Hi all, having problems with a superbass my friend owns. It has worked well for years and just suddenly the other day the signal became almost non existent other than a weird farty abrupt sound to the notes when played hard.
Bear in mind i'm a player not a tech but have some knowledge and history of successful repairs.
Here's some findings so far -
All valves seem fine , bias steady at -56v on all pin 5's, no redplating or excessive hum.......
No burnt smell, no burnt components
screen grid resistors all read approx 1k
Can't see any loose or bad solder joints anywhere via magnifiying glass
i/p and o/p jacks all ok and everything cleaned by me
fuses all good and correct value
I piggy backed 50uf 450v axial caps over all the big filter caps in case any were gone and it made no difference to symptoms
checked speaker leads my friend uses , all good and operational
*Now, and I don't know whether this will give any clues but I checked impedance with power off from pin 3 of each group of two power valves to end of HT fuse and got around 36 ohms one side and a little more the other side.
Do any of you experienced guys have any ideas as to what might be going on?
many thanks in advance ! Rob
Bear in mind i'm a player not a tech but have some knowledge and history of successful repairs.
Here's some findings so far -
All valves seem fine , bias steady at -56v on all pin 5's, no redplating or excessive hum.......
No burnt smell, no burnt components
screen grid resistors all read approx 1k
Can't see any loose or bad solder joints anywhere via magnifiying glass
i/p and o/p jacks all ok and everything cleaned by me
fuses all good and correct value
I piggy backed 50uf 450v axial caps over all the big filter caps in case any were gone and it made no difference to symptoms
checked speaker leads my friend uses , all good and operational
*Now, and I don't know whether this will give any clues but I checked impedance with power off from pin 3 of each group of two power valves to end of HT fuse and got around 36 ohms one side and a little more the other side.
Do any of you experienced guys have any ideas as to what might be going on?
many thanks in advance ! Rob