Tag Archives: easy

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.

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Roland CR8000 buttons repair made easy

Roland Compurhythm drum machine CR8000 with faulty or worn buttons.

Sounds a lot like the TR808, but a design fault makes these buttons useless after a while.

You will have to pull the plastic covers first, to reveal the spring and rubber dome under which we will drop a bit of conductive paint..

To pull the plastic part you need to push the sides using a screwdriver or two like on this video:

Youtuber The Imp Of The Perverse has made a few vids of his restoration-he used my method too, check them

SammichSID Novation Zero SL mkii template

Those geniuses at Novation shipped this controller with a couple of software disks but alas, no TEMPLATE EDITOR for people who dont use a pc to make music.

Download the template editor program from their support pages, connect the Zero SL to your pc via usb, switch it on and fire the software. Press Global options on the SL, choose mem protect off.

Load the syx file provided by yours truly:

Masuto’s SammichSID template 😊

and then.. select

Press Write, and bob’s your uncle.

I saved it in location 20 (empty) and made it the startup template.

To use the drumpads to send cc (mod depth 1,2,3,4,5,6) on the novation zero SL you must first press REVIEW and then use the drumpads-you will see their assigned value increasing because we are using them as step switches.

For your reference, heres a crudely PAINT assembled wildcard:

Happy knob twiddling!

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)!

Creating a drum program on the Akai S900

Ok this is as basic as it gets, but still it’s nowhere to be found on the actual Akai S900 manual, since it deals mostly with pitched sounds and how to spread them on the keyboard.

How do you make a drum program from recorded samples on the Akai S900, and play those sounds from a controller in midi in?

Well, first of all you must understand what a keygroup is.

The keygroup is the number of samples in the program. Or something like that.


Here the guide, how you do it, step by step:

-press the function button sample rec, press “letter” function and enter the name of the new sample, scroll down and set the sample rate: choose 16000 for best definition (it will be punchy nevertheless) then scroll the page down until you can assing that specific sample to a key on the keyboard- I normally start from A1. For easier operation, use a keyboard plugged in the midi in port.

-record sample.

-press edit sample function, since they are drum samples you dont want any scaling of the single hits so deactivate any transpose function, then set the sample start and end points.

Scroll the page down and choose (right arrow twice) to discard whatever is before the start and after the end points (aka sample truncate).

-press edit program and choose (right arrow) the name of the sample you just recorded.

At Program screen 03, KEYGROUP,  add one more keygroup to the total keygroups by pressing + on the COPY line. Then scroll page down, assign the keygroup to the sample you just edited, and set the sample pitch range-since it is a drum sample, you want the range to be of just one key, so set it to the key you assigned upon recording for both range figures. If you assign it to another key, the sample’s pitch will be affected. You will not be able to listen to the sample as you do this so make sure you write down what note the sample was assigned to.

-press save, scroll down page to (right arrow twice) save prg and samples.

That’s it, plain and simple, easy guide to make drum programs on this legendary sampler.

Remember to drive the inputs a bit when recording-i always record at 16000 (best quality) but sometimes in a drum kit i like to have also low fidelity drum hits, so i record also some kicks and snares at like 8000-they add some dirt, just dropping them in the pattern, they add character.

Roland TR-505 stuff

Points for individual outs (audio signals-add ground from ground point)


Ground

Points for bit-crushing effects: just solder to leads and strike them against the other at pleasure.. i dont like bending stuff, but this is the way it came when i bought it second hand..

I bought a ROM expansion that adda DMX, LINN DRUM and LN1 sound samples.

Desolder IC11


Solder the ic socket


Solder the switch to the pcb



All done! 

You can buy the expansion here:

http://harryaxten.altervista.org/tr505expansion.html

Yamaha RS7000 keyboard soft touch button repair

I bought some soft touch button replacements for my RS7000, because the keyboard had to be banged on to operate.. 

Here’s how i carried out the button repair.

Disclaimer: please carry out this repair only if you have electronic skills such as soldering, desoldering, handling pcbs and know how to handle electronics. Remove the mains plug on the RS7000 and use care. Do not touch the power supply components. I shall not be held responsible if you hurt yourself or other people or the machine in the process.

First of all, check the new buttons. There are a few tutorials on how to check switches’ functionality using a digital multimeter on the net, google that up. 

Remove all the knobs from the front panel.

Wash them with soapy water using an old toothbrush!

Turn the unit face down, using some soft padding to relieve the knobs from the weight.

Keep this pic as a reference: the position of the midi sockets.

There are 3 types of screws..Put them somewhere safe (i used three fruit jam lids) and remember where each type goes. An additional set of two very thin screws belong to the scsi port. 

As a rule of thumb:

short ones-> they hinge the metal sheet that separates the top from the bottom pcbs. The top left and middle left ones secure the bottom to the metal cover of the power supply as you will realise opening the unit.

Remove the bottom lid. 

Unscrew the midi assembly and the buttons holding the input/ output panel in place and take it off.

Take pictures of the pcbs. 

Pay extra attention to the cables, what goes where. How they are turned, and move them the least you can. They are the right lenght to be assembled, very neatly laid out, Yamaha styleπŸ˜‰πŸ‘ŒπŸ».

The bottom cables are all tied together and they originate from under the shielding metal sheet..right where we want to get! Carefully, gently rock them to pull them out of their sockets.

You will have to remove the card reader assembly, the flat wire (just pull it) and all the screws that link the metal sheet to the case will have to go (pay no mind to my pics cos mistakenly i unscrewed also some of the pcb’s).. 

Below, this is the central layout, the wiring harness pops out from underneath the metal sheet shielding. 

The plastic motherboard shield will have to go. Please note how its left side kind of sits on top of those surface mounted chips. 

Gently lift the shielding metal sheet, get your girlfriend or boyfriend or your best caring and patient relative to hold it up for you.


Remove the cables that hold the keys assembly in place, and carefully slide it out from one side.

Here is the ugly mother.. Turn it around and take a look at how the key covers are snapped in their places. It takes a little inward motion using two fingers from the bottom side, push and they will spring out.

Put them in a sink and wash them with shower soap and water. Brush them with that old beaten toothbrush. Carefully, but with authority. 

Please note that generally there are soft touch and clicking buttons, maybe you want to dust the encoders too, i took a rag and dusted the pcb too, TAKING EXTRA CARE.
If you are feeling tired and the stress of the procedure so far has got you on your knees, put the board in a padded cover and go to sleep.

When you are in the right mood and focused, you may proceed.

Take a look at how the soft buttons are put, their position from all angles. Your new ones will have to be laid out just like that. Maybe even better, if they all look twisted like mine!

Turn the board over, using a hot soldering iron heat up one of the two soldered poles of the switch and using a desoldering pump suck the solder off. Do the same for the other. 

The nice folks at Yamaha have bent the two poles in opposite directions, one upwards – the other downwards, so that to remove the button you must heat up a bit the two points (solder side) while gently applying a circular motion to the button, taking it with two finers, component side..

πŸ‘ Like in this video:

RS7000 removing soft touch switches

Using the same procedure, you could also replace a few LEDs if you feel inclined, just be careful with the LEDs height.

Once you are done replacing the faulty keys, put the button masks back on. 

The tap button does not have an LED, but its mask is like all the others (check pic)-it’s all right.


Putting everything back in its place, take special care with the central wire harness: the cables have to reconnect to their original sockets, so beware if they get stuck somewhere they should not-you might not be able to plug them in. Reassemble everything with care in respect to the wires.

It is quite a long procedure, also given how many screws you will have to work with-panic may take over you once you realise there are two pcb levels in this machine, but fear not. It CAN de done!

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