Topic: GridSeed 5-chip USB miner voltage mod - page 36. (Read 156988 times)

I did the 49.9k resistor mod, but I'm having an issue:

http://i.imgur.com/fXkhIQq.png

For some reason, although the Gridseeds are running at 7.65 Mh/s collectively, I"m only getting around 3.6 Mh/s effective. It's like this no matter what pool I use. Is this normal, and if not, any idea on how I can fix it?

Thank you ZiG, that explains exactly what I saw happening.  I'm new to this so lots to learn.  I actually had to re-do the bridge again as the first re-do produced some errors when hashing.  On the second re-do I could see a bit of copper and got a good solder bond.  Now I know what to expect.

Wolfey - undoing this mod and going back to stock would be simply bridging the axial resistor at the solder points.  You could even leave the resistor in place as you'd be bypassing it.
Also Wolfey, I did vmod1 (the two bridges) and ran dual mode 850MHz for half a day.  SHA mode would take 1000 MHz but I could only get to 850MHz dual.  66 watts power consumption dual mode 850MHz vmod1. Kind of high and I'm not sure if it would shorten the device's life or not.

To sum up - you add one resistor with this mod.  You don't remove any resistors. One bridge to reverse the mod if ever needed.  

Right, I don't know if something has changed in the rumor mill or not regarding the possibility of SHA coins actually becoming mineable by small time hashers like us. Our pods just don't have the oomph it takes to make real money with btc. I thought it was pretty much agreed by most folks that Scrypt only is the way to go, so that is how the R52 mod came into being. Alter it and forget about mining SHA for good, period!
So are these other mods really necessary? Beneficial? Or just more useless tinkering trying to solve a problem that really doesn't or won't exist again any time in the foreseeable future? I mean, who can predict what the market is going to do with any great accuracy, anyway?
Then again, the unpredictability of the market may be one reason to have an easily reversible mod? Just in case!
But if so, that reverses the decision we all agreed to when we made the 'permanent' mod for Scrypt only. Who is right? I suppose, only time will tell.
Just food for thought.

Yes, that was an idea I had and even hooked up a 50k pot to test things out.  I just haven't had the chance to do anything more since the gridseed I've been  testing things on hasn't been the same since it blew the 3022m mosfet while trying to dual mine at too high of a voltage/frequency (47k in place of r139 and running at 1100Mhz).  

The real idea I had was to do the single bridge mod, and replace or even add a another resistor in parallel to get the value of 49k so removal of r139 wouldn't be necessary.  This way if one wanted to run in vmodded overclocked mode for scrypt only they could simply use the voltage=1 parameter in the command line options.  Omission of the voltage=1 parameter would be running it in stock mode.  

However....I think it is possible to overclock the gridseeds and run in dual mode, just not anywhere near the level they are being voltmodded and overclocked for scrypt only.  I think 1000Mhz would be possible.

So...really...there are quite a few options to explore as far as modding the gridseed to allow for this.  We could simply do the single bridge, and replace the stock resistors to the voltage=1 parameter could be used, or forget about the voltage=1 parameter and use a physical switch.  Obviously both methods have their merrits.....but then again we could do BOTH, and change the value of r66 (36k - which is activated with voltage=1) to 50k, and change r139 (33k - stock or voltage=0) to 38k-40k.  What this would (in theory) is allow the gridseed to run at a slightly higher voltage which should let it reach 1000Mhz for dual mode (and not let out the magic blue smoke), and enable the use of voltage=1 parameter to set the VID to use r139 (49.9k/50k) to raise the voltage enough to allow 1200Mhz+ for scrypt mode.


Anyone is welcome to take this idea and run with it.  I'm working on getting funds together for another gridseed since I can't really determine stability on the one the mosfet blew on.

EDIT:  Obviously the merit of using voltage=1 would be if you don't have physical access to the gridseeds and wanted to switch from dual mining to scrypt, it could be done via software in cgminer.

Has anyone tried a 20K pot across R46 as suggested by ZiG? this would make it very easy to switch from stock to overclock and back again.

If I'm understanding this mod correctly. Reversing it will still require the same amount of work to reverse as reversing the R52 mod.
One thing that is better about this mod though is that all one has to do is remove the 17K resistor to put it back to original specs.
I for one do not look forward to soldering those two bridges again! I was happy we did away with that. It's a real pain to do, even for a master of soldering.
If all I have to do is solder on a 17K resistor to those two points, I agree that is it a better option than removing 'r139' (aka r52) and soldering in a replacement resistor only to later have to remove it then solder back in that tiny SMD resistor.
Still, why has no one yet figured out how to overclock SHA mode? Will any other value resistors allow this? A happy medium between SHA and Scrypt overclocking? I mean, it would be great to be able to overclock dual mode if the need ever arises.
The best thing to do is add a SPDT switch for MOD IN - MOD OUT.
I believe someone else envisioned this option a while back.

Hey Happydaze,

The trouble you are having is caused by the red layer on the top of the board...so called "Solder protective mask" ...it is preventing the solder to stick to the surface of the board except to the designated for soldering actual components/parts...

Because R46 is just a bridge of copper trace between 2 pads...without actual component present...they cover the whole area with this red mask...including pads and the bridge ...

So, you need to SCRATCH the pads...VERY GENTLY...to remove the red top layer...and to uncover the THIN copper surface underneath...Be CAREFUL...no force...otherwise it is easy to remove the pad(s) itself...the same way as you remove the copper bridge in between...

After that...Use the flux and solder to try to cover the pads with nice small ball of solder...before actually soldering the new Rmod  

Hope it'll solve your problem...

ZiG  

looks good... any other photos of different vantage points?

An Axial 1/4W 1% resistor will work just fine in place of any SMD type resistor.
They are easy to find and cheap to buy!
Extremely easy - much easier than SMD resistors - to hold and solder in place.
I see the practicality of making sure the mod is reversible if one decides to revert back for SHA or DUAL mining. I'm glad someone figured this out.
Still, axial resistors are just fine to use in any case!

0402 (1005 metric): 1.0 mm × 0.5 mm (0.039 in × 0.020 in). Typical power rating for resistors = 0.1 [8] or 0.062 watt[9]
0603 (1608 metric): 1.6 mm × 0.8 mm (0.063 in × 0.031 in). Typical power rating for resistors = 0.1 watt[8]

Reference ...:

http://en.wikipedia.org/wiki/Surface-mount_technology

Guys I think its PERFECT SIZE

http://www.topline.tv/drawings/images/capacitors/SC0603.gif

1.6mm in length this should still fit on the pads Nicely right?

Definitely more space to work in over by R46.  I'd like to put a jumper and a resistor there but might not bother. 



That's 1/4 watt resistor in the photo (wrong value).  I could only find 1/2 watt locally today and I gave up trying to fit it in with a jumper.  Thanks for the "rollback" info Nemercry & ZiG - that gives more options should it ever be needed. 

I was having a bit of trouble soldering over at R46.  For some reason I could not get the solder to bond well on the inner point.  It would break free easily. No problem with the outer point.  I gave up and re-bridged it. That was with the 1/2 watt resistor.  I'll try again when I get the 1/4 watt resistors I ordered.

While the resistor itself may be larger you're still restricted to the size of the pad you're soldering to.  So if it's longer than the 402's it could effectively make things a little more difficult because it will be blocking the pads to solder to.

EDIT:  I do not know the difference in size dimensions between 0402 and 0603 other than the 0603's are larger.

I just had a thought for the R46 pads since this is all alone, couldnt we solder a larger resister in the place?

PANASONIC - ERJP03F1692V - RESISTOR THICK FILM, 16.9KOHM, 1%, 0603 Price For: 25

I would imagine the 0603 is larger than the 0402?

But will this fit on the pads? PLease if someone can advise as I am in a posistion to purchase the larger ones if they work as this will be much easier right?

Actually I got Confirmation that Vmod3 is 47K exact... if we are talking about the name Vmod3? As this name came from sevenholmes they do not do the 49.9k mod There Vmod4 is a 56k Resistor but with extra cooling for longer lasting device.

I personally am going for the middle 49.9k reason for this is because I already have these on the way now... aswell as cooling ontop of this .. may help with reduce of HW...

BUt I am thinking I may actually do the Zigmod by ordering 16.9K 1% 0402 and placing it on r46 may be much easier


Hey Zig,

Thanks, I really dont think it is possible to get 0 HW errors for EVERY single pod, for example if you have 30, 40, 50, 60 + devices each device may have a different setting to get it to 0 This will take you FOREVER to work out... lol

<5HW per 24 hrs is fine you will not tell the difference in accepted shares, you know how I know this? Because after 24 hrs I have noticed devices with 0 HW comparing to a device with lets say 5 or 7 and the device with 5 or 7 HW errors actually has more accepted shares than alot of the devices with 0 HW errors..

Although when you start getting 20,30,40+ HW per day this is when you can see the effects of the accepted shares.

Just my 2 cents

Hi Nemercry,

There is just 1 (ONE) resistor to be solder...I called it Rmod =17K/16.9K...

It is to be soldered to the cut-off bridge pads of R46...1 cut...1 solder...that's it...simple...

The original resistor...Orange at position #1...You called "R52"... is in reality R139 = 33K...the  last resistor in the chain of VID resistors ...the same one that you are replacing...This one is just STAYING in place...untouched...NO un-soldering needed... simple "work?.. no thanks"...

You are completely correct as of doing 2 bridges...marked "Yellow"  to "undo" the R139/"R52" mod and to shift the Voltage reference back to resistor in the "green" position...=36K...

I am doing reversal of the Rmod in R46 position by simply shorting back R46 pads...even with Rmod in it...So effectively we back to R139/"R52" value = 33K...ORIGINAL stock value...schematics...performance...etc...
 
I hope it is clear now...

Regards, buddy...

Thank you, it worked!

A number of posts have been moved to services. If you think something should be still in this thread repost it. Service discussion is strictly offtopic here and will be treated as such from now on with either deletion or further bans.

Thanks for the fast and in depth reply.
I marked some spots for you. If you do only the R52 Mod (marked as nr. 1) you got the possibility to undo the mod by doing the soldering on the two yellow bridges.
If you do so you will enable the green 2 resistor. Which is the original 950mhz mod aka 36kOhm.


Can you probably post a picture of your mod ? For now i dont see why it should be faster than replacing the R52.
(Probably i missed something)

Regards nemercry

Anytime for you, Nemercry... I greatly appreciate you time and effort to share first the results of "R52" called mod ...!

R46 cut-off and soldering additional Rmod is Adding 16.9K to R139 = 33K ...resulting in 49,9K as you suggested in the first place...but is simpler procedure...easier to implement...and reverse...no messing with un-soldering R139  ("R52" as they called it) ...

The value of "R52" ...or to be precise R139 + Rmod in series ...doesn't NOT need to be exactly 49.9K IMHO ...this is why I just rounded to 50K...This difference has no effect on the resulting Voltage supplied to the Gridseed chips...less than couple mV ...

It is the same Mod as yours ...has the same effect...Rising the Reference voltage of the Voltage regulators...implemented in a different way...which requires less work...or possible mistakes...I believe...

ZiG

P.S.

Why I am doing this...Very simple...A friend of mine and myself are putting together Scrypt farm of 500 Gridseeds...After putting together $55,000 capital ...the order is already made and shipped...I have to come with reliable solution to squeeze every possible drop of performance...ready to go 24/7 ...and I don't want to spend my life to modify them...and babysit later...plugging-unplugging...messing with cables, hubs and what not...

Competition with Wolfey2014...the hell not...I was also telling him in the early days of this thread that I could use his services as well...NOT anymore...I'll be more than glad to hire somebody to do it... to my specs...

And after a month and a half in this thread, I just decided to share back...That's it...

Happy modding...