Simplistic NJFET RIAA

[Salas]

Very nice very homely looking system. Interesting tonearm.

 

[Joel Wesseling]

The designer is a member here!

https://www.diyaudio.com/community/threads/diy-tonearm-project-going-commercial.373427/

 

[Russellc]

Oh boy. Just got the CMR caps and other small parts to finish this phono pre. I am bent to finish this and my also basically done DCG3 preamp

Opening case of the phono, I noticed the only board parts not yet soldered in, the M1 and M2 pairs and their small bag were not to be seen.

As I recall these were some of the "super matched" items and are irreplaceable. I bought the "big" kit. If this is so, I will find them, I thought they might be in the DCG3 case, but nope. I'm sure I will locate, there are just a lot of places to look.

Otherwise, perhaps they are an easy to replace part? Rarely do I miss place those, it's the difficult ones I put "somewhere safe." Usually, that is in the case. I wonder if I took them out when I opened to solder C3 and Ç4, the big CMR caps. Nutz.

So, must find these, or easy to replace. I think I already know the answer. I have a lot of boxes to go through!


Russellc

 

[Russellc]

They are just regulator parts, ought to be easy to replace, but I will find these.

Russellc

 

[Salas]

M1 & M2 are the reg's power MOSFETs and they are Indeed replaceable with unmatched. Remember their tabs must be mounted with insulation.

 

[Russellc]

M1 & M2 are the reg's power MOSFETs and they are Indeed replaceable with unmatched. Remember their tabs must be mounted with insulation.

Thanks, still looking, I'll find them as soon as I order replacements.

Russellc

 

[RickRay]

@Russellc ain't that the way it always goes. Don't know how many times I did that or remembered something else right as I hit the order button.

 

[A321Drvr]

Hey Folks Starting to Stuff my Boards Raw power done. Works great. Started testing resistors for the UBiB 1.3. The schematic shows
5.6R at the R1 position. The resistors I have test at 6.1R is this an acceptable range?

Tea-Bag a little help on the writing please... and a little help on the general vicinity of their placement.

Thanks

 

[A321Drvr]

Anyone? I can make out the word resistors on both bags and the word signal on the right bag.

Any thoughts on the 6.1 ohm resistor vs the 5.6 ohm on the schematic @ the "R1" position.

See above post.

Thanks

 

[glenv6]

Anyone? I can make out the word resistors on both bags and the word signal on the right bag.

Any thoughts on the 6.1 ohm resistor vs the 5.6 ohm on the schematic @ the "R1" position.

See above post.

Thanks

Hi A321Drvr - The BOM is color coded. Look at the blue section on the BOM. Measure each resistor, lookup that value in the blue section and label the resistor with the location. Rinse and repeat until you have gone through them all.

 

[RickRay]

left says "signal resistors" right says "0.1% signal resistors" I guess being an educator does have some perks, I can read illegible writing! I'll let @teabag respond to the 5.6 to 6.1 question.

 

[A321Drvr]

Thanks @glenv6 and @RickRay

The BOM and parts placement will be so easy, Even I can follow that. Doh

In my profession all writing has to be legible but you Scrawl your Signature too be able to deny it was you.

Thanks again guys

 

[Salas]

I am not sure if 5.6 vs 6.1 is an approximation in value, it could also well be matching to the particular 2SK369s IDSS provided. But only Tea can confirm.

 

[A321Drvr]

Sorry Salas I am referring to the "Shunt UBiB 1.3S" "R1" I have tested the resistors with 3 different DVM's and both of the resistors test at 6.0R to 6.1R. The schematic states 5.6R

Any thoughts? Should I get a 5.6R or is 6.0R going to work?

Thanks

 

[Salas]

Did you press the zero (delta) button? Could be the test leads residual adding.

 

[Salas]

Any thoughts? Should I get a 5.6R or is 6.0R going to work?

Thanks

Makes very little diffidence to the programmed CCS current result even if that 0.4R deviation is real

 

[A321Drvr]

I don't think I have a delta button on my meter. I spent about $60 on this meter from "Home Depot" here in the States. I will go out to the shop and read through the documentation.
Just a thought would a temperature of 10 to 15 degrees C have an effect? These are the temps in my shop.

 

[Salas]

I don't think such a temp range would change things much.

 

[RickRay]

Try measuring some of your 0.1% low value resistors and see if they match. We know they are .1% of value. That will tell you if the meter is slightly off, which I suspect.

 

[A321Drvr]

Making progress, trying to read all of the decimal points is tough on an old man.
@RickRay I took your suggestion and measured some 0.1% resistors, right after I changed all three batteries in my DVM's. All of them measured spot on or maybe a ".1 or .2" out. I guess these "Southwire" DVM's just don't like very low ohm resistors.
Funny thing is my $20 meter which is not an auto ranging meter measured "5.8ohms" . Go figure