An evil mix of EL84s, ECC83s and SMD on the same PCB.
Oh, and a DSP chip hiding on the back of a tiny PCB that holds 3 jack sockets.
But none of these were the problem.
The amp would run OK for about 10 mins and then power itself down - all the lights go out and the sound fades away.
Turning the power off and waiting a few minutes restored operation, but not for long.
Who has come across this one?
.... Phil
I have never seen one of those but a first guess, look for a cracked smd resistor that opens up with heat. Maybe you can spray some freeze spray around to see if you can localize the problem.
Is it RoHS?
"tm"
** All the clues are there.The amp powers itself off, valve heaters and the dial light goes out and will not restart by itself.
A few minutes with the AC off does the trick.
... Phil
-- I've never seen one of those units, but I'll take a guess that a PTC resettable fuse is in the power transformer primary. It's clicking the set off due to an overcurrent condition (bad transformer, filter caps, rectifiers, etc.). Dave M
"Arfa Daily"
** LOL !!** Give that man a Kewpie doll................. ** For some whacky reason, the Chinese included a PTC ( aka Polyswitch ) in series with the 6.3 volt AC heater supply - adding to their bad judgement, they picked one with too low a current rating.
The heater draw in the Cub 12R is a tad over 3 amps ( = 20 watts) and is the largest load on the AC tranny.
Seems these Polyswitch devices deteriorate with age, if run hot all the time - until they trip and go high resistance. With no heater supply, the dial lamp goes out and the amp goes slowly silent and the same scenario can be repeated indefinitely.
From reading the Laney user's forum, the fault is endemic with the model and you need to fit a 6 amp rated PTC to fix it for sure.
Or just leave it out.
... Phil
If you can't afford freeze spray a Q-tip with 91% alcohol will chill components.
That sounds like it could easily be a dying polyfuse.
?-)
"Arfa Daily"
** Errr - he just answered one ...... Phil
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.