Hello future home to my serious nerdy mind
I'm pretty new to circuitry. I have built some kits and recently re-housed and modified a JHF1 Dunlop Fuzz Face. Works awesome. I'm a germanium transistor collector and have learned a bunch over the past year. I just bought a Newmarket Transistor amplifier circuit (pre-made) from the 60's. The Reverb ad said something about being a Deacy amp. It has a basic schematic diagram for the wiring but I've tried a bunch of different things an I can't get the thing to work. I figured I would ask if someone can help me understand what wires go where and where to solder them on the jacks and the only pot. I figure I'll mod it later but I just want to make sure it works first.
Pics are attached.
Q's
1 - Where does the input jack signal go to? The pot? Which lug? Which is in and which is out? Do I need to ground the pot? Do I need to ground the input jack?
2. Where does the pot wire/signal go in the circuit? Hole C?
3. Which hole is ground? Where should I solder the circuit ground wire? A jack?
4. Where do I solder the 9 volt red positive and black negative? Do I need to have an on/off switch?
5. I'm not attaching wires to a speaker like the outline shows. Where do those two wires go? The output jack? Do I need both wires?
6. Two holes look like they indicate 'lamp'. Does that mean I can add an LED through one of these holes?
I really appreciate any help anyone can give. I'm about to smack my head off a wall as I don't know what my neck steps should be after doing an ineffective troubleshooting.
Cheers
First Time Member...Help with wiring up a Newmarket Transistor amplifier circuit
Information
- Posts: 1
- Joined: 30 May 2023, 05:18
- mauman
- Cap Cooler
Welcome to the forum!
Signal to lug C, ground to lug A.
If you want a volume control, wire it in before the signal hits the PCB. That's the "VOLUME CONTROL" schematic. 5k pot, C (reverse audio) taper, wire the incoming signal to pot lug 3, then volume pot lug 2 to PCB C, volume pot lug 1 to PCB A (which is also power ground.)The pot? Which lug?
C & A are in, D & E are out.
Which is in and which is out?
Yes, lug 1 to ground.Do I need to ground the pot?
Yes, shield to pot lug 1 and PCB lug A.Do I need to ground the input jack?
Yes2. Where does the pot wire/signal go in the circuit? Hole C?
Lug A3. Which hole is ground?
Make the ground common to PCB lug A, volume pot lug 1, and the 9V negative terminal.Where should I solder the circuit ground wire? A jack?
9V negative to ground as above. 9V positive to PCB lug D.4. Where do I solder the 9 volt red positive and black negative?
Optional, if you do, wire it as shown between battery + and PCB lug D.Do I need to have an on/off switch?
This is an amp, not a pedal, so PCB lugs D and E go to the terminals of a speaker. The schematic calls for 15 ohms, but 16 ohms would be fine. PCB lug D is also connected to +9V, but lug E is NOT connected to anything except the speaker (no ground.)5. I'm not attaching wires to a speaker like the outline shows. Where do those two wires go? The output jack? Do I need both wires?
"Lamp" almost certainly meant "incandescent" at that time, so I'd start with a 9V or 12V incandescent bulb, once you get the rest of the circuit working. You can also use a meter to determine what's sitting on those two lugs (PCB B & F?). Probably voltage on one and ground on the other, but maybe not.6. Two holes look like they indicate 'lamp'. Does that mean I can add an LED through one of these holes?
- soulsonic
- Old Solderhand
Information
I'd like to add that it's wasn't accurate for them to call it a "Deacy" amp. The Deacy amp circuit uses two small transformers: one to drive the push-pull output transistors, and the other is the output transformer. You see this alot in old transistor radios.
If I had this, first thing I'd do is pull the heatsink off the two output transistors and see if they're NKT275s. If they are, you probably got some $$$.
If I had this, first thing I'd do is pull the heatsink off the two output transistors and see if they're NKT275s. If they are, you probably got some $$$.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran