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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 9:44 pm
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I agree 1000000000000% that they are worthless now!!
Ok power caps are wired as in the weber schematic..


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 9:46 pm
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Just saw your other post.. The mtone diagram has the B portion of the power caps running through pin 6 through a 470ohm res and connects to pin 4..


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 9:47 pm
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michaelbpuccio,

Let's start from ground zero. You need to have a proper wired power supply and power supply filters, or nothing is going to work properly except your fuse (hopefully). :D

Speakers connected. No volume. No guitar plugged in. New fuse. Measure the DC voltages not resistance at points A, B, C, D, and E.

Let's see how well the PS rail is operating, first.

NOTE: that resistor is attached to the socket on pins 4 and 6 to minimize lead lengths. It is the screen resistor. PIN 6 IS NOT USED in a 6L6GC. Only pin 4 (screen). So Pin 6 is acting only as an attachment point for the resistor.

http://i243.photobucket.com/albums/ff18 ... 420001.jpg


Last edited by BMW2002Ti on Wed Sep 18, 2013 9:53 pm, edited 1 time in total.

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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 9:52 pm
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Quick question, am I to run a ground wire for every power cap or just one since they are all wired together? I know it's a dumb one....


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 9:57 pm
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If the four caps (-) are wired together --- run ONE LINE ONLY to the chassis at the appropriate point. This is usually onto the brass grounding plate on nearly all Fender amps. One black wire, from the cap's negative side to the ground plate.

See brass plate under the pots?

Image


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 10:12 pm
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Yes I see how your amp has the brass underneath.. Unfortunately I was not given that in my kit. So I will have to make a temp ground and pick some brass from the hardware store tomorrow.. Ok there are three tabs on the input jacks, I do not understand how they are wired.. With the 1m resistor... Can you simplify this?


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 10:16 pm
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BMW2002Ti wrote:
michaelbpuccio,

Let's start from ground zero. You need to have a proper wired power supply and power supply filters, or nothing is going to work properly except your fuse (hopefully). :D

Speakers connected. No volume. No guitar plugged in. New fuse. Measure the DC voltages not resistance at points A, B, C, D, and E.

Let's see how well the PS rail is operating, first.

NOTE: that resistor is attached to the socket on pins 4 and 6 to minimize lead lengths. It is the screen resistor. PIN 6 IS NOT USED in a 6L6GC. Only pin 4 (screen). So Pin 6 is acting only as an attachment point for the resistor.

http://i243.photobucket.com/albums/ff18 ... 420001.jpg



Ok so this means that the wire coming in to the tube socket to be attached to pin 4? And not to pin 6?


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 10:35 pm
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This is how I'm interpreting the schematic for the input jacks... Please correct me if I'm wrong..

Image


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 10:48 pm
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Ok I have it all back together and about to grab my guitar and plug in.. Here we go!


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 10:59 pm
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michaelbpuccio wrote:
Image


This is a one-meg ohm grid-to-ground resistor. There are 68K-ohm grid loading resistors from the jack to the input tube's grid.

I think I may have confused you about the resistor on the 6L6GC (pin 4 to 6). The line from the board goes to pin 6. And a resistor goes from pin 6 to pin 4. So... the power is going from the board to pin 6. Then through the 470-ohm resistor into pin 4. Just as diagrammed on the schematic.


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 11:01 pm
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michaelbpuccio wrote:
Ok I have it all back together and about to grab my guitar and plug in.. Here we go!


Keep the Halon handy!

:wink:

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 11:06 pm
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Or go to Costco and get a gross of fuses.

:D :mrgreen: :D


Last edited by BMW2002Ti on Wed Sep 18, 2013 11:11 pm, edited 1 time in total.

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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 11:09 pm
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Halon was handy!! :lol: SHES WORKIN AND NOT POPPIN FUSES!!! Oh yeah!! And she isn't muffled and sounding like its under water!! Man this is awesome guys!! Thank you so much for all your help and putting up with my noobie questions! So I guess what we all learned from this experience is that the mojotone build is good but their schematics are way off and need some updating.. And that the Weber schematic is the one that works!

Thanks again guys! 8)
Oh yeah one more question... How do I get the middle to be only middle tone control and not a blend of bass and treble? Or is this something that isn't possible? And seriously are my jacks wired in correctly? Lol!!


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Wed Sep 18, 2013 11:39 pm
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BMW2002Ti wrote:
michaelbpuccio wrote:
Image


This is a one-meg ohm grid-to-ground resistor. There are 68K-ohm grid loading resistors from the jack to the input tube's grid.

I think I may have confused you about the resistor on the 6L6GC (pin 4 to 6). The line from the board goes to pin 6. And a resistor goes from pin 6 to pin 4. So... the power is going from the board to pin 6. Then through the 470-ohm resistor into pin 4. Just as diagrammed on the schematic.


BMW
I knew exactly what you meant.. Thank you for your help in opening my eyes on this build! I did in fact move the connections to pin 4.. I must have overlooked your post as I was getting closer to firing her up.. So it is supposed to be connected to pin 6 then goes through the resistor to pin 4.. Ok I'll have to make that change.. As it does have a little bit of hum..

My question still is with how the input jacks are wired because I do not understand the schematic on them.. But it is working now and sounds amazing! So I guess I did it correctly..


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Post subject: Re: Bassman LTD conversion to PTP
Posted: Thu Sep 19, 2013 12:00 am
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BMW2002Ti wrote:
michaelbpuccio wrote:
Image


Ok... see the brown-black-green-gold resistor? This one = 1 meg-ohm. See the blue-gray-orange-gold ones (68k-ohm) on the board? Compare this to the schematic's layout:

http://www.webphix.com/schematic%20heav ... _schem.pdf


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