6550 to EL34 - bias splitter change necessary? 2204

[Greazygeo]

Is cap forming that necessary? I also don't have a variac to do that.. I've attached a pic of the filter caps and their readings as well. I don't know where to go from here. Checked the cap under the board as well to ensure a good connection.

Just lift one leg and check the PV

What do you mean? I've checked it now with both feet on the ground if that is what you mean. It is over 650 steadily on pin 3.

What are you reading pin 4 and also pin 5?

Are the tubes in or out of the amp? And which tubes do you have in there now?

 

[LP Freak]

Is cap forming that necessary? I also don't have a variac to do that.. I've attached a pic of the filter caps and their readings as well. I don't know where to go from here. Checked the cap under the board as well to ensure a good connection.

Just lift one leg and check the PV

What do you mean? I've checked it now with both feet on the ground if that is what you mean. It is over 650 steadily on pin 3.

I hope that was a joke.

I'm extra careful...One leg lifted and one hand behind my back when working on amps....makes soldering a bitch but..I'm safe

......I stand on my head.

 

[Kapo_Polenton]

It was a joke but I wasn't quite clear on whether you meant to disconnect one of the primaries to take a voltage. Anyway fellas, stay tuned for this epic RIG TALK FAIL of the month...... I checked my fuses..... ......... bingo. Swapped one out and I am getting a plate voltage reading of 376. 5+ hrs later.... a fuse..... seriously.

Anyway thanks for springing into action guys! On a side note, can anyone recommend a good place to grab some proper spec'd slow blow fuses. I had some on hand from a local electronics place but they are not specified as slow blow. RAting seem similar to the one I pulled out though: it was a 1/2A , 250v fuse which i replaced with a .5A, 250 v.

 

[glip22]

It was a joke but I wasn't quite clear on whether you meant to disconnect one of the primaries to take a voltage. Anyway fellas, stay tuned for this epic RIG TALK FAIL of the month...... I checked my fuses..... ......... bingo. Swapped one out and I am getting a plate voltage reading of 376. 5+ hrs later.... a fuse..... seriously.

Anyway thanks for springing into action guys! On a side note, can anyone recommend a good place to grab some proper spec'd slow blow fuses. I had some on hand from a local electronics place but they are not specified as slow blow. RAting seem similar to the one I pulled out though: it was a 1/2A , 250v fuse which i replaced with a .5A, 250 v.

Going to a lower rated fuse should not have affected your pv. Admit it it was your batteries. Good deal. I bet you are relieved.

 

[Kapo_Polenton]

lol fresh battery and two diff multi meters def. helped clarify who the problem was here... Now i am going to write down that plate voltage inside the chassis so i don't forget.

 

[LP Freak]

It was a joke but I wasn't quite clear on whether you meant to disconnect one of the primaries to take a voltage. Anyway fellas, stay tuned for this epic RIG TALK FAIL of the month...... I checked my fuses..... ......... bingo. Swapped one out and I am getting a plate voltage reading of 376. 5+ hrs later.... a fuse..... seriously.

Anyway thanks for springing into action guys! On a side note, can anyone recommend a good place to grab some proper spec'd slow blow fuses. I had some on hand from a local electronics place but they are not specified as slow blow. RAting seem similar to the one I pulled out though: it was a 1/2A , 250v fuse which i replaced with a .5A, 250 v.

I just meant lift one leg of the resistor that you added to take it out of the circuit to test the stock PV. Glad to see it's all good though. It's easy to over look the obvious.

 

[Kapo_Polenton]

Ahh gotcha. Yes I did try that actually. One of the first things I did. Also in trying to scour the internet for more info, I saw that people solved the problem of their 6550 JCM's sounding too harsh by tapping onto the 8ohm tap rather than the 4ohm which is where mine was. I had felt the amp was stiff before so now I'm looking forward to seeing how better she sounds with KT77's / EL34's. Interesting side bit of info for anyone not liking the response from their amp.

 

[codyjarrett]

Ahh gotcha. Yes I did try that actually. One of the first things I did. Also in trying to scour the internet for more info, I saw that people solved the problem of their 6550 JCM's sounding too harsh by tapping onto the 8ohm tap rather than the 4ohm which is where mine was. I had felt the amp was stiff before so now I'm looking forward to seeing how better she sounds with KT77's / EL34's. Interesting side bit of info for anyone not liking the response from their amp.

Here's a trick that sounds cool, join the NFB wire to the back of the output jack and then plug your cab into that output jack.

By codyjarrett at 2012-09-08