[sdiy] Spare MN3009 for Juno 106

[rsdio at audiobanshee.com]

That’s a handy page.

Parts are so cheap today that I’d recommend replacing the 8.2 kΩ resistors with 2.05 kΩ resistors. You have to buy 1% resistors, probably metal film, to get that value, but they’re only $0.10 in single quantity, so shipping will be more than that anyway.

The reason I say this is that the 2.2 kΩ suggestion on that web page could be as much as 13% too high, resulting in a longer delay than original. Assuming the factory resistors are 5%, the 2.2 kΩ resistors could change the tone of the chorus.

It’s cheap enough to literally divide the original resistor values by 4 and just spend a few pennies more to keep the delay times as close to original as possible.

I didn’t see resistor values for anything besides the Juno 106, so I didn’t look into it any further.

Brian


On Jun 16, 2018, at 1:55 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
> It doesn’t sound that difficult, actually:
> 
> http://www.florian-anwander.de/roland_string_choruses/index.html#comments 
> 
> Replace the MN3009 with MN3007 (which aren’t so impossible to find) and then change a couple of resistors to boost the clock frequency. Pretty straightforward.
> 
> On 16 Jun 2018, at 06:35, Ian Michael Ferguson wrote:
>> I'm afraid that's above my pay grade. :)
>> 
>> On Fri, Jun 15, 2018 at 9:24 PM Jackalope Billy wrote:
>>> What about substituting another MN30xx chip and just modifying the circuit to make it work?
>>> 
>>> On Fri, Jun 15, 2018 at 10:49 AM, Dave Magnuson wrote:
>>>> It’s such a bummer, too. Small Bear has a couple flavors of the MN30xx chips, but alas, not the 3009
>>>> 
>>>> From: Ian Michael Ferguson
>>>> Sent: Friday, June 15, 2018 1:03 PM
>>>> 
>>>> Oy...the nightmares are coming back to me.
>>>> 
>>>> I searched long and hard a few months ago for the "106 Chorus" eurorack module.
>>>> 
>>>> You either had to buy a whole salvaged chorus section to take used chips out of, or risk one of the eBay vendors which are frequently bogus counterfeits.
>>>> 
>>>> The only thing I didn't try was calling around repair shops, who might have old stashes.
>>>> 
>>>> Maybe Switched On?
>>>> 
>>>> If you find a reliable one, please let ME know. :)
>>>> 
>>>> -Ian
>>>> 
>>>> On Fri, Jun 15, 2018 at 6:50 AM Tom Wiltshire wrote:
>>>>> Does anyone know where a person might be able to get hold of MN3009 for a Juno 106 chorus repair?
>>>>> 
>>>>> Someone was asking me about it, so I said I’d enquire here on their behalf.
>>>>> 
>>>>> Thanks,
>>>>> Tom
>>>