Roland SH2 with internal surface rust - suggestions please

[FreqFarm]

I am servicing/restoring a Roland SH2 which is in pretty good cosmetic condition externally but is definately in need of some love.
Internally there is some surface rust which needs to be sorted, the original paper inspection sheet and info is in perfect condition so it feels a bit like vandalism to just strip it back to metal, rustpoof and repaint so I am flirting with the idea of maybe doing something like sealing the internal panel with automotive wax or varnish or something yet to be determined to stop the rust progessing, stop any rust particles being released and to keep it in original condition, sort of like the japanese Kintsugi methodology where they repair cracks in pottery with gold.


before and after on the portamento fader just for fun and to explain which the bender module is in the current state



would love to hear your thoughts on what the best way forward is, even if it's a "shut up and paint it you fanny"

 

[FreqFarm]

oh and if anyone has a bender for sale or a NOS uA726HC (yeah I know but I thought I would ask anyway) please hit me up

 

[RoadrunnerOZ]

I am servicing/restoring a Roland SH2 which is in pretty good cosmetic condition externally but is definately in need of some love.
Internally there is some surface rust which needs to be sorted, the original paper inspection sheet and info is in perfect condition so it feels a bit like vandalism to just strip it back to metal, rustpoof and repaint so I am flirting with the idea of maybe doing something like sealing the internal panel with automotive wax or varnish or something yet to be determined to stop the rust progessing, stop any rust particles being released and to keep it in original condition, sort of like the japanese Kintsugi methodology where they repair cracks in pottery with gold.

View attachment 134376
before and after on the portamento fader just for fun and to explain which the bender module is in the current state

View attachment 134377

would love to hear your thoughts on what the best way forward is, even if it's a "shut up and paint it you fanny"

You can use baking soda paste as an initial treatment to remove/react the surface rust off the chassis - rub it in well, leave it on for at least an hour and then rinse off.
Then use a soft fibre wheel buff - either felt or laminated cloth strips on a shaft - these come in a kit with the graded abrasive wax bars and various buff shapes - you coat the buff with the fine abrasive polishing wax by spinning the buff with the abrasive wax held against it to coat it - with polishing the metal will be bright again but will continue rusting unless you use a surface protectant.
There are a few ways of doing this but if the rust has progressed to pitting the metal I would say you might want to get the chassis sand or bead blasted and then re-galvanised or zinc/nickel dipped if you wish to retain originality. The original was a yellow zinc/nickel/chromate dip IIRC - common to most chassis - the same used on screws and bolts you get from the hardware store that have a yellowish bright finish.
I worked for a luxury supercar (Ferrari, Lamborghini, Maserati, McLaren, Aston Martin, Rolls Royce etc.) auto paint, panel and detailing service shop for over 5 years and we used to send parts off for re-plating all the time - chrome for grilles, bumpers, door handles, mirror surrounds and trim bits and the yellow dip for framework parts that were originally of that type - like battery trays etc. doesn’t cost much but there may be waiting time as they need enough parts to fill a plating tank.
DIY rust removal won’t give you back a permanent clean surface as there will be exposed steel which will always continue to rust. There is painting but this becomes an issue where ground points are concerned but can be overcome fairly easily - if you do decide to paint you will need to use an outdoor bare metal zinc based spray primer designed for steel first then apply your finish paint.
The pots shown are readily obtained - genuine original - any rust removal is likely to damage the carbon tracks inside the pots and they’ll continue rusting anyway.
There are places that have parts for the SH2 like:
https://syntaur.com/keyboard.php?keyboard=Roland_SH-2

oh and if anyone has a bender for sale or a NOS uA726HC (yeah I know but I thought I would ask anyway) please hit me up

https://www.soundtoparts.com/en/41-sh-2
https://www.soundtoparts.com/en/roland/18-bender-lever-complete-set-roland.html
Be wary of phosphate rust removers as they will leave you with a black iron phosphate - okay if you’re priming and painting but not good as a finish surface.

 

[FreqFarm]

@RoadrunnerOZ thanks for the really detailed reply - I will definately be following your advice

 

[FreqFarm]

The pots shown are readily obtained - genuine original - any rust removal is likely to damage the carbon tracks inside the pots and they’ll continue rusting anyway.

thankfully these are the proper old skool roland sliders which can be completely stripped down to the component parts, I can use a heavy hand + rotary tool and isopropanol on the metal case, leaving the internal carbon/metal tracks to be treated with kid gloves and a little DeoxIT F5, then reassembled with a healthy dollop of fader grease to get that straight from factory feel.

and to help matters, there is a tonne of gunk inside the faders along with a good porton of the dust cover now it's crumbling, but no corrosion inside which makes servicing a whole lot easier.

I suspect the bender module has had some liquid in there at some stage, I will need to compare with the main bank of fader once I get there to see if that is true or it's just been stored in a damp shed or basement.

 

[RoadrunnerOZ]

A good cleaning solvent which is completely safe on faders and rotary pots and plastics is CRC CO Contact cleaner - this is really good for removing contamination and cleaning PCB’s as well - it evaporates completely and leaves no residue. I use this to flush the F5 out of faders, after using the F5 for initial clean, that are supposed to be a dry track fader as the residue from the F5 will attract dust gradually if it is left on the carbon tracks. Faders like the P&G sliders which use conductive plastic should only be cleaned using water or the CO cleaner and a cotton bud, the sliding bush and rod using light silicon oil to lube after cleaning.

What brand of fader grease are you intending to use?
You can buy new dust covers - I have made dust covers if I couldn’t get the original replacements using super thin black stiff felt which comes in 1 foot square sheets - cut out with an exacto knife and a steel rule straight edge.
I’m restoring an old Moog Rogue which has dust cover residue all over the faders, inside them and all over the PCB.
In any of the old faders the carbon track may be worn through if they’ve had lots of use while dirty - the dirt tends to sand off the carbon so an out of circuit test is advisable with a resistance meter. Rotary pots like on the bender can have the terminal pressure joint clamp/rivet come loose over time causing open contact or intermittent contact - a forceful squeeze with long nose pliers can remake proper contact with the carbon track ends (this applies to linear faders as well after you dismantle them).

 

[Brian Roth]

@RoadrunnerOZ I hadn't seen that particular CRC product before. I guess it's similar to what I've used for many years and readily available in the USA at places like Home Depot....even Walmart.

https://www.crcindustries.com/qd-electronic-cleaner/

Bri

 

[RoadrunnerOZ]

@RoadrunnerOZ I hadn't seen that particular CRC product before. I guess it's similar to what I've used for many years and readily available in the USA at places like Home Depot....even Walmart.

https://www.crcindustries.com/qd-electronic-cleaner/

Bri

The QD is hydrocarbon and alcohol based, the CO is Isohexane - not sure how different they are but the CO doesn’t dissolve the carbon bonding in pots, alcohol washes off the carbon but I’ve not seen what effect the QD would have on pots - I’m not so familiar with the properties of the QD as I’ve been using the CO for many years now - when cleaning off oily residues and dust from PCB’s I sit them horizontally and flood them with the CO and use a paintbrush to loosen the crud then stand vertically and rinse with the CO - works like a charm and leaves a really clean board. I also use it to clean contact strips on keyboards - the little carbon buttons on the rubber press-strips and the gold contacters on the contact strip boards.
The CO is available in most electronic supply stores and also some automotive outlets. Not sure where in the USA. 350g spray is about $30AU here.

 

[Brian Roth]

I went to CRC's website for the CO cleaner:

https://www.crcindustries.com/co-contact-cleaner/

And used the website's feature there to look for distributor inventory and pricing here in the USA.

Wow!!! Anywhere from $70-something to nearly $100 per can. Won't be on my shopping list! lol
Example:

https://www.amazon.com/dp/B00A704AJK?tag=price20025-20&ascsubtag=wtbs_66bbfce0925ecde67ce6ab7e&th=1


Bri

 

[RoadrunnerOZ]

Wow - that’s really expensive - I just checked pricing here and it’s about $21 for a 350g can. The last time I bought 2 cans and it cost me just over $30 - not $30/can as I said above. Some places here sell it for close to $40 but $70US is a ripoff - around $105AU

 

[FreqFarm]

A good cleaning solvent which is completely safe on faders and rotary pots and plastics is CRC CO Contact cleaner - this is really good for removing contamination and cleaning PCB’s as well - it evaporates completely and leaves no residue. I use this to flush the F5 out of faders, after using the F5 for initial clean, that are supposed to be a dry track fader as the residue from the F5 will attract dust gradually if it is left on the carbon tracks. Faders like the P&G sliders which use conductive plastic should only be cleaned using water or the CO cleaner and a cotton bud, the sliding bush and rod using light silicon oil to lube after cleaning.

What brand of fader grease are you intending to use?
You can buy new dust covers - I have made dust covers if I couldn’t get the original replacements using super thin black stiff felt which comes in 1 foot square sheets - cut out with an exacto knife and a steel rule straight edge.
I’m restoring an old Moog Rogue which has dust cover residue all over the faders, inside them and all over the PCB.
In any of the old faders the carbon track may be worn through if they’ve had lots of use while dirty - the dirt tends to sand off the carbon so an out of circuit test is advisable with a resistance meter. Rotary pots like on the bender can have the terminal pressure joint clamp/rivet come loose over time causing open contact or intermittent contact - a forceful squeeze with long nose pliers can remake proper contact with the carbon track ends (this applies to linear faders as well after you dismantle them).

Thanks for the CRC CO recommendation I will grab some

>What brand of fader grease are you intending to use?

I have a tub of DeoxIT Fader Grease DFG-213

>You can buy new dust covers

I have a set on the way that are laser cut, which is a great time saving and godsend to be able to get them.

>so an out of circuit test is advisable with a resistance meter.

100%! I have been checking them with a multimeter before installing back into the PCB.
At $30 a pop to replace them I would rather service those that are still in working order and replace the ones that are beyond saving.

>Rotary pots like on the bender can have the terminal pressure joint clamp/rivet come loose over time causing open contact or intermittent contact - a forceful squeeze with long nose pliers can remake proper contact with the carbon track ends (this applies to linear faders as well after you dismantle them).

That is some golden wisdom right there! thanks, I will make sure to do that.

 

[RoadrunnerOZ]

At $30 a pop to replace them I would rather service those that are still in working order and replace the ones that are beyond saving.

https://www.synth-parts.com/en/bundels/6704/roland-juno-sh-101-fader-set-30mm

 

[RoadrunnerOZ]

The faders in the above listing may match your SH2

 

[RoadrunnerOZ]

In the past if I couldn’t get the right fader - the slider shaft may be shorter but the value and footprint match, I buy Roland faders of the right value then I dismantle the old fader and the new fader and swap the shaft/wiper assemblies so I’m given a new body case and new carbon tracks on baseboard and using the original wiper assembly after cleaning the wiper tips.
Anyway here are the original part numbers for the pots used in the SH2:
Part number 13339420 100KA 30mm
Part number 13339421 100KB 30mm
Part number 13339422 1MA. 30mm
Part number 13339328 100KA 20mm
Part number 13339329 100KB 20mm
Part number 13219274 100KA Rotary
Part number 13219242 100KB Rotary
Part number 13219275 1MA. Rotary

 

[RoadrunnerOZ]

This list may have faders that match - just scroll down and look at the Roland ones and at the base configurations for ones of the correct value, curve and travel.
https://www.synth-parts.com/en/products/potentiometer/slide-potentiometer/?p=7