Dangerous Marshall Valvestate Repairs PT II

[Mr White]

Alright lads.
I finally got my 8080 back from some guy who was trying to fix it. He reckons it was a transistor that had blown. BUT He rang Marshall up to find out what it was and they wouldnt tell him. B*ASTARDS!!! [img]images/icons/smile.gif[/img]
Unfortunately he just had the chassis, and I got it back and rigged it up etc and still it doesnt not live. However, all the leds light up and sh*t, but no sound.
Any ideas as to whats wrong with it?.

Jamesy

PS- Ill be more careful with it this time [img]images/icons/wink.gif[/img]

[lerxstcat]

Re: Dangerous Marshall Valvestate Repairs PT II

You'll think I'm nuts, but Pete said this and it worked on my 8040:

Take a short 1/4" patch cord (pedal to pedal type) and patch it between your effects send and return. If it comes alive then the contacts in your effects loop jacks are bad, or dirty. If not, take it to a real tech who Marshall will talk to. They're probably busy all day talking to their authorized repair techs so they won't give the time of day to someone not in their system. Just a guess.

Of course, make sure your cable's good,
the speaker's hooked up to the leads, etc.. too, before you run off to a tech.
Self-explanatory, but we all forget the basics sometimes!

[ June 07, 2003, 07:01 AM: Message edited by: lerxstcat ]

[Mr White]

Re: Dangerous Marshall Valvestate Repairs PT II

Ah.
Thanks man.
Ill try that [img]images/icons/smile.gif[/img]

Jamesy

[Mr White]

Re: Dangerous Marshall Valvestate Repairs PT II

Arg no that didnt work [img]images/icons/frown.gif[/img]
The thing is, it lights up (all the LEDs on the front etc) but I dont get any sound. Theres no noise when I plug the lead in or anything.
[img]images/icons/frown.gif[/img]

James

[jgcable]

Re: Dangerous Marshall Valvestate Repairs PT II

Does it smell burnt? Did any of the caps vent? Plug a speaker cable into the speaker out jack and put a meter on the + and -. What kind of reading are you getting? If it is a transistor or a power supply the chassis will smell.

[Mr White]

Re: Dangerous Marshall Valvestate Repairs PT II

Right Ive gone and found this old knackered voltmeter, (I really need to buy me a multimeter lol). The amp doesnt have a specific speaker out, only a 'Line Out' which I presumed to be the same thing. Plugged a lead in, checked the voltage - there was bugger all (none).
[img]graemlins/scratchhead.gif[/img]

Jamesy

[Mr White]

Re: Dangerous Marshall Valvestate Repairs PT II

Ill try that.
I dont remember it smelling burnt, but I have had burning/smoking problems with it before (remember that lads? Woo! [img]images/icons/grin.gif[/img] )
I was repairing it outside so I havnt noticed any smells as of yet.

James

[Mr White]

Re: Dangerous Marshall Valvestate Repairs PT II

F*ck it [img]graemlins/laugh.gif[/img]
Im taking it to the shop tomorrow [img]images/icons/smile.gif[/img]

Jamesy

[toejam]

Re: Dangerous Marshall Valvestate Repairs PT II

Poor Jamesy. I hope you get that thing up and running soon! [img]images/icons/smile.gif[/img]

[Mr White]

Re: Dangerous Marshall Valvestate Repairs PT II

Hehe thanks. Me too.
I can't use a practice amp for much longer!!! [img]images/icons/grin.gif[/img]
Im spending so much money atm lol. I went from not buying much to buying a guitar neck and some bits from the states (Im in England), a guitar body, im gonna have to get this amp sorted, Im gonna get a set of EMGs off Ebay.com (in the USA) for this project, then Im gonna have to pay to get it set up. And I need to buy a car this summer. Lol, ah well. [img]images/icons/grin.gif[/img]

Jamesy

[Steve]

Re: Dangerous Marshall Valvestate Repairs PT II

since your in England it's a small contry lol take it to marshall your self and cause some serious **** man thats not something that should happen and don't tell em you tryed to fix it or your screwed !!! how far is the marshall factory from your house 3 / 4 hours ? and I bet theyed give you a vip tour as well ! lol !!! I had a crate blue voodoo that did that and they gave me my money back no problem and it was 2 years old ! that kinda **** isn't soppose to happen at all , if you know what your doing and you sound like you do , I've played 15 to 20 year old amps [marshalls] that have never done that ! it's a factory problem let them take care of you and stand behind their name . //Steve

[toejam]

Re: Dangerous Marshall Valvestate Repairs PT II

Steve, I don't think it's a factory problem. I think James said in the old post that it was opened and it looked like somebody had "unprofessionally" tampered with it, IIRC. [img]graemlins/scratchhead.gif[/img] Though, maybe he could still take it direct to Marshall and see if they can fix it.

[Ace]

Re: Dangerous Marshall Valvestate Repairs PT II

The line out is NOT the same as the speaker out. The speaker out signal will be amplified, the line out will be at line level. That is a good idea for diagnostics though. Have you tried running the line out into a small speaker? Have you tried the headphone jack? If you hear sound from those, then you've proably blown your power amp, if not it's probably the preamp.

[Mr White]

Re: Dangerous Marshall Valvestate Repairs PT II

Thanks for your replies lads.

Steve - Hehe yeah the Marshal factory is only about 3-4 hours away, but the amps about probably at least 5 years old. I got it free off my cousin, who got it off a mate of his. He has the same amp himself. He said he got it off his mate who just gave it to him cos he didnt play in a band anymore, and my cousin kept one amp downstairs and one upstairs (convenient! [img]images/icons/grin.gif[/img] ) and he said that he was playing this one and it just stopped working.

Joe - When I opened it up, it seemed dusty, and a coin fell out, but I dont remember saying it had been unprofessionally tampered with... I might've done lol, but youre probably thinking of someone else. If the amps been unprofessionally tampered with, its probably me thats done it [img]graemlins/laugh.gif[/img]

Ace - I thought as much (about the line out being quieter), but theres no headphone socket on the amp [img]graemlins/scratchhead.gif[/img] So in my wisdom, I got my CD walkman, got some old headphones, cut the actual earpieces off, got the bare wires, disconnected the amp from the speaker and tried to see if i got any response/noise using it as a speaker for my CD player. No noise [img]graemlins/scratchhead.gif[/img]

Its lunchtime now, Im gonna take it into the shop this afternoon.

Actually, this is a bit of a stupid question but the power lead is just a standard one isnt it? Standard house plug to three pin power lead? Like a kettle or a computer? What I mean is there isnt a transformer in it or anything? Cos it didnt come with a lead, so I had to, ahem, 'source' one [img]images/icons/smile.gif[/img]

Thanks lads.

Jamesy

[ June 13, 2003, 07:26 AM: Message edited by: Mr White ]

[Ace]

Re: Dangerous Marshall Valvestate Repairs PT II

There is no transformer in the power cord that goes from the wall to the amp. All the Marshall's I've ever opened up were without money, but having a coin floating around in there could easily have shorted something out. I think your vavlestate should have a 12AX7 in the preamp section, have you checked that?