6100 problem

[manubro1]

just hooked up the cab to my 6100 head, and theres a problem. all three LEDs are on at the same time and all I hear is the same clean sound. Even when I switch channels (either with the footswitch or on the amp) theres always the same clean sound and all three LEDs stay on. Whats my problem and how do I fix it?

 

[rjohns1]

You might need to do a reset on the midi circuit. Download the manual from Drtube.com. If that doesn't fix it, report back.

 

[rjohns1]

http://marshallamps.com/downloads/files/30th Anniv. hbk.pdf

 

[ACHIEVEIT]

A permanent solution on your problem is to change the value of a cap that is responsible for the reset of the midi module. I don't remember exactly which one it is right now but you can find a big thread (5-6 pages long) about 6100 in the workbench section, look up my posts and you will find the correct value

 

[rjohns1]

A permanent solution on your problem is to change the value of a cap that is responsible for the reset of the midi module. I don't remember exactly which one it is right now but you can find a big thread (5-6 pages long) about 6100 in the workbench section, look up my posts and you will find the correct value

That was gonna be my next suggestion, but you beat me too it. The original cap is 10uF, I put in a 47uF.

 

[plexilespaul]

You might need to do a reset on the midi circuit. Download the manual from Drtube.com. If that doesn't fix it, report back.

hey rjohns
how do you do a reset on the midi circuit?
is it what it says on the manual? presing reset and channel 1 button while switching the amp on from standby to power?

 

[rjohns1]

Yes, that is what you do.

 

[anitoli]

You might have lost the UVEEPROM. If nothing else works i can help you out.

Pete's 6100 MIDI Support Service

Marshall wont deal with those circuits anymore and they are only rated for 10 year memory retention so you get any code dropout and its over, no more channel switching.

 

[plexilespaul]

You might have lost the UVEEPROM. If nothing else works i can help you out.

Pete's 6100 MIDI Support Service

Marshall wont deal with those circuits anymore and they are only rated for 10 year memory retention so you get any code dropout and its over, no more channel switching.

sounds bad
in the worst case senario can't the midi be pulled out?
and have a mod that switches the channels in an other way?

 

[anitoli]

Modding a 6100 for non-midi switching would be an act of engineering genius.This amp has an extremely complicated yet easy to maintain circuit provided the parts remain available. Being a 5 volt circuit the odds of having a major fry-out are nil, so you need only concentrate on what WILL go wrong. That being said the most vulnerable part is the 27c64 UVEEPROM. This contains the 80c31's operating system and if this loses data or becomes inoperable nothing else will work either. The 93c46 serial eeprom's only purpose is to store the external MIDI addresses for remote switching and nothing more. This chip can be totally erased ( as in pushing the store-channel one button at start up) and will have no effect on the channel switching.

These amps are getting old, and the 27c64's were rated for 10 year memory retention. Just like losing a CMOS cluster on a hard drive resulting in a system crash, losing any of the programmed address line on the EEPROM will give the same results.

Pete's 6100 MIDI Support Service

 

[manubro1]

Ok, thanks for the comments guys. It turns out that this problem only happens sometimes. One time, I'll turn on the amp and all 3 LEDs are on, and another time, it works fine. Do you guys think that I should do something about this?

 

[plexilespaul]

Modding a 6100 for non-midi switching would be an act of engineering genius.This amp has an extremely complicated yet easy to maintain circuit provided the parts remain available. Being a 5 volt circuit the odds of having a major fry-out are nil, so you need only concentrate on what WILL go wrong. That being said the most vulnerable part is the 27c64 UVEEPROM. This contains the 80c31's operating system and if this loses data or becomes inoperable nothing else will work either. The 93c46 serial eeprom's only purpose is to store the external MIDI addresses for remote switching and nothing more. This chip can be totally erased ( as in pushing the store-channel one button at start up) and will have no effect on the channel switching.

These amps are getting old, and the 27c64's were rated for 10 year memory retention. Just like losing a CMOS cluster on a hard drive resulting in a system crash, losing any of the programmed address line on the EEPROM will give the same results.

Pete's 6100 MIDI Support Service

from your experience does it actually happen???what's the best pervention steps to take?

 

[Marshall Mann]

Ok, thanks for the comments guys. It turns out that this problem only happens sometimes. One time, I'll turn on the amp and all 3 LEDs are on, and another time, it works fine. Do you guys think that I should do something about this?

As Achivet and RJ mentioned you may want to replace the cap in the switching circuit, and increase the cap size while you are at it. This should cure the problem.

 

[anitoli]

from your experience does it actually happen???what's the best pervention steps to take?

Dont think you can prevent it, just have to deal with it when it happens,and it does happen. I've sold quite a few of these eeproms and no one has ever came back to me and said it didnt solve the probem.

Curoiusly any one out there with a known bad UVEEPROM? Be willing to send it to me sans shipping? I'd really like to make a code comparison to see whats going on. Any takers?

 

[anitoli]

Ok, thanks for the comments guys. It turns out that this problem only happens sometimes. One time, I'll turn on the amp and all 3 LEDs are on, and another time, it works fine. Do you guys think that I should do something about this?

Eventually you will isolate the cause of the problem. Intemittents are the most annoying type to deal with. If you are gigging with this amp it wouldnt put alot of faith in turning it on and off always solving the problem-the problem is there and it will fail sooner or later.

 

[anitoli]

You might need to do a reset on the midi circuit. Download the manual from Drtube.com. If that doesn't fix it, report back.

This procedure resets the MIDI store on the 93c46 as in the manual:

The MIDI section of your Anniversary amplifier is really very simple to
use. It allows you to control your amp’s channel switching (1,2 or 3)
via MIDI program change messages. The Anniversary amp has an
internal memory and can store Channel 1,2 or 3 selection in 128 MIDI
addressable patches. These correspond to the 0 - 127 MIDI
PROGRAM CHANGE message.
Note: The Anniversary amp is preset to receive MIDI messages on MIDI
CHANNEL 1 only.
On pressing the store button, the amplifier channel selection will be
stored in the PATCH number that was LAST received. If no patch message has been received then no store will be
made. Try this example;​

A. ​

​

​

​

​

Send MIDI PROGRAM CHANGE to Anniversary amp (for example 24) B. Select ampchannel (for example 2) C.​

Press store until all three channel LED’S flash momentarily. Now, whenever the Anniversary amp receives MIDI
PROGRAM number 24, it will automatically select Channel 2. The memory will be retained when the amp is switched off.
Note: The internal memory of your Anniversary unit can be reset (all patches Channel 1) by holding down the channel​

1 button and the store button during switch on. Be sure you really want to reset the memory first!

additionally restarting the amp will reset the midi as the MCU has to reload the Program from the 27c64 at the same time. The default channel selection is always channel 1. An intemittant read failure on the 27c64 will cause these strange anomolies but may not nessesarily do this every time. If you are not using external MIDI control the 93c46 does nothing in the circuit.

 

[manubro1]

so i should just press the reset and channel 1 button while switching the standby? this will fix my problem?

 

[CAPDUNN]

If I ever have a problem with channel switching I will send you my chip when I order a replacement from you.

Try the reset and see if it works for you manubro1.

 

[anitoli]

so i should just press the reset and channel 1 button while switching the standby? this will fix my problem?

TO erase the address patch store you press those at power on, not with the standby.

You could try changing the capacitor as others have suggested as this is an easy and inexpesive to try and could cause an issue at startup. Heres why: the 80c31's reset pin #9 is connected to C301 and R301- this configuration is a hard wired reset designed to reset at power up. Vcc is connected to the cap. When power is applied the cap goes high (5vpos) The 80c31 allows the oscillator a few cycles to stabilise then after two machine cycles checks pin #9 for state condition and if high resets the MCU by reloading the program from the 27c64. This only takes a couple of milliseconds so if C301 is dried up and taking too long to reach voltage the startup reset function could be impaired.

To whoever pointed out this-Thank You- this is great trouble shooting stuff.

Since the 80c31 has no interal ROM this is why it needs the external chip and needs to be reset at every power up.

You could change the cap- easy enough to do- and see if that helps, if not you probably got an issue with the 27c64.

 

[anitoli]

If I ever have a problem with channel switching I will send you my chip when I order a replacement from you.

Try the reset and see if it works for you manubro1.

That would be cool, Thanks.