YMI5150 Early '68 12xxx build journal

[vh junkie]

Use the second hole for now... bigger signal next to other signals will cause you problems!

Another possibility is to move the presence to the back, and put the LARMAR up front... but for now just use the second hole... its easy to return that to its current state...

... an issue with the LARMAR (brought up even by Mark if you search) is that the more you turn it down the less the Presence control will seem to have an effect...

... search for "aiken reverse cut" for a presence mod to deal with that! A lot of folks love the larmar as is... so just start there!

[Strat78]

Question for 78 - I"m not 100% sure I put the magnet in the correct orientation. It sounds great. Would there be an obvious signal if it was installed wrong? again - A8 in MM Vintage.

Question for any of you - what's the cheapest way to get a decent recording to post (aside from my digital camera)?

I'll try to get something posted this weekend so we can compare.

Cheers!

At one point I was laying magnets on the table and going at them with another magnet (of which I kept track of how it was placed when I pulled it out of the pickup), If the other magnet jumped away from the marked magnet, I put it in the pickup with the same orientation as the marked one. Does this make sense? Actually I'm not sure it matters if it is the only pickup in the guitar? To tell the truth, I have no clue, but mine sounds good too, so that is all that matters at this point. The pickup in my last clip was with a vintage cream MM fitted with an A8 and lots of wood spacers to keep the pole pieces from touching the base plate, but it was not potted. I love the rawness of that pickup!

I don't think there is a cheap way to record, well at least depending on what you mean by cheap. I bought an old Macki mixer a couple of years ago and I did not have much luck with it until yesterday when (on a whim) I used an even older Lexicon PCM 60 reverb unit as a pre-amp for the sm-57 into the Mackie (and into the Delta break out box into the computer). I just put the mic on a 45 degree angle right up against the grill cloth (a cab with pre-rolla greenbacks that had enough sloppy glued tares in the cones to make them affordable), attenuated the amp 50% with the marshall power break (Ralle mod) and hit record. It's not perfect, but it is better than any damn POD recording I ever got. The lexicon PCM 60 reverb is sick but they run for about $400 on ebay. I bought mine back in the early 80's I think. It seems to make the amp sound the way it does in the room.

[vanhalen5150]

Mags are simple. Pull the old one out 75% of the way. Lay your new one on top so its sticks and doesnt repel in any direction. Thats the way it has to go in. Opposites attract in all planes. Lengthwise, heightwise etc.

[vanhalen5150]

This will help too.

http://home.comcast.net/~jbjdav26/1959/ ... 0PPIMV.JPG" onclick="window.open(this.href);return false;

I'm doing mine this weekend.

Thx!

You gonna drop it in where the second output is or drill a fresh hole?

Hole #2.

[YMI5150?]

tough day yesterday guys. My wife miscarried at 22 weeks. telling our other boys was the toughest thing I've had to do.

I installed the master volume right before I got the news so haven't tested it much.

[myfoot]

tough day yesterday guys. My wife miscarried at 22 weeks. telling our other boys was the toughest thing I've had to do.

I installed the master volume right before I got the news so haven't tested it much.

So sorry to hear about this. My daughter had this happen a few years back and it really shook up our family.

[vanhalen5150]

tough day yesterday guys. My wife miscarried at 22 weeks. telling our other boys was the toughest thing I've had to do.

I installed the master volume right before I got the news so haven't tested it much.

Not an easy part of life guy. Sorry to hear that.

[YMI5150?]

yep. the ripple effect is huge. its rocked the whole family and friends.

i got rid of the 500uf on volume 1 pot, swapped 47k bias resistor for 68k to match yours. not really getting the tone sought after but closer after doing that. volume 1 sounds like the guitar is out of tune, volume II is closer but muddy. I'm going to replace remaining resistors for AB resistors that I missed the first go around.

quick question(s)
what NFB tap are you guys running? I had 16 but am dropping it to tighten things up.

it seems that the PPMV affects measured bias voltage. what should the new readings be? i'm measuring around 5mv instead of 30-40. my B+ voltage is up to 490 or so after replacing the 47k.

[vh junkie]

it seems that the PPMV affects measured bias voltage. what should the new readings be? i'm measuring around 5mv instead of 30-40. my B+ voltage is up to 490 or so after replacing the 47k.

Take care messing with this stuff till you've had time to work it all out... don't want to do this if your mind is wandering...

Always want to bias with the PPIMV all the way up... be sure your measuring with DC volts at the tube sockets...

Changing the bias resistor should have no effect on B+... but the amp will change a lot in the first 20 hours, and then continue for the next 80... but slower...

Make sure you let the amp a warm up... a minute on standby(center)... then a couple of minutes before measureing voltages... 20 minutes off standby before listening to it...

I wouldn't bother with changing the AB CC's for now...

Post some pics...

[Strat78]

Just be fiercely supportive and patient with your wife right now. Wow, this kind of news hurts to the core, but it sure brings us into touch with humanity. Sorry for your loss. Time and hard work will heal all.

[YMI5150?]

it's been hell. 22 weeks isn't just a miscarriage any more. she had to deliver. we have our good moments and tough ones. we'll get through it. we live 3000 miles from family so not much support.

This is an outlet for me. I'm grateful to have a constructive outlet rather than destructive one...

I'm baffled by the bias voltages. still measuring ~ 4mv on all sockets. it was fine before putting in the MV. all I can think of is the relative ground (shielded wires and pots) go to bias circuit, correct? it seems that its shifted values. teh pot still affects the value but not the same range. all other voltges are in the ball park. B+ is up around 482-490 VDC.

I don't want to play it until I know its safe to. I did a bit yesterday and it sounded good.

Please let me know when you could be available to work with me remotely. I'd like to resolve this quickly. I'm off all week, traveling Thursday for Holiday.

[vanhalen5150]

So you bias with it turned up? So turning clockwise engages the MV and decreases the sound or is it the other way around?
Still havent done mine yet. Spending way too much time on the golf course. Shot an 83 yesterday.

[YMI5150?]

Nice! I haven't been out there in over a year. Hope to on this vacation. 83 means you're having real fun out there and spending no time looking for balls...

the MV position does not seem to affect bias reading. I just went through everything again and it seems to be in order. can't figure it out.

to answer your question, the MV pot is the same as a normal pot. turn clockwise to get more volume.

the pot takes the place of the two 220k resistors and I'm measuring about 230k resistance between each pol and the center pin where the 220s used to converge. the orange and green wires have been removed from the valve connections like they should. they ends were cut, heat shrinked and tucked away under the board. that should be sufficient.

My bias resistors are now 27k, 15k, and 68k

My NFB tap is now on 4dB.

Hmmm...

[vanhalen5150]

Don't you remove the orange/green wires completely?

[YMI5150?]

You're supposed to but I cant get under the board. they're attached to the turret on one end but nothing on the other. Heat shrink to avoid shorting. I don't see how that could affect things.

I just remeasured all DC voltages:

V1 pin 1 - 150
V2 pin 1 - 174
V3 pin 1 - 220, pin2 - 26, pin 3 - 42
V4 pin 3 - 485, pin4 - 484, pin5 - -53, pin 6 - 484
V5 pin 3 - 486, pin4 - 484, pin5 - -53, pin 6 - 485
V6 pin 3 - 485, pin4 - 484, pin5 - -53, pin 6 - 485
V7 pin 3 - 486, pin4 - 484, pin5 - -53, pin 6 - 486

bias voltage on pin 8 ranges from .9mv - 9mv depending on pot setting. can you say witch hunt???