Repair Log: Roland Space Echo – Chorus Echo RE-301 SN: XXXXXX

Log last updated – 02/02/18

Copyright retained by Terry Relph-Knight

Value – £100,  They can be found for £155 in very good condition (which this one isn’t)

The Roland Space Echo RE-301 tape loop delay has a sound-on-sound playback head and three delay playback heads. It also has a built in BBD chorus and a spring reverb.

Note – The Roland user manual says – ‘Wow and flutter is minimised by the use of a free running system, which also serves to extend tape life over 300 hours.’ So tape loops still need to be changed relatively frequently.

After a lot of investigation it looks very much as though this unit has been patched together out of two or more broken RE-301s and possibly further ‘repairs’ have been carried out over the period it has been in use.

Front panel controls are –

Metering – Peak level LED, MC VU meter

Input mixer – 3 x Input level rotary controls, -20 -35 -50dB slide switch and three ¼ inch input jacks.

Direct signal on/off slide switch – Switches between Wet and Dry mixed or Wet/effect only.

Chorus – Intensity control, indicator LED, Chorus on/off via push button or remote jack

Echo – Indicator LED, Echo on/off via push button or remote jack, 6 way mode switch for playback head selection, Sound-on Sound toggle and remote jack, volume, repeat rate (with a remote jack) and intensity controls, a toggle switch allows switching to single delay regardless of the setting of the intensity (regeneration) control. At some point this switch has been replaced with a three way centre off switch.

Reverb – Volume control

Output – Bass and Treble controls, -15,-25,-35 dB three way level slide switch, A (A+B) and B output jacks.

Power toggle switch, VU meter illuminates when power is on.

Head order (left to right)

Sound on sound PH4, Erase head, Record Head, PH1/Mode1, PH2/Mode2, PH3/Mode3

(Visually the azimuth on S on S, PH2 and PH3 looks off).

Problems – In just for a general check over and alignment. The electronics seem very temperamental, it seems to act differently every time it is turned on. For example on one occasion echo modes 3,5 and 6 passed little signal with lots of hum. One another occasion, when first powered up the regeneration did not work, then with some control fiddling it came to life. The Chorus makes a sort of on/off gargling sound. The spring reverb just hums. Even switched off the RE-301 hums when plugged in to an amplifier indicating a ground problem somewhere.


Periodically the tape slips so the echo produced is not constant and regular. I now think this is entirely down to the tape loop. Even though the MTE replacement loops I bought are supposedly manufactured for the Space Echo I don’t think they are of good enough quality.

Work done

All but one of the original M3 thumb nuts (supplemented by one ordinary M3 nut) that secure the acrylic plate over the tape loop bin where missing. These were replaced with 5 stainless steel M3 thumb nuts.

Dirt and old tape oxide were cleaned from the tape bin, the head plate and the top surface of the unit. The two felt tape pressure pads were cleaned of dirt and oxide. The pinch roller was removed, cleaned with isopropyl alcohol, the centre bearing lubricated and the roller replaced. NOTE – All rollers and pads now replaced.

The hard rubber pinch roller has a sintered bronze sleeve bearing mounting onto a polished steel shaft. It is secured by an M3 screw that has a small spring washer, a larger plain washer and then there is a felt ring to capture any excess oil. The screw and washers are concealed under a black rubber mushroom push-on cap. The head of the M3 cross head screw holding the pinch roller was quite chewed up so this was replaced with an M3, stainless steel, hex button head screw.

The feed roller bearing on the other side of the tape path was removed cleaned and lubricated (now replaced). The feed roller is held in place by an M3 12mm countersunk cross head screw that passes through an aluminium disc and a nylon spacer that fits in the centre of the ball race bearing used as the feed roller. The ball race bearing is spaced top and bottom by a thin bronze washer.


A new tape was loaded and then the bias trap was adjusted for maximum rejection and the bias level set. All the heads where cleaned with isopropyl alcohol, magnetically degaussed and were checked and adjusted for height and azimuth.

Replaced the VU meter 12V pea lamp with a wide angle white LED fed from an 820ohm resistor.

Unplugged all 16 internal Molex connectors, wiped the contact pins with DeOxit and plugged all the connectors back in.

To fix general hum problems I removed the step down auto-transformer from inside the case and re-wired the echo unit with a long mains lead terminated in the US 110V mains plug. This can now plug in to the auto-transformer sited outside the case.

Glued down all the pealing edges of the Tolex around the wooden case where the original adhesive had failed.

Further problems With the MTE RT-1L tape loaded the unit developed tape slip resulting in pitch wobble. As the only reliable source of Space Echo parts I ordered two service kits from EchoFix.com in Australia. The original order went missing somewhere between the sorting office and my house. EchoFix sent me another set for the cost of postage. I also paid a customs charge on the original shipment.

Each kit contains a new pinch roller, feed roller, a set of friction felts and two replacement tapes. Having fitted all these parts the tape slip problem seems to be solved.

I re-set the bias trap, re-biased for the new tape and checked all the head azimuths. Note – playback from head 3 seems to be half that from the other two heads. There do seem to be level adjustment presets on the main PCB, but I did not adjust them.

Fitted a new TA7200P integrated power amp in an effort to get the reverb to work. Nope sadly not, although the chorus has come back to life.


This unit has either been ‘pragmatically’ repaired, or is a Frankenstein. An etched aluminium plate screwed to the back of the case clearly states it to be a 220V AC unit and indeed it does run on UK mains. However an internal examination shows that a  240V to 110V conversion auto-transformer, supplied by the UK electrical chain Ryness, has been fitted inside the case. This is fed by the external mains cable and the Roland power transformer (which must have a 120V primary – it does, the primary wire colours match those for a 120V supply as shown in the Roland service manual) is plugged in to the output socket of this extra transformer with a large yellow US three pin plug that mates with a socket on the side of the extra transformer.

Either this unit has been cobbled together from a US and a European unit, or the original Roland 220V mains transformer blew and was replaced with an original 110V transformer, making it necessary to add the extra conversion auto-transformer. Which by the way has input neutral (now blue) wired to the right (white, which is US neutral) on the US plug. US live is black and is on the left looking in to the socket. The actual Roland power transformer fitted inside the unit is definitely the transformer designed for 110V input because it has the white (neutral) and green/blue (live ,fused) input wires as specified on the Roland circuit in the service manual. A 240V unit should have a Roland transformer with red (250V), brown (230V) and white (neutral) as the primary wires. The Roland transformer is connected the wrong way round – the green/blue wire should go to the internal fuse.

In any case this extra transformer is mounted right next to the built-in spring reverb tank at the output end of the tank. As a result the reverb hums because the output picks up the field of the transformer.

The spring tank itself had been moved to the right to make room for the auto-transformer and one of the support brackets that holds the case together removed to make room for the tank. The spring tank is an interesting design, an OC Electronics Folded Line Reverberation Device Type 60, apparently “Manufactured by beautiful girls in Milton, Wisconsin under controlled atmospheric conditions” with a folded Z configuration of three springs. The drive and pickup coils are sited at the ends of the Z with the angles supported on resilient mounts. Unfortunately the drive signal for the reverb seems to have gone AWOL, there is audible spring clang if you tap the tank, but no reverb effect. Connecting a 3V light bulb continuity tester briefly across the input coil also produces a crash so the input coil is intact and the delay tank seems to be working. Either the reverb drive amplifier no longer works, or it is not receiving an input signal. The reverb drive chip is a TA7200P, a 3.3W single chip audio power amp in a 10pin SIL package. EBAY £3.08.

The chorus only makes some rather weak wobbling sounds. Adjusting the BBD clock balance and BBD bias trimmers does not bring the clock signal close to the symmetry shown in the service manual. The chorus delay is produced by a MN3004, a 512 stage Bucket Brigade Delay chip in a 14 pin DIL package. These can just about be found on EBAY for £50.

Pilot / VU meter filament pea bulb has blown (has previously been replaced by splicing the wires). Voltage is 13.45V DC. Replaced with a wide angle white LED 30mA max 3.1V drop. 10V 20mA = 560 ohms, hmm I have 820 ohms to hand I’ll use that, seems bright enough.

Unreliable operation – There are 16, Molex 0.15pitch SIL connectors, 5 on the power and bias board and 11 on the main PCB. It appears that these have been unplugged and re-plugged several times in the past and is very possible that these aren’t all making reliable contact. Also the echo mode switch seems very uncertain in its operation. Unfortunately this is a sealed switch.

Power supply

The power supply is in two sections – a bipolar +14.5V, -14.5V to feed the op-amps and other electronics and a supply for the variable speed servo motor. Pin 1 of IC4 / R406 is labelled – 13.3V (fast) to – 5.5V (slow).

Measured supply voltages are now –

Measured supplies –   Minus 13.91V Plus 14.04V

Servo at Pin 1 of IC4 – 6.33 to 12.53V

Basic functionality tests from input to output

All three input mixer channels work and behave identically. The level controls function, the level switches work (there are internal pre-sets to balance the input gains VR15, VR16, VR17). The peak LED and VU indicate as expected.

The Direct signal switch switches the mix of the direct signal on and off. With all the effects off the clean signal sounds reasonably free of hum and noise and is relatively undistorted. The mixed output with the Direct switch on appears on the A+B jack, the B jack is always effect only.

With Direct off and Chorus on the output is vibrato only.

The Chorus switch does switch in an effect, but rather than a smooth swirling chorus, there is a two step phase change sound. It may just be that the chorus circuit trimmers (VR12 BBD bias, VR13 BBD clock balance) need attention or it may be a general power supply problem (having cleaned all the connectors, cleaned the back of the PCB of dirt and flux and set the two trimmers to their centre positions the chorus now seems to have come back to life).

The Echo mode switch results in an audible delay although not particularly prominent delay on positions 1,2 and 4. There is a strong hum and little signal on positions 3,5 and 6. According to the cheat sheet on the lid “Echo rate decreases in the order of 1-2-3. Positions 4-5-6 give you soft echo with complex effect”. From the circuit diagram modes 1,2 and 3 select either playback head 1,2 or 3 through JFET switches. Using a simple diode matrix, modes 4,5 and 6 select either 1+2, 2+3 or 1+2+3. So any mode that involves switching Playback 3 is compromised. Either playback channel 3 (head and or pre-amp) is compromised or the switching voltage or JFET is dead.

Echo Intensity easily goes into echo feedback (VR18 sets the intensity limit).

The spring reverb hums because of the proximity of the step down transformer.

The output tone controls and the output level switch seem to work and the A+B and B jacks output signal as expected.

Sound on sound produces a strong signal (SonS level is VR14).

Either this unit has a power rail problem, or all the presets have drifted a long way, or someone has been inside and fiddled with all the presets without knowing what each one does.

Parts ordered – I ordered two Service Kits for the RE-101,201,301,150 at 110 AUD each (£67.41) on the 18/08/17 (around then anyway)

Paid a customs charge on 07/09/17 of £ 32.69

Ordered a TA7200P from Ebay 8.40 Euro paid by PayPal 07/09/17.

Parts –

5 x Stainless steel thumb wheel nuts £ 3.99

1 x high intensity LED to replace the incandescent pilot light £ 00.50

2 x service kits – from Visa 21/08/17 £123.62 + £3.70 fee = £127.32

Customs charge £32.69 – from Visa 08/08/17 £32.69

Postage for the second set of kits – from PayPal 28/09/17 AU $ 23.70 £14.47

Space Echoes – Invoiced to date – 2007240 18/03/17 RE-150 Space Echo £68

Invoice for this RE-301 – 2007275

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