and help me further, perhaps even ms paint how the hookup wires would go on the pics I provided, it would be greatly appreciated!!!  I can take additional photos if it helps as well.

Thanks!

side view

Looks like the 220 ohm 2 watt resistor is already there. That's the big blue one hanging there with red red black gold bands. That's that parts that's usually between one of the secondaries and the meter. What's connected to either end of that big blue 2w resistor?

hey hymentoptera,

thanks for taking a look.  really appreciate it.

It does indeed look like one side of that resistor is going to one of the vu meters....and the other terminates to the small pcb in the middle...is that for the power supply or 'secondary'. Its a red wire coming off both ends of the resistor.

Do these photos help?

other side

Can anyone help?

I can't see. One end is connected to PSU, the other disappears in the loom. Does it go to the meter? If so, the meter lamp might already be hooked up. Check voltage at the meter? Is a lamp installed?

Yes, one end of that red resistor wire goes to the psu and the other end of that goes to the meter lamp.  The two meter lamps always been hooked up and working properly.  Its simply the power light bulb now that I need to wire.  Its directly to the left of the meter lamp in that last photos.  Just not hooked up to anything yet.

unscrew the black part at the rear of the lamp and see what kind of bulb is in there.  If it's a 12V bulb, then you can do what the builder told you, otherwise, I usually remove that rear part and secure an LED in there.

Yes, it is a 12V bulb I have. 12.5 to be exact.

As I was trying to explain, I do want to do as the builder suggested, but the issue is my general lack of understand what a -10 rail is and what the power supply return.
I was trying to provide photos in hopes someone could simply edit the photos I provided and draw hookup wiring going to these points so I could follow......if thats even possible.

Thanks for all the help!

Jason

Ah I see, I thought you meant the VU meter lamps.

I supposed you could wire it into the -10 rail. Most people who are installing "on" or "pilot" lights are, I think, wiring them into the transformer's secondaries, which are the thicker wires coming into the PSU (the small board in the middle is the PSU), The center terminal with two wires stacked is the center tap, and the terminals on either side are the dual secondary out of the transformer. These are the lower AC power.

On the other hand, the thin wires exiting the PSU board and jumping to each main board are the DC rails which power everything else. One of these will be "ground", or 0 volts, and the other two +30 and -10 respectively. If you have a multimeter it should be easy to figure out which is which.

I think it's interesting that the builder connected the VU lamps to the DC rails using the 220 ohm resistor... I guess he connected it between +30 and ground? If that's the case then you could likely connect the pilot lamp the same way, if a resistor is used. Otherwise putting it between ground and -10 could mean a much lower value resistor (or none at all!) might be okay too.

There really is numerous ways to do this, but i'm not prepared to draw on those photos without knowing what's what. If you don't have a multimeter, get one, and browse this site... chances are you'll soon know what the right questions are to ask.