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Pick up a 9V battery clip, a 9V battery and a diode (1N4001 or so) and a 10 ohm 1W resistor. Put the 9V battery positive lead in series with the forward biased diode. Put two of your Ez-hooks at each end. If you have a red clip call it positive. Two 22 ohm 1/2 W in parallel will work to.
The 1N4148 is a bit wimpy at 300 mA max FWD current. The idea is to prevent accidently trying to charge the battery. It might be OK. The resistor is to make it current limited. You usually need the 9V clip to make the connection to the battery. Heat shrink tubing would be useful.
Wattage of resistors is generally determined by physical size.
I'm surprised you haven't given up yet. I'll tell you a true story. A construction article for a low TIM (Transient Intermodulation Distortion) amplifier and appeared in Audio Magazine about 1976. I really liked the amp. It boasted a frequency response of 0 to 800 kHz open loop and used RF construction techniqes. I wanted to build the amp. I learned how to "tape" layouts at Hewlett Packard in a Boy Scout's Explorer's Post in 1972, so I taped up the layout with a ground plane and had the boards made. Eventually, I made some changes to the original design (power supply, case, choice of components, and I added a custom "thump suppression" circuit). I could not for the life of me determine why I could not get it to work, but I was determined. What I had done was made a mirror image of the board. Believe it, or not, I was able to use the board. I was able to switch the positions of the NPN and PNP transistors and make very few trace modifications and use the board. I struggled. I learned. The AMP is described here: Leach Amp Plans - Part 1 by the designer. The amp is intentionally rolled off to have a frequency response of 0.5 Hz to 40 kHz.
ZD1 = 17mV ??
E-C of Q3 13V(assuming the base is the pin on the right side here, can' find any other voltage in any other combination anyway)
R4 = 0
R5 = 0
E-C of Q7 = 0V
R13 = 0
R14 = 0
I seem to be getting a lot of null values... Pretty sure the circuit is plugged in as planned though, since I pick up a current beween R11/15 and R12/16, from the battery?
Those readings were done with the 'battery' plugged in; I was hoping to see some more voltages... Not just null values - unless I have misread them or done something wrong. i'll double check tomorrow with a clear head.
The 1N4148 is a bit wimpy at 300 mA max FWD current. The idea is to prevent accidently trying to charge the battery. It might be OK. The resistor is to make it current limited. You usually need the 9V clip to make the connection to the battery. Heat shrink tubing would be useful.
I'll get a better diode and some heatshrink when I can.
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Wow. Actually had the boards made, that's impressive! Literaly built from scratch. Fantastic recuperation with the NPN PNP inversion too, quite a story. And now I understand how you quickly caught on to the "thump suppression" cry for help on my end.
In all honesty, the sub is not that great; but I tend to be stubborn, and am really using this as an opportunity to learn. As challenging and frustrating as it may be at times (magic smoke!), I'm actually enjoying it, learning from it loads, and could well even consider building some (simple) electronics from scratch after this. I have a fair bit of reading and learning to do though. The basics I was taught at school are slowly coming back, but I haven't fiddled with electronics in a long time, and never to that extent.
Once again though - I really appreciate your responses, time spent and help here. Even if I do end up burning everything to oblivion, it's a good learning experience (and I won't give up unless the whole thing literaly catches fire!). I'm even surprised you carried on advising me, especially after a couple of clumsy mishaps that clearly show my incompetence!
I'll take at look at that article, it looks like fun, but rather daunting!
Unfortunately, it seems they are in the orientation. The board actually has markings to show the orientations, except for Q5, Q6, Q8 and Q9. I'm pretty sure those are in the correct order, as I was extra careful soldering them in (having forseen the problem) but I can double check those.
The battery test also required you to have AC power applied too and the system out of mute. R15 and R16 MUST be lifted. You want just enough signal to turn the amp on.
If Q3 isn't turned on, you can't measure anything else. With Q8,Q9,Q10 and Q11 disabled nothing can draw appreciable power.
The first step is to get 5.6 volts across ZD1. Then determine if Q3 is turned on. Then determine if the differential amp is working (R4/R5 voltages). Then determine if the bias regulator is working (E-C) of Q7. With catastophic failures, I would expect possible problems with R11, R12, R15, R16 and R17, but don't go removing them to test just yet. R15 and R16 MUST stay lifted.
If you want to play with just the battery alone, you have to short E-C of Q19, so that's another option. R20 must be lifted as before.
I have enough signal for the amp to switch on (although i can also force it on manually), R15 and R16 are lifted. I can't seem to get any voltage across ZD1 though, whether the battery is applied or not.
With the battery device NOT applied, but the amp on (and R20, 15 and 16 lifted), I get the following readings:
ZD1 = 0V
ZD2 = 5.2V
ZD3 = 15.4V
D1 = .6V
D2 = .42V
D3 = 2.1V
D4 = .26V
I'm a bit confused as to why I can't get anything from ZD1, I'll keep searching...
Well I changed ZD1 (have a couple of spares), and same problem, unfortunately, can't get any voltage on ZD1... R15-16 and R20 lifts won't have anything to do with this?
Take the path of conventional current:
+9 to top of R4, then through Q1, and through Q3 and R6 to battery -.
+9 to the top of R5, through Q2, through Q3 and through R6 to battery -
+9 to emitter of Q19, through short, through D1, R3 and ZD1.
It may not turn on because of no parth through R2 and R7.
Actually, this may be good news though.
What do you have across:
R11
Q5; E-C
Q7; E-C
Q6; E-C
R12
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