DC-3 LDR's
- Thread starter Teleman
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I don't remember if they are the VTL-5C9's or the 5C1's.
Versions A & B of the DC-3 will have 3 of them.
1 controls the signal being fed to channel 2
1 grounds out channel 2 if channel 1 is sellected
1 turns the EQ on and off
Basically, if they are not firing correctly you will get a mixture of sounds from both channels, no sound at all, or things will not switch when you try to change channels or engage the EQ.
Usually it is the tubes that cause bad sounds.
On some of the older DC's, it is the filter caps occasionally.
What exactly is your amp doing that makes you want to look into this? Knowing what it's doing will help greatly!
Versions A & B of the DC-3 will have 3 of them.
1 controls the signal being fed to channel 2
1 grounds out channel 2 if channel 1 is sellected
1 turns the EQ on and off
Basically, if they are not firing correctly you will get a mixture of sounds from both channels, no sound at all, or things will not switch when you try to change channels or engage the EQ.
Usually it is the tubes that cause bad sounds.
On some of the older DC's, it is the filter caps occasionally.
What exactly is your amp doing that makes you want to look into this? Knowing what it's doing will help greatly!
Thanks for your reply;I have retubed with a set of JJ med. gain,cleaned all pots and jacks,and resoldered the power tube sockets due to intermittent noises.Yet it seemed that the GEQ did little when engaged,virtually unnoticable.When the standby is switched off there is a slight clicking or buzz,but not when the footswitch is unplugged.I did notice that when I had a chance to turn the volume up to band levels(which requires my dear wifes absence)the GEQ was much more effective.So I am not quite sure if there is a problem but would Like to ensure of reliabilty in the future,I am very pleased with this amp and want eliminate anything that may hinder its capabilities-Other than my playing-Kevin
Well, definitely read this first: http://www.aikenamps.com/SafetyTips.html
If it were my amp, I would replace the following:
Big Blue Filter Caps (5)
LDR's (3)
4N33 chips (1 in the A version)(2 in the B version)
That is a good place to start. All of the parts can come directly from Mesa. That way, you know you are putting high quality stuff back in there.
The drawing is available at www.schematicheaven.com
Just make sure that you are good with a soldering iron and comfortable with working in the amp.
Definitely make sure that you have unplugged the amp and the filter caps are discharged. Just yesterday, I took it for granted that the caps were discharged and did not put my meter on a switch in a Maverick. It was only 50 volts DC, but made some really big sparks!
If it were my amp, I would replace the following:
Big Blue Filter Caps (5)
LDR's (3)
4N33 chips (1 in the A version)(2 in the B version)
That is a good place to start. All of the parts can come directly from Mesa. That way, you know you are putting high quality stuff back in there.
The drawing is available at www.schematicheaven.com
Just make sure that you are good with a soldering iron and comfortable with working in the amp.
Definitely make sure that you have unplugged the amp and the filter caps are discharged. Just yesterday, I took it for granted that the caps were discharged and did not put my meter on a switch in a Maverick. It was only 50 volts DC, but made some really big sparks!
Good advice-I have been repairing amps for a few tears,I'm no expert,a bit weak on electronic theory but have pretty good problem solving skills and I have produced my share of sparks.Aikens website is a great resource,I go there often.Thanks for the suggestions,I plan on relacing the filter caps before too long.By the way I dig your idea for repair kits I hope that works out for you.I haven't met an amp yet that couldn't be personalised.
Let me know if you have any questions. I can talk you through lifting the circuit board to replace the big filter caps.
I usually get all of my Mesa replacement parts directly from them. Not sure what they cost most people, I think they give their techs a little discount on some of the stuff.
If you don't care whether or not the caps say, 'Mesa' on them, you can get IC brand caps from www.tedweber.com The 220mf/300v are much smaller and easier to put back in. If you use the huge Mesa ones, you basically have to lift the board out of it's spot to get to some of the solder connections. Otherwise, it is a huge pain.
I usually get all of my Mesa replacement parts directly from them. Not sure what they cost most people, I think they give their techs a little discount on some of the stuff.
If you don't care whether or not the caps say, 'Mesa' on them, you can get IC brand caps from www.tedweber.com The 220mf/300v are much smaller and easier to put back in. If you use the huge Mesa ones, you basically have to lift the board out of it's spot to get to some of the solder connections. Otherwise, it is a huge pain.
Thanks I appreciate that;I had the main board out when I repaired the GEQ.What a *****.I may have some Sprague filter caps of the proper value on hand.Once the maintenance repairs are done do you have any recommendations for making the lead channel less dark,more lively?
