Some time again, David (from the motherland) donated some stuff to the trigger.
This Leak amplifier was amongst the issues he dropped off…
Courting from round 1974, and largely worthless… eBay costs these at about £30 on the time of writing.
Nonetheless, there isn’t any level in it simply sitting in a pile…
It has been by way of the wars a bit, however that is OK. I want one thing to practise my veneering abilities on, for a forthcoming turntable venture, so this may occasionally do as a take a look at mattress…
I might labelled the amp up “Hums” ….
Powering up immediately blows each 5A fuses on the principle board. You possibly can see within the picture, I’ve lifted R3 and R5 on the small vertical PCB. That is the safety board. It is goal in life is to blow fuses by shorting out the availability rails with a triac within the occasion of there being extra that 0.5VDC on the speaker outputs. A kind of crowbar circuit.
Powering up once more, with new fuses and checking the speaker outputs (with no audio system connected) for DC exhibits the whole lot so as.
R3 and R5 are soldered again into place and energy is utilized once more. All is effectively. I’m wondering if one rail got here up earlier than the opposite as a result of new/bigger caps?
I verify around the caps on the principle board for ESR. Remarkably, all of them try OK. Each final certainly one of them! I even checked the calibration on the ESR meter as a result of I doubted it!
I had a brief size of LED strip left over from after I fitted some lighting in my kitchen, so I lower off a brief size. The voltage provide for the lamps is half wave rectified, with no smoothing. It peaks at round 20 volts, so I added a 470 ohm resistor to restrict the present a bit, and added 100uF to clean the availability a bit, so the LED’s do not flicker.
I eliminated the unique lamp holder, and stuck the strip in place with a spot of hot-melt.
After a protracted take a look at within the workshop, the amp stays well-mannered, and sounds respectable. It is quiet and produces round 30 watts into eight ohms. I am truly fairly taken with it, a lot so, I will put it in the principle hifi arrange for a bit.. one challenge although… the enter sensitivity. It is a tiny 140mV for line inputs. We’ll want to suit an attenuator on the enter I intend to make use of for the CD participant. Fortunately there’s an attenuator swap fitted to the Tuner enter, which is switched on the again for 2 totally different ranges. Trying on the circuit, my calculations present it’s going to do because it stands. Excellent news!
Now to make up some 5-pin DIN to RCA leads, and order some veneer!
Speaking of 5-pin DIN plugs… this Leak does not fairly observe conference….
four is Proper output for Tape/cassette
5 is Left output for Tape/cassette….