well that at least is a start
always was a pet bitch of mine that the Japanese Receivers always were always stripped down versions in the lower power ranges and if you wanted a thing you had to step up in output power class to get it so even if you did not need or want 200WPC if you had a desire for tape dubbing or pre-main outputs or any number of other useful controls you were fked.
Crank that back to the "Golden Age" of Audio and you could get an integrated with a moderate output power of say 10-20 watts with more controls than you would use in your life time and ALL designed to be actually usable in a real world system.
Rant Mode off
that makes it a bit more difficult to weasel out the dark forces at work here
The fact that there is a small amount of discoloration does not always mean something is amiss when talking about solid state power sections.They generate heat and heat WILL over time cause such even when the gear is operating full balls prefect.
add to that the Power MOSFET is immune to thermal runaway having an internal mechanism as part of its makeup that will actually
reduce current delivery in a fault state rather than ramp it up as in a bipolar that will in the end eat itself in an attempt to create
more more more power dammit !Why you never see the term SOA (safe operating area) used with power mosfets and why the multiple parallel parings of output devices not as extreme.
If the MOSFET has a weakness it is at the gate and even a seemingly innocent AC transient spike if the impulse high enough in magnetude can take them out (furnace clicking on
).
I would do a "google" on the model number and see what spits out.Don't read the "Web" links but instead go right to the "images" page and see if maybe you can weasle up a schematic (if you get jammed up post the model and I'll scare up the schemo if one is out there
).With that in hand you can then have a starting point that will allow :
1-check for the output device availability/replacement cost or if obsolete (likely
) the replacement
2-Find the point on the pcb were you can inject a signal directly into the power amp section input to see if maybe the problem lies elsewhere or if in fact the power devices are toated.
Tools needed ?
Shit speakers and a portable CD player with test tone disc burned on your computer from any of the free to download test tone files,adapter cable with a Mini TRS Plug on one end (PCDP Output) to probe tip (hot)/clip on tip (Gnd) so you can get the signal where you need to.
I should add if you murder yourself by being inattentive of the HUGE power supply capacitors and while probing just happen to brush your inner wrist against them I will not be held responsible dude
A damn fine idea for "second system" ampage and I have one kicking around the house ready to rock at a moments notice any time I have a neeed for a "utility" amp.not the last word in SQ compared to my Triode amps or even my Beam Pentode mini-amp but nice just the same.Check the thread I opened in the DIY section for leads
switch contactsd are self wiping so any time i get my paws on a piece of vintage gear on the bench the very first thing I do,even before lashing it up and plugging 'er in is I cycle through all the controls rapidly and for a period of time to break through any possible crud built up over the years of non use or rare use.
BTW-A used control is a
HAPPY control so also good practice to do a monthly audio system control "wakeup call" just because it is a
good thing (ode to Martha
)
Contact cleaners have a place but the "Quick and Dirty El Cheapo Monster Squad" like to go straight to "free and easy" as option #1 then if we must,and only then actually do some work and/or spend some loot
very cool
Treat it nice man ! You don't want the rickmonster coming over there to straighten you out !