My amptech saw my dead RM100. He was startled. DESIGN FLAW!

[Voodoo Amps]

i talked with Voodoo Amps on this. They suggest bigger Transformer so that doesnt happen.

basicly they're saying:
"after buying a randall, you need to rip out the tranny for a better one or it blows up"

While upgrading to a higher quality power transformer will give you a better tone, a lower noise floor and easier to play/smoother feel, it will not prevent high voltage arching on a printed circuit board. For that you will need Corona Dope.


Hope it helps
Trace

 

[skunky_funk]

Check out what my amptech did to my RM100:

He used a cutter to destroy the PCB track between the ground and 1ohm bleed resistor (Check the grey resistor at V4A), and installed a jumper instead. Apparently, the 1ohm resistor is the first line of defense to avoid arcing, which works sort of like a fuse. 2 of the 1ohm resistors opened which was why my amp kept on blowing fuses.

 

[Bewitagos1]

2 of the 1ohm resistors opened which was why my amp kept on blowing fuses.

But what caused the two 5 watt resistors to fail? Outside of physically damaging a resistor, they typically only fail due to a increased amount of current/heat. Even in a back EMF situation when other components fail, its the surge of electrons exceeding the wattage value of the resistor. Keep us updated and thanks for sharing the pictures.

I would have shared photos of mine but basically I just stranded enough wires to create a bridge over the trace and worked it through to the other side of the board to be certain it could handle the current. Not pretty, but hopefuly effective. <Fingers crossed>

Jimmie

 

[skunky_funk]

2 of the 1ohm resistors opened which was why my amp kept on blowing fuses.

But what caused the two 5 watt resistors to fail? Outside of physically damaging a resistor, they typically only fail due to a increased amount of current/heat. Even in a back EMF situation when other components fail, its the surge of electrons exceeding the wattage value of the resistor. Keep us updated and thanks for sharing the pictures.

I would have shared photos of mine but basically I just stranded enough wires to create a bridge over the trace and worked it through to the other side of the board to be certain it could handle the current. Not pretty, but hopefuly effective. <Fingers crossed>

Jimmie

one major complaint that my beloved tech said that the PCB layout in itself was sacrilege! Maybe Randall wanted those spade connectors from the OT wires to be installed quickly without having two or more separate PCBs. the only separate board I saw was the MIDI board. But putting a high voltage terminal and surrounding it with a ground is a huge no-no. The higher the master volume, the higher the current, and more chances of arcing.

I guess Randall should be paying my tech for making this "bug report".

 

[Whoopysnorp]

So I don't suppose there's anything that can be done to correct this flaw, given that it's a PCB?

 

[skunky_funk]

So I don't suppose there's anything that can be done to correct this flaw, given that it's a PCB?

That's what my tech tried to resolve- by putting two jumper wires as a "flyover" for the grounds. The cutesie electrons would prefer to pass there than jump over air.

 

[Whoopysnorp]

So I don't suppose there's anything that can be done to correct this flaw, given that it's a PCB?

That's what my tech tried to resolve- by putting two jumper wires as a "flyover" for the grounds. The cutesie electrons would prefer to pass there than jump over air.

Oh, right, gotcha. Well that would probably be a good preventive measure for any RM100 owner to take, huh?

 

[Bewitagos1]

So I don't suppose there's anything that can be done to correct this flaw, given that it's a PCB?

That's what my tech tried to resolve- by putting two jumper wires as a "flyover" for the grounds. The cutesie electrons would prefer to pass there than jump over air.

perhaps an easier solution can be found at this link (as proposed by someone else) I just hate repairing boards after this product has been applied, the fumes will burn the hair right out of your nostrils.

http://www.mgchemicals.com/downloads/appguide/appguide0404.pdf?PHPSESSID=51382bd04a9fb86b38fa710606250756

 

[bones]

You really have to keep in mind that many people use these amps trouble free every day with no issues what so ever. Most of the time if you are reading it in a public forum like this, someone had an issue and is seeking opinions and advice. How often do you read "hey my amp is/has been flawless for "X" amount of time and I was wondering why?"

I have had all of the MTS line except the RM20 at one point and currently have 2 RM100's. One I bought used with several known issues upfront (Randall fixed it for free and it was out of the warranty period) and the other was used and in great condition (I upgraded it with a MM OT). Both are flawless performers (as were all 4 of my MTS rigs through the last 3 years) and have never once let me down with 2 rehearsals a week and 2-6 gigs a month. I also gig confidently without a backup.

Just food for thought.

yeah i'm still trying to figure out how my amp is so fucking awsome

 

[Daryl]

i talked with Voodoo Amps on this. They suggest bigger Transformer so that doesnt happen.

basicly they're saying:
"after buying a randall, you need to rip out the tranny for a better one or it blows up"

While upgrading to a higher quality power transformer will give you a better tone, a lower noise floor and easier to play/smoother feel, it will not prevent high voltage arching on a printed circuit board. For that you will need Corona Dope.


Hope it helps

Hey Trace,
WTF is Corona Dope? And how do you use it? I am assuming you aren't reffering to snorting Mexican beer. I suppose that it is a insulating layer that allows better electrical isolation between traces. Let me know, bro. Peace :shock: :shock:

 

[m0jo]

i talked with Voodoo Amps on this. They suggest bigger Transformer so that doesnt happen.

basicly they're saying:
"after buying a randall, you need to rip out the tranny for a better one or it blows up"

While upgrading to a higher quality power transformer will give you a better tone, a lower noise floor and easier to play/smoother feel, it will not prevent high voltage arching on a printed circuit board. For that you will need Corona Dope.


Hope it helps

Hey Trace,
WTF is Corona Dope? And how do you use it? I am assuming you aren't reffering to snorting Mexican beer. I suppose that it is a insulating layer that allows better electrical isolation between traces. Let me know, bro. Peace :shock: :shock:

Bewitagos1 just mentioned something like it.
I assume Trace is talking about the same type of stuff.

I'm thinking of doing that on my RT2/50 .. I really don't want any chance of failure, even of there's a veeery low chance of it.

 

[Bewitagos1]

What you need is a power distribution board that is of the newer revision. Both of mine were older boards that the Chineese modified from Bruce's original design. Either get the newer board from Randall or, if you have a skilled hand and a dremal tool and don't mind having boards that look like ****, trim a wider gap between the traces that are 500 volts next to the ground busses. Doug sent me two revised boards at a really good price, now I hear Randall is asking 150 bucks? I got mine sent to me for 35 bucks a piece. This is Randall's fault, and we shouldn't have to pay for their decision to cut corners. Its not the Transformers either. The other thing I have found is to run the master volume on the amp higher, and keep the module volume settings between 9 and 12 o-clock.
Jimmie

 

[m0jo]

What you need is a power distribution board that is of the newer revision. Both of mine were older boards that the Chineese modified from Bruce's original design. Either get the newer board from Randall or, if you have a skilled hand and a dremal tool and don't mind having boards that look like s*&t, trim a wider gap between the traces that are 500 volts next to the ground busses. Doug sent me two revised boards at a really good price, now I hear Randall is asking 150 bucks? I got mine sent to me for 35 bucks a piece. This is Randall's fault, and we shouldn't have to pay for their decision to cut corners. Its not the Transformers either. The other thing I have found is to run the master volume on the amp higher, and keep the module volume settings between 9 and 12 o-clock.
Jimmie

Hmm, any idea how I can see from the outside which revision mine is?

I just closed it up and racked it again after taking gutshots.
But from the gutshots I can't quite make it out.

Maybe someone can check my pics and see wether I have the older or newer revision?
I'd really appreciate that

Here are the pics: http://www.filedropper.com/randallrt2-50

 

[Bewitagos1]

Maybe someone can check my pics and see wether I have the older or newer revision?
I'd really appreciate that

Here are the pics: http://www.filedropper.com/randallrt2-50

I couldn't open the file, check out this thread and see if you have the same problem, the last pic pretty much sums it up, and is the principle in how spark plugs work...
:lol:
http://mtsforum.grailtone.com/viewtopic.php?t=6793&highlight=

 

[m0jo]

Maybe someone can check my pics and see wether I have the older or newer revision?
I'd really appreciate that

Here are the pics: http://www.filedropper.com/randallrt2-50

I couldn't open the file, check out this thread and see if you have the same problem, the last pic pretty much sums it up, and is the principle in how spark plugs work...
:lol:
http://mtsforum.grailtone.com/viewtopic.php?t=6793&highlight=

Awesome, by the looks of it my board has double the space between the traces.

If you're still interested, here's one you can open (I forgot not everybody has WinRar)
http://www.filedropper.com/randallrt2-50_1

 

[Bewitagos1]

Maybe someone can check my pics and see wether I have the older or newer revision?
I'd really appreciate that

Here are the pics: http://www.filedropper.com/randallrt2-50

I couldn't open the file, check out this thread and see if you have the same problem, the last pic pretty much sums it up, and is the principle in how spark plugs work...
:lol:
http://mtsforum.grailtone.com/viewtopic.php?t=6793&highlight=

Awesome, by the looks of it my board has double the space between the traces.

If you're still interested, here's one you can open (I forgot not everybody has WinRar)
http://www.filedropper.com/randallrt2-50_1

Cool, the only other thing that I recommend then is to run the master harder and keep the preamps lower...

 

[m0jo]

Maybe someone can check my pics and see wether I have the older or newer revision?
I'd really appreciate that

Here are the pics: http://www.filedropper.com/randallrt2-50

I couldn't open the file, check out this thread and see if you have the same problem, the last pic pretty much sums it up, and is the principle in how spark plugs work...
:lol:
http://mtsforum.grailtone.com/viewtopic.php?t=6793&highlight=

Awesome, by the looks of it my board has double the space between the traces.

If you're still interested, here's one you can open (I forgot not everybody has WinRar)
http://www.filedropper.com/randallrt2-50_1

Cool, the only other thing that I recommend then is to run the master harder and keep the preamps lower...

Hmm is there any rationale behind this?

Because I think these voltages don't have much to do with which master/volume is full on, if anything it will be the end signal coming through.
This won't be any different, because both masters are in front of the power tubes.
the master on the RT2/50 isn't an attenuator, it's just a last volume knob before the signal hits the tubes.


BTW appropriatly: my band is called SparkPlug :lol: I don't really want my amp to start acting like on though!

 

[Bewitagos1]

Hmm is there any rationale behind this?

Because I think these voltages don't have much to do with which master/volume is full on, if anything it will be the end signal coming through.
This won't be any different, because both masters are in front of the power tubes.
the master on the RT2/50 isn't an attenuator, it's just a last volume knob before the signal hits the tubes.


BTW appropriatly: my band is called SparkPlug :lol: I don't really want my amp to start acting like on though!

The way it was explained to me, is that the Power Output section puts out whatever amount of noise that is thrown at it. Overdrive the pre-amp voltage and the Power Output has to amplify that. Sort of like a trim on a board for a mic, push it into the red and it sounds like **** and then you'll notice how things start getting sideways. So I listened to that advice and tonally, it sounds much better than diming everything to ten.

Jimmie

 

[m0jo]

Hmm is there any rationale behind this?

Because I think these voltages don't have much to do with which master/volume is full on, if anything it will be the end signal coming through.
This won't be any different, because both masters are in front of the power tubes.
the master on the RT2/50 isn't an attenuator, it's just a last volume knob before the signal hits the tubes.


BTW appropriatly: my band is called SparkPlug :lol: I don't really want my amp to start acting like on though!

The way it was explained to me, is that the Power Output section puts out whatever amount of noise that is thrown at it. Overdrive the pre-amp voltage and the Power Output has to amplify that. Sort of like a trim on a board for a mic, push it into the red and it sounds like s*&t and then you'll notice how things start getting sideways. So I listened to that advice and tonally, it sounds much better than diming everything to ten.

Jimmie

You're still not getting what I'm saying
However you configure the two pots: the end signal is what's hitting the power output, wether your run the modules at 10 and master at 1 or the other way around.

The difference in tone between the two has to do with the tonechanges that the pots themselves impose on the signal and whatever circuitry is between them.

The mic analogy doesn't work since the trim = gain on our amps.
The signal is already overdriven.

Maybe we're talking a different language here

 

[Bewitagos1]

Maybe we're talking a different language here

I think perhaps just the opposite is happening. one more time though. if I dime the volume on the module and run the master volume knob on the head low, at least on my rig it sounds horrible, squeels, rumbles etc. not to mention overdrives my GMajor and it refuses to work. But then again am running two very high-gain modified modules. if I reverse the order and run the master volume high where the power output section can breathe and run the volume on the modules lower, i.e.; 9:00, voila! Am also running an ART SLA2 along with it to get W/D/W - total output is around 500 watts into 3- 4X12 cabs.