Blulite
hey guys... here i go again with another audio system issue.... the story of my life...lol.
so my elictricity tripped today while i had my hifi setup running in the living room.... i sorted everything out... seems my dishwasher didnt want to play ball for some reason.. but its fine now.
anyway, i swiched my amp back on and it went "BUUUUUUUUUUUUUUUUUUUUUUUUUURRRRRRRRRRRRRRRRRRR" at full volume..... i almost had kittens...
i messed around with switching it on and off an d pulling and plugging speakers and inputs....
if i unplug the laptop from the amp, i still get the "BBBUUUUURRRRRR" so im assuming the power outage has caused a problem with my amp...
any ideas????
so my elictricity tripped today while i had my hifi setup running in the living room.... i sorted everything out... seems my dishwasher didnt want to play ball for some reason.. but its fine now.
anyway, i swiched my amp back on and it went "BUUUUUUUUUUUUUUUUUUUUUUUUUURRRRRRRRRRRRRRRRRRR" at full volume..... i almost had kittens...
i messed around with switching it on and off an d pulling and plugging speakers and inputs....
if i unplug the laptop from the amp, i still get the "BBBUUUUURRRRRR" so im assuming the power outage has caused a problem with my amp...
any ideas????
Inviato Mon 31 Oct 11 @ 2:04 pm
djnutz
I would consider getting a Fuhrman power conditioner. They have a warranty that if their equipment does not prevent damage from surges, etc, they will pay for the repairs or replacement.
Inviato Mon 31 Oct 11 @ 9:08 pm
Dazmax
Hi Blu.
Your H/H amp uses a pair of TO3 ouput transistors. If a large forward or rearward movement of the Bass cone occurs when you switch on (Don't do this repeatedly BTW) its a fair bet that one has failed or that one of the power amp rail fuses has failed (Fuses mounted on the power amp PCB). You can also check this with a multimeter if you have one. Set to the DC volts range and check at the output socket (Anything above a few millivolts is a problem and if the OP stage has failed you may well see around 40 to 50 Volts DC so watch your fingers!!!!) The origonal transistors are hard to get hold of now but part No 2N3773 transistors are a good alterate swap (You MUST change both tho).
Other possible faults that can give you the same symptom would be a failure of one side of iether the regulated +-15v power supply (used for the pre amp ic'sand mesured on the front PCB.) or one side of the main power amp supply (Mesured on the power amp PCB fuses. 1 for + and one for -)
I still have schematics for most of the H/H gear so let me know if you get stuck. Any mesurements should be taken between audio ground and the mesurement point.
Good luck But be safe!!!!
Daz
Your H/H amp uses a pair of TO3 ouput transistors. If a large forward or rearward movement of the Bass cone occurs when you switch on (Don't do this repeatedly BTW) its a fair bet that one has failed or that one of the power amp rail fuses has failed (Fuses mounted on the power amp PCB). You can also check this with a multimeter if you have one. Set to the DC volts range and check at the output socket (Anything above a few millivolts is a problem and if the OP stage has failed you may well see around 40 to 50 Volts DC so watch your fingers!!!!) The origonal transistors are hard to get hold of now but part No 2N3773 transistors are a good alterate swap (You MUST change both tho).
Other possible faults that can give you the same symptom would be a failure of one side of iether the regulated +-15v power supply (used for the pre amp ic'sand mesured on the front PCB.) or one side of the main power amp supply (Mesured on the power amp PCB fuses. 1 for + and one for -)
I still have schematics for most of the H/H gear so let me know if you get stuck. Any mesurements should be taken between audio ground and the mesurement point.
Good luck But be safe!!!!
Daz
Inviato Tue 01 Nov 11 @ 4:07 am
Dazmax
Hi Blu
If you are after any parts or info on H/H gear check this company out. www.majelectronic.co.uk They cary most spares and are very helpfull.
Daz
If you are after any parts or info on H/H gear check this company out. www.majelectronic.co.uk They cary most spares and are very helpfull.
Daz
Inviato Tue 01 Nov 11 @ 5:43 am
Blulite
just an udate and another question, after the amp was off for a day or two while i was busy, i turned it back on and its now fine.
the next question is ive noticed a hiss as t low volume or zero volume levels, is this normal?
the next question is ive noticed a hiss as t low volume or zero volume levels, is this normal?
Inviato Sun 06 Nov 11 @ 4:06 am
Clayton.G.Finley
its probably a grounding issue, this more than likely will fix low level hizzing problems. get one of those 50 cent plug adaptors that has a three prong into a two prong (for plugging something in to an outlet that does not have a ground) and that should take care of it.
(i have to run these on my gear, due to the shitty old ass apartment i live in) it could potentially damage your gear, so keep that in mind.
(i have to run these on my gear, due to the shitty old ass apartment i live in) it could potentially damage your gear, so keep that in mind.
Inviato Sun 06 Nov 11 @ 11:25 am
Dazmax
H/H amps were never the quietest in the world. Especialy ones with the mechanical Spring Reverb units.
One tip is to set up a gain structure for the amp. Set the master to a low level, turn up the input gain until you hear it start to distort and then wind the input gain back untill it sounds nice and clear. Then only use the master to control the volume level. If you are still getting a realy noticable hiss that was not there before, with the Master turned right down then there may be a problem with the power amp stage so keep an eye on it.
If you were realy bothered by it you could change the OP AMP ics (Think they are standard 741 type and noisy as hell) for a quieter more modern chip (TLO71) for example. Just changeing the two chips on the input stage, the last one that provides the signal from the pre amp to the power amp and definately the one on the power amp board can make one of those older amps much quieter. Watch out for that other problem coming back. If it does it could be that a component is breaking down under certain conditions. Bridge rectifiers used in the power supply can be a candidate for intermittent issues like this.
If you are working on the amp make sure you leave plenty of time between switching off, unplugging and doing any work inside. The power supply capacitors need time to discharge. Remember that when they are still charged they sit with over 100VDC between the + and - rails.
Daz
One tip is to set up a gain structure for the amp. Set the master to a low level, turn up the input gain until you hear it start to distort and then wind the input gain back untill it sounds nice and clear. Then only use the master to control the volume level. If you are still getting a realy noticable hiss that was not there before, with the Master turned right down then there may be a problem with the power amp stage so keep an eye on it.
If you were realy bothered by it you could change the OP AMP ics (Think they are standard 741 type and noisy as hell) for a quieter more modern chip (TLO71) for example. Just changeing the two chips on the input stage, the last one that provides the signal from the pre amp to the power amp and definately the one on the power amp board can make one of those older amps much quieter. Watch out for that other problem coming back. If it does it could be that a component is breaking down under certain conditions. Bridge rectifiers used in the power supply can be a candidate for intermittent issues like this.
If you are working on the amp make sure you leave plenty of time between switching off, unplugging and doing any work inside. The power supply capacitors need time to discharge. Remember that when they are still charged they sit with over 100VDC between the + and - rails.
Daz
Inviato Fri 18 Nov 11 @ 2:51 am