Roland RE-501 1µ "M" capacitor ?

[saint gillis]

Hello,
There are 4 electrolytic capacitors on the RE-501 main board that are labelled "M"

There are many other 1µ capacitors on the board, but these 4 are different, they are orange, others are black IIRC

They are C63, C66, C69 and C72 on the schematic and the "M" is also mentioned on the schematic so I guess it is important.

Are they specifically low ESr or something like that?

 

[Bo Deadly]

No idea.

But if you're looking for the best possible / non-compromise / overkill solution, four 1uF film caps would set you back less than the cost of a bottle of water and probably fit the footprint perfectly if you buy films with the right pitch / leads.

Personally, I would just drop in whatever 220n - 2uF I had in the bins. They're just not critical parts by any stretch.

 

[saint gillis]

No idea.

But if you're looking for the best possible / non-compromise / overkill solution, four 1uF film caps would set

Yes that's what I thought , but I was just minding what it meant..

 

[Khron]

That triangle logo looks like the old Panasonic Industrial / Matsushita logo, and the caps are "MR" series, i'd reckon.

 

[abbey road d enfer]

Hello,
There are 4 electrolytic capacitors on the RE-501 main board that are labelled "M"

There are many other 1µ capacitors on the board, but these 4 are different, they are orange, others are black IIRC

They are C63, C66, C69 and C72 on the schematic and the "M" is also mentioned on the schematic so I guess it is important.

Are they specifically low ESr or something like that?

These caps are inserted in a very high impedance circuit (about 400k) I they were leaky, they would develop significant DC, which would resut in a loud click when the switching FET's are turned on. They definitely need to be low leakage.
I agree with Bo, take the opportunit to replace them with film caps.

 

[saint gillis]

Awesome and educational answer as usual, thanks a lot !

 

[Bo Deadly]

These caps are inserted in a very high impedance circuit (about 400k) I they were leaky, they would develop significant DC, which would resut in a loud click when the switching FET's are turned on.

True only if they're switched fast and it looks like they're not.

 

[Bjorn Andersson]

Regular 1uF/50V caps. Use a good one (Nichicon or Panasonic).

 

[abbey road d enfer]

Regular 1uF/50V caps. Use a good one (Nichicon or Panasonic).

Define "good".

 

[JohnRoberts]

Define "good".

new, modern...

film might be nice but too big

JR

 

[Bjorn Andersson]

Define "good".

Good = quality capacitor brand like Nippon Chemicon (Nichicon) or Panasonic, preferable made i Japan if possible ;-)

 

[abbey road d enfer]

Like saying all German cars are good.

 

[Khron]

Well, with a couple of very specific and rare exceptions, Japanese electrolytics have been pretty flawless (Nichicon, Panasonic, Elna, Rubycon, Nippon / United Chemi-Con, and what used to be Sanyo). Which is more than can be said for at least some of the Taiwanese brands, and most (if not virtually all, with one or two exceptions) Chinese brands.

Not being "nationalistic" or anything, just statistics...

https://www.badcaps.net/forum/showthread.php?t=388

 

[soapfoot]

1uF 63v MKT film cap probably not too big in 2022

 

[abbey road d enfer]

Not being "nationalistic" or anything, just statistics...

These "statistics" are a bunch of subjective comments without any definition of what parameters are deemed "bad".
One of the posts clearly mentions some Sanyo caps being bad, so the claim that all Japanese caps are good cannot be sustained. Actually, many "Japanese" caps are made in Elsewhereland.
I'm not sure a broad assessment can be made for a single series from a given manufacturer. That is the nature of manufacturing.
There are indicators of durability that must be evaluated by designers. If a product does not conform, then the manufacturer is liable and should be called to his responsibilities.

 

[saint gillis]

I remember repairing for a friend a little orange amp full of electrolytics that were completely bloated after only few years, so called 105° capacitors that looked incredibly light and cheap, it's a pity I don't remember the brand, but chinese for sure, well these combos cost 50 or 100€ new, I guess you get what you pay

 

[JohnRoberts]

I have been out of the trenches for decades but saw my share of bad capacitors from good companies over the years, but that is what happens when using millions of them in production. My most dramatic capacitor fail was when a manufacturer's tooling broke and we didn't notice until thousands were inserted into SKU and hundred were shipped. I even recalled one container full of finished goods that was headed overseas to replace the faulty capacitors.

The fault was a broken swaging tool that mechanically secures the capacitor lead to the capacitor foil. The leads were making a weak mechanical connection. I discovered it when the factory incoming inspection technician asked me to approve a tolerance deviation that was outside the normal AQL (acceptable quality level). Out of a test sample of 10x 1000uF electrolytic caps a handful were measuring single digit nF. That is not out of tolerance, that is busted, but that's why they call me. I took the outlier cap apart. When I unwound the capacitor foil I found the flawed loose swage connection. The majority of the caps measured good, but the foil was hanging on, attached by only a thread, and I didn't trust them to survive a lifetime of thermal cycles in the field.

Since we had decent manufacturing quality control, I was able to track all the SKUs that were built with the same production lot of questionable caps. After I alerted the manufacturer they immediately found the broken tooling in their factory and worked to make us whole. I don't know how much this drama cost them (a bunch) but they made good compensating for us reworking hundreds of SKUs, not to mention recalling that one container. These 1000uF caps were widely used in tens of SKUs.

They were a quality company so stood behind their product, just like we did ours.

In general popular brands that are widely used, are popular for a reason. I also dealt with a few less reputable capacitor sellers who marketed branded capacitors, but they sometimes reskinned caps made by who knows who. One distributor after I took him to the woodshed over a batch of bad caps, offered me a job working for him as his "capacitor expert". I am not a capacitor expert but among the blind he with one eye is king.

JR

PS: We had an xray machine in the factory capable of looking inside metal capacitor cans, but I found that I had to take them apart to really see what was going on inside.