I repaired an old drum machine and made a video. More?

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äggmedskägg
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I repaired an old drum machine and made a video. More?

Post by äggmedskägg » Sun Jun 09, 2019 2:25 pm

I got some stuff that need repairs/refurbs, and I finally got around to it. I made a blog post last time (Tascam M-2524 mixer) but that was a lot of work. So I tried a video this time, I like that better.



Now, question is, does anybody want a video for any of the other things I need to fix? It's a Fostex A-8LR tape multitrack, a Roland Space Echo, an OSC Oscar, and I think my TR-909 needs an overhaul, or at least a proper clean. :-)

Tell me if any of that is of interest.

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Post by spacessound » Sun Jun 09, 2019 5:09 pm

always love seeing inside old gear :nana:

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Shrigg
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Post by Shrigg » Sun Jun 09, 2019 5:47 pm

I'd love to see an OSCar teardown video
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Post by calaveras » Sun Jun 09, 2019 6:35 pm

those Muji screwdrivers are great.

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Post by äggmedskägg » Sun Jun 09, 2019 10:18 pm

calaveras wrote:those Muji screwdrivers are great.
Yeah, best ones I've ever had. After the box got old and broke on the first ones I got in the 80's (or maybe early 90's), I bought another set a few years ago. :-)

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Post by äggmedskägg » Sun Jun 09, 2019 10:23 pm

Shrigg wrote:I'd love to see an OSCar teardown video
OK, I will definitely do that one then. It's amongst the last on my list, because it's a big project and I'm also worried that I'll break it. :-) But it'll come.

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Post by ExtrasensoryPerception » Mon Jun 10, 2019 2:42 am

Lovely video. i'd enjoy more...always curious about what's inside the box!

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Post by hw408 » Mon Jun 10, 2019 1:29 pm

TR909 video would be very nice. :hail:

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Post by CosmicFlight » Mon Jun 10, 2019 3:03 pm

Interesting video 8-)
Yeah 909 and Space Echo please

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Post by calaveras » Mon Jun 10, 2019 4:14 pm

I should have made a vid of the TSR24 I upgraded over the weekend.
I was surprised that it was all through hole, and had a number of whacky circuit revisions that involved passive components and trimmers just kind of stuck together like you might see inside an electric guitar, or an amp from the 60's. Odd to see that on a digital multieffects from 30 years ago.
But it was super easy to swap the crystal and the firmware.

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Post by äggmedskägg » Thu Jun 13, 2019 4:42 am

I was surprised that it was all through hole
Yeah, surface mounted things were only used for real mass production things back then. Or if you needed it to be small. By the mid 90's the company I worked for then started making SMD boards even for the small run stuff we were doing, because by then you couldn't get processors in DIP packages any more. Too many pins. :-)

TR909 video would be very nice.
Will do. That will take time though, and markusfuller already did a good one.


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Post by monads » Thu Jun 13, 2019 9:19 am

One issue to be cautious of when servicing the TR-909 is the connector cables that are connected to the keypad/buttons PCB. Roland soldered one end of the cables directly to the board. This is not normally a problem except from old age and when you try to service this board the cables can get in the way and worse become unsoldered!!! Trying to resolder them can be a nightmare. I actually removed them. Soldered connectors (like on the main PCB) to the board and made a connector on the other end of the existing cable. So now the cables can easily be disconnected and reconnected!

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Post by jabberwalky » Thu Jun 13, 2019 11:44 am

Cool video! All those trimmers! Great sound on the early Vermona stuff. I've had some experience repairing the Korg Minipops3/SR-120. Definitely not for the faint of heart. Early Korg has a very "garage built" feel.

I'm all for anyone making repair videos!

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Post by äggmedskägg » Mon Jun 17, 2019 2:06 am

monads wrote:One issue to be cautious of when servicing the TR-909 is the connector cables that are connected to the keypad/buttons PCB.
Thanks for the headsup! If they cause any trouble I'll do the same!
jabberwalky wrote:Early Korg has a very "garage built" feel.
Somehow I'm not surprised.

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Post by äggmedskägg » Fri Jul 05, 2019 3:11 pm

Next video is up now, short and perhaps not very interesting.



Working on the Fostex A8-LR 8 track now, that will be more substantial, but will take a few weeks.

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Re: I repaired an old drum machine and made a video. More?

Post by äggmedskägg » Sun Feb 02, 2020 7:05 am

Well, I got distracted, mostly by the realization that the OSC OSCar's battery could possibly be leaking, but also by the Fostex missing a lot of screws, so I worked on the OSCar instead. It's a nightmare :help: , and amateurs like me shouldn't do anything more than replacing the battery.
It's not done, but I got three videos up. There may be more. :cry:




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Re: I repaired an old drum machine and made a video. More?

Post by thispoison » Sun Feb 02, 2020 8:26 am

Many thanks for the OSCar videos - really enjoyed them and appreciate the effort.

I'm grateful that you've made me give myself a shake and remind myself that building a few diy kits doesn't mean I have the skills to work on my own OSCar.

After the first video I was thinking of giving it a go, but the second two were a wake up call for me.

Best of luck getting yours back to full health. :guinness:
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Re:

Post by doombient.music » Sun Feb 02, 2020 1:44 pm

Shrigg wrote:
Sun Jun 09, 2019 5:47 pm
I'd love to see an OSCar teardown video
Much more than this I'd love to watch the OSCar being re-assembled again, with no parts being left at the end...

Stephen

äggmedskägg
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Re: Re:

Post by äggmedskägg » Sun Feb 09, 2020 8:30 am

thispoison wrote:
Sun Feb 02, 2020 8:26 am
Best of luck getting yours back to full health. :guinness:
Thanks!

doombient.music wrote:
Sun Feb 02, 2020 1:44 pm
Much more than this I'd love to watch the OSCar being re-assembled again, with no parts being left at the end...
I *might* have enough footage of assembling it to make that happen, but I'll make no promises.

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Re: I repaired an old drum machine and made a video. More?

Post by Seaweed » Tue Feb 25, 2020 9:11 am

Hi.. I've just joined the forum to get some help with my OSCar and it looks like you might be able to help me (!) My OSCar was in storage for ten years or so and obviously the battery needs replacing - trouble is, it was modded by SSC back in the 90's to make the battery more reliable (and even self-charging?? Maybe I dreamt that..) and after popping the hood, I can't find the battery anywhere! I'm not good enough at circuit boards to spot something clever but maybe someone out there can see something relevant?? I realise that it's going to have to go to an engineer eventually but I'm just trying to do the simple stuff first..! Any opinions would be most welcome..!
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Re: I repaired an old drum machine and made a video. More?

Post by thispoison » Fri Feb 28, 2020 10:59 am

Top row, four knobs in from the right you will see an empty space marked B1 (above IC9) - that's where it should be. Likely the modded battery is connected to the underside of that location now (or you don't have a battery at all?).
Where have I seen you before?
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Re: I repaired an old drum machine and made a video. More?

Post by Seaweed » Fri Feb 28, 2020 11:56 am

Hi..thanks for replying! I knew that was where it was meant to be and I did check underneath but no dice, I'm afraid. When I talked to SSC, they unhelpfully said "it must be on the board somewhere" but I'm starting to think, like you, that there might not even be one - is it actually possible for it to operate without one? how does it keep the sounds/sequences etc?? I'm sure that SSC did something clever because it worked reasonably reliably for many years afterwards but after ten years in a flightcase it's only spouting gobbledygook..! I've tried midi-dumping various factory libraries back in but nothing is working, so it feels like it needs a battery. I know I'm being a cheapskate and I'll have to take it to an expert eventually but I didn't expect to be stumped at first base..!

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Re: I repaired an old drum machine and made a video. More?

Post by äggmedskägg » Sun Mar 01, 2020 7:43 am

That big green thing on the processor board is a capacitor on mine, and a much smaller one. It that green thing a capacitor? It doesn't look like an electrolytic capacitor. It kinda looks like a battery. Can you make a closeup?

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Re: I repaired an old drum machine and made a video. More?

Post by Seaweed » Mon Mar 02, 2020 4:41 pm

Hi.. thanks for replying - I've got work for a few days but I'll get a close-up when I get a chance.. that's the first suggestion I've had so I'm grateful for the input!

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Re: I repaired an old drum machine and made a video. More?

Post by Seaweed » Sun Mar 08, 2020 1:24 pm

Hi.. result! You are officially a genius! The good news is that now I know where the battery is - the bad news is that it's soldered to the board in a very non-user-serviceable kind of way (!) I might see I've got a mate with more solder skills than me but frankly it looks like a job for a professional..
Thanks so much for taking the time to spot that though - it's been keeping me awake at night and now at least I've got an idea of what I'm dealing with!
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