the Poor Man 660 support thread

[[silent:arts]]

Also if the heatsinks are not attached to anything ,
then shouldn't need the insulators right ?

my rule:
ALWAYS insulate the heatsinks.
you never know, in a few years you want to check and touch the heatsink, and you don't know (or don't remember) what voltage will be there. in the poor man this is up to 250V on some heatsinks.
it is just a security thing, and costs nearly nothing ???

 

[[silent:arts]]

Wiring Guide for the PM660 Slow Start PSU

 

[Moby]

Wiring Guide for the PM660 Slow Start PSU

Looking great 

 

[lolo-m]

I'm not at all familiar with all the high current regulator options out there, but I was wondering...

the slow start heater regulator can't handle enough current for 2 channel operation. Why wasn't a better suited regulator selected for this task? Why wasn't it designed so that it would handle the current for 2 channels?

Seems a bit counter productive to have two of them side by side.

The real problem in the choice of the regulator is to find a regulator able to handle 5,2A out. I don't know any (but they maybe exist  ;D). The LM350T or LM338 are only able to handle one PM channel but they are easy to find and are both pin compatible and the board can fit the two certainly without any mod...

 

[Moby]

The real problem in the choice of the regulator is to find a regulator able to handle 5,2A out

LM338 can handle that but with serious cooling. Inside PM660 is so much heat ,so it's much safer to go with two regulators.

 

[SaMpLeGoD]

TRIMMERS
(how they are set in analags unit)
got this news via eMail:

Quote from: "analag"
RV3 is adjusted to -2.4V and RV6 is set to -4.5V

-2.4V and -4.5V DC isn't it?

Eddie ;D

 

[joe-electro]

Anybody ever used this device before? Looks like it might fit this application.

http://www.datasheet4u.com/html/L/M/3/LM396_NationalSemiconductor.pdf.html

---Joe

The real problem in the choice of the regulator is to find a regulator able to handle 5,2A out

LM338 can handle that but with serious cooling. Inside PM660 is so much heat ,so it's much safer to go with two regulators.

 

[SaMpLeGoD]

Hey, sorry my dumb previous post! as long as -AC voltage doesn't exists... of course is DC voltage... damn

Cheers,

Eddie  :

 

[lolo-m]

Anybody ever used this device before? Looks like it might fit this application.

http://www.datasheet4u.com/html/L/M/3/LM396_NationalSemiconductor.pdf.html

---Joe

The real problem in the choice of the regulator is to find a regulator able to handle 5,2A out

LM338 can handle that but with serious cooling. Inside PM660 is so much heat ,so it's much safer to go with two regulators.

This regulator seams to suit better the needs indeed... It's a real 10A...

LM338 can handle that but with serious cooling. Inside PM660 is so much heat ,so it's much safer to go with two regulators.

Yes, you're right (Iout = f (Vout-Vin)) but I always limit myself to the first data sheets specs... I consider them as the real maximum you can expect... LM338 is meant to be a 5A regulator, I won't try to pump more than than 5A... But you right, it should be able to handle the current of a PM670  ...

 

[Moby]

Anybody ever used this device before? Looks like it might fit this application.

http://www.datasheet4u.com/html/L/M/3/LM396_NationalSemiconductor.pdf.html

---Joe

As far as I know LM396 is discontinued device. Again, go with LM338 dual boards and be happy. At last you can go with cheaper TO220 version but ensure some cooling .  ;D

 

[Kingston]

Is "2 x (optional) Electrolytic, min 250V, max ø 12mm" a reference to the 2 unmarked caps next to the power connections on the PM660 board?  I assume so, based on the few other Q&A's about them.  I measured  2.5 or 5mm lead spacing for both positions.  

Voltage is obvious from the B+ rails.  Benefits from adding substantial extra capacitance is the question for everyone to consider.  They are simply in parallel with the 100 mfd PSU caps exiting the PSU, so it's simply a matter of physical placement.

This very basic electronics question might have been answered elsewhere on the forum, but I could not find it by searching...

I realise adding those extra caps will have a benefit of removing some ripple, if there still is any at that point,

but can there be any negative (parasitic or otherwise) effects of adding them in?

 

[Grooveteer]

I'm almost done with my PM670, or maybe not as there seems to be a problem with the heater voltage. I'm using Volker's slow start PSU.  Without the tubes I can dial in a perfect 6,3V  but after placing the tubes the voltage drops and I cant set it any higher than 4.3V.

Any idea if I should be looking at the the slow start PSU or at the PM itself?

Is 4.3 way too low anyway? The tubes seem to glow alright...

Cheers!

G

 

[[silent:arts]]

as far as I know bernbrues first prototype still works with 4.3V ;D

what PST transformer do you use ?
do you use one slow start PSU each channel ?

 

[bernbrue]

5,3V ;D
regards
Bernd

 

[Grooveteer]

Yes I'm using 2 slow starter PSU's. Just hooked up the second channel.  3.9V 

Weird.

I'm using the trafo from Bernd's group buy by the way.

 

[[silent:arts]]

- does the voltage regulator gets hot ?
- measure the current between the slow start PSU and each PM660 PCB

 

[Grooveteer]

- does the voltage regulator gets hot ?

Very. They're both bolted to the chassis (insulated of course) and the screws are too hot to touch.

Not sure with what you mean by measuring the current between the SloStart PSU and PM660 pcb.  (noob here  ) From which point to which?

The unit does work by the way. Not sure what the effect of such low heater voltages would be on the sound?

 

[Moby]

Not sure with what you mean by measuring the current between the SloStart PSU and PM660 pcb.  (noob here  ) From which point to which?

You have to insert the ampermeter between Slostart and PM660 and measure. Than we will know where is the problem 
Here's the little explanation about how to measure current 
http://www.electronics-radio.com/articles/test-methods/meters/how-to-measure-current.php

 

[Grooveteer]

Thanks Moby!  (I recalled something like "in series" for current, but I wasn't sure)

Any way: It's 3,8A for each channel.

The second channel has a problem with audio as well. Very faint and hi-passed sound. Channel one is fine. Tried swapping tubes and heater PSU, but that did not matter.  We'll get there  ;D

Oh, and by way: be careful to connect all wires again before powering on. (forgot threshold and had to replace R10 which immediately passed away  :'( ) 

 

[pH]

Finally getting close to testing, I'm wiring it up on a piece of plywood since I still don't have a case.

One question: since I'm not wiring this for keeps I'd like to only do one channel for now. I know the heater resistor will have to be adjusted for mono, but can I fire up just one channel on the PSU even though it has the IRF840 soldered in?

-paul