Tag Archives: vintage

Roland SH1000 recapping

Sometime ago i bought Roland’s first ever synthesizer, for about a quarter of what it goes for these days-it was in dire condition, mind you. The control panel rusty and battered, the silkscreen on a couple of spots barely readable.

I always believed mint condition items belong to museums, not being fit for use, abuse and misuse.. i feel the same way about vinyl records-people who wrap them in polypropylene covers from day one and treat them as if they’re going to break anyday soon.. good grief

I must say that although i truly love the instrument- i also fit the Kenton cv/gate control board a year ago, i rarely ever used it.

The other day i took it out for a spin and the tuning was way off, it was drifting. It wouldnt even span an octave-it was that bad.

Time to recap, i thought, and pulled out the Elnas, the Nichicons and the soldering iron-i figured i’d give a refresh to the power filtering section, part of what the service notes call the “Pulse Sheet Assembly”..

Before
I also upgraded the caps from 35v tolerance to 50v

Just a note: although the unit was in working condition, albeit out of tune, most of the 1uF caps on this board, were off their nominal capacitance-the 2.2 uF cap measuring a whooping 8.5 uF! Of the big 1000 uF caps, two were measuring 1200something uF, whereas the other two were still closer to the 1000 mark-and they all showed low ESR (40+ year old caps!). The three tantalum capacitors on this board were still working great, their value as per specs.

I fired the synth after recapping this board-the sound was a bit more definite, but the tuning was still off.

I decided to check the VCO board, pictured above. But, alas, no electrolytics there to substitute. I checked very carefully the board-and there it was, staring at me:

Polarity is negative at diode soldering onto the board

The diode+resistor combination to the upper far right of the board: the diode was broken in two!

The schematic calls for diode, 1S2473.. i checked a few diodes I had, and landed on a 1N4148 as a fitting substitute!

And.. yes now it IS tuned! The snipped diode was the issue!

Assorted pics of the wiring at the back of the oscillator board

Altec 1592B repair, 1588B module, XLR pinout output etc

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:

Troubleshooting:

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.

Akai S612 sampler

I opened my newly acquired Akai S612..to check for spiders and animal residue from its previous owner – i was intrigued by the “cassette interface”. Mine was screwed behind a closed metal door.

I realized right away it is the same cassette port as the Commodore 64.

And yes, you can save, verify and load your samples using an old (non)trusty tape Datassette!

I sampled a sound, got some tape to record, went fast forward 004 counts on the tape counter, pressed rec and play and then pressed save on the Akai panel. Red light, it’s recording.

Counter reading 044, the Datassette automatically stopped. I rewound the tape, switched off the Akai (remember with these old machines it is better to switch them off before plugging or unplugging devices from serial ports..), on again and Load. Pressed play on tape, and yes. It’s working. Easy.

No need to buy the MD280 rack to load discs on the S612.. you just need a Commodore Datassette (clean its heads and fix azimuth before doing anything)!

Hohner Basset

When i bought it it looked like this


I opened it up to clean it and realised this wasnt its original colour.


It really was taupe gray before, but the years had the plastic chassis yellowing

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..


Keyboard:

Circuit board and caps jungle:

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.

Video below..

Pcb: 3.1967!!

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!

Output DIN and 3 pronged jack, fuse

Video showing the lamp going off when a note is keyed.

Electro Harmonix Vintage Black Finger 

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.

Jh-1 Dunlop Jimi Hendrix Fuzzface

   Jim Dunlop holds the name FUZZFACE licence. Before it was spelled, FUZZ (space) FACE.

   Silicon BC108 transistors, vintage style build.

UPDATE BEWARE

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! 

Awful. 

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.