Grail module

MTS module area including module modifications

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strato62
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Grail module

Post by strato62 » Wed Apr 18, 2007 12:50 pm

Hi guys,

I know some of you have the Grail module.
I wonder if any of you could post a good hi-res pic of this module with the tube shield removed to see how it compares to the MrScary that it's pic was posted on this forum not too long ago, since neither schematic is available on this site.

It would be fun to compare the two.

Thanks, and keep on rocking those MTS/Egnater rig :D

Claude

JKD
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Post by JKD » Wed Apr 18, 2007 2:09 pm

Here ya go:

Image

JKD
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Post by JKD » Wed Apr 18, 2007 2:12 pm

Oh .. the solder blob on the LED was me...I gut out the old LED and soldered a new one onto it's legs...LOL :D

strato62
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Post by strato62 » Wed Apr 18, 2007 2:33 pm

Thanks for the fast reply :lol:

Awesome pic,

In fact at first glance it looks closer to an XTC by it's configuration than a Mr Scary. I thought they where (Mr Scary vs Grail) closer circuit wise.

I see there are some marks around c10, have you removed it ?

And , if you don't mind, can you tell us what color code is the resistor next to the cap?between r28 and that brown cap c29?

It's 470k (yellow,purple,yellow) on my XTC.

I'm also curious about the tone stack red capacitor which is c11 or c14 ...

Thanks in advance,

Claude

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Post by JKD » Wed Apr 18, 2007 2:53 pm

I've made no mods...I noticed on two of my (new) Modules marks (from rework?) around components....just q QC thing I guess...

I assume you mean r26 (between c9 and r28) - it's yellow, purple, yellow, gold so 470k +/- 5% ?

c11 is erm.....couldn't find it

c14 is 470 / 630 - presume that's 630V but not sure of power of 10...u or p ?

Dunno if this is relevant but the tube planar says "BRIT-TUBE" 100-101 REV 1.10 08/15/04

I have a Mr Scary but not an XTC...never really thought to compare them :D

Looks like R38 on my module is on it's way to burning out...wonder what value that is??? Can't read it :-(

strato62
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Post by strato62 » Wed Apr 18, 2007 3:11 pm

Thanks a lot for those infos :)

I couldn't figure if the red tone stack cap was C11 or C14, now i know ...
So it's most probably 470pF, a standard value in tone stacks.

I noticed your soon to be out of this worls R38. :(

It's or should be ... the same value as it's neighbor R37, so it should be 4,7k.


Thanks again

strato62
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Post by strato62 » Wed Apr 18, 2007 7:53 pm

Comparing Grail with MrScary was fun and instructive.

Here's my findings for now:

While the Grail mod pcb is very similar to the XTC pcb their values differ quite a bit.

I just finished comparing the Grail module pic to the Recto schematic found in the schematic section, and they're almost identical. Nothing too suprising here since they're both supposed to aim at Mesa's DR.

On the pic of the Grail module C3 looks to be 500pF, while Recto's value for this part is 2,2nF.

Can't tell either if C8,C9,C17 and C18 are 22nF like the Recto but by judging from the pic they look a little bigger, maybe 33nf ???

Could someone confirm these values please ??

NuSkoolTone
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Post by NuSkoolTone » Wed Apr 18, 2007 8:28 pm

I was wondering how hard it would be to convert a recto to a grail.
That would be killer if for nothing else but to try a grail before buying
one in a sense. Plus if I'm modding from one to the other and they're
sorta close I can come up with my own recipe even.
This is where you write stuff no one reads anyway.

strato62
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Post by strato62 » Thu Apr 19, 2007 5:51 am

Shouldn't be too hard if you are able to handle a soldering iron without damaging the part, pcb and injure yourself.

If the only difference resumes to C3 it should be pretty stait forward and easy to get the required capacitor and replacing it to make it like the Grail module.

Now if C8,C9,C17 and C18 are of different value this would just require a little more work.

Would be nice if someone could post these values :roll:

NuSkoolTone
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Post by NuSkoolTone » Thu Apr 19, 2007 9:34 am

strato62 wrote:Shouldn't be too hard if you are able to handle a soldering iron without damaging the part, pcb and injure yourself.

If the only difference resumes to C3 it should be pretty stait forward and easy to get the required capacitor and replacing it to make it like the Grail module.

Now if C8,C9,C17 and C18 are of different value this would just require a little more work.

Would be nice if someone could post these values :roll:
I see some resistor changes too. I don't have the codes memorized,so I'll just name colors:

I Can't see R6(Prob same as R5), R9, R38(Looks burnt?), R37(Prob same as R38)

R16, R17, and R36 look the same as recto, but color is not clear enough to be sure.

Definitely Changed:
Recto Grail
R1:Yel-Pur-Brn-Gld R1:Brn-Grn-Brn-Gld
R2:Yel-Pur-Brn-Gld R2:Brn-Grn-Brn-Gld
R3:Yel-Pur-Brn-Gld R3:Brn-Grn-Brn-Gld

The OPamps look the same.

So what's left is Q1, Q2, (Though these are all probably just standard values making them the same) and the Caps.

C8, C9, C16, and C17 appear to be "Fatter" so are probably a larger value.

C6, and C13 look the same.

C2, C4, and C11 might be the Same (Probably are).

C14 appears different by if nothing else, packaging.

C3 is well documented and is a matter of taste.

So wow, it's a tweaked RECTO mod!

So we now know to change those 3 resistors, now we need the value of C8,C9, C16,C17, and C14. Possibly C3 to be complete.

Anyone Generous/Brave enough to take them out an measure them?

Thanks!
Last edited by NuSkoolTone on Thu Apr 19, 2007 1:08 pm, edited 2 times in total.
This is where you write stuff no one reads anyway.

JKD
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Post by JKD » Thu Apr 19, 2007 10:25 am

C8, C9, C16 and C17 are all same value - marking F223K b 630MPP1 so presumably 630V 22pf=0.022uF ?

C14 I posted earlier in the thread - 470pf / 630V

strato62
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Post by strato62 » Thu Apr 19, 2007 11:08 am

NuSkoolTone :

I think R5/R6, like Q1 and Q2 are only involved in swicthing circuit as well as R1/R2/R3 that are related to the H11F1 that are Bilateral Analog FET Output Optocoupler that are used in switching the module in or out the audio path between the first preamp stage and the power amp section.


JKD:

The 223 marking on the caps means 22nF = 0.022uF, so same value as the Recto mod.

So that means that the only difference would be the first cap ( C3) at the input of the module ....

I will try this cap mod as soon as i can get one, and i may give the R1/R2/R3 a try, just being curious, but i won't be able to make any comparison since i don't own both Recto and Grail.

Maybe someone on this forum have both and is willing to try to Grail his Recto or Rectified module and posts his impression, or better post a clip ??? :lol:

Thanks guys

NuSkoolTone
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Post by NuSkoolTone » Thu Apr 19, 2007 12:17 pm

strato62 wrote:NuSkoolTone :

I think R5/R6, like Q1 and Q2 are only involved in swicthing circuit as well as R1/R2/R3 that are related to the H11F1 that are Bilateral Analog FET Output Optocoupler that are used in switching the module in or out the audio path between the first preamp stage and the power amp section.


JKD:

The 223 marking on the caps means 22nF = 0.022uF, so same value as the Recto mod.

So that means that the only difference would be the first cap ( C3) at the input of the module ....
Hey strato,

Cool you're in on this! Gotta say, I HIGHLY doubt that C3 is the ONLY change. I think the R1/R2/R3 Change is probably responsible for the Clarity some guys are saying vs. the Recto. Remember These resistors ARE used as mods in the clean modules, so there might be something to it.

Also where is some good documentation explaining markings on the caps relate to a certain value? IME markings on the cap often have nothing to do with the value and the only way to know is to pull it and check (Of course YMMV). Now if there are the SAME markings on multiple caps on the same manufacture, good chance they're the same value.

Plus those caps at C8, C9, C16 and C17 appear to be of the same type and are obviously bigger than the ones on the Recto. Honestly I'd be shocked if they were the same value. Since we know C14 (Thanks JKD), all we need to know for certain is the value of ONE of those caps since they're all the same. Then with little effort, those interested in the Grail can convert their Rectos!
This is where you write stuff no one reads anyway.

NuSkoolTone
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Post by NuSkoolTone » Thu Apr 19, 2007 12:59 pm

Ok, I'm a dumbass. I found some info on the cap markings (Duh) here:
http://www.arar93.dsl.pipex.com/mds975/ ... nts01.html

So for the the other knuckleheads there you go I guess.

So other than 3 resistors and a cap at C3, can that be ALL there is to it? I Mean everyone poops on the Recto and is raving about the Grail. Is this purely psychological?

Those 4 caps bugs me out though since they look twice as wide as the ones in my recto and appear to be the same type of caps. Weird!

What's also weird (to me) is the fairly meaty C3 Cap value .005, I always preferred the tightness of .001. Perhaps it's time to taste test again...

I'm just shocked it's 4 parts difference with new knobs and faceplate.
This is where you write stuff no one reads anyway.

strato62
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Post by strato62 » Thu Apr 19, 2007 1:15 pm

They sure bug me also,

At first i thought that the differences where those 4 fatter caps, but it doesn't seem to be the case.

Nothing prevents you to try 0.033uF though ....
or change that R31 for a 33k or a 56k, this will also have an effect of changing the way the tone stack eq your sound.

Changing C3 to a 500pF as it shows on the picture would change the way the Recto sounds for sure (recto is 1nF=.001uF=1000pF) since it will cut some bass going into the module and give a tighter attack giving a different feel to the module ....

Claude

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