Tag Archives: analog

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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Acetone FR1 FR2L recapping

Since there were some errors on the schematic, please refer to these values should you need recapping your vintage Ace Tone drum machine:

Recapping divided by 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.

Dynacord EC280

Was this the very first BBD delay? 

 
Tabletop machine, self oscillating AND from past internet auctions and reviews it is apparent, nobody knows how to determine if theirs is in working order (😂), because it is very temperamental and does a lot of different things.. But when it behaves, it’s magic!

Echo, reverb and has a very weird chorus.

Amazing and beautiful, nothing like a tape echo or a memory man.. Far less predictable!

A delay with character.