how does rm100 respond when midiboard is discon'd from amp?

[MegaGoo]

So im having a problem in which my randall shorted out the module in the middle slot of my 3-slot rm100 (see http://mtsforum.grailtone.com/viewtopic.php?t=13345) and after tracing down the resistors that blew on the module, it led back to the midiboard. so i disconnected the midi board to see if that would solve things.

the biggest question i'd like answered is: is there any harm in running 1 module in the middle slot, with the midiboard disconnected. i only want to test to see if the module works, i.e. doesnt blow the resistors like it did last time


so i disconnected the midiboard and this happens:
with a module only in socket 1, i can play fine through the module

with a module in socket 1 and another in socket 2, when i turn the amp on and leave on standby, the light on the module indicating that it is selected comes on BOTH. i was afraid to switch off standby

i just cant remember if the modules shorted out upon turning the amp on, or turning it off of standby.

so what is the normal response when you use the amp with the midiboard unplugged? is there any way i can switch modules? the manual channel select button did not work when i had 2 modules plugged in. maybe if i had 3?


also is there any way to tell if my midiboard is indeed the problem? the traces have some wear - the copper (or whatever material) is exposed in spots. the board says rm100-F

and if i have to get a new board, how much will randall charge about?

 

[MegaGoo]

i got antsy and plugged a module into middle slot by itself and turned it on. doing this prior blew up the module, but it didnt do it this time. the only difference is i disconnected the midiboard

only problem is that the output is low, and when i hit the strings really hard, the sound spikes very sharply for a split second. almost as if there is a strong gate on the signal. is this indicative of not having the midi board plugged in? or the sign that there may be something else wrong with my amp? trying to avoid having to send this back to randall

 

[m0jo]

The midi board switches certain relays to select the modules (in the modules themselves I think), so you won't be able to select any modules then.
It's interesting that all modules came on, probably the relays are open by default..

About the sound, that could be because the switching is screwed up due to the missing midi-board, or there's something wrong (very likely).

I'd try and contact Bruce with this before you do anymore.
Something is seriously wrong, and doing random things might cause more damage (no offence meant, but Bruce will actually know what effect a certain action might and should have so you will be able to safely troubleshoot).

 

[MegaGoo]

Hm ok - What is the best way to get in touch with Bruce? I figured he would just re-direct me to randall support

The midi board switches certain relays to select the modules (in the modules themselves I think), so you won't be able to select any modules then.
It's interesting that all modules came on, probably the relays are open by default..

About the sound, that could be because the switching is screwed up due to the missing midi-board, or there's something wrong (very likely).

I'd try and contact Bruce with this before you do anymore.
Something is seriously wrong, and doing random things might cause more damage (no offence meant, but Bruce will actually know what effect a certain action might and should have so you will be able to safely troubleshoot).

 

[m0jo]

Hm ok - What is the best way to get in touch with Bruce? I figured he would just re-direct me to randall support

The midi board switches certain relays to select the modules (in the modules themselves I think), so you won't be able to select any modules then.
It's interesting that all modules came on, probably the relays are open by default..

About the sound, that could be because the switching is screwed up due to the missing midi-board, or there's something wrong (very likely).

I'd try and contact Bruce with this before you do anymore.
Something is seriously wrong, and doing random things might cause more damage (no offence meant, but Bruce will actually know what effect a certain action might and should have so you will be able to safely troubleshoot).

There are some e-mail addresses floating around here, but you can also PM him. (and hope his inbox isn't full).

I'll see if I can find the e-mail I had from him, but PM should work too.
Or putting "Bruce, help!!" in the topic title haha)

 

[Daryl]

Sounds like something other than the MIDI board to me, my friend. I am not an electronics pro like some of the other guys, but I don't believe that the MIDI board has any real bearing on the function of the signal path. It handles switching. (Correct me if I'm wrong, fellas)
The low output situation you mentioned reminds me of an almost identical issue I had with my RM100. I was stumped, until I remembered to clean all of my jacks thoroughly, particularly the effects loop jacks. Solved the problem. I kicked myself for that one...If I were you, I'd check the fuse on the MIDI board, re-install the board, and clean all jacks and contacts with Deoxit5. Check to see if there is excessive corrosion on any of the contacts in the jack assemblies and if there is: use some 400grit Wet/dry sandpaper to remove the buildup. Don't use anything other than Wet/dry paper unless you want grit in your chassis...LOL I hope someone speaks up about the blown resistors on your module. That is not fun...Never had that happen, knock on wood...

 

[Mister Joshua]

Sounds like something other than the MIDI board to me, my friend. I am not an electronics pro like some of the other guys, but I don't believe that the MIDI board has any real bearing on the function of the signal path. It handles switching. (Correct me if I'm wrong, fellas)
The low output situation you mentioned reminds me of an almost identical issue I had with my RM100. I was stumped, until I remembered to clean all of my jacks thoroughly, particularly the effects loop jacks. Solved the problem. I kicked myself for that one...If I were you, I'd check the fuse on the MIDI board, re-install the board, and clean all jacks and contacts with Deoxit5. Check to see if there is excessive corrosion on any of the contacts in the jack assemblies and if there is: use some 400grit Wet/dry sandpaper to remove the buildup. Don't use anything other than Wet/dry paper unless you want grit in your chassis...LOL I hope someone speaks up about the blown resistors on your module. That is not fun...Never had that happen, knock on wood...

You are correct. The MIDI board does not affect the signal path. I would do as Daryl says about cleaning and inspecting the amp thoroughly and see what happens. 90% of all problems can be solved with a good cleaning and maintenance run. Let us know if the problem persists and we'll shoot out a plan B

Peace, Joshua

 

[Daryl]

...90% of all problems can be solved with a good cleaning and maintenance run...
Peace, Joshua

Especially when there is an issue that is intermittent. If it works and then doesn't and then works again, it is probably a dirty contact or even loose terminal connection. Terminals...I'd check those little suckers while you are in there. They can wiggle loose over time. We'll get you taken care of eventually, bro. PM'd.
Peace....

 

[MegaGoo]

will check all terminals and clean all jacks etc with contact cleaner and report back.

thanks
Eddie

 

[MegaGoo]

i do not need this answer any more as i have resolved the issue of blowing modules. although, it does appear that the amp will not act normal when the midi board is unplugged