What the hell is wrong with me? (within MTS context)

[Mattfig]

You've got a screen grid problem with the runaway bias. I'll put money on it.

Could that cause (or be a co-symptom of whatever is causing) the LB's bass-shyness?

I pulled the chassiseses out of both combos tonight and noticed the C4 spot on the input board has a cap on the RM50 and no cap on the RM50-LB.

Took the [RM50-LB] for a spin and it sounded pretty good on clean and slightly broken up sounds, though on some modules I had to crank the Bass and Density controls just to get to the same level of low end I normally get on other RM amps by turning down the Bass a bit, leaving the Density off, and using a od/boost/eq pedal to tighten up the input signal a bit.

I also noticed this on the no-sound-makin' RM50:

? RM50 combo, silver cloth. Previously owned. Seemed to work fine until I decided to swap out the 6CA7EHs that came in it with EL-34s and noticed that one of the tube/fuse failure lights was on. Replaced the fuse, put in the new tubes, re-biased. No failure light now, but no sound either. Not even hiss.

Gee, that can't be good!

I'd try giving that mess a bit of a gentle cleaning with a few q-tips and some 90+ % iso alcohol...Probably needs some very careful scraping (for lack of a better term) too....

 

[iekobrid]

I'd try giving that mess a bit of a gentle cleaning with a few q-tips and some 90+ % iso alcohol...Probably needs some very careful scraping (for lack of a better term) too....

That was my first instinct too, but on closer inspection that isn't shmutz on the surface of the board -- it's where the surface of the board has been gouged, scraped, burned or dissolved away. Wherever there's no green showing, it's because that layer got up and left.

 

[HughJasol]

I was going to say it looked like acid ate the PCB away . . .

 

[JKD]

Looks like someone self-modded that with a dremel?

 

[iekobrid]

Whatever it was, it didn't affect just the power tube sockets -- it also made a line corralling that row of spade connectors. Must be the infamous Demon Powder mod!

http://youtu.be/qz7z_Ga2e5Y?t=1m13s

 

[crankyrayhanky]

I think I can still return the amp if all this seems like it adds up to another repair I'll never get around to, but I'd have to arrange it within the next 24 hours

 

[iekobrid]

Different amp, unfortunately. Remember, ALL electronics hate me. :/

The most recent one -- the Lynch combo -- ultimately didn't have any problems I felt I couldn't live and/or deal with.

The one in the photos with the gouged circuit board is a plain ol' RM-50 I got earlier this year. From the classifieds here, I think..?

 

[Julia]

I've got a solution for you. Get a decent acoustic guitar. Give up on electronics. Taylor makes a good one. Heck, even Fender makes a decent one for around $400. Or Epiphone Masterbuilt for around $800. You can also save money on these by getting used. Some people just are not supposed to be around electronics.

I could tell you the story about the woman in my office who kept killing her computers. The hardware kept burning out. Mostly the keyboards. It was her hardware until I moved the box about 6 ft away from her. Then we started frequently replacing keyboards.

I'm another one. High voltage stuff like tube amps and I do not play well together. Low voltage stuff (like a modeler) is fine.

 

[iekobrid]

I've been haphazardly saving up for a Taylor for a little while now, yeah.


This gougified RM-50 and a beat up Crate combo I found in the garage this weekend got me thinking -- what's the proper method of old amp disposal? Can they be thrown in a bulk trash dumpster, or do the circuit board metals and capacitors and such mean they need to be taken to a special location, like old batteries and paint and transmission fluid and whatnot?

 

[Julia]

I've been haphazardly saving up for a Taylor for a little while now, yeah.


This gougified RM-50 and a beat up Crate combo I found in the garage this weekend got me thinking -- what's the proper method of old amp disposal? Can they be thrown in a bulk trash dumpster, or do the circuit board metals and capacitors and such mean they need to be taken to a special location, like old batteries and paint and transmission fluid and whatnot?

Goodwill takes and recycles old electronic equipment working or not.

 

[GtrGeorge!]

Not to be a downer but...
Id return the amp pronto..
stating the obvious is my hobby so...

When the PCB board is shot its pretty much game over.

The old persistant problem with PCBs is they are inflexible, and they can't take a serious impact. It's weird but old amps used a more flexible material and If you look at a 1964 Fender Deluxe reverb the "board maybe buckled but it works great 9 outta 10 times!!
Sometimes progress isn't progress.

GtrGeorge

 

[iekobrid]

The returnable amp and the screwed up PCB amp are two different ones, sadly. I've got four different MTS amps in this thread that refuse to cooperate with me in one way or another.

 

[GtrGeorge!]

Hey man..if it makes you feel any better..
I also own some gear thats in need of help.

But I always buy used and I do really use my gear once I own it....so its somewhat to be expected.
All my gear hassles over the years has taught me alot..and THAT's why I am so harsh on production outside the US and why I am quick to bash dumb-*** designs...ya know like when the genius'smount the front knob POTS to the PCB...
that will NOT last!
so you aint alone and hey its ok....We all have a herd to maintain.

GtrGeorge

 

[kc2eeb]

First,
Randall had high voltage arcing problems because the the ground foil around the output tube sockets was a little too close to the tube pins.
It's entirely possible that was done at Randall although what I've seen come from Randall is a litter neater.
Both of the replacement power amp boards I've gotten DIRECT FROM
Randall have the ground plane foil removed from the output tube sockets to avoid arcing.
Second,
The high voltage is connected to the boards by white wires from the power supply and then to the center tap of the power transformer.
You can also get arcing there.
See this link to work I did on my own amp.
http://mtsforum.grailtone.com/viewtopic.php?t=12785&highlight=lots+pictures+rm50+repair

 

[iekobrid]

I'm considering taking advantage of Funky Munky's MTS deals to treat myself to a brand new amp for a change instead of always inheriting other peoples' problems with used amps.

In our collective experience, which model seems to have had fewer manufacturer defects and/or "design flaws" -- the rm50 or the rm100?

 

[puddy]

I don't think you can have too many amps. I am pretty sure Hoarders doesn't even consider multiple amps as hoarding, its just part of being guitartid :lol:

 

[madDdog67]

Yeah, all this discounted MTS stuff is killing my bank account. I just grabbed a RM20 head and the matching deep cab & a cheapo Ultra mod (for a donor).
This is 2 weeks after buying an RM20 combo, which was 1 week after getting the RM50 head. Hmmm...I see a pattern here .

 

[grbassist]

I have the same issue in my house.
I have four MTS amps. Two do not work.
Instead of fixing the broken ones, I replaced them.
There IS something wrong with us :?
(I'm posting some pictures of my WORKING amps now)

 

[Mattfig]

HI, my name is Fig and I'm an MTS hoarder...

 

[iekobrid]

Hi, Matt! Hi, GRB! You're amongst friends here.

I received a brand new 100KH last week -- $800, shipped straight from Randall/USM. Haven't even opened the box yet. It's still sitting on its end in my entry way, propping up my junk mail. :/