Blue caps?

Started by glasswing, September 12, 2022, 07:56:23 AM

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glasswing

Has anyone had to replace their blue caps?  I read somewhere they go south and then leak. 
I haven't done that yet.  Advice?
Pro Tools Ultimate HD
Mac Studio Ultra
Lots of things that blink and sometimes burp
RELEVANT TO THIS FORUM:
Roland GR300/303/808 w DB25 mod (Joness)
BX13VX Joness
Axon AX100 mk 1 (never used)
Roland F2 Volume pedal
AxFXII+
Pedals etc

expelec

Yes, I redid the whole power supply in my GR-300.  These old blue tantalum caps are notorious for failures.  If you have any soldering experience it should be too difficult.

igmillichip

My GR-300 is awaiting me to solder in replacements for the tantalums .......... I've been a bit lazy of late.


gumtown

Do as many caps as you can, even the electrolytics have a limited lifespan, which the age of a GR-300 is well past the replacement date.
Might even breath some new life into the GR-300's tone too.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

Chrismiami

I bought one that had been capped already but the other one needs some expert TLC. Are there any shops known for excellent GR-300 work?

Elantric


Chrismiami

Quote from: Elantric on April 16, 2023, 11:13:23 AMWhat city?

I'm in Miami but I'll FedEx it wherever it needs to go!

Elantric


Chrismiami

Quote from: Elantric on April 25, 2023, 12:47:31 PMContact these
https://www.service-center-locator.com/roland/florida/roland-miami-florida.htm

Thanks! But —do you think they'll do the Jones mods and a full power supply revamp as well as renovating all capacitors?

Elantric

Quote from: Chrismiami on April 25, 2023, 02:08:37 PMThanks! But —do you think they'll do the Jones mods and a full power supply revamp as well as renovating all capacitors?

Call and negotiate.

 Or raid a dumpster for an old electronic item to learn on , buy some tools and learn to solder and do it yourself

Chrismiami

Quote from: Elantric on April 25, 2023, 02:13:37 PMCall and negotiate.

 Or raid a dumpster for an old electronic item to learn on , buy some tools and learn to solder and do it yourself
I know the basics, my problem with soldering is that any IC's in the circuit get too hot and fry. I learned that you're supposed to let the wires melt the solder, not the soldering iron. That has always meant roasting the chips no matter how I've tried to heat sink with pliers. Just one mistake here and that's money down the drain.

I'll call and negotiate, because my GR300 is somehow fried. Nothing seems to work. IDK how that happened. It was just sitting there unplugged with a t-shirt dust cover!

Chrismiami

Quote from: expelec on September 29, 2022, 05:33:54 AMYes, I redid the whole power supply in my GR-300.  These old blue tantalum caps are notorious for failures.  If you have any soldering experience it should be too difficult.
I'd like to do this too! Did you replace the transformer, etc? I'm seeing them go for £425 at audiophile electronics sites! 😱

Elantric

Transformer rarely fails

Chrismiami

I'm looking at audiophile parts for the Output Mod but I'm expected to supply a wattage along with the resistance value - any clue what the watts value should be for the 100k and 5.6k resistors?

Chrismiami

Is there a list floating around of the capacitors needed to recap the GR-300?  If I don't know a capacitor from a transistor, are there things I should learn before selecting replacement parts?  I saw one post that someone changed the 16v capacitor to a 25v one successfully but I'd have thought that'd fry something...

Elantric

#15
Start with All electrolytic caps in the power supply
Any AC Ripple current on the DC Voltage power distribution results in non operation
C28, C29, (10uF/16V Radial)

C32, C33 (1000uF/35V Axial)  in power block


And
C14, C15, C20, C21, C26, C36, C37 on main board (47uF/25V Radial)

Verify each type matches the axial or radial orientation of originals - to correctly fit the PC footprint

https://www.joness.com/gr300/service/G-303_G-808_GR-300_SERVICE_NOTES.pdf


https://www.joness.com/gr300/GR-300.htm

If you are unfamiliar with identifying electrolytic capacitor types  and soldering - have a capable electronic technician perform the work.




Chrismiami

I went and found the highest quality electrolytic capacitors for high end audio that I could. But the uF/v measurements are a bit larger than the specifications you gave, @Elantric.

You cannot view this attachment.

I'm sure in the power supply the larger cap caps will be ok, but not sure if the others need exactly 47uf/25v ratings?

Elantric

#17
Verify each type matches the axial or radial orientation of originals - to correctly fit the PC footprint

Chrismiami

#18
Quote from: Elantric on April 27, 2023, 08:21:21 AMVerify each type matches the axial or radial orientation of originals
OMG I thought axial or radial was just a type of construction option and had no bearing on the performance of the item!

Also - there are probably upwards of 150 capacitors on these boards.  Why are we only replacing like 12 of them?  Why are these the only critical ones?  Are they the only electrolytics?

And if so many people have already done this, why isn't there a list of how many radial and how many axial ones I need?  I mean, when I'm done I will definitely post a parts list, but surely I can't be the first?

Chrismiami

I really appreciate all the bits of info you're sharing, @Elantric. You have a very zen style of guidance.  ;D

Chrismiami

So, I'm hoping maybe if I ask again someone WHO HAS DONE THIS might be willing to share the number and type of capacitors needed.  I know, I know, "just open it up and find out for yourself!"  --But, why not create a comprehensive knowledge base so people can shop first and THEN bust open the device?

Elantric


Chrismiami

I don't see it. There's nothing in the schematic that says if a cap is axial or radial.

Elantric