Replacing a Quadraverb screen

Aaaages ago, on some kind of Nineties techno kick I bought a cheap Alesis Quadraverb, and this is how the screen looked

Quadraverb broken Screen

…which is a boringly common problem, apparently. It made using it a bit of a chore, so I’ve left it stuck on a random massive reverb patch.

Replacement screens have been popping up on ebay so I decided to fix it. Here’s the new one:

Quadraverb replacement screen - front

Quadraverb replacement screen - back

No soldering needed to install it apparently, so I sat in front of the Belgium-Italy match and started to take it to bits. Have some shots of the guts:

Quadraverb main board - above

Quadraverb main board - angle

The code here dates my Quadraverb to 27th March 1991:

Quadraverb date code

Here’s the original screen in place:

Quadraverb original screen - in-place

…just a header cable and four screws to undo to get it out. Here’s the new screen installed:

Quadraverb new screen in-place

Power on… and… well, it turns out I’ve got a Quadraverb Plus. The pixels on that side of the screen were always broken, so I couldn’t tell. Here’s a picture of the screen from the front, much brighter than the original:

Quadraverb new screen front

From start to finish it took me about twenty minutes, including pausing to gawp at Belgium being unexpectedly useless, hooray. Totally recommended if your Quadraverb screen is playing up.

Still not fixed my broken Midiverb II though, I keep poking around at it.

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Acrylic 716 panel

acrylic 716 panel


Roland System 700 709 sample and hold clone

Roland System 700 sample and hold PCB

It samples! It holds! Here’s an aggravating demo.

We’re into the area of circuits that I should have probably just built on stripboards, but anyway.

IC1 is a TA7504M in the service manual, I just used a 741. I even replicated the legs-in-the-air arrangement for the junction of Q3/C9/IC2 pin 3 as detailed in the service manual, presumably meant to minimise leakage.

S&H legs in the air

The schematic in the service manual didn’t need any corrections, it works fine as it is.

Just now looking at the service manuals I realise the 100m version looks more fun as it includes a slew – if you were looking for one to do, maybe try that one.

I included the 716 mixer as on the original, but I’ve not got round to making that up yet (probably ‘cos it’s not going to be very exciting).

Another board done, onto the next…

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