Members fitterhappier Posted August 15, 2005 Members Share Posted August 15, 2005 I'm having pretty big problems with my DSL401. A few weeks ago, the overall volume started dropping. It eventually reached the point where I could have everything cranked up to 10 and it would only sound a little bit louder than a "bedroom practice" kind of level. I used to be able to get the same sort of level at about volume 4. I originally assumed it was the power valves, as I hadn't replaced them since I bought the amp about a year ago. So I bought some Ei Elite EL84's a few days ago and changed the valves, but this didn't help. Then yesterday, I turned on my amp, waited for it to warm up, flicked on the standby and struck a chord - but there was no sound. I checked the connections and all the levels, and they were all normal. The power light was on, and I could switch between the channels as usual, but there was just no sound. The only thing I could hear was a very quiet, very low hum, which I could only hear if I press my ear right up against the speaker. Then I looked in the back of the amp and noticed the valves weren't on! I changed back to the old power valves, but still no sound. I looked at the HT and mains fuses, and they're both fine. Any ideas what could be wrong? I'm hoping it's just something simple and inexpensive, but I've got a scary feeling that could just be wishful thinking. Link to comment Share on other sites More sharing options...
Members JimH Posted August 15, 2005 Members Share Posted August 15, 2005 Preamp valves? If no then it's probably tech time, unless you know your way around. Link to comment Share on other sites More sharing options...
Members GCDEF Posted August 15, 2005 Members Share Posted August 15, 2005 You may want to try a search. There are quite a few threads about DSL-401 problems, including volume drops. Link to comment Share on other sites More sharing options...
Members Biz Markie Posted August 16, 2005 Members Share Posted August 16, 2005 My guess would be a faulty preamp tube eventually gave out and caused a fuse to blow. I know you mentioned you checked the HT and mains fuses, BUT I'm thinking there's another one on the circuit board you overlooked. I say this because I had a similar incident with my Marshall JCM 600. Turned the amp on, power indicator lit up, but tubes did not glow at all. I checked the mains fuse and another visible fuse and assumed the fuses weren't the problem, BUT a couple weeks later I did a more thorough investigation of the circuit board and noticed a fuse I overlooked and it was the culprit. Picked up several replacement and popped one in and it's been running fine ever since. I'm giving Marshall the benfit of the doubt in this case. Take another close look at the circuit board and see if you can find another fuse hidden somewhere. Just be careful! Link to comment Share on other sites More sharing options...
Members fitterhappier Posted August 19, 2005 Author Members Share Posted August 19, 2005 well, I checked the fuse inside the amp and it looks fine, and I changed the preamp valves and it still doesn't work looks like I need to carry on my never-ending search for an amp tech thanks anyway for the help, people Link to comment Share on other sites More sharing options...
Members cap'n'crunch Posted August 20, 2005 Members Share Posted August 20, 2005 Cold solder joints are quite common with these amps. I had a tech go over my entire DSL401 5 years ago. Its been fine since. Though, I don't use it much anymore. Just keep it around for a backup. Link to comment Share on other sites More sharing options...
Members pureanalog Posted August 31, 2005 Members Share Posted August 31, 2005 dead output transformer? Link to comment Share on other sites More sharing options...
Members Stratotone Posted August 31, 2005 Members Share Posted August 31, 2005 Sounds (and looks) to me like a problem with power to the filaments... Pete Link to comment Share on other sites More sharing options...
Members kannibul Posted August 31, 2005 Members Share Posted August 31, 2005 Originally posted by fitterhappier I'm having pretty big problems with my DSL401. A few weeks ago, the overall volume started dropping. It eventually reached the point where I could have everything cranked up to 10 and it would only sound a little bit louder than a "bedroom practice" kind of level. I used to be able to get the same sort of level at about volume 4.I originally assumed it was the power valves, as I hadn't replaced them since I bought the amp about a year ago. So I bought some Ei Elite EL84's a few days ago and changed the valves, but this didn't help.Then yesterday, I turned on my amp, waited for it to warm up, flicked on the standby and struck a chord - but there was no sound. I checked the connections and all the levels, and they were all normal. The power light was on, and I could switch between the channels as usual, but there was just no sound. The only thing I could hear was a very quiet, very low hum, which I could only hear if I press my ear right up against the speaker.Then I looked in the back of the amp and noticed the valves weren't on! I changed back to the old power valves, but still no sound. I looked at the HT and mains fuses, and they're both fine. Any ideas what could be wrong? I'm hoping it's just something simple and inexpensive, but I've got a scary feeling that could just be wishful thinking. 1) Did you rebias the amp when you changed the power tubes? 2) Did you look at the fuses, or did you check them with a meter? 3) Do the tubes have a red glow inside (you should only be able to see the tops of them, not the whole tube!) 4) It's probably a preamp tube - either V1 or the PI, if nothing works... 5) Did you try another cable? 6) Did you try another guitar? Link to comment Share on other sites More sharing options...
Members blackba Posted August 31, 2005 Members Share Posted August 31, 2005 Originally posted by cap'n'crunch Cold solder joints are quite common with these amps. I had a tech go over my entire DSL401 5 years ago. Its been fine since. Though, I don't use it much anymore. Just keep it around for a backup. This would be my guess too, a colder solder joint, or 2.... Link to comment Share on other sites More sharing options...
Members rgt320 Posted August 31, 2005 Members Share Posted August 31, 2005 Man, any of you guys see what these amps run for (new) today...like $1000 Link to comment Share on other sites More sharing options...
Members wor lez Posted August 31, 2005 Members Share Posted August 31, 2005 Therell be a crappy joint for the filament supply. Get that fixed and should be fine. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted August 31, 2005 Members Share Posted August 31, 2005 Originally posted by fitterhappier I'm having pretty big problems with my DSL401. A few weeks ago, the overall volume started dropping. It eventually reached the point where I could have everything cranked up to 10 and it would only sound a little bit louder than a "bedroom practice" kind of level. I used to be able to get the same sort of level at about volume 4.I originally assumed it was the power valves, as I hadn't replaced them since I bought the amp about a year ago. So I bought some Ei Elite EL84's a few days ago and changed the valves, but this didn't help.Then yesterday, I turned on my amp, waited for it to warm up, flicked on the standby and struck a chord - but there was no sound. I checked the connections and all the levels, and they were all normal. The power light was on, and I could switch between the channels as usual, but there was just no sound. The only thing I could hear was a very quiet, very low hum, which I could only hear if I press my ear right up against the speaker.Then I looked in the back of the amp and noticed the valves weren't on! I changed back to the old power valves, but still no sound. I looked at the HT and mains fuses, and they're both fine. Any ideas what could be wrong? I'm hoping it's just something simple and inexpensive, but I've got a scary feeling that could just be wishful thinking. Why did you replace the power tubes? Your initial problem sounded more like a preamp tube to me. Have you tried swapping them out one at a time? Link to comment Share on other sites More sharing options...
Members EpiPaul03 Posted August 31, 2005 Members Share Posted August 31, 2005 If you're having a volume problem, it's probably the POWER tubes...The power amp boosts the weak signal of the pre-amp. I don't think pre-amp tubes are the problem here. Link to comment Share on other sites More sharing options...
Members Stratotone Posted August 31, 2005 Members Share Posted August 31, 2005 Originally posted by EpiPaul03 If you're having a volume problem, it's probably the POWER tubes...The power amp boosts the weak signal of the pre-amp.I don't think pre-amp tubes are the problem here. If none of the tubes are lighting up, it's the filament supply. Or at least that's part of it. Pete Link to comment Share on other sites More sharing options...
Members tlbonehead Posted August 31, 2005 Members Share Posted August 31, 2005 Originally posted by Stratotone If none of the tubes are lighting up, it's the filament supply. Or at least that's part of it.Pete Yes,although some tubes don't get very bright. So if they have never looked at them before this problem,they may just think they really aren't lighting up. But if they truly aren't lighting up,yes,you could well be right. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted August 31, 2005 Members Share Posted August 31, 2005 Originally posted by EpiPaul03 If you're having a volume problem, it's probably the POWER tubes...The power amp boosts the weak signal of the pre-amp.I don't think pre-amp tubes are the problem here. Yes,I've been told that a number of times. I've also had quite a few volume loss problems that were solved with a preamp tube swap,usually the V1. Pretty common in higher gain amps. Link to comment Share on other sites More sharing options...
Members XXX Posted August 31, 2005 Members Share Posted August 31, 2005 Originally posted by Danocoustic Waa.WAA.WAAAAAAAAAAAAAAAA!!! Link to comment Share on other sites More sharing options...
Members kannibul Posted September 1, 2005 Members Share Posted September 1, 2005 Originally posted by wor lez Therell be a crappy joint for the filament supply. Get that fixed and should be fine. Where do you get filament supply from his description? It could easily be a lot of other things... EDIT: Duh, 'noticed the valves weren't on' Link to comment Share on other sites More sharing options...
Members kannibul Posted September 1, 2005 Members Share Posted September 1, 2005 Originally posted by EpiPaul03 If you're having a volume problem, it's probably the POWER tubes...The power amp boosts the weak signal of the pre-amp.I don't think pre-amp tubes are the problem here. lol... Think about what you're saying...cause it's wrong. If one of the preamp tubes aren't working correctly, they won't put out much, and you'll have to turn that volume up more to compensate. Link to comment Share on other sites More sharing options...
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