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MB6582 passive cooled (purple and green SCREEN/LEDs)


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i made a passive design, since the fan which came from mouser, was dead from the beginning... since it is a 6582, it was not going very hot anyway... but i drilled Holes into the pcb under the SID-Sockets, and cut aways some plastic from the socket too.

i too drilled some holes in the plastic body under the Main-PCB too, the backside off the SID should be  enough to get rid off the hot air...






Edited by Phatline
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  • 4 months later...



I've just come into possession of one of these; it works quite well over MIDI on the first three channels, but not the fourth (which is a pair of 6581s rather than the first three which are 8580s..) I haven't been able to determine any broken paths or components around the fourth voice, and have tested it with every MIDI channel in case that affected it - there's no noise at boot, though there is some clicking that can be heard when feeding it notes and CC data...


It also has interface issues; the panel lights but each character is blanked / filled and while many of the knobs and buttons work, they're often unpredictable and not entirely reliable in various ways... Inspecting the wiring between the main board and the interface panel, it doesn't entirely look like many of the builds I've seen photos of; a good few wires lead from the main board directly to points higher up on the display board, rather than to the corresponding pin as it appears to do on photos I've seen here... one or two have broken away even with the very gentle manipulation I've given it, so maybe it's a lot of dry jointing (the unit was fully functional 10 years ago according to the previous owner / builder, but he's not inclined to fix it himself now - I guess his fun was had :) )


Is there a definitive build guide to be found anywhere? I'd like to unravel all this as soon as I can, but without some eejut proof guidance I might be a bit stuck!


In any case, I'm probably going to seal it back up and MIDI control it so I can sample it to death in case I later muck it up somehow... 


In general, if resoldering this sort of PCB, is there some clever way to make it work nicely? - I've messed up before and not found enough metal to get a decent solder / contact to ...


many thanks for any answers / guidance!


Chris Krupa



Edited by KrupaX
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the buttons have a scan matrix... - i dont know if i remember correct by debugging such devices > if a LED is dead then that scan off buttons is also bad...

i sugess: check if all leds are lighting up correctly.

By the way this tactil switches - dont last forever, they are the cheapest and badest parts ever (ok, i think so...) ... could be that they are end off live alreday.


@ blank screen > do you mean it is blanked when connected to the Master-Core (the Core with ID0)?   when this happend to me, it was bad solderpoints... on the Core-PCB

This PCBs have some design errors - not in sense of routing - but in sense off Thermal-Distress, often and speciall on the Ground-Vias it sucks so much Heat away to the groundplane whille soldereing, so you you have a bad or no contact...., when resolder those Pins remove the ICs first > so they dont get an Heat-Death... then Solder very hot and long! (first on the pad then on the pin... use a good soldering iron)

On the very oppiste on the LED: , they are very Heat sensitive... if you resolder a LED do it short and with less Heat.... and when you start to demage them its harcore to desolder and replace them without demage the PCB, this is also a weak point off these ReD-Pcbs often vias liften up or whole traces (bigger vias would be good so the desolder is easier)

.... often its better to just order a new fronpanel pcb, order new encoders, switches and leds... specially if you have to desolder a lot off dead parts.... specially a lot off LEDs are very dimm already - and you want to replace them... then its take time to find out the correct color and Brightness for those replacements.


@ 6581: isnt that a 12V Chip --- and the others are 9V >>> do they get the corret voltage?


...  i already repaired 4 off them... and build some... I dont like to repair them...


- mike.


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Cheers Mike, that's all very good advice, I'll definitely bear it in mind - especially the bit about taking chips from the sockets before soldering... I think I'll probably give it a good while and a lot of thought, maybe an expert eye in person before taking any more action - the 6581s are getting 12 volts, I did check that right at the start as it seemed obvious... I might pull them and try then in a eurorack module I have to make sure they're not DOA... it feels as though all the buttons are fine tbh, and I haven't noticed any of the LEDs not lighting, just that they're not always indicating the right thing - controls like the envelopes and filters all seem to work ok.... I'm getting a lot, in fact most, of what I want from just MIDI CC control anyway fro now - sample tastic!


thanks again, really good stuff to know,



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  • 4 months later...

Now a Purple Passive Cooled is alive:

Temperatures after 1,5h:
Front panel:  29-31C°
Bottom off the Box: 30-43C°
Back panel: 28-40C° (40C° on the Plastic above the Ventilator-Air-Hole, 33C° above the small Air holes)

SID-Chips: 45-54C°
7809: 44C°
PCB near 7809: 40°C
PICs: 36°C

I will drill some more holes, and post some measurements later on.

this picture is near off the Color that it in reality has... but the camera cant face this UV things good:



here where the case color is like it looks in reality (but not the LEDs)


back plate, with some AIR Holes, since it is a passive Cooled Design:


I made a single PSU option (+12VDC) that on the 5V Rail i used a Traco Power Switching Regulator (which is cool)
on the 9V Rail i used a standard 7809, which i mounted on a ALU-Cooler, which i mounted with thermal paste everywhere around on the PCB, the screw thru the PCB i fastened again with thermal paste everywhere, on the blank Ground-Plane off the PCB,
On the bottom off the Case i made a lot off Holes so Air can get in...

(the 2 holes under the SID is a Air Intake, and i also cut away the plastic off the DIP-Socket so Hot Air behind the SID can get away.... there are also holes on the bottom off the Case for some Air intake!)


(i drilled away some plastic from the MIDI-Sockets, and also from the PCB , so i can safely mount a Power-plug into the back panel, the Takeaway from the PCB is also some way to get rid off some hot air, coming from the underside off the PCB where the 7809 produces heat)


In this picture you see that i soldered a 220nF Cap between the Reset Line and Ground off the SID... this took a way a high chirping sound out off the equal loud noise floor... I tried different other things to reduce noise, switching a 9V Switching Regulator to a standard 7809 made nothing hear able difference, also by adding LC Filters on the 5V Rail changed anything... this 220nF made the most difference in sound quality (and off course the EXT-IN>Ground Jumper :)
(the screw is the Thermalthienk for the 7809)

single wires to the Frontpanel is for me the best solution:

i also used on the whole PCBs Pb Solder, the melt with slower temperature, and is more fluid, this is good for this PCB because the VIA Spacing between Solder point and Groundplane is almost not existent, so Shorts cant happen so easy...

Edited by Phatline
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made a few changes on the cooling:

more holes


Made 3 holes where the ventilator "should be"

Drilled the 2 M3 Mounting holes on the right to a bigger diameter

Drilled a hole near the 7809


cuted also the second "bar" off the IC-Socket (left socket) - before i had only cuted the top one (see middle socket)

i had fear that it would not hold in the socket, or they would bend to much... but the SID hold the socket togehter once it sits in it.

so i have even more thermal pathes...


lets see what this changes on temperatures:

SID: 48-55C°
Bottom Case: 32-38 (on one point 45C°)
7809: 45
pcb near 7809: 32-37C°
Frontpanel: 32C°
Backpanel: 32C°

Edited by Phatline
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  • Phatline changed the title to MB6582 passive cooled (purple and green SCREEN/LEDs)

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