Since there were some errors on the schematic, please refer to these values should you need recapping your vintage Ace Tone drum machine:
Recently i got a nice Altec 1592B mixer.
Each input requires a dedicated preamp/transformer module, for microphones there’s preamp, 1588B or preamp+12v phantom power, model 1588C.
I had to do a massive recapping job on the 1592B- the original caps values were all over the place-and i mean not only electrolytics-the only ones that were still measuring ok were the tropical fish and some of the lower values disc caps- though most of the electrolytics were good quality, Mallory or West Germany made, ROE (Roederstein). I replaced them all with Elnas (they seem to be the standard nowadays).
Also, the resistor after power transformer 7818 (that feeds part of the tone section, so if you have an unit that powers up but does not produce a sound, check for +18v at pin 6 of the tone board, that is linked to the power board after (out) the aforementioned 7818) was burned-clear sign that some damage had taken place. The schematic calls for a 10 Ohms resistor-i decided to put a 100 ohms substitute, much better.
Sounding good, i decided to recap also the 1588B module i have here (more are on the way, and when factory new, they were fitted with 3 modules).
After using a small screwdriver to pry the enclosure open, i took a look at this interesting blog (check it) for the schematic-i also took the time to sub the carbon comp resistors with metal film and yes-noise went down.
For your reference, here’s the resistors network:
Q1 and Q2 pinout:
If the preamp is not working, check carefully the resistors-they break easily. One immaculate looking (inside and out, the spongy filler still in good soft condition, no leakages on the plastic screen etc) 1588B i have had a resistor broken at its base, and since the components are so squeezed together it was impossible to see it-i decided to test the transistors (thats why i took the q1 and q2 pics above) since everything was looking proper-and there-i spotted the broken resistor! The preamp would still burst in noise if i knocked the mic gently on the capsule, yet it wont amplify it properly. Thats the resistor connected to ground on the white wire-a pain to desolder too.
If you must desolder stuff, be patient-these boards wont take a 300 degrees hot iron-the circuit tracks will lift if you heat them up too much-use care.
Since someone over at the Tape Operator forum has raised the warning that the power supply may have been ill designed, i am powering it using an external psu (using the battery option), 24v dc.
Terminal: from left, my battery (external psu) connections (- and +) and pinout to wire an XLR balanced jack to the output: hot, cold and ground… in the mess between high and low impedance i went with, 600 ohms, good for any mixer or recorder input. PLEASE note 2 and 3 terminals are bridged (connected) at the terminal post. The signal is nice and strong.
I will not mod this unit, i like it as it is. Nice and retro sounding.
A couple of gutshots of the 303 simulator (cannot call it clone since it doesnt have a BA662a..)..
Some kosher transistors (1583, 2291) but most of them are just 2N3904.
Sounds quite good.. i remember staring at the Turnkeys window in Charing Cross Road (98?) when these came out, along with FAT’s other offerings, rebadged MAM, like the cool resinator (the resonator) and some other rack in sexy colors!
When i bought it it looked like this
I decided to restore it to its original colour (or as close as i could…)
After 5 months of great fun, I had to open it up because the output went silent.
Gutshots of the Hohner Basset!
Lets start with the DIN jack that connects it to the bass amp..
Inside the white enclosure there’s a lamp and a ldr.. this assembly is the actual “percussion” section.
You press a note on the keyboard, the light goes off slowly (sustain) according to the knob position, when not in auto mode.
Ahem this means the caps have been doing their job for 50 long years! Only one of the capacitors has failed, please note- the blue valvo 100uF cap now measures 1uF!
Video showing the lamp going off when a note is keyed.
My beloved Hohner Cembalet I has gone silent, all of a sudden.
Here we go with a few pics i took for reference of the main board.
They may help someone else whos trying to fix his Cembalet.. I hope.
Schem and user manual (in kraut):
Update: the Cembalet healed itself and now it works great. I did not have to do anything to it, it just works again, magic, bang.
A friend who’s an electronic repairer said that the most important part to watch out for is the inductor (Spule in german), as it’s custom wound to specs for this instrument.
This must be a very early one, word has it that Jimi Hendrix tried one of these boxes for its big muff-like forced sustain. It is one of the earliest electro harmonix effects.
It is powered by TWO 9v batteries and so much for it “being distortion free”, it is very hissy and noisy, and colours the tone. The compression is VERY apparent and squashed.
Transistors: FS36999, the same as early 70’s Big Muffs.
The tube version Black Finger is a much different, more reliable and usable item.
Much to my surprise, and horror, the other day i decided to have a better look at the board. Well.. AT THE BACK OF THE BOARD, HIDING, it’s all SURFACE MOUNT TRIMMERS. EEEEEEEEEK!!!! This is the fakest pedal ever!
I decided to sell it right away. Although:
How does it sounds? Not bad in my opinion.. And the presentation is quite lush.
The Hendrix family on the other hand.. Geez they never got it with their son being a genius. And now that they can remix his oeuvre in the most appalling way, they went for it.
I mean.. Has any of you listened to the reissued experience lps?
Awful out of focus fx added, messy sound image (changes at every other track on the Are You Experienced lp), poor original sources research, no whatsoever idea of whats goin on: they managed to DESTROY even a song as straight forward as Fire!
Idiotic panning solos? Yeah!
And before you can say ‘man’, they put out the jimi hendrix fragrances. As if the world needed them badly.
So all in all this is possibly the only instance of the hendrix genius almost given a proper name.