Tag Archives: psu

Ace Tone FR8L recapping and external psu, trigger mods

Assorted pics of the actual boards.. might be useful to someone.

That good old recappin’ blues:

Since one of the boards was GLUED to its standoff, i had to solder some caps on top of the older ones.. now one of the caps had leads so short i thought it might be useful to remind myself where does each lead went (see pic w scribble).

And the odd freaky transistors that didnt have its legs cut off (and indeed they were perilously almost touching)

The FR8L can produce 13 drum sounds-and very crispy too, thats why i decided to modify it..

Circuitbenders.co.uk’s trigger module: wires aplenty, but this will allow me to trigger each drum sound from a midi to trigger highly liquid board, that has been assembled back in the day to control my fr3-a build/mod and brilliantly carried out by circuitbenders.co.uk (you can see it HERE and HERE TOO).

The trigger board for the fr8l can be ordered HERE but remember, stock is limited.

Please note a male/female hex spacer (m3 22mm) is needed to screw the trigger board to the existing hex nut.

I decided to put the trigger input jacks in an external box-lots of fun soldering all the tiny jacks!

External PSU mod:

From an idea by circuitbenders.co.uk

READ ABOUT IT HERE

Due to the nature of the machine it is best to reduce background noise as low as possible-and an external power supply may be a better power source than the provided transformer since the filtering in the power supply section is basically nil.

I had to make a quick mod here so if you may, bear with the crudeness of these connections-i was also low on cables so pardon the lacking colour scheme..

Remove the transformer (WARNING: Dangerous voltages around this area)

First of all take a nice picture or two of where the transformer cables were originally.

The plastic thing where the red orange and black wires go is a diode bridge-check the schematic from the FR8L service manual, it has to be removed along with the transformer. We’ll reuse thosw wires so just cut them and leave them hanging for now.

Then when everything has been unscrewed and cables cut, make a bridge connection between the two pins of the on off switch at the tagboard end (pink cable).

Red and orange cables soldered to the positive side, grey cable connecting all black leftover cables to the negative side.

To attenuate noise from using a switching psu i put a choke in series with the positive pole, and a 2200uF 50v capacitor in parallel between + and – like this:

Remember the resistor between + at the psu and the orange cables (you can barely see it in the picture because i used some spare shrink tubing to prevent shorts).

🙂

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TR707 TR727 reset, midi out, tricks etc

Reset your TR707 or TR727 to factory settings.. here is the buttons combination to give your drum machine a fresh new start and to check leds and screen, buttons.

Keep pressed CLEAR and INSTRUMENT/GUIDE and switch on the legendary (yes, legendary) drum machine.

All the lights will turn on, then step leds will blink one by one.

After the light show, press ENTER/CARTRIDGE to proceed with the screen test.

Press the buttons and see the relevant dots show up on the screen.

Switch off.

How to use the TR707 or TR727 to output midi notes, and use it as a midi controller to play other midi modules, samplers (bear in mind its defaut midi channel is 10):

STOP the pattern/track if it is playing.

Enter TRACK PLAY mode.

Holding SHIFT press INSTRUMENT/GUIDE and MIDI CHANNEL.

This procedure will mute the instrument’s internal sounds but will allow you to control external gear using the TR707 or TR727.

To revert back to default, using the internal sounds but NOT transmitting midi notes, and if you have a TR707/727 that is silent, just use the same keypresses again.

Common troubles with these machines:

PSU jack fail, power transistor 78M05 (can be substituted with 78S05), power supply section electrolytic caps.

Dim screen=check the power supply section.

Try different psu transformers too: Roland’s own are recommended, etc

These are machines that heal themselves.. put them aside for a while or leave them turned on for some time and they will fix themselves.

Maybe.

Hohner Cembalet repair

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):

Hohner Cembalet User Manual with schematic

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.