When to repair/replace suitcase electronics?

Started by spave, May 20, 2022, 07:46:25 PM

Previous topic - Next topic

spave

Hi all,

For the Peterson suitcase owners out there, when do you know it's time to have a tech look at the electronics? Both of mine (mostly) work but I'm worried about the amp fires that I've heard about over the years. Is that the usual way these amps die or is it just a rare situation that could have been prevented by proper care (ie not leaving the amp on overnight)? Right now I'd prefer to spend the money on getting my wurly setup but I also don't want to wait for my Rhodes to self combust either...

Here's the situation with both:

1969 KMC Home: original preamp and suitcase electronics. Occasional crackling and pops with slight constant hum that seems to only come from 1 channel. Also has occasional power loss on 1 channel.

1971 Suitcase: rebuild preamp and original suitcase electronics. One amp is dead and is currently disconnected, the other amp has a slight hum but otherwise sounds ok.


I guess my question is, can I continue playing both until they just stop making sound or are they ticking time bombs destined to go down in a blaze of glory that will cost way more to fix?
1969 KMC Home Rhodes Prototype

Will

#1
Hi Spave,
Good question.
I know nothing about amp fires, so I won't discuss that topic. If you unplug your Rhodes from the electrical outlet after use and if they have their proper fuse, I'd say you're safe.
However, we can talk about repair or maintenance.
Of the electronic components in your Rhodes, electrolytic capacitors have the shortest life span. This type of capacitor has a lifetime of 1000s of hours. This information is usually found in the manufacturer's data sheet. But this varies a lot with actual operating voltage and operating (ambient) temperature.
If you use your Rhodes 6 hours a week, these capacitors will be out of use in 10 to 20 years. If your Rhodes has never been serviced, the capacitors inside are worn out. The situation you describe can be caused by this, but not only...
If you maintain your Rhodes (i.e. change worn components), you will have a more satisfying experience with your instrument.

But what if you wait for a complete breakdown?
In some cases, a capacitor can leak and spread chemicals on the PCB, which is not good for other components. It can also "pop" with the same result, plus an acrid smell. It can cause a short circuit, dragging other components down.

My opinion is to change the capacitors if they are too old. They are located on the 2 amplifier PCBs, on the power supply PCB plus 2 on mounting clamps, and on the preamp. Changing caps is not a big deal if you know how to use a soldering iron and a desoldering pump. You can find maintenance kits on the website of online dealers. If you are not too confident with this, you'd better ask a professional technician because there is a safety hazard with the current here. He could find other issues too, not adressed only by the capacitors.

An example of successful maintenance here: https://ep-forum.com/smf/index.php?topic=10612.0

Keep us in touch.

spave

Hi Will, thanks for the info!


I highly doubt either Rhodes electronics have been worked on since they were new. The KMC spent the last 40 years in a garage and the 1971 was supposedly played regularly for decades by a "little old lady" church pianist that played it so often some of the keycaps wore down.

I don't have the soldering skills to recap them so I think I'll try pressing my luck until I get the $$$ to have them properly rebuilt... or something drastic happens :o. I already play them sparingly and I'm religious about never leaving them on unattended so hopefully that will buy me some extra time  :)
1969 KMC Home Rhodes Prototype