roland tr-808 drum machine = vintage 80's

[Mars Amp Repair]

Hello folks,
has anyone found a good replacement for the start/stop & Tap switches for this unit?

They are fairly specific momentary push switches. these units are now very sought after and are selling for around $1500 at this point, so I want to make this look as original as possible.

The switches are sealed and drilling a hole in them to get deox in was no help.
Mouser has nothing like it that would be the same shaft size as the knob.

thanx, glen

[mozwell]

Hi Glen
No idea as to the switches, but ther service manual for the 808 is here Audio Roland : Service Manual free download,schematics,datasheets,eeprom bins,pcb,repair info for test equipment and electronics
The manual for the 606 is also there
Clone information for drum circuits from the TR808 is here
eric archer . net » 808 clones if you want to build a triggerable sound module for each drum sound.
I know its not what you are after, but maybe someone is interested.....

Cheers
Andy

[Mark Hammer]

Smallbear Electronics carries several different momentary switches for Boss and Ibanez pedals. They might have something similar, if not identical.

[Mars Amp Repair]

Hey thanx guys,
I actually was able to get these little buggers apart & then coat the little carbon button with that Caigcoat stuff. It works pretty well. We've used it on keyboard sensidome strips for some of the Korgs where the strip is no longer available.

See pix attached...thanx again all...glen

[cjlectronics]

From the pictures you posted, the switch looks a lot like the bypass switches used in the Boss pedals. Get a few DS-1's and rob the switches out of 'em.

[PacificState]

Interesting

Mars, how did you get the switch apart, and how did you get it back together? I'm facing the same problem.

[Mars Amp Repair]

Hey guys, thanx for the suggesions. they do look like the pedal switches from the Boss variety.
As to how I got them apart..it's a bit difficult to determine from the pix I posted, but on either corner on the bottom of the switch, there are two larger looking post 'indentations'.
What they did was melt the top of these posts into the bottom cover of the switch. If you take a drill or possibly an exacto knife & dig-cut out the melted 'muffin top' portion of that post, the swtich will come apart.

I orginally tried to cut the post off through the separation between the top & bottom of the switch, but quickly determined this was a problem & the switch wouldn't align correctly when I attempted to put it back together.

the 3rd pic in my post above best shows the tiny posts. I epoxied the switch back together once I was certain the coating would hold. I did blob the coating on fairly thick, as the switch puts a fair amount of pressure on the little carbon button & I was concerned a thin layer would wear off.

Take it slow & cautious & it's really too difficult...you only get one shot! thanx, glen

[Mars Amp Repair]

WOW. Yes, Smallbear does have the identical switch...for only $1.95.

Switch - SMK for BOSS DS-1

I'll definitely go that route next time...thanx, glen

[Mars Amp Repair]

One Caveat...
I just noticed I do have some of what looks like this switch from Smallbear in stock. I tried them & as I recall, the height & size of the actuator is slightly higher & larger, so some modification will be necessary to get everything to work properly.

The knobs on the TR808 have a cross ' + ' shaped hole in them that has to fit the ' + ' shape of the actuator on the switch. The switch from the Boss pedals is slightly larger than the knob on the TR808, so it might be a bit tricky to get it to fit & still look ok.

As I recall now, I decided to go the 'repair the switch' route to keep the Tr808 as original looking as possible a well as it looked like more time involved. These things are very much in demand right now & are selling for like $1500.00!

I do think however that this could be accomplished...thanx again, glen

[Mars Amp Repair]

Sorry...I just remembered further.
I disassembled one of those boss switches with the idea of exchanging the rubber dome contact piece inside...they are completely different inside...the Boss switch uses hard metal contacts & not that rubber dome piece that the original has in it.
Just trying to save ya some time here....glen

[Mars Amp Repair]

Better pic of switch:

See attached. you can see the impressions of the top of the posts on the bottom of the switch. glen

[PacificState]

Thanks!

I managed to do it, though it was hard to get it back together - my switch was completely sealed. I took a scalpel to the seam, cleaned the contacts, used Caig Coat as you describe, then epoxied it back together. It's now good as new, but I'd hate to have to do it again - I'm still looking for spares...

[Robin-Whittle]

Service manuals,part numbers & a second type of this ALPS keyswitch

I tried the dismantling and epoxying approach in the past, but
did not succeed in making the epoxy strong enough. I used a
little fine wet-and-dry paper on the rubber contact, and I
think I used some isopropyl alcohol and then some fine wet-
and-dry paper on the metal contacts. In that case, I
installed some different kinds of switches and buttons, which
was far from ideal.

Recently, I was able to obtain two switches which were
proper replacements, from an unused MC-4 keypad panel.
These were mechanically entirely compatible, though the
details of the body were quite different and the shaft is
black, rather than white. Both types had the ALPS oval
trademark on the bottom. The new ones can easily be
unclipped and clipped back together. So if their rubber
contacts start to fail, it will be a matter of desoldering them
and unclipping the side parts to clean the contacts, rather
then replacing the whole switch.

I was wondering what the ALPS part number was, but my
only copy of the TR-808 service manual was an old
photocopy, missing the part numbers. Today, thanks to this
forum, I discovered Eric Archer's TR-808 clone drum sound
page: eric archer . net » 808 clones and was
very happy to find an excellent scan of the TR-808 service
manual there. This is "3rd printing June 1986 C-2", so I guess
it is the final version. (The previously mentioned service
manual at fileshare.eshop.bg was a .zip file in two parts and I
couldn't easily find a way of unzipping the two.)

Unfortunately there's no ALPS part number in the service
manual. Just listings of "KED1001" for the Start/Stop switch
and button combined, and "KED10903" for the Tap switch and
button. These have surely been out of production for 25
years or so, but its always good to have a part number. I
have some ALPS catalogues from the late 1980s and early
1990s, but I can't access them right now. If I find a proper
part number for these switches, I will post it to this forum.

Googling KED1001 lead to VINTAGE PLANET - Parts Service for Vintage Synthesizer Repair - Roland Parts
but they have none in stock. It also lead to another copy of
this beautifully scanned service manual:

http://manuals.fdiskc.com/tree/Rolan...e%20Manual.pdf

This directory: Index of /tree/Roland has a bunch
of Roland service manuals. Stepping back to the tree
directory, there are directories for many other musical
instrument manufacturers - a treasure trove of manuals,
including for some obscure machines.

There is an MC-4 manual, from 1982, which is a little after
the 1981 date at the top left of the TR-808 manual. So my
guess is the MC-4 is somewhat later and this use of the
black-shaft switches indicates that ALPS changed their
design from the heat-sealed white shaft approach to the
side-clip black shaft approach. Unfortunately, there's no
ALPS part number for the keyswitches - just KEH4AO06 for
the 10 key assembly, presumably with buttons included.

I think, with care, it may be possible to reassemble the old
switches and make them strong enough. I think it would
require epoxy on the outside of the case, with some kind of
reinforcing to the PCB, which would make it all hard to
dismantle in the future. These switches can get a lot of
sideways force, so I think the case needs to be well
supported since just epoxying the two pins is not, in my
experience, strong enough.

- Robin

[Mars Amp Repair]

Well that's great thanx for all the research. I do have the original manual as well am Roland authorized, so I can still print it from their authorized website. Yes, no Alps number.

I forgot that the switches were somewhat fused together. I was using a very sharp long exacto knife in the seam to rock it back & forth & break the seam. It wasn't fused that badly.

As for the epoxy...I used the 5min JB Weld (would never use the other semi-clear crap). I put a slight amount in the seam before I closed it up & I'm tellin' ya, this weld will not break.

the switches afforementioned that go in the boss pedals probably could be modified to work, however they only have 2 connection pins as opposed to the 4 of the original (for strong mounting given the leverage that big knob has) & as mentioned the 'Cross' shaped actuator is slightly larger than the original...wouldn't be as big an issue if the knob also had a cross mounting in it.

If anyone ever enounters a switch that will retrofit easier...let's post it...

thanx, glen

[dumbassbob]

I just midi to a cheap keyboard and I get double 2 snares BD, CB HH, ect.Alot easyer to play live then tapping on a little keypad.Not wear it out.Istarted getting some distortion on the snare,with the Keyboard it is gone...