plexi 50watt lead help

[RiffRaff]

Just finished and not working
any help would be great
these are the voltages
without tubes
v1 pin1: 430 pin2: 0 pin3: 0 pin4: 0 pin5: 0 pin6: 459 pin7: 0 pin8: 0 pin9: 0
v2 pin1: 451 pin2: 0 pin3: 0 pin4: 0 pin5: 0 pin6: 468 pin7: 464 pin8: 0 pin9: 0
v3 pin1: 472 pin2: 0 pin3: 0 pin4: 0 pin5: 0 pin6: 473 pin7: 0 pin8: 0 pin9: 0
v4 pin1: 0 pin2: 0 pin3: 496 pin4: 496 pin5: 0 pin6: 498 pin7: 0 pin8: 0
v5 pin1: 0 pin2: 0 pin3: 496 pin4: 496 pin5: 0 pin6: 496 pin7: 0 pin8: 0

with tubes
v1 pin1: 108 pin2: 0 pin3: .273 pin4: 1.86 pin5: 0 pin6: 122.6 pin7: 0 pin8: .55 pin9: 1.88
v2 pin1: 109.4 pin2: 0 pin3: .21 pin4: 1.87 pin5: 197 pin6: 151.9 pin7: 114.2 pin8: 109.7 pin9: 1.88
v3 pin1: 134.7 pin2: 13.5 pin3: 14.8 pin4: 1.97 pin5: 197 pin6: 135.5 pin7: 10 pin8: 12 pin9: 1.88
v4 pin1: .03 pin2: 0 pin3: 243 pin4: 239 pin5: .06 pin6: 244 pin7: 1.9 pin8: 0
v5 pin1: .02 pin2: 0 pin3: 246 pin4: 242 pin5: .07 pin6: 498247 pin7: 1.9 pin8: 0

Thanks
Tim

[toner]

How are you measuring the heaters? Should be with meter set to AC, black lead on chassis. I'll assume the "197" on a couple of your preamp pin 5's is really "1.97". Power tubes pin 2 should have AC voltage (not 0) so that may not be wired correctly.

The negative bias supply (power tubes pin 5) is not working so don't put the power tubes in until that's fixed. Bias diode may be backwards? You should get around -35 VDC there.

All the plate voltages are too low, especially the power tubes, so something in the power supply line is wrong.

Can you post pictures?

[RiffRaff]

I'll have to check the voltages again but I'm pretty sure I measured correctly
here are some pics for now
I used a layout from metro 50 watt lead and wired it the same as the triode layout so maybe thats where I have gone wrong

[RiffRaff]

If you want better pics let me know and I will try and get better ones

[toner]

Better pics would help.

Just starting with the PPIMV...

I don't see any negative bias connection from the board to the PPIMV. Looking at the picture below, it would normally go from the green point to the left lugs of the PPIMV (near the preamp side).

I don't see any purpose for the black wire labeled "Is this grounded?". It needs to be removed, regardless. If it is grounded and you have the under-board jumper shown in blue, you are sending the bias voltage to ground.

*IF* the blue under-board jumper exists, remove the above mentioned wire and run a wire from the green-marked turret to the left lugs of the PPIMV pots.

If the under-board wire is NOT there, run a wire from the top point of where the blue jumper would normally be (top of the 47k bias resistor that connects to the bias pot) to the left lugs of the PPIMV. NOTE: The blue line I drew looks like it connects with a red wire going to a filter cap, but that IS NOT the turret I'm referring to.

We'll figure the rest out once this is fixed. Maybe someone else will spot something.

[toner]

Check your PPIMV pot wiring closely and make sure it matches this:
http://metroamp.com/wiki/images/9/93/Lar-Mar_PPI-MV.jpg" onclick="window.open(this.href);return false;

I can't tell for sure from the pictures but it looks like the buss wire connected to the speaker jack ground lugs goes to the left (preamp side) lug of the PPIMV pot. Are the grey shielded cable's shields grounded to that same buss wire? Technically, it's okay to ground the shields there but the left lug of the PPIMV CANNOT be grounded.

[RiffRaff]

First off Toner I really appreciate you helping me out. I'll have to buy you a beer afterwards
just did a continuity check on the chassis and it's shorting out ( don't know why I didn't try that sooner )
don't think I should take pin voltages until we figure this out?
Maybe we can start with the trannies to make sure I have them wired correct
I'm using Classic Tone trannies
(40-18023 power transformer and 40-18025 output)
and this is how I have them wired
does this look correct?

plus all the black wires on the turret board I have on the back side

[RiffRaff]

and the stray black wire is what I thought was included in the lar/mar master volume which I just grounded on the pots buss bar instead of the rightside lug of the mv. i took out on your request
as seen here ( it was already clipped on one end)
And the buss bar does not touch the left side mv pot, it goes directly to the right side which is why I thought the clipped wire was ground ( see the blue wires in pic)

[RiffRaff]

I'll post better pics when ever I can figure out how to use my camera
taken about 50 pics now and maybe two are clear

[RiffRaff]

ok I've removed stray wire and added the blue wire from the green lug to leftsides of mv pot
not sure I understand though since that lug is grounded by the buss bar on the pots
Should the buss bar run to the left side of the mv pot?

[RiffRaff]

also just found that I had tip of the speaker jacks running to ground instead of the sleeve

[RiffRaff]

ok after fixing the speaker ground and the mv wire I started it up again with my lightbulb limiter with no tubes and no shorts
put the tubes in and took these voltages with the bias pot turned right down
and I did unhook the buss bar from the left side of the mv, do i need to hook this back up?
they seem a bit high? still no sound

v1 pin1: 167.2dc pin2: pin3: .98ac pin4: 3.35ac pin5: 3.35ac pin6: 214.8dc pin7: pin8: 1.97dc pin9: 3.35ac

v2 pin1: 1.69.5dc pin2: pin3: 1.15dc pin4: 3.36ac pin5: 3.36ac pin6: 306.8dc pin7:dc pin8: 170.9dc pin9: 3.35ac

v3 pin1: 233.3dc pin2: pin3: 43.3dc pin4: 3.36ac pin5: 3.36ac pin6: 227.8dc pin7: pin8: 43.3dc pin9: 3.35ac

v4 pin1: pin2: 3.38ac pin3: 505dc pin4: 504dc pin5: -163.7dc pin6: 503dc pin7: 3.36ac pin8:

v5 pin1: pin2: 3.39ac pin3: 504ac pin4: 503 pin5: -163.6dc pin6: 503dc pin7: 3.37ac pin8:

[demonufo]

Why all the shielded cable everywhere?

You have introduced an awful lot of capacitance that is neither necessary, or wanted...
There is no substitute for normal flyleads and a tidy lead dress, and this certainly is not one.

Only PPIMV, and maybe v1 input grids need shielding, but unless cascading the front end, I wouldn't even do the grids, myself.

[RiffRaff]

Ok ..well thats something I didn't know.
I thought it would make the amp quieter
I'll change it all and just keep the mv shielded wire in
thanks demonufo

[RiffRaff]

Another thing
I have these connections (outlined in red) connected the same as the metro layout
but the triode layout has them on opposite sides of the board
which would be correct for me?