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Roland Cube 60 (orange) hot to the touch

Started by johnpotter, October 08, 2018, 06:04:40 PM

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johnpotter

New amp day, all good except back panel got almost too hot to touch in about 20 minutes. Ambient temperature was about 77 F. I put a fan on it, and cooled right down. I can't imagine these run that hot, and am not looking to cook it to death. Ideas? Comments? Off to the tech?

phatt

If it's **almost** too hot to touch in about 20 minutes,, then likely it's normal.
As long as the sound is clear and strong with no bad Humm or Buzz then I'd leave it.
If the unit is brand new then ask the shop,,
If it's 2nd Hand I'd email the maker for advice.
Phil.

johnpotter

#2
The unit is 40 years old, maybe older. Roland knows nothing about these units, there are 2 or 3 generations of redesigns which are quite dissimilar to these.

MS

phatt

OK then turn it on, plug in your guitar, turn master volume down to zero, wait for 20 min.
It should be at room temp or just warm. If it's still too hot to touch when not passing signal then it may have a problem.
Phil.

Jazz P Bass

#4
" Ambient temperature was about 77 F"
Please provide the next data set.
What is the actual temperature of the back panel?

Is this anomaly seen when playing the amp or at idle?
If at playing: what wattage output?

My point is that the amp consumes power.
O/k.
Power equals heat.
There is a known power dissipation at idle and at full power output.

Whether or not there is an issue with the unit depends on these specifications.

johnpotter

#5
Quote from: phatt on October 09, 2018, 09:34:00 PM
OK then turn it on, plug in your guitar, turn master volume down to zero, wait for 20 min.
It should be at room temp or just warm. If it's still too hot to touch when not passing signal then it may have a problem.
Phil.

After 20 minutes at idle or playing at no louder than a conversational level, the back panel is much hotter than I would want any of my h-fi equipment to get; maybe not too hot to touch, but other ss amps from my past (Acoustic 123, Acoustic 134, Peavey Renown, Bandit 65 (x2), Nashville 400; Fender Frontman 100 (x 2) did not get this hot.

solderer25

You need to find out which component/s is/are getting too hot. If it has two or four output transistors (usually bolted to the back panel or a heat sink) and these are getting hot then it may need rebiasing. There is usually a small variable resistor (preset) somewhere on the
circuit board to adjust this. Warning - do not attempt to do this adjustment unless you have suitable experience with electronics. You could do more harm than good if you start adjusting things ad hoc.

johnpotter

Quote from: solderer25 on October 10, 2018, 05:09:54 PM
You need to find out which component/s is/are getting too hot. If it has two or four output transistors (usually bolted to the back panel or a heat sink) and these are getting hot then it may need rebiasing. There is usually a small variable resistor (preset) somewhere on the
circuit board to adjust this. Warning - do not attempt to do this adjustment unless you have suitable experience with electronics. You could do more harm than good if you start adjusting things ad hoc.

Off to my tech......