Forum Replies Created
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Hey Tim, thanks for the welcome!
To be honest I wish I did understand much of what I’ve written lol. Well, I do wish I’d apprenticed to one of those great amp tech guru types in my youth and studied audio electronics (both pro audio and hifi) as I’m much more an analog type of person, even though I’m a computer consultant by trade. Heck, I listen to most of my music on LP or open reel tape *grin*.
Anyhoo, I’ll be seein’ ya round de boards, b’y.
Cheers
Thanks again. I’ll start whispering sweet nothings into the ears of the folks at the Plexi forum and see if I can get some insight.
BTW, assplosions generally are what happens the morning after the night before of multiple pints followed by the inevitable consumption of otherwise inedible greasy nosh at a place even the health department wouldn’t step foot in whilst sober. 😯
Cheers
Sorry if those schems made your head swim – they just about made my head assplode lol.
I do believe there is trouble with the muting feature. I first replaced all the 12AX7s with known working ones, but still no joy.
I don’t have replacement output tubes handy, but I believe it is possibly not them due to an apparently healthy glow from their guts as well as the fact that I took the output of the FX send circuit to an external amplifier and still no joy. I’ve tried injecting a signal back into the FX return and still nuffin.
I read where the mute works electronically (it’s not a matter of purely physical switching), but I can’t find the post which stated this and how it worked.
As I said, it’s the complete lack of output anywhere on this thing which has me thinking it’s in a permanently muted state. Another thing: I tested the caps which seem to relate to the muting in situ and one of them tests fine, but the other doesn’t give me a reading at all. I am going to try testing that guy out of circuit to see if it’s just that and go from there.
Thanks again for your help here. I don’t want to be seen as a noob who just barges onto a forum and demands help then leaves. As I learn more hopefully I’ll be able to help other noobs as well 😉
Cheers
Ah, hi 1bass! Thanks for replying.
I’ll give you a more detailed rundown on the sitch here.
Again the problem is that there is no output from any orifice on this thing, such that neither the pre nor power sections can be isolated as the culprit.
I’ve noted that this and some of the newer (and older? I dunno) Marshalls have muting circuitry as part of their Neutrik 1/4″ connectors, so that if you don’t have anything plugged into the input the whole system is in mute mode. I’m heavily leaning towards the possibility that it’s somehow not unmuting when I plug in. The fact that there is utter silence from the speakers indicates to me that, assuming the OPTs are good, it’s just a matter of finding out why the system is in mute mode permanently.
You can find the schematic for my amp at:
http://www.schematicheaven.com/marshallamps/jcm2000_tsl60_60w.pdf
I’ve not done any live testing yet, but I am somewhat experienced working with hifi tube amps in the past and the safety issues involved. I’m a total wimp when it comes to pain and electrocution so I certainly won’t be taking any chances when it comes to measuring voltages, etc. lol.
If you can maybe give some insight on how to maybe test the muting circuit and/or fix it I’d be most grateful. I’d just as soon give this unit to an official repair shop, but there ain’t none for about a thousand miles, and even then the cost of shipping would make it prohibitively expensive to do.
Cheers
Hey b’y! <-- A common, friendly greeting here in Bermuda 😀 Thanks for the warm welcome - I'm currently bashing out a reply in the other thread, but just wanna say that you're an incredibly cool guy for helping out a total noob to the board here. I hope I can contribute back at some point to other noobs lol. Cheers!
Hey, thanks for the welcome, lee. And thanks for the link to the Plexi forum – most useful.
And I’ll have to be sure to make 1bassleft a cuppa and sit him in a comfy chair so I can sweet talk him about my amp’s problems 😀
Seriously, I’ll be buzzing around here often, so I’ll see ya ’round.
Cheers
