I've owned this particular 808 for I think 15 years and in all that time I never opened it up.
This is how I purchased it. ... The knobs are wrong, and the step switches have certainly been replaced.... with the wrong colours too. But I never really cared as it just sounded amazing.
Who knows how many hands it has passed through since the 1980s.
And which technicians have worked on it ??
Lately it has started to play up ...mainly the step switches 3 & 9 have stopped working.
Everything else is OK.
Maybe some dust has got in under the switch contacts.
The choice is to replace the individual switches or the whole switch board.
I've decided to try the easy option first and just replace the board.
If I discovered more problems, Id send it to my technician.
Anyway, I purchased the switch circuit board and some knobs from Sound To Parts in France.
https://www.soundtoparts.com/en/3-roland
They have parts for all the major brands.
Be careful when you open up the 808.
Screws can go missing. And different types of screws are used in different parts of the machine.
So put them in safe places.
Long silver headed screws are mainly used on the underside, whereas black ones are mostly on the face.
... shorter ones on the front metal cover and the front. These hold the circuit board to the metal panel.
The sides of the 808 are plastic... the black screws are longer and designed to screw into plastic.
Enough jabbering. Lets get to it and find out what we have.
i DECIDED to take the knobs of first.
This volume knob is certainly wrong.
I started removing the 6 black screws on the front & rear.
These 6 screws are what hold the front panel to the base.
(The base secures the power supply. The actual electronic circuit board it secured to the front panel).
jUST the 3 on the bottom of the rear
And the 3 at the bottom edge on the front.
Next, remove the side plastic panels.
They are held in with 6 screws.
2 on the top & 4 on the bottom
On my machine, the top screws were black, and the 4 lower were silver.
You can remove both side panels, but it's not really necessary.
I just removed the left plastic panel.
Once you remove these 6 screws, it just slides out.
You should be able to now lift the top half from the base. The bottom half is the PSU .. consisting of the transformer, a power supply circuit board & the battery compartment.
A close up. Don't touch this unless you are a qualified techno. It can kill you. The whole body and case of the 808 is metal, so any shorts or loose wires from your mains or PSU board could conduct electricity to the front panel and case. (plastic cases like the ones used by Roland in the TB303 or TR606 don't have this problem).
You can't separate the top and bottom completely as the the main on/off switch is part of the top panel
and the PSU is fixed to the base. This is all hardwired.
The green wire connects to ground.
To Be continued....
Roland Tr 808 repair - Part 2
Links
Transistor at the heart of the 808
