I need a new circuit board for my Marshall 20/40 combo amp. I turn the amp on and it will play for a little while and then all sound ceases until I turn it back on. I've change out tubes to no avail and I broke out my old amp mod equipment and tested circuits. That's the only piece I am unfamiliar with so I'm thinking that's the issue. My vendor tells me they can't order it because the amp is discontinued. Where can I order one so I can fix my amp?

Hello everyone,,

I know that turning a "TUBE" amp on without a speaker load on the output will damage the amp.

(the no-load condition will cause the output voltage to increase until the output tubes burn out, which can then lead to other component  damage)

Is this also true for a CODE 100 amp?  Is there a risk of damage to the output section, with turning the unit on without a speaker cab load connected?

Would it be safe to operate the amp with just headphones connected instead of a speaker cab?

Would it be safe to operate the amp without either a speaker cab or headphones connected?

I ask because my computer (which is a desktop) is in a different location in my house than my amp.

Doing firmware updates or testing out patches requires either moving my computer or my amp, both of which are very inconvenient.

It would be much easier if all I had to move was the head.

Hello

I want to exchange valves in my Origin 20h, ordered some from Tube Amp Doctor. After I exchange them do I have to rebias it? Is there a manual for rebiasing? I wasn't able to find anything which would give me even slight bit of a hint about it .

thanks

iosman

I have a bunch of Marshall amps and recently added a Code 100H to my collection.

I'd like to connect it to a JMD1 102, in order to use it as a valve power amp and cab for the Code as a preamp. I usually do it on my other amps by connecting the send from the "preamp" to the return of the "power amp", but in this case it didn't work, the only way to get some sound from it was connecting the headphones output to the input of the JMD1, but that's not what I expect once I have another preamp in the chain. Did anyone tried something similar?

Currently my JVM410HJS squeals periodically.  Initially this would only happen occasionally and I was still able to gig with it, but now it has become to frequent to use.  It will do this even if unplugged from a guitar and will do it no matter which channel it is on.  Channel switching does not stop it.  I am not sure where to start.  Am going to change out the tubes and reset the MIDI switch, but otherwise will have to travel a good distance to find a qualified tech.  Anyone else ever had this issue?

Ive started playing guitar again later in life after first playing at the age of 10. My skill level is probably moderate but I enjoy playing again. I don’t gig or plan to be in a band. I’m either playing at home by myself or I have a buddy that I will go play with at his house. I have a couple nice Epiphone’s and 2 Yamaha DG60 amps. Theses amps are pretty good and have allot of different adjustments for different sounds. They both have an intermittent issue where something cuts out like the gain or reverb. I’ve though about taking them to get looked at but that’s another decision other then my request. 

Lately I’ve been kicking around getting a new amp. The more research I do the more I get confused. Get another solid state amp, a modeling amp or a tube amp. I’ve never had a Marshal and out of pure envy I’d like to get a Marshall but only if it’s the right amp for me. Money isn’t a deterrent. I’ve worked my way up to looking at a Marshall combo 2x12 100 watt. JVM210C. 

The reallity is I don’t think a 100W tube amp is a smart choice for me. Currently I play my 60W no more then 50% volume. And from what I’ve been told is you need to turn up a tube amp to saturate the tubes to get the most out of the sound. I’d probably only turn a 100Watt up past 50% on rare occasions like when I’m drunk and think I sound better then I really do. 

Is there a 1x12 or 2x12 Marshall tube amp that you can switch between 50W and 100W? That might satisfy my needs? What about the JVM215C? What about the code 50?

I should note I like to play classic rock/rock and metal, Led Zeppelin, Black Sabbath, AC/DC, Kiss, Jimi Hendrix, UFO, OZZY, Pantera..... 

I want something that sounds great played quite or LOUD! I don’t want something that needs a bunch of pedals for different sounds. But I don’t want an amp that has a bunch of effects but just has that fake/cheap sound. I know I’m asking allot. I just need some good advice from someone that has been around music allot and has knowledge about amps. Then I can narrow down some choices and then go to a guitar center or somewhere  and play a couple!

Thank you in advance,

signed “confused” Jeff

Hey Mates,

Having issues with a clients amp, seems that after a retube that i did, he was playing and after about 30 min, it gradually started losing sound and then cut sound completely.  I did the re-tube myself, and biased it properly and i was able to play it for about 40 min with absolutely no issues.  List of troubleshooting steps i have done:

tried a different speaker cable

tried a different guitar cabinet

tried a different guitar and guitar cable

tried the old tubes, additionally bought a 12ax7 and tested each pre-amp tube

tried a different power source

Have tried different power tubes

have checked and replaced the fuses

Now this is what i am THINKING is the problem, I think it might be something with either the heater curcuit fuse, or i think it's called a BRT1 Rectifier?  I did alot of research and it seems that the people having MY issue, explain the same symptoms of what i am having.

Now i have to make this clear, I AM NOT A PROFESSIONAL TECH, just a guy helping bands out with tech stuff that they don't know how to do.  So any help is appreciated.

Thanks!

Hi. I have bought the Marshall Code 212 cabinet with 8OHM. Now I want to buy Marshall DSL1HR tube head with 16OHM. Can I connect 16 OHM head to 8 OHM cabinet? Thanks in advance

So I've been thinking about buying a Celestion F12-X200 speaker for my code 50 and was wondering it this would work. The reason I need to know this is because even though I know you can use an 8ohm speaker on a 4ohm tube amp, I'm not sure about a digital amp. Could anyone tell me if this is possible.

hi everyone, i have a CODE 50 and the biggest complaint i have is finding a preset that allows the amp to be "sensitive" to the controls on my guitars.

you know with any halfway decent tube amp you can ride the volume knob on the guitar to not only turn down (attenuate) the volume but actually change the tone. i know most people use what i call "help me box's" to do this, however, i never use those things. my question is, does anyone know a preset that i can program that will achieve this?

the basic sound would be any Fender or Marshall.

i look forward to anything you all have to say,

thanks,JP

Hey everyone,

I'm hoping someone can help me troubleshoot a new piece of gear I purchased. I recently bought a used Marshall DSL40CR that was running fine, but just tonight the High channel stopped working. Low is perfectly fine, but Highstarted having a  heavily muddied sound and now I'm hearing nothing out of it. All tubes are glowing, but I figured I'd seek out some sage advice before taking things apart and potentially making things worse.

Thanks!

Hi 

I have a TSL 100 that gives low output on crunch and lead channel. (no tube problems)

I´ve seen that this problem is common. Do you have a suggestion what could be wrong?

I suspect one of the J-Fet switches are faulty but I can´t locate any faulty ones?

(I do amp service part time)

Regards / Lars

My J60 tube amp made a loud POP while jamming. All the tubes are secure and lit up, and the fuse still looks good. The amp isn’t making any sound at all though. Any suggestions on what might be the problem?

Can anyone tell me the correct bias settings for a Marshall TSL602? There is conflicting info out there.

Tthe TSL range have 3 pins under an inspection cover on the back. Some people say that the bias should be set to 40mv between the middle pin and the outer (total 80mv). Others say that it should be 80mv per side.

I’ve had the amp for 18 years and always have it set just short of 80mv, but I never seem to get much life out of my valves – probably half the 1,000 hours you’d expect. And the sound always seems to lack a bit of treble. Whenever I have it serviced, it always seems to come back set at around 80mv per side but it always seems to run a bit hot to me.

 Should I be lowering the bias?

High, first off, I am new to the modeling world, my main rig is peavey and Line6 DT25 tube rigs.

I bought a Code 50 as a quick and reliable solid state backup/practice amp to gig with if needed.

I love the sounds of it but at times the BASS just takes over even when Bass knob is rolled to

zero. no matter what settings i use the Bass is booming. I am thinking of a speaker upgrade

possibly but is there any advice on settings that may help me pull the mid range out more. I 

use Super Cleans and Gritty Gains. Hard Rock/Metal sounds

Wes

I recently bought a new DSL40CR. Great sounding amp! Great tones! I am noticing that the low end sounds a bit flubby. I was reading in some forums that this can be caused by improperly adjusted BIAS. Can anyone direct me as to what the mV for each left and right tubes should be set to?

Hello Group! I am about to receive my new Marshall Origin 50 watt head on Monday (March 5th). I'm excited as hell! I was looking for a 50 watt platform to go through my hand made Tweed 1X12 cab with a EVM12L that I built three years ago. I just had a bad expierience buying a Fender Bandmaster VM with a blown digital effects board. The repair facility could not obtain this part from anywhere. I wound up returning it to Reverb.com and was out all the repair money, two 5 hour round trips and $55 to ship it back. I was really devistated until (by accident) I stumbled onto this Origin series amp. I owned a few Marshalls in my day but this one really caught my eye. My question to you guys is this; normally amps come through with pretty basic tubes. I have no idea what the Origin comes with as far as stock tubes. Being the perfectionist that I am and the gear freak I've always been, I'm already wanting to upgrade the 12AX7's (EC83s) and the EL34s. Any suggestions as to a good upgrade or are the stock tubes pretty good? Thanks guys (and gals)

Hi guys,

I want to exchange valves in my Origin 20h, ordered some from Tube Amp Doctor. After I exchange them do I have to rebias it? Is there a manual for rebiasing? I wasn't able to find anything which would give me even slight bit of a hint about it...