Update: Urgent Help. Amps died!

dilithium85

Update: So my amp lasted a couple more practices and gigs then died last week withe same issue but no resurrection. Anyone know someone who can repair amps in Suffolk or near Ipswich Colchester way?

Marshall dsl40c all power is on, was making sound, now not. May be tubes which have some glow but very dim.
Tried different leads and guitars. I have gig Friday anyone about around Ipswich area, get in touch

Alex2678

You can isolate the issue to the preamp if you plug in to the effects loop return and get a sound, you might need to plug a cable into the send jack to activate the loop.

ICBM

If the power is on, the channel LEDs light up but the valves aren’t glowing properly it’s likely to be a filament supply issue. The valve filaments are all in parallel on these so if more than one is dim, it’s not a valve fault.

dilithium85

Alex2678 said:

You can isolate the issue to the preamp if you plug in to the effects loop return and get a sound, you might need to plug a cable into the send jack to activate the loop.

I'll try this at some point today, return with results. 
When I press the button for channel select, it doesn't change, so could be the issue

ICBM

dilithium85 said:

When I press the button for channel select, it doesn't change, so could be the issue

If the channel select isn’t working it’s not a valve problem, it’s something in the low-voltage power supply. Unfortunately this is going to be a tech job.

dilithium85

OK, so just plugged in at home and amp working perfectly fine!?
It died at and practice, could it be there was not enough power coming from wall socket or it was faulty? Just odd as the wall socket next to it was fine

ICBM

dilithium85 said:

OK, so just plugged in at home and amp working perfectly fine!?
It died at and practice, could it be there was not enough power coming from wall socket or it was faulty? Just odd as the wall socket next to it was fine

Hard to tell unless the fault recurs. It could be an intermittent fault with the amp, or it could be a wall socket problem - the one next to it working proves nothing, there can easily be a bad connection between the two even inside the same double outlet.

If the lights on the amp were as bright as normal I suspect it's the amp though - the wall voltage would have to be really low before no sound came out of the amp, and I think you would notice the mains switch neon and channel LEDs being dim. 

Fingers crossed that I'm wrong about that.

inewham

Dry joint, jiggled in the car on the way home?

dilithium85

It's more frustrating now it's working. I could try get it fixed then be charged if there's no problem or the issue can't be replicated
The amps been great for me, nearly 10 years with no problems

RiftAmps

dilithium85 said:

It's more frustrating now it's working. I could try get it fixed then be charged if there's no problem or the issue can't be replicated
The amps been great for me, nearly 10 years with no problems

That's why you need a tech who offers a 'can't find fault, no fee' deal and free safety checks. Not everyone is out to fleece you.

fretmeister

What is your spare amp for the gig?

snowblind

Some of the DSLs, especially early revisions have issues with the low voltage supplies. Definitely get the thing opened up and have a look. Might be a resistor that has been cooked and is breaking up a bit giving an intermittent connection. 

Danny1969

I think I've seen 2 of these with similar symptoms. No sound and no channel changing ?

I fixed one by changing a couple of diodes in the channel switching circuit. Zenors I think but can't remember. 

The other one had a bad Atmel chip. This chip is used for the channel changing and just changing it for a new one won't help as it it needs the code in it. I got the chip from someone on here, @RiftAmps I think ? 

It's possible your IC has moved in it's holder ... this is under the DSP board for the reverb as far as I can remember. This often happens with vibration and chips in sockets. 

I have a spare chip in stock already coded 

dilithium85

Thanks for the insight. I'm definitely not technically savvy enough to replace and fix this problem but that I can inform the person who is

Teyeplayer

Had a similar problem with a HRD some years back. Worked fine, then didn’t. After a few hundred quid of it going in and out of the tech it was sold on. Bloody nightmare. Good luck op, I know how frustrating this is, particularly with gigs on the horizon. 

ICBM

RiftAmps said:

That's why you need a tech who offers a 'can't find fault, no fee' deal and free safety checks. Not everyone is out to fleece you.

I once worked on the most frustrating intermittent fault - a Fender red-knob 'The Twin' which would randomly change channel, and no amount of testing with the chassis out on the bench could replicate the fault, it was only when it was bolted back into the cabinet - it was something caused by the vibration from the speakers at a very specific frequency and/or tension on the chassis. I must have had the thing apart and back together at least twenty times before I eventually found a cracked solder joint in the switching circuit - even then it was pure luck, really. A day's worth of work... for a one-off one-hour bench charge, since the actual fix took all of five minutes.

But I learned a lot from that. I probably should have 'shotgunned' the whole switching circuit and resoldered every joint, even if it looked and metered OK, at a much earlier stage - but although with hindsight that would have fixed it, I didn't know that at the time and I was determined to find out *why* it was faulty... because without that, you can't be certain it won't do it again after it's gone back to the customer.

Danny1969

I've had loads of CD and DVD players where the mech would work fine until everything was screwed back up. Then the laser wouldn't track anymore. 

I charge to look at everything now but the max cost is capped. For a  £30 diag charge I will spend an hour on a board, that's the minimum and the max cost fixed is around £180. Often I will fix something for £30 but still only charge the diag because I don't trust the rest of the circuit not to go wrong. 

I don't fix guitar amps at all any more. They are too time consuming and take up too much room in relation to what the customer expects to pay. A Macbook motherboard customer however will happily pay £180 even if all I did was resolder a QFP chip. 

robgilmo

I remember having to go through my Deuce with ICBM's help to try and figure out why it was cutting out, it turned out that the wiring in the mains plug had come loose.

randella

I remember spending a couple of days raking through an annual leave calendaring system that I'd written trying to find a fault that only presented in seemingly random circumstances. 

Eventually tracked down the problem - the only bit of the system I couldn't automate was the addition of bank holidays. I wrote a bit of UI that enabled HR to enter them manually and someone had added easter Monday twice. 

And yes, there should have been a check. I added one shortly afterwards.

dilithium85

Update: played gig last night and all was fine. Drove 40 mins down some windy back roads so it got moved around. Think I'll still buy a backup amp pedal