A few questions about my current attempt at retubing...

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SadisticMagician

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1) I'm putting SED =C= 6550s into my VH4 and I'm wondering does it matter where the EL34 / 6L6 switch is? If so, where should I have it set?

2) I'm trying to read the plate voltage of the VH4 but unlike my other amps there seems to be a white rectangular piece that's blocking the pins so I can't exactly see the 3rd pin. Is there anyway around this besides getting a Bias Rite?

3) Does anyone have a layout of the VH4 preamp tube section? I thought I only had 5 but apparently I have 7. (Though one may be a driver tube, I didn't look thoroughly)

Thanks.
 
1) 6L6

2) Bias rite is a great piece of kit (I have one), but I believe you can take a reading from the OT tap, I'm sure I saw a thread about it a while ago, here is the websites method:

http://diezel.typo3.inpublica.de/tech-corner.3.0.html

3) The above document has the tube layout at the bottom.

Have fun and please be careful!
 
Argh....

Well that sure ruined my day quickly.

So I was reading those instructions you linked me to as I was doing the plate voltage reading.

Everything is great, I grounded the center wire in the primaries and I'm taking a reading off the leads.

I'm getting a 471v reading.

Soon as I pull the DMM lead away I hear a heart wrenching pop and my amp turns off.

I have no idea how it could have happened but I'm almost certain the output transformer blew out. :cry: :cry: :cry:

Why does God hate me. :aww:

Funny thing is, I followed the instructions religiously.

EDIT: I've done this many times before so I'm not new to it. I just re-tubed and re-biased my JVM this morning.
 
Now that I've got my pussy cleaned up and started trying to figure out what the issue is, I think I may have just blown the main fuse in the amp.

Going to go replace it now and see if it works.
 
ahh crap, really sorry to hear that :aww:

Might just be a fuse? I had a couple of fuses go with an almighty pop.

Does the amp power up still? when you switch to run do any of the fuse indicators light up?

Worth sending an PM to Peter so see what he has to say (or he might spot this post)
 
Everything is good to go. :D :D :D :lol: :LOL: :lol: :LOL:

Now I'm redoing the process making sure I'm getting all the right voltages.

Bought extra fuses just in case. :rock:
 
I wouldn't suggest doing the shunt method (one on the site) unless you have a VERY good LOW RESISTANCE multimeter. If your multimeter has a high resistance the reading can be off by as much as 20%(so if you bias for 70% dissipation it could be as high as 90% actual....not good). A simple bias probe like the Groove Tubes one or the one from http://www.eurotubes.com is more than sufficient and fairly cheap. If you can't get to pin three to read the voltage then you probably shouldn't be toying around in the amp because even with the screen grid resistor above it, it's not very hard to get to. I apoligize if I come off as rude but I'm just saying.

In reality anywhere from 470-500 volts is only going to be 1-2 mA different from where you would set the bias anyway so get a probe and bias to the suggested mA and be done with it. Then :rock: out.
 
Oops, posted after you said you got it sorted.
 
Hey_bert_whtcha_doin_bert":2gi25xnh said:
I wouldn't suggest doing the shunt method (one on the site) unless you have a VERY good LOW RESISTANCE multimeter. If your multimeter has a high resistance the reading can be off by as much as 20%(so if you bias for 70% dissipation it could be as high as 90% actual....not good). A simple bias probe like the Groove Tubes one or the one from http://www.eurotubes.com is more than sufficient and fairly cheap. If you can't get to pin three to read the voltage then you probably shouldn't be toying around in the amp because even with the screen grid resistor above it, it's not very hard to get to. I apoligize if I come off as rude but I'm just saying.

In reality anywhere from 470-500 volts is only going to be 1-2 mA different from where you would set the bias anyway so get a probe and bias to the suggested mA and be done with it. Then :rock: out.
Click to expand...

I know how to get to Pin 3, I was just worried about ruining such an expensive amp by fucking with the resistor or something.

Either way, I got to Pin 3 and I'm getting the same 471v reading.

Shunt method is pretty accurate thus far.

Setting my bias now, can't wait to try this baby out. :rock:
 
Haven't played it just yet but look forward to it very soon.

Hopefully today or tomorrow.

I got confused with the shunt method, for some reason my brain was registering it as a way to read plate voltages. :confused:
 
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