So many problems with my DRRI !

[Jazz P Bass]

Learn how to 'drain' the B+ voltage.
Amp off, hook a 1K/2 watt resistor from B+ to ground.
I like to 'monitor' the B+ when working on an amp, just to be sure it is drained.

[Wil]

So here are the results :
ImageShack® - Online Photo and Video Hosting
Anything wrong, doctor ?

Edit : when I need to work on the inside of the amp, I usually link Pin 1 of any preamp tube to the chassis for about 10 seconds, is that a safe way to discharge all lethal voltages ?

[Amp Kat]

So here are the results :
ImageShack® - Online Photo and Video Hosting
Anything wrong, doctor ?

Edit : when I need to work on the inside of the amp, I usually link Pin 1 of any preamp tube to the chassis for about 10 seconds, is that a safe way to discharge all lethal voltages ?

If you put a resistor in between that then yes it's ok. In all reality yes it will discharge the plate voltage in the form of a

loud pop and it's really not good for the capacitor to discharge that fast and causes arching. Use about a 1k to 10k resistor to discharge with. The larger the longer it takes.

[Jazz P Bass]

So here are the results :
ImageShack® - Online Photo and Video Hosting
Anything wrong, doctor ?

Something is amiss with the V1A tube.
Pin 1 is higher then normal & pin 3 has zero volts on it.
Possible causes:
-The tube itself is bad.
-The pin 1 plate resistor is open or not connected.
-The pin 3 resistor: same thing.
-The socket itself could be at fault.
For all appearances, the first half of the tube is not conducting.

[Wil]

Something is amiss with the V1A tube.
Pin 1 is higher then normal & pin 3 has zero volts on it.
Possible causes:
-The tube itself is bad.
-The pin 1 plate resistor is open or not connected.
-The pin 3 resistor: same thing.
-The socket itself could be at fault.
For all appearances, the first half of the tube is not conducting.

Thank you for taking the time to help me! I'm sorry I forgot to say that I'm running my amp with the "Pull V1 mod", so there's no tube in the V1 position.
Otherwise, are the other voltages "normal" ?

[Jazz P Bass]

The Vdc voltages look good, yes.
Now you need to insert a sine wave.
Those are the TP's in the ovals.

[Wil]

Ouch... I don't think i'll be able to do this. I only have a multimeter. So, you think the transformers are alright ? I'll probably go PTP so I only need the transformers.

[Jazz P Bass]

Ouch... I don't think i'll be able to do this. I only have a multimeter. So, you think the transformers are alright ? I'll probably go PTP so I only need the transformers.

A multimeter is all that is required.
As to whether or not the tranformers are 'alright', that cannot be verified without further testing.

[Zer09]

Wil,
Just a note on your original post and your statement on considering redoing the amp PTP. I bought one of those DRRI amps back in the mid 90's, used it for a year or 2 and then it sat for years unused.I couldn't stand the brittle sound of it. Tried new speakers, NOS tubes, etc... and no improvement. Aside from a couple recap jobs on my own amps I knew very little about working on amps. I decided to gut it and handwire it rather than have it sit. I bought new transformers (Heyboer), rebuilt the amp, and the difference in tone was just amazing. Even with the original Eminence speaker it sounded great. When I put an old C12N in it only got better. It's been my main gigging amp since. Obviously the change in tone was due more to component and transformer quality than anything to do with handwiring (though it is much easier to work on). Well worth the effort.

[Wil]

Wil,
Just a note on your original post and your statement on considering redoing the amp PTP. I bought one of those DRRI amps back in the mid 90's, used it for a year or 2 and then it sat for years unused.I couldn't stand the brittle sound of it. Tried new speakers, NOS tubes, etc... and no improvement. Aside from a couple recap jobs on my own amps I knew very little about working on amps. I decided to gut it and handwire it rather than have it sit. I bought new transformers (Heyboer), rebuilt the amp, and the difference in tone was just amazing. Even with the original Eminence speaker it sounded great. When I put an old C12N in it only got better. It's been my main gigging amp since. Obviously the change in tone was due more to component and transformer quality than anything to do with handwiring (though it is much easier to work on). Well worth the effort.

Thanks that's really helpful !
Mine has Mallory 150's everywhere, electrolytics are all Philipps and the transformers are mercury magnetics. Theorically it has to sound great haha! But there's something wrong I can't fix and that's invisible to the naked eye... I'm fed up with having the amp always sitting of my desk so I think I'll go PTP.
I'm a little skeptical about doing it myself. I can solder, I can follow a schematic, I can set the bias... If everything is wired correctly, what risk do I take making it myself ?

[Zer09]

Quite honestly Wil, if all of that has already been upgraded I would try to get it fixed. The guys on here are very generous with their time and knowledge and can probably guide you through it. There are a lot of people who know their sh&t on here and are willing to help. I would save the PTP for only if it were necessary. Having said that there was nothing like playing that amp for the first, hearing the difference, and knowing that I did it. It was addictive. To answer your question, if all else is within spec when you're done, all you need to do is bias. If you do choose to use this amp as your first build be very particular about lead dress. There are a lot of wires running through that little amp and you can drive yourself nuts trying to solve those problems afterward. I got very lucky and all I had was some hiss when I was done which was cured by shortening grid wires a bit.

[JoeM]

I dont think going PTP is necessary. I have a DRRI that I've done a few simple mods, new speaker and new tubes. It sounds incredible. About a week or so ago played a new one in a store and mine is so much better, absolutely no comparison. Get it fixed correctly and you will have a great sounding amp.

[Wil]

I don't really know where to start. The amp works but it simply doesn't sound good. I want to put 6L6 in it and I really want this amp to sound like it should. With PTP I have 95% of chance to reach my goal. It's gonna be a big investment in one go (does this sound right in english ?) instead of plenty of small investment that may not make me reach my goal...

[Zer09]

Fair enough. I know that feeling. I won't try to talk you out of it because I would do it again in a heartbeat. After having been in nothing but vintage amps I was shocked at how cheaply they were made when I gutted it, but they are made to price points so it's to be expected. And you have a point about one big expense versus slowly beeing bled to death trying to make step-by-step changes.

Keep in mind that you'll most likely have to upgrade the PT to run 6L6's. However, when I did mine I was able to sell the original parts on ebay (circuit board and xformers) which covered most of my xformer costs.

[JoeM]

I don't really know where to start. The amp works but it simply doesn't sound good. I want to put 6L6 in it and I really want this amp to sound like it should. With PTP I have 95% of chance to reach my goal. It's gonna be a big investment in one go (does this sound right in english ?) instead of plenty of small investment that may not make me reach my goal...

If you go the PTP route, do you know someone with experience doing this? PTP isnt without potential problems either. Lead dress and grounding are really important.