DSL 100 headphone in emulated out, disconnected speaker: blew a fuse or transformer

[AamirZ]

My apologies in advance as I'm sure I've done something stupid. I have a DSL1 CR which I've played with headphones and the manual specifically states to disconnect the speaker before doing so. So I figured do the same on my DSL 100HR and some badness has definitely occurred. The volume was very weak and distorted through the headphones so I kept increasing the volume and sure enough something blew. There was a flash of light and then no sound. The tubes look fine and the mains fuse looks fine. From what I've read I've likely blown the HT fuse or output transformer. I will take it to Guitar Center for them to have a look. What is the most likely problem, and can it be fixed? And why is it ok to disconnect the speaker cable on the DSL1 but not on the DSL100?

Thanks in advance. I'm very sad .

 

[PelliX]

to the MF!

My apologies in advance as I'm sure I've done something stupid. I have a DSL1 CR which I've played with headphones and the manual specifically states to disconnect the speaker before doing so. So I figured do the same on my DSL 100HR and some badness has definitely occurred.

That was indeed not very wise, ouch.

The volume was very weak and distorted through the headphones so I kept increasing the volume and sure enough something blew.

Did you have it on standby or not? I presume not?

There was a flash of light and then no sound. The tubes look fine and the mains fuse looks fine. From what I've read I've likely blown the HT fuse or output transformer.

If you're lucky it will be the HT fuse. There's a reasonable chance that the output transformer got fried. Always check the fuse first though - might be an easy fix.

I will take it to Guitar Center for them to have a look.

Be aware this is not covered by warranty. GC do regular repair work, too, right?

What is the most likely problem, and can it be fixed?

See above, output transformer, fuse, output valves - there are a few things that can fail.

And why is it ok to disconnect the speaker cable on the DSL1 but not on the DSL100?

Technically, no valve amp should run without a load (speaker, let's say). On the DSL1 it's possible to get away with it, because it's putting out ~1W and that amount of energy is easy to dissipate in the form of heat. 100W not so.

 

[AamirZ]

Is the HT fuse easily accessed and replaced? I cannot see any external access on my unit, only for the mains fuse.

 

[PelliX]

Is the HT fuse easily accessed and replaced? I cannot see any external access on my unit, only for the mains fuse.

Relatively, yes. You would have to remove the screws holding the chassis in place (on the bottom of the amp) and slide it out. On the main PCB, next to the mains transformer there should be a few fuse holders. Obviously be careful while in there.

 

[AamirZ]

Roger that. I'll give it a look-see. Much appreciated.

 

[AamirZ]

This would be nice if a $0.99 part will salvage my $1,099 amp. Won't make that mistake again. All this so I wouldn't disturb the neighbors...

 

[PelliX]

This would be nice if a $0.99 part will salvage my $1,099 amp. Won't make that mistake again. All this so I wouldn't disturb the neighbors...

Most certainly would be nice if that's the extent of the damage. I'm still curious as to why you didn't have the amp on standby to use the E-out/headphones? Just for the record, you don't need a load/speaker connected when an amp is in standby. In the case of the DSL the preamp and so on is still fully active then. On the DSL1 there is no standby switch, so the only way to mute the output is to disconnect the speaker (or connect a dummy load instead).

 

[TassieViking]

Make sure you get a slow blow fuse, the T stands for slow blow on the fuse.
630mA slow blow.

 

[AamirZ]

Most certainly would be nice if that's the extent of the damage. I'm still curious as to why you didn't have the amp on standby to use the E-out/headphones? Just for the record, you don't need a load/speaker connected when an amp is in standby. In the case of the DSL the preamp and so on is still fully active then. On the DSL1 there is no standby switch, so the only way to mute the output is to disconnect the speaker (or connect a dummy load instead).

I simply wasn't familiar with the proper procedure and was just repeating what I had done with my DSL1 (and double-checked the DSL1 manual to be sure that was the case). Actually, I didn't know (until now) that the amp (or preamp) would put out any signal into the e-out when on standby. I looked for some direction in the DSL100 manual and there is none, not even a mention of being sure to have the speaker connected at all times (although it does say so in capital letters on the back of the amp). I had something in my head about being sure the amp had a proper load at all times, but could not confirm that in the manual and so decided it must be the same procedure as for the DSL1. The bottom line is I don't understand electronics well enough to have known any better, but I do wish it was spelled out better in the manual, especially for something so potentially catastrophic. You can't even read what's written behind the amp if you're simply reaching over to remove the speaker cable.

 

[AamirZ]

Yes, I did order the T630mA. I just hope the original fuse didn't take so long to blow that it didn't entirely prevent additional damage downstream. I guess I'll find out in a couple of days when I receive and install the replacement fuse.

 

[AamirZ]

So I got the replacement fuse today and swapped it out, and much to my dismay I still heard no sound out of my amp . My beloved amp was toast. However, I did notice that if I cranked the volume all the way up to 11, I could faintly hear a horribly distorted signal. At least there was a faint sign of life.

I figured let's just take one more look at the PCB and I noticed that another fuse was discolored and didn't look particularly healthy, although it didn't appear to be completely blown. I replaced that one too, and voila, my amp now sounds completely normal again! I was tempted to swap out the other two HT fuses as well just for good measure, but they looked pristine and the amp sounds pristine so I just left them be.

Boy, I really dodged a bullet there!

 

[Gunner64]

The manual of the Dsl1hr I have does tell you to unhook the speaker when using headphones. Actually it's kind of a warning iirc.

 

[PelliX]

The manual of the Dsl1hr I have does tell you to unhook the speaker when using headphones. Actually it's kind of a warning iirc.

Yeah, because how else would you mute the amp in order to use headphones silently?

The bigger brethren have a standby switch which takes the HT off the output stage, but leaves the preamp fully powered.

 

[Gunner64]

They could have used a switching jack for phones like most small amps I have do.

IMO The headphone outs sound terrible on every Marshall I have that has them.

 

[PelliX]

They could have used a switching jack for phones like most small amps I have do.

Fair point, I guess. I guess this gives you "more flexibility"... no idea what they were thinking during R&D

IMO The headphone outs sound terrible on every Marshall I have that has them.

Yes. It's a complete disaster. That's where Blackstar actually score way higher in my book. Those emulated outs actually work fairly well.

 

[Gunner64]

Fair point, I guess. I guess this gives you "more flexibility"... no idea what they were thinking during R&D



Yes. It's a complete disaster. That's where Blackstar actually score way higher in my book. Those emulated outs actually work fairly well.

Oh yea. I have a Blackstar I'd core 10 that sounds incredible through phones.
I also have a little HT1 Watt head that sounds pretty good through phones.

 

[AamirZ]

My H&K Tubemeister automatically engages a mute circuit if the speaker cable is disconnected. I wonder how difficult that would be to include on a Marshall as a failsafe.

 

[Leonard Neemoil]

My H&K Tubemeister automatically engages a mute circuit if the speaker cable is disconnected. I wonder how difficult that would be to include on a Marshall as a failsafe.

The bean counters will claim it's very difficult.

 

[PelliX]

My H&K Tubemeister automatically engages a mute circuit if the speaker cable is disconnected. I wonder how difficult that would be to include on a Marshall as a failsafe.

Of course I understand your point, yet consider this; the failsafe *is* the fuse. Regardless of the type of fault condition, the fuse will completely open the HT circuit. Muting the amp (like a volume knob) will reduce the chance of damage though there are catches to this. Some amps engage a dummy load - which is a nice feature at first glance. It's actually more expensive to implement than a fuse, does not protect against other fault conditions, does not prevent you from defeating the jack mechanism by plugging in a cable with no cab attached and causes thermal stress inside the amp if used for long periods of time generally. Remember, that's about 200W worth of dummy load we're talking about. Of course one can have both, but from an economical perspective I don't think it makes much sense. While hardly any Marshall amps have this feature, let's also not forget that the DSL is intended to be affordable.

 

[AamirZ]

The irony is that because it's a cheaper option, it becomes more attractive to the less sophisticated user such as myself who generally wouldn't have the wherewithal to crack open the amp hunting for blown fuses.

Another point to consider is that there seems almost unanimous agreement that the em/out feature is garbage anyway, and if I wasn't hunting for a headphone option this wouldn't have happened in the first place. So maybe that's not such a great feature to begin with.

Or most obviously, just document these issues in the manual.

"Put the amp on standby if you plan on using headphones in the emulated out. Do not unplug the speaker cable with the amplifier on!"

It would take like 2 sentences.