Post by Deleted on Oct 24, 2013 22:47:18 GMT
Went to listen to some music last night, turned on my amp and . . . nothing.
No lights, no display, no glowing valves, nothing. Oh, oh!
Removed my mains cable, a good quality Kimber cable, and plugged it into my PSU case for my X-Cans V2. Result? Power on. So I knew it wasn’t a fuse in the mains cable plug as I had hoped. Damn.
I had recently changed my small signal valves from 6N3P’s to the American General Electric 2C51, so thinking maybe one of them had blown, I changed back to the 6N3P’s and switched on – nothing. Sh1t!
O.K., one of my power valves (EL34’s) started glowing brighter than the others last year, so I took the opportunity to bin that one and buy four new valves, keeping the 3 old ones as spares. So I wheeled out my 3 old EL34’s and fitted them and then proceeded to try each of my new valves in the final position, hoping that one of them would be working fine and my amp would fire up – nothing. Damn!
I know that there are supposedly lethal voltages inside valve amps, but the amp hadn’t been on for a few days, so I figured any residual current would have dissipated by then and if I was careful about touching stuff I would be fine, as I just wanted to check any internal fuses. Unplugged everything from the back of the amp and lifted it out of my rack. Not easy as it’s very, very heavy. Unscrewed 20-odd screws from the base to reveal the innards. Immediately spotted a fuse on its own near the switch and 6 others in the middle of the board. According to t’internet it’s best to check fuses on a MM because some can look visually fine but are in fact blown. So I checked the one nearest the switch and found it was fine. Damn!
Removed the other six plastic covers and began to remove the remaining fuses. The second last one broke as I removed it, leaving the end-cap in place in the holder. So I thought (hoped) that this was the culprit and that having blown, had now came apart as I levered it out of its holder. At least I hoped. I inspected the end-cap, found the spec, and went on to Maplins and reserved some for me to pick up the next day. Being late I then went to bed.
Getting up the next morning I thought that if that fuse was not the culprit then I had exhausted my knowledge and capabilities and maybe I should go on to t’internet again and look for valve amp repair specialists. I came across a site called Servicesound who are the repair arm of the valve amp manufacturers English Valve Amps. Faffing around looking at their gallery of repaired amps instead of emailing them for a quote, I came across a write-up of the Tube Technology Unisis amp. In the text it mentioned that they had fitted a fused IEC mains socket to the amp for the customer.
BING! :)A large light-bulb went off in my head. I quickly went to the back of my amp and lo-and-behold – a fuse-holder built into the IEC socket. It was not very obvious and not particularly visible but it was there. I quickly slid the holder out and there it was - a 2.5 amp 250 volt quick blow fuse that had well and truly blown. Back on to Maplins and ordered some of them too. Picked them up today and fitted the 1 amp internal and the 2.5 amp IEC fuse. In a final embarrassment, I noticed that there was a spare fuse in a little compartment behind the one in use – Doh!
So the moral of the story surely is, don’t assume the worst and start with the simple basic things.
No lights, no display, no glowing valves, nothing. Oh, oh!
Removed my mains cable, a good quality Kimber cable, and plugged it into my PSU case for my X-Cans V2. Result? Power on. So I knew it wasn’t a fuse in the mains cable plug as I had hoped. Damn.
I had recently changed my small signal valves from 6N3P’s to the American General Electric 2C51, so thinking maybe one of them had blown, I changed back to the 6N3P’s and switched on – nothing. Sh1t!
O.K., one of my power valves (EL34’s) started glowing brighter than the others last year, so I took the opportunity to bin that one and buy four new valves, keeping the 3 old ones as spares. So I wheeled out my 3 old EL34’s and fitted them and then proceeded to try each of my new valves in the final position, hoping that one of them would be working fine and my amp would fire up – nothing. Damn!
I know that there are supposedly lethal voltages inside valve amps, but the amp hadn’t been on for a few days, so I figured any residual current would have dissipated by then and if I was careful about touching stuff I would be fine, as I just wanted to check any internal fuses. Unplugged everything from the back of the amp and lifted it out of my rack. Not easy as it’s very, very heavy. Unscrewed 20-odd screws from the base to reveal the innards. Immediately spotted a fuse on its own near the switch and 6 others in the middle of the board. According to t’internet it’s best to check fuses on a MM because some can look visually fine but are in fact blown. So I checked the one nearest the switch and found it was fine. Damn!
Removed the other six plastic covers and began to remove the remaining fuses. The second last one broke as I removed it, leaving the end-cap in place in the holder. So I thought (hoped) that this was the culprit and that having blown, had now came apart as I levered it out of its holder. At least I hoped. I inspected the end-cap, found the spec, and went on to Maplins and reserved some for me to pick up the next day. Being late I then went to bed.
Getting up the next morning I thought that if that fuse was not the culprit then I had exhausted my knowledge and capabilities and maybe I should go on to t’internet again and look for valve amp repair specialists. I came across a site called Servicesound who are the repair arm of the valve amp manufacturers English Valve Amps. Faffing around looking at their gallery of repaired amps instead of emailing them for a quote, I came across a write-up of the Tube Technology Unisis amp. In the text it mentioned that they had fitted a fused IEC mains socket to the amp for the customer.
BING! :)A large light-bulb went off in my head. I quickly went to the back of my amp and lo-and-behold – a fuse-holder built into the IEC socket. It was not very obvious and not particularly visible but it was there. I quickly slid the holder out and there it was - a 2.5 amp 250 volt quick blow fuse that had well and truly blown. Back on to Maplins and ordered some of them too. Picked them up today and fitted the 1 amp internal and the 2.5 amp IEC fuse. In a final embarrassment, I noticed that there was a spare fuse in a little compartment behind the one in use – Doh!
So the moral of the story surely is, don’t assume the worst and start with the simple basic things.