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Rumble 200 needs repair after coffee spill; options?

R

Ralph124C41

Sep 20, 2012
510
435
#1
So I bought a used Rumble 200 and got a great deal on it, about $250 total with shipping. Then ... after a week or so I managed to spill a cup of cold coffee into it. First when I turned it on there were loud distorted noises and no actual bass sounds. So I dried it out the best I could and let it sit with the power unit out.

Today I turned it back on and once again I can hear my bass. But ... the background hiss, although much reduced, is still there. As a layman I'd say it sounds like radio static on an untuned-in station. It doesn't seem to increase as I add volume but it's just there.

What is causing that and what can I do about it? My area really has only one repairman and he charges a lot and I've had problems before with his amp on some electric guitar and acoustic guitar work but I've never had an amp repaired under him.

Worse come to worse I could have it converted into a cab but I'd rather not do that because as I said I can get it to play the n otes OK but that background noise is unacceptable.
 
#2
Ralph124C41 said:
So I bought a used Rumble 200 and got a great deal on it, about $250 total with shipping. Then ... after a week or so I managed to spill a cup of cold coffee into it. First when I turned it on there were loud distorted noises and no actual bass sounds. So I dried it out the best I could and let it sit with the power unit out.
Click to expand...
You should have let it dry first before attempting to power it on. Trying to power it on while still wet was the worst thing you could have done.
 
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#3
liquid damage can be very harmful. even after it dries out, corrosion starts to eat the electronics. so you definitely want to get the electronics cleaned and properly dried, especially if the spillage actually made it malfunctioning while wet.

actually turning it on while still wet could make a damage (basically by interconnecting the electronic components that were not meant to be interconnected), so now it could end up in a really expensive repair.

if you’ll face this again, turn the electronics in question off immediately and don’t turn it on until you visit a tech that will clean and dry it, until it happens it’s not safe to power on. in some cases it dries and works, in some not. laptop repair folks face this often.
 
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#5
Ralph124C41 said:
You're right. But I can't turn the clock back and so I have to try to make the best of this situation and that's why I made this post.
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I guess I will have to take it into that guy to have him clean it out etc. He will charge me about $100 ... nearly half what I paid for the amp itself. But he is the only guy around here to do amp repairs and I called and posted on Craigslist.
 
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#8
Not sure if you tried this yet, but there are a number of electronic cleaner sprays. I know there are folks on this forum that poo-poo this approach :thumbsdown:, but having been a Tech on Seismic crews and commercial fishing boats this is a common approach to electronics exposed to contaminants. CRC QD Electronic spray is one brand, there are other brands made for PC's. You probably already googled, 90% Isopropyl alcohol with a Q-Tip is also an option. When we had issues with seismic gear we would disconnect any power and disassemble as much as possible then thoroughly spray out the PC boards, look for any stains or collected spillage. Once sprayed and cleaned as best we could use electronics safe compressed air cans to blow everything out and allow to dry overnight. Then reassemble the next day and test. Similar for VHF radios soaked or dropped in the water, back in the day before the newer waterproof gear.

$100 is probably a standard test bench fee, might be time to assess how much you are love with the amp... I doubt there are many replaceable parts on that PC board. Coffee without cream and sugar is probably less corrosive, just my 2 c's (no facts). Worst case you have a speaker cab that you can use.

Good luck with your amp...
 
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#9
tothemax said:
Not sure if you tried this yet, but there are a number of electronic cleaner sprays. I know there are folks on this forum that poo-poo this approach :thumbsdown:, but having been a Tech on Seismic crews and commercial fishing boats this is a common approach to electronics exposed to contaminants. CRC QD Electronic spray is one brand, there are other brands made for PC's. You probably already googled, 90% Isopropyl alcohol with a Q-Tip is also an option. When we had issues with seismic gear we would disconnect any power and disassemble as much as possible then thoroughly spray out the PC boards, look for any stains or collected spillage. Once sprayed and cleaned as best we could use electronics safe compressed air cans to blow everything out and allow to dry overnight. Then reassemble the next day and test. Similar for VHF radios soaked or dropped in the water, back in the day before the newer waterproof gear.

$100 is probably a standard test bench fee, might be time to assess how much you are love with the amp... I doubt there are many replaceable parts on that PC board. Coffee without cream and sugar is probably less corrosive, just my 2 c's (no facts). Worst case you have a speaker cab that you can use.

Good luck with your amp...
Click to expand...
Yes, we poo-poo this approach because without knowing what you are doing AND using appropriate materials you can make a bad problem even worse rather than better. YOU might think it's appropriate, but anybody in manufacturing and support of such gear (professionally) wouldn't agree. Generally, marine electronics PCBs are conformally coated, which is an entirely different process and can be washed more aggressively, but NO amplifier uses conformally coated PCBs.

For example, what was spilled into the OP's amp was a polar compound, therefore CRC QD and all other electronic sprays (which are non-polar solvents) will do absolutely nothing useful. You might want to review your chemistry: https://research.cbc.osu.edu/turro.1/wp-content/uploads/2017/02/PolarityofSolvents.pdf

What's used in industry is deionized water with a sufactant plus a thorough dionized water rinse with an air knife and warm air dry. We do this occasionally on higher value amps (because to do it right AND WARRANTY THE REPAIR) because it's fairly labor intensive and not always successful.

For the OP, if the cost is $100 minimum regardless of success, you may want to consider a replacement amp as that may be less expensive in the long run.
 
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#10
agedhorse said:
Yes, we poo-poo this approach because without knowing what you are doing AND using appropriate materials you can make a bad problem even worse rather than better. YOU might think it's appropriate, but anybody in manufacturing and support of such gear (professionally) wouldn't agree. Generally, marine electronics PCBs are conformally coated, which is an entirely different process and can be washed more aggressively, but NO amplifier uses conformally coated PCBs.

For example, what was spilled into the OP's amp was a polar compound, therefore CRC QD and all other electronic sprays (which are non-polar solvents) will do absolutely nothing useful. You might want to review your chemistry: https://research.cbc.osu.edu/turro.1/wp-content/uploads/2017/02/PolarityofSolvents.pdf

What's used in industry is deionized water with a sufactant plus a thorough dionized water rinse with an air knife and warm air dry. We do this occasionally on higher value amps (because to do it right AND WARRANTY THE REPAIR) because it's fairly labor intensive and not always successful.

For the OP, if the cost is $100 minimum regardless of success, you may want to consider a replacement amp as that may be less expensive in the long run.
Click to expand...

when i was maybe 15, my bass teacher who was in the amplifier business showed me a can of that spray and said "just promise me you'll never spray this on any of your gear."

he was a wise man..

totally agree that the OP may need to just find something that will last rather than get into expensive repairs on this particular unit.
 
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#11
Cold coffee? The horror! I only pour fresh, hot coffee into my amps, really opens up the soundstage.

Seriously though - if milky coffee then you can expect a horrible smell and mould. If black coffee you can expect a different horrible smell, and mould (but slower).

It’s the sort of thing that’s either an easy fix or it isn’t. Either way it’s time consuming removing all the boards to clean them (and dry them), then re-assemble and test. Then fault-find, fix etc.
 
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#13
BTW....I'm surprised you didnt see any sparks and smoke. I guess it's possible that your tech can bring the amp back, but frankly, I'd never trust it. Now, I say this as someone who almost never uses an amp. However,
I was a military-trained electronic tech when most of our components still plugged into multi-pin sockets. Water and electronics just dont go together. All those dudes you see on stage with their beers sitting on their amps? Yeah, those are guys who can afford new amps.
 
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#15
mikeoso said:
BTW....I'm surprised you didnt see any sparks and smoke. I guess it's possible that your tech can bring the amp back, but frankly, I'd never trust it. Now, I say this as someone who almost never uses an amp. However,
I was a military-trained electronic tech when most of our components still plugged into multi-pin sockets. Water and electronics just dont go together. All those dudes you see on stage with their beers sitting on their amps? Yeah, those are guys who can afford new amps.
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When my old Ampeg BA-115 died I did see a puff of smoke. I just never bothered to having it fixed so I used it as a 62-pound doorstop.
 
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#17
On a happier note a few small droplets of condensation once made it from a overhead pipe through the vents in my Walter Woods Electroacoustic Ultra

it shorted the amp. Walter was able to repair it and it’s still working fine today. So maybe there’s a light at the end of the tunnel.
 
#18
Wavy said:
Interesting. Is that because of cost?
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Partially cost (because it's not generally helpful) and partially because conformally coated PCBA's are much more difficult to troubleshoot and repair.
 
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#19
Wavy said:
Interesting. Is that because of cost?
Click to expand...
It’s not going into an airplane or space rocket, or an engine bay, or oil rig, etc, there’s no environmental reason to do it, the volumes are generally low by mass production standards. Also, the components are generally large compared to PCBs whose components are microelectronics and SMT components so the coating would be odd to apply. Also, most bass amp boards have fly leads rather than sockets so these pads/holes would need screening prior to coating. As would grounding points/holes.
Also, you’d add a coating stage after PCB assembly.

For a SMT flow/wave soldered assembly line you can have a coating stage practically on the same conveyor.

All these reasons are cost. And there’s no need to do it.

Two most horrible things - aerosolised diesel and oil.
Second most horrible - aerosolised salt
Basically… oil rig!!
 
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#20
agedhorse said:
Yes, we poo-poo this approach because without knowing what you are doing AND using appropriate materials you can make a bad problem even worse rather than better. YOU might think it's appropriate, but anybody in manufacturing and support of such gear (professionally) wouldn't agree. Generally, marine electronics PCBs are conformally coated, which is an entirely different process and can be washed more aggressively, but NO amplifier uses conformally coated PCBs.

For example, what was spilled into the OP's amp was a polar compound, therefore CRC QD and all other electronic sprays (which are non-polar solvents) will do absolutely nothing useful. You might want to review your chemistry: https://research.cbc.osu.edu/turro.1/wp-content/uploads/2017/02/PolarityofSolvents.pdf

What's used in industry is deionized water with a sufactant plus a thorough dionized water rinse with an air knife and warm air dry. We do this occasionally on higher value amps (because to do it right AND WARRANTY THE REPAIR) because it's fairly labor intensive and not always successful.

For the OP, if the cost is $100 minimum regardless of success, you may want to consider a replacement amp as that may be less expensive in the long run.
Click to expand...
Listen to this guy - he knows what he's talking about. Accidents happen - time to shop for a new amp!
 
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