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Discussion Starter #1
Hey guys, I am a toolmaker by trade, i know a little about electricity and electronics, but everything I know is from reading and asking questions. I can follow a layout no problem. But when it comes to terminology I am lost. I'm 99% finished my Trinity build. I need one more component before testing. But before I
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test I want to add something that is mentioned in the guide as a "convenience"

Here's the deal, In the amp builders guide that comes with a trinity amp, there is a section telling you how to power up the amp for the first time. But because of the dangers of Caps holding juice, they recommend putting in a temporary or permanent resistor to drain that power to ground when the power is shut off. I get that, but what i don't understand is where to put it. The terminology of the description is above my pay grade. LOL

So, you can permanently install a 220k 2W resistor on the B+ line to chassis ground.

So I emailed Stephen at Trinity amps, but his answer is a bit too technical for me. I was not sure what was meant by that, especially since I have added the VRM module. From the description, I assumed I should put a resistor from the B+ ground side of the board to ground. This is the response.

"That would work or might be easier from the first or second filter cap +ve to ground. 220K 2W if you are inclined to do so.
Just put it from positive to negative terminal."

So where is the first and or second filter cap? Is that on the turret board?

Here is a pic of the setup. You'll notice a blue and white wire not hooked up but that is for the indicator light which my cat stole for a toy. Another is on order so I thought I would add this jumper for draining the cap. Hopefully someone can show me where this should go.
 

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The first and second filter stage would be the big chassis mounted can cap.
Which lug is first and second we can't tell because the picture is not complete and you have not posted any documentation such as layout or schematic. ;)
I'll guess the 220K 2W bleeder resistor will go between one of those lugs and the 3rd lug which is connected to chassis via the green wire.
 

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Discussion Starter #3
Looks like you put it from any positive post on the big cap to the negative post. Not my picture, found on google.

 

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In your first picture i see a black wire going to the cap. If that's coming from the rectifier, that's ideally the side the bleed resistor should go to, but the side with the red wire will work just fine too, whichever is easiest for you to wire. The other end of the resistor goes to ground.
The value of the resistor is not critcal. A larger value will drain slower, but won't get as warm. A smaller value will drain faster but may get hot, so i wouldn't go too much smaller.
 

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Discussion Starter #5
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The second picture is stolen from the web via Google.

The black wire in the original picture is the B+ out from the VRM board. Here is a better picture
 

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Discussion Starter #6 (Edited)
Well, I think I fried the mofset, either I tightened the screw too much, or it wasa little too wide, but when checking for continuity, i found the middle pin shorting to ground. took out the screw, not longer shorting, but not working either.

Going to remove the VRM module for now, ( has to come out anyway to replace the chip) then I'll rewire without and retest.
 

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Discussion Starter #7 (Edited)
So, my bad and I didn't notice that I forgot to change the meter from AC to DC when measuring the amp voltages. I put it all back together again and I am getting high voltage readings (due obviously to no tube load as yet). I think everything is ok so now it's time to pop all the tubes in and finish checking all the voltages.

I didn't put the bleed resistor in even though I redid all the wiring over there, because I don;t have one right now. I had to grab a few things on top of that so added them to my order then I'll pop it in and replace a few more wires.
 

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Like you said, you had to take the VVR out to change the Fet anyway. If you had a short that disappeared from removing the screw, then the Fet case was cracked. (Unless the Fet does not have plastic back side but metal? If that's the case it needs insulation from chassis.)
As you say, there will be no voltages to check without the rectifier tube. So when they said 'no tubes' they meant 'no tubes other than the rectifier'.
According to this diagram, the rectifier goes to standby switch, then standby switch to VVR to first filter cap. So your bleeder resistor goes from black wire to green wire lugs on the cap. can, like Dan said.
 

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You need the rectifier tube in place. Power it up and take it out of standby. You should read high voltage on pins 1 and 6 of the preamp tubes, and pin 7 and 9 on the output tubes (6BQ5). As well there should be high voltage on the filter caps. Any place there is no voltage is your problem. If the VRM mosfet is shorted, you should read full voltage, same as if it wasn't there.
 

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Discussion Starter #10 (Edited)
I have high DC voltages at all the pins you have mention Dan. But when I rotate the pot on the VRM nothing changes. So I'm assuming that the FET is toast.
I did not change the FET, as I have no replacements here. Assuming the FET is working, I should see the B+ voltage drop at the big can?
Forgetting about the VRM module, I assume it is now safe for me to put in the rest of the tubes and power up again? then retest?
 

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Discussion Starter #12 (Edited)
Well I tried to plug all the tubes in and one of the el84's won't go. Took a closer look and the darned hole is full of solder... time for some surgery to see if I can get enough out to allow the pin to enter... sigh
 

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Discussion Starter #13
So, I was able to remove the plugged pin, but damaged it as it came out. Luckily It is not used. I removed a pin from another socket and put it in place of the broken just in case.

So turned on the amp, nothing funky happening, plugged in the guitar code, no funky noises. Plugged the guitar into channel 1 and I hear a guitar! But, it's sending the signal to the wrong half of the amp. I'm plugged into Channel one which has TMB and volume. None of those knobs work, but when I use the volume and tone on channel 2 i get volume and tone.

Plug into channel two and nothing but a very light hiss.

Back to the drawing board. Oh, and the VRM doesn't work either.
 

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Discussion Starter #14
So I'm blind and read the drawing incorrectly about the inputs, so moved the wires accordingly and the clean channel is working great. Thank got I opted for VRM this thing is freaking loud at 2!.

I'll take a look inside again tomorrow to see why the dirt channel is not working
 

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Discussion Starter #15
Well, the new Fets arrived today so i reinstalled the VRM with the new chip. Turned on the amp and watched the rectifier start arcing blue inside the tube then a slightly brighter glow, I slapped at the standby but it was too late. Is that a normal way for a tube to die? I'll recheck my wiring but I'm sure the VRM is installed correctly.
 

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Discussion Starter #17
I checked the diode and it was fine. yes the insulator is there, and I made sure not to crank it down too hard. I was going to say if there was a short, shouldn't the fuse blow first?
 

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I'm not an expert but I've installed a vrm and power scaling and can say that often the fuse blows but not necessarily before a more sensitive part fails. Those mosfets can be tricky. I had a similar situation installing power scaling in a marshall style el34 circuit and I remember blowing fuses but also having a diode blow up in that split second before the fuse blew. I'll leave the troubleshooting to Dan and JB they're far more knowledgeable. Another thing to look out for is a tear/rip in the insulator. If it catches on a bur on the screwhole it can get a tiny nick and short the mosfet to the chassis.
 

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I'm pretty sure he can't see my posts, but I'll give one more try. :D
Can you check again whether the FET middle pin reads short or low resistance to ground?
Is there any chance they gave you a screw that is too large for the hole in the FET and it is cutting into the side of the hole?
Aside from that, rectifier tube failure like that seems all too common with modern production rectifier tubes, and when they do fail they usually exhibit the symptoms you mentioned.
 

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Discussion Starter #20 (Edited)
jb_welder I can see your posts. I will be checking all that tomorrow. I have 4 broken ribs, so after going to the doctors today then groceries and going up and downstairs a few too many times I was pooped. If I could test the amp with no load it would be a piece of cake, but my workbench is downstairs and my cab is upstairs. To test it I have to bring it upstairs to the 2x12, so whenever I flip it upside down to check voltages I must have bumped the rectifier tube too many times. Not a fan of the wire spring clips. If I was inclined to do 20 amps I would build a jig that rotated 360 degrees.
 
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