the Poor Man 660 support thread

[bernbrue]

Hi,
verify, that C7 and C9 are ok. What about the tubes, are they ok? Check wiring from PSU to audio board. Check R10 of audio board as well, it burns when threshold pots are not connected. Check the wiring guide once again, especially if the transformers are connected the right way. What about the input and threshold pots? check their wiring twice, cause it´s quite complicated. I don´t think, that there is any mistake in the transformer, in case, measure secondaries as well. Good luck, mate.
regards
Bernd

 

[inputoutput]

Thanks Bernd,

The tubes should be ok, since the voltages drops with only one random tube inserted. I have an extra set of tung-sol 5687 which also has been tested.  Wiring triple checked now...  The transformers "see" 30K on their secondaries, so the attenuators should be ok too. right?  Will disconnect and check transformers later.


Anybody experienced something similar, and found a cure?

 

[skal1]

Hey inputoutput


I had a similar problem with my poor guy dipping voltages with load attach, i do not know much about this thing but if was you i would exchange those IRF840A type , just a suggestion, i got mine from here www.bitsbox.co.uk  worked first time  and they delivery world wide 


skal1

 

[idylldon]

I've read through the thread and looked over the .pdf offerings and schemtic, but I can't find the fuse value.  I must be damn dense or have just read over it, so could someone post the mains AC (120) fuse value?

I'm finally down to doing a final parts order and then it's assembly time.  I can't wait as this thing is one of the coolest projects I've yet attempted.

Cheers,
--
Don

 

[lewilson]

Here are a couple of pix of my 670. I went cheap and used pots instead of rotary switches, It works great.
  I had some trouble early on with the power supply. I had to make some jumpers on the pc board due to some  damage I created while desoldering. If there ever is another chance to buy a power supply board put me first in line!

 

[tommypiper]

Wow.  Thanks for the photos. 

What the heck is that huge power transformer with the flag on it?  Are you happy with it?  I'm looking for a power transformer for mine.

 

[kazper]

Wow.  Thanks for the photos.   

What the heck is that huge power transformer with the flag on it?  Are you happy with it?  I'm looking for a power transformer for mine.

It's a edcor, most likely the one made for the PM670 project. XPRW063 is whats on my box, but don't quote me..

BTW your not the only one who has lifted a pad on the pcb... in the +/- section on mine.

Like the old school Simpson meters you used.. Is that a meter zero pot placed on the front ?

Tell us a little more about the pots... IE what you used and or changed.. 25K pot?

 

[lewilson]

Yes, edcore power  transformer.  Zero adjust are 100 ohm cermet pots at front.
  I used 25k dual pots which work fine for threshold and input.

 

[giltmastering]

about to solder resistors on my rotary switches.  have some questions and need help.
i'm trying to make sure that pin 1 & 2 is the lowest resistor position with the 178ohm resistor?
which is also counter clockwise all the way left on the dial, right?
so then all the way clockwise right would give us position 24... resistor value 1620, correct?

also,  if the threshold switch is wired exactly as the input...  does that give us more compression or less compression when turned right, clockwise? 

 

[W DeMarco]

Gettin close to done with my PM but need a bit of help with the "uraltone" switches.  I've got all resistors in place and Im a bit concerned about the interconnects to them. 
T1 connects to both decks 1st resistor
Middle pin from the gain header connects to the 24th position resistors and daisychains across both decks
Pins 1 and 3 from the gain header connect to the small lugs between both decks closest to the first set of resistors?

Is this correct, On the uraltone switch there are two sets of lugs, not sure why there are two sets. Are there two for using the switch CCW?

Thanks fellas!

 

[lolo-m]

about to solder resistors on my rotary switches.  have some questions and need help.
i'm trying to make sure that pin 1 & 2 is the lowest resistor position with the 178ohm resistor?
which is also counter clockwise all the way left on the dial, right?
so then all the way clockwise right would give us position 24... resistor value 1620, correct?

also,  if the threshold switch is wired exactly as the input...  does that give us more compression or less compression when turned right, clockwise? 

On the way to put the resistors, you're right.
Turning clocwise the threshold pot actually gives you more compression.

Gettin close to done with my PM but need a bit of help with the "uraltone" switches.  I've got all resistors in place and Im a bit concerned about the interconnects to them. 
T1 connects to both decks 1st resistor
Middle pin from the gain header connects to the 24th position resistors and daisychains across both decks
Pins 1 and 3 from the gain header connect to the small lugs between both decks closest to the first set of resistors?

Is this correct, On the uraltone switch there are two sets of lugs, not sure why there are two sets. Are there two for using the switch CCW?

Thanks fellas!

The 2 descks replaces 2 ganged pots (look at the schemo)

 

[W DeMarco]

Lolo
I think I could have worded that better.  The two sets of lugs Im refering to are what I assume to be the outputs of each deck,  just not sure why there are two sets and which set I should use.

 

[lolo-m]

Lolo
I think I could have worded that better.  The two sets of lugs Im refering to are what I assume to be the outputs of each deck,  just not sure why there are two sets and which set I should use.

If I did undertand well that time, you're talking about the 2 legs on each desk... Didn't test on mine, but if I remember well they're connected together... Certainly to help (or not :) soldering or placement... I did use the first one (the closer to resistor one).

 

[giltmastering]

thanks for the answer lolo.
i was thinking of making the threshold the other way around,
where turning it counter clockwise gives me more compression....
so, i might just wire that part backwards.

 

[tommypiper]

  I didn't realize Edcor made a PS transformer for this project.  I vaguely remember it being mentioned, didn't realize it went through. 

Is XPRW063 the correct part number? 

Was it a special group buy? 

I'll call them for availability, but just wanted to hear from you guys first...  It seems it would work for many other tube projects as well.

Have you guys had any circuit noise radiation problems with it?

Is it as quiet as a toroid?

thanks.

 

[lewilson]

There is a bit of hum. Its very low. I have not measured it yet,maybe - 80 or -85db
    I left space for a mu metal shield that is not shown in the picture. When its in place there is no hum at all. I place the shield next to the audio transformers closest to the pt.
   I think if you placed the audio transformers a little more carefully  than I did this would not be a problem.

 

[kazper]

  I didn't realize Edcor made a PS transformer for this project.  I vaguely remember it being mentioned, didn't realize it went through. 

Is XPRW063 the correct part number? 

Was it a special group buy? 

I'll call them for availability, but just wanted to hear from you guys first...  It seems it would work for many other tube projects as well.

Have you guys had any circuit noise radiation problems with it?

Is it as quiet as a toroid?

thanks.

Made to order.

Make sure it's grounded well (like Drip recommends on the Dripopto) and has a good Star ground based on the case. I use lock washers all around and make sure it bites in a bit.

It's not a toroid so you loose those aspects.

If I remember right it was like $45

 

[giltmastering]

would anyone besides me like to get a Toroidal supply for this unit?

 

[tommypiper]

would anyone besides me like to get a Toroidal supply for this unit?

Yes.  I'm still collecting parts for mine; (my usual slow schedule due to wild kids and a full plate of domestic duties and issues).   

I contacted Haeboer several times to request shielded toroids.  I believe they make good audio-quality toroids, and I think shielding is a good investment.    But they have continually dropped the ball and don't reply or follow through.  If we could get an order of 10 or more we might get their attention and better service.  I could order 6 myself for various compatible tube projects... how many would you want?  Where were you thinking of ordering yours?

 

[Brolik]

yup, I'd be in for one of those as well