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bjp · 06-28-2009, 03:58 AM

To everyone,

I own a Super Lead 100 head made in Sept 1971, when I aquired it in 1991, it was not working. It needed a power transformer, rectifier diodes, and one grid resistor (all burnt out ). I rebuilt the power supply, replaced all the valves and other components that looked damaged or were out of spec. I used it a couple of times , then let it sit for some time till recently ( Last month ). Naturally it didn't sound too good after so long and there was a lot of hum. So I replaced all the filter caps as they were about to let go.This reduced the hum significantly, but it seems to persist a bit, particularly when the volume controls were turned up ( without anything plugged in). The hum is a 50hz, also the presence control introduces a scraping sound when it turned up or down and the hum increases as it is turned up. Yesterday I replaced the presence pot and nothing has changed.

When I tried the amp out after recapping, despite the abnormal hum, it sounded great. Loud and really quite majestic, so potentially this amp holds a lot of promise and I would like to use it at gigs ( now that I'm playing in a band again ). When testing I noted that under heavy use valve 3 would glow differently than the others intermittently, all valves remained an orange color. I have decided I will replace all the valves, output with winged c's .

Last night I planned to use / trial the head at a gig, I set it up turned it on - let it warm up and did a sound check at low volume it was all good until the end of the sound check. Just before switching to standby there was a crackle/pop sound, which made me leave it on for a while longer, the frequency of this increased. I switched the stand by on back off again and it started to motorboat, I turned the amp off and swapped amps. It was disappointing as the super lead sounded so much better .

Has anyone any ideas as to why

1) the hum is occurring ( there is a slight humming sound from the power transformer when the amp is turned on but it remains moderately cool in use. )

2) Why the presence control causes this scraping sound

3)what could be the cause of the motor boating now occurring

Any ideas, knowledge, solutions ( no matter how technical ), or experiences anyone can share I would be really appreciative.

Thanks for reading this

Best regards to all BJP

06-28-2009, 03:58 AM	#1 (permalink)
bjp Junior Member Join Date: Jun 2009 Posts: 8	1971 Super Lead 100 problems To everyone, I own a Super Lead 100 head made in Sept 1971, when I aquired it in 1991, it was not working. It needed a power transformer, rectifier diodes, and one grid resistor (all burnt out ). I rebuilt the power supply, replaced all the valves and other components that looked damaged or were out of spec. I used it a couple of times , then let it sit for some time till recently ( Last month ). Naturally it didn't sound too good after so long and there was a lot of hum. So I replaced all the filter caps as they were about to let go.This reduced the hum significantly, but it seems to persist a bit, particularly when the volume controls were turned up ( without anything plugged in). The hum is a 50hz, also the presence control introduces a scraping sound when it turned up or down and the hum increases as it is turned up. Yesterday I replaced the presence pot and nothing has changed. When I tried the amp out after recapping, despite the abnormal hum, it sounded great. Loud and really quite majestic, so potentially this amp holds a lot of promise and I would like to use it at gigs ( now that I'm playing in a band again ). When testing I noted that under heavy use valve 3 would glow differently than the others intermittently, all valves remained an orange color. I have decided I will replace all the valves, output with winged c's . Last night I planned to use / trial the head at a gig, I set it up turned it on - let it warm up and did a sound check at low volume it was all good until the end of the sound check. Just before switching to standby there was a crackle/pop sound, which made me leave it on for a while longer, the frequency of this increased. I switched the stand by on back off again and it started to motorboat, I turned the amp off and swapped amps. It was disappointing as the super lead sounded so much better . Has anyone any ideas as to why 1) the hum is occurring ( there is a slight humming sound from the power transformer when the amp is turned on but it remains moderately cool in use. ) 2) Why the presence control causes this scraping sound 3)what could be the cause of the motor boating now occurring Any ideas, knowledge, solutions ( no matter how technical ), or experiences anyone can share I would be really appreciative. Thanks for reading this Best regards to all BJP