Fried neovibe, Or just lightly crispy?

[Steveo77]

Built the neovibe 5 years (or so) ago. Used a 24 vdc transformer. No diode bridge. Voltages were good and It worked and sounded great for years. And then one day it started to smoke. Unplugged it quick, opened it up and everything of course looked fine. So tempting fate I plugged it back in. The smoke was coming from the area of the voltage regulator and two big filter caps. The transformer casing looked damaged (cracked). I assumed (perhaps in error) that the transformer was damage and had caused the problem. A new 18 vdc Dunlop transformer was ordered in, new filter caps installed. Unfortunately I had a lot of trouble finding a new voltage regulator. From an old post about using an 18 vdc transformer RG had said that if you were planning on using only the 18vdc transformer and nothing else that certain components could be omitted from the board and appropriate jumpers put in instead. Namely the diode bridge, one of the big caps and the voltage regulator. So with that all done I plugged it in and presto I've got the light back on. Unfortunately it just stayed on steady. Ran some tests with my multimeter and read a bunch of old posts and came to the conclusion that the q11 12 and 13 May have been damaged as well. Installed new ones and for One test the bulb flashed very dimly. On the next test the bulb no longer works. So... probably blew the bulb. Ugh! New bulbs ordered in. No radio shack in Canada anymore and no one carries mini bulbs.
So... after this long winded recap. My question is do these voltages look anywhere close. Keep in mind I'm using an 18vdc transformer and have omitted several components.
         C                    B               E
Q1   2.43                1.65          1.21

Q2   5.21                2.41          1.84
 
Q3   13.54              5.21          4.55   

Q4   18.27              5.78          5.35

Q5   13.64              5.33          4.64

Q6   18.27               5.76         5.32

Q7   13.66               5.32         4.63

Q8   18.27               5.76         5.32

Q9   13.66               5.32         4.62

Q10 18.27               7.15         6.59

Q11 18.27           7.02-10.12    8.82-10.48

Q12 18.27           7.02-10.12    8.82-10.48

Q13 17.68                 3.6          2.9

Q13 readings taken with depth and speed turned down

If I understood correctly, there is supposed to be .6-.7v difference between B and E. if that's the case I have a bunch of readings off. 1, 2, 4, 6, 8, 10. Is that thought right?

The reading on 11 and 12 B and E were difficult to get accurate.
Third question. Is using a 12v .25 ma bulb with this setup just going to keep blowing bulbsas the bulb is seeing around 18v?

This worked once. I'm determined to get it going again. Any help appreciated!!

[PRR]

         C                    B               E
Q2   5.21                2.41          1.84
Q4   18.27              5.78          5.35
...supposed to be .6-.7v difference between B and E. if that's the case I have a bunch of readings off. 1, 2, 4, 6, 8, 10....

Q2: 0.56V is not sure-wrong.

Some of the "low Bs" may be meter loading.

Link to the specific circuit you are working from?

[Steveo77]

http://www.geofex.com/Article_Folders/univibe/vibeupdate.pdf

This is the one. Designed by RG keen I beleave.

[Steveo77]

I jumped the gun about the bulb. Removed it from the circuit and tested it. Showing good resistance.
So, now the question would be why is the bulb not lighting up?
I will of course go start re doing all solder joints.

[ElectricDruid]

From what you've described as the sequence of events, solder joints sounds extremely unlikely to be the cause. After all, why would a solder joint go bad after all this time? What you've described is a power-related problem, and I doubt that would affect the soldering.

T.

[Steveo77]

Ya had thought the same. Was really just checking the solder joints of the recently installed transistors. I repaired a few suspect looking wires, plugged it back in a presto light is working. However very dim. I have had to turn the trim pot off to get enough light for it to work. The bulb is showing 18 volts on one side and 15-17 on the other.  If anyone's got any expereince or thoughts on what to try it would be appreciated.
It's breathing again I'm so close to having it up and running full speed. I will continue testing and looking for the obvious.

[PRR]

> Is using a 12v .25 ma bulb with this setup just going to keep blowing bulbsas the bulb is seeing around 18v?

There is a transistor, R48, and a trimmer sharing the same 18V.

At a glance, the base and emitter of the transistor may jiggle around 10V. That makes just 8V across the 12V lamp. Which probably comes out as a 4V-12V jiggle. Which would be full-bright to essentially-dark.

That may not be quite right. But I would trust the Univibe designer and R.G.'s study before I would rack my brain too much.

[Steveo77]

Ok so here's where I'm at.
Used GGG circuit board. RG keen circuit. I'm using a Dunlop 18vdc 500 ma adapter. As per a recommendation by RG on another post I have eliminated the regulator, bridge rectifier and one of the filter caps. It is operational and sound is getting through and actually sound great. The problem remains that the bulb is dim. I have to turn my trim pot to 0 ohms to get enough light out of the bulb. The controls work, but if I turn the depth down the light quickly goes out. In other words I have barely any depth control, but it is there.
I have now replaced all 2n3904 I had in the lamp driver section Q 1 11 12 13. No change. All voltages remain the same as post above.
I'm going to redo the wiring in the depth and speed pots. Ground continuity is good.
Not sure what else to try.
Happy that it works, uneasy at the idea that I have to have the trimmer off and it's only partially working.
Thanks PPR for the help so far. Meter loading makes sense, or bad meter usage by me perhaps. I will admit my theory with all this is weak. Your explanation about he light helps. This almost feels more like a current problem across the bulb, but I can't figure out why.

[Steveo77]

Success!!!!
This is totally a case of read everything the first time (don't tell my wife!). Didn't fully understand that changing the R50 resistor was also part of he bias. I hadn't needed to the first time around so assumed that all that was needed was adjusting the trim pot. Changing all the half broken wires from all the moving it around helped to.
Again cheers PPR for the help.