[sdiy] Roland M16C / M64C memory module - Connectors

[sleepy_dog at gmx.de]

The contacts in the receiving socket can definitely be bent towards the 
surrounding plastic (and they come back), after some playing with a 
screw driver, so I guess they are spring loaded.
Alas I don't have such a memory cartridge and don't feel like spending 
80..90 bucks + shipping, which is why I wanted to make one. If it 
weren't for the connector, it'd be in the high single digit EUR range as 
part of my "PCB with a lot of other small circuits" + parts :-D

For the near future, there is no plan for quantity.
Yeah, I saw that "my" cheap PCB maker can do 2mm PCB thickness, which 
could be enough, but recommends against all the 0.4mm hole vias on the 
other circuits on the board, his old tech might not electrically connect 
both ends properly. I used them a lot.
Sure I can start trying out other makers, although oshpark is only cheap 
if you need a bunch of tiny PCBs of the same circuit (last time I 
looked). For some of my little circuits that could be good, for others 
and esp. prototypes, not so much.

As for the contacts: I thought about making 1.0 or 1.6 mm card edge, and 
then solder thin brass plates on the pads to make them thicker (instead 
of tinning).
If the receiving socket gives enough spring action...


Steve


> By the way, that photo makes it look like the total thickness is much greater than the standard 62 mil, but there is spring-loading that allows significant compression. I'd like to see the receiving connector, too, because if it isn't spring-loaded then forcing an incompressible PCB into the connector is not going to last very long. Wouldn't want to ruin a JX8P just to make a cheap cart!
>
>
> On Jul 18, 2017, at 1:49 PM, rsdio at audiobanshee.com wrote:
>> PCB fab houses have a variety of thicknesses available. The Soundplane Model A uses a 125 mil thick PCB under the force sensor, and that's 3.175 mm. There's no sense limiting yourself to cheapo PCB makers when the professional prices are still quite competitive. After a few prototypes, you should be able to order in sufficient quantity to get the price down to the cheapo level, or even below. Prototron Circuits in Redmond, WA, (and AZ) has beat OSHPark prices on quantity orders.
>>
>> That said, the standard size for a PCB is 62 mils, which works out to 1.5748 mm, so I don't see why there's a problem unless someone is quoting the wrong thickness. Get some decent calipers and measure a Roland cartridge, then talk to your fab house.
>>
>> By the way, I recommend against "tinning by hand" to achieve the required thickness. Lots of products have failed due to this manufacturing technique, so I recommend a more consistent process. I know for a fact that some service manuals and support departments had to deal with methods to repair for failures in the field where such manual tinning was used. Just say No.
>>
>> You could also order 2 oz copper for your PCB, but I've never bothered to calculate how much that affects thickness. Perhaps it's not significant.
>>
>> Brian
>>
>> On Jul 18, 2017, at 12:07 PM, MTG <grant at musictechnologiesgroup.com> wrote:
>>> If memory serves it's 1.6mm.  I remember back in the day some PCB carts were tinned by hand to make the thickness work. There are some web pages where people have made new cartridges with varying degrees of success. It always comes down to this connector.
>>>
>>> On 7/18/2017 11:51 AM, sleepy_dog at gmx.de wrote:
>>>> Hehe, yeah, PCB card edge is my plan B, too, but the slot width must be rather thick compared to usual PCBs:
>>>> http://www.joness.com/gr300/pics/M-64C/Roland_M-64C_Battery_Replacement_04.JPG If that PCB is something like 1.5mm, you'd have to make a super thick PCB to get the same pressure of contact springs, judging from how thinck that connector looks.
>>>> I don't think my cheapo PCB maker can do that.
>>>> Steve
>>>>> Good luck. Let me know if you find some!  I've been looking for years. If you take one apart you can get the part number right off it. I think it's JAE or something ... been a while. Some Japanese company.
>>>>>
>>>>> I think most people make carts just went the PCB contacts route. Which is iffy.
>>>>>
>>>>> GB
>>>>>
>>>>> On 7/18/2017 11:22 AM, sleepy_dog at gmx.de wrote:
>>>>>> say, those memory modules for the Roland JX8P etc synths.
>>>>>>
>>>>>> The black plastic connector at the end with all those gold contacts:
>>>>>> What is that, Roland-specific, or some sort of standard, and if so, is stuff like that still available for a reasonable price?
>>>>>>
>>>>>> Steve
>
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