the Poor Man 660 support thread

[rrs]

OK not sure if I have measured this right but 8.2A DC is what I thing I have.This is mesured at the end  (Heater) pin PSU Board output
The output voltage of the transformer measured before it gets to the Heater rectifier is 8.95V.

These are measured under load.

 

[Moby]

OK not sure if I have measured this right but 8.2A DC is what I thing I have.

There is something wrong with tubes or smoothing cap is leaky. It should be around 5.2A for stereo unit.Try to measure without tubes . It should be zero. Than if it is 0  try to disconnect one channel , and figure out is the consumption same on both channels. It can be that some of tube is shorting filament. Hope this helps  :

 

[emrr]

RRS meant volts, not amps, I'm pretty sure. 

Sounds right to me, you just need a smaller dropping resistor. 

 

[Moby]

RRS meant volts, not amps, I'm pretty sure. 

Sounds right to me, you just need a smaller dropping resistor. 

Well, if you right that he measured voltage than it's OK 

 

[rrs]

I did mean Amps but I'm sure I've measured it wrong.
I haven't used my multimeter to measure Amps before. It say's to measure in series and I'm not sure what they mean by that.( Where to connect the two probes).
I just tried measuring with one probe connected to Heater pin and one to ground and got a spark so I'll give up on that till I find how to do it properly.

 

[emrr]

that shorts the filament to ground!  Disconnect the filament wiring from the supply, and put the meter in series.  In other words, use the meter (in the correct range setting!) as the wire from supply to filaments. 

 

[Moby]

I posted this link about measuring current, but here it is again. http://www.electronics-radio.com/articles/test-methods/meters/how-to-measure-current.php 

 

[casrec]

hello all,
  I'm sure it has already been posted, but 51 pages is a lot to search through. Anyways, can someone please tell me what the average cost is to but a 660 together. Also, i just put together a mnats 1176 with relative ease, is the 660 something a beginner should be able to tackle? Thanks everyone!

Brandon

 

[rrs]

that shorts the filament to ground!   Disconnect the filament wiring from the supply, and put the meter in series.  In other words, use the meter (in the correct range setting!) as the wire from supply to filaments. 

Thanks for all the help guys.

OK I have measured current with the two PCB's connected at 4.72A. With just the single boards both measured 2.92A exactly each.

I think this may be too low. 5.2 Amps was mentions earlier.
Or is this acceptable if not what action should I take to rectify this?

 

[Moby]

It seems exactly like I mentioned before. Voltage drops on the transformer sec. And yes, filament current is exact like it has to be. You have 8.2V in front of the resistor and 5.71V after.Current is 4.72A. For 9V in front of resistor you will have 6.3V , 5.2A  .
Try to change your resistor and pray that filament winding will "survive" . BTW, do you have voltage drop on other sec. windings when you connect filament supply? If not, than go ahead.  ;D

 

[emrr]

5.2A is correct draw at 6.3V.  You have less voltage.  Lower R15 value, voltage goes up, current goes up.    R15 eats power, you need less power eaten.  Both supply and load are relative constants.  The power transformer is rated to deliver 9VAC at 6A AC.   10.2VAC at no load.   This assumes 115 or 230 VAC on the primary; confirm primary voltage first and measure sec AC again.   Looks like you are supposed to be on 240VAC/50 Hz there?  The filament winding is rated for 6A, so it will have no problem surviving unless it's actually bad.   Did you confirm zeroish current between the rectifier and the first cap with no tubes in?  Check AC and DC current.  You mentioned 13.5V with no load connected to the PSU board; that's clearly higher than the transformer 'no load' rating of 10.2VAC.   

I think the average cost for a PM660 is probably $600+. 

 

[rrs]

Well guys I have made some more measurements which have really left me scratching my head.
So here they are:

With boards not attached
Pin 1 Heater = 14V
Pin 2 Heater = 0V
Pin 3 245V = 401V
Pin 4 136V = 218V
Pin 5 -17V = 17.12 (Trimmed)
Pin 6 Ground
Pin 7 +17V = +12.08 (Trimmed)

With 2 Boards attached
Pin 1 Heater = 6.03V
Pin 2 Heater = 0V
Pin 3 245V = 311V
Pin 4 136V = 169V
Pin 5 -17V = 17.12 (Trimmed)
Pin 6 Ground
Pin 7 +17V = +12.08 (Trimmed)

This don't look good does it  :'(

Could I have the Toroid wired wrong?
The funny thing is that I measured 136V the other day and it was only a couple of volts out I'm sure. Also the Pin Heater is measuring higher although this could be due to power fluctuation.

 

[noulou]

Coming along nicely

Do not ask me to comment on the sound though yet. I have some issues to iron out.

Namely some low-level buzzing, the vu meters issue...

I think I will also mod it for a  couple quicker release times at the first time constant steps. Attack is fast enough for me.

Heater resistor in mine is 0.33R. I also have a 6.3V lamp on my front panel also though.


When I have it proper up and running I'll post some clips.

BIG thanks to everyone involved in making this happen for us.

 

[analag]

Can you make one for me?.....good job.

analag

 

[Moby]

Looks great 

 

[noulou]

Thanks for the kind words.

Here's the seriously good looking purusha case also.
My apologies for the crap photography.

 

[emrr]

Well guys I have made some more measurements which have really left me scratching my head.
So here they are:

With boards not attached
Pin 1 Heater = 14V
Pin 2 Heater = 0V
Pin 3 245V = 401V
Pin 4 136V = 218V
Pin 5 -17V = 17.12 (Trimmed)
Pin 6 Ground
Pin 7 +17V = +12.08 (Trimmed)

With 2 Boards attached
Pin 1 Heater = 6.03V
Pin 2 Heater = 0V
Pin 3 245V = 311V
Pin 4 136V = 169V
Pin 5 -17V = 17.12 (Trimmed)
Pin 6 Ground
Pin 7 +17V = +12.08 (Trimmed)

This don't look good does it  :'(

Could I have the Toroid wired wrong?
The funny thing is that I measured 136V the other day and it was only a couple of volts out I'm sure. Also the Pin Heater is measuring higher although this could be due to power fluctuation.

WHAT PRIMARY AC VOLTAGE WAS PRESENT WITH THESE MEASUREMENTS?

How are the primary windings connected? 

Are we still considering 0.33R for R15?

Note that C1 and C3 in the PSU are possibly at the limits of rating with nothing connected; depends on what you used. 

The only thing you could possibly do wrong in toroid wiring, and get anything similar to normal voltage ranges, would be to have the wrong primary connection.  Anything else would have probably started a fire.  You have correct ranges present, though not correct voltages for B+.  +/-17 seems proper regulation.  I can't address B+ other than to say check that all parts values are correct in each position.  It would certainly help if someone having a normally operating unit would post voltage measurements within the PSU (and audio), for troubleshooting purposes; a list of junctions and measured voltages.  Mine isn't up and running to check yet. 

 

[rrs]

My primarys are:
brown to IEC 1
blue to IEC 2
Grey and Purple tied together (does that mean they should be connected together)?

I am still using .33 at R15.

I will re check all values soon.

 

[emrr]

Sounds right for 230 VAC primary connection.  You are on 240V 50 Hz there, right?  So you will see slightly higher voltages because of that. 

 

[noulou]

I got an email with questions from klaus2you. I'm posting the answer here for anyone else having the same problems.

I also finished my poor man in purusha case last night but have issue i need to fix, vu meter also, put a 4k trim and didn't help. Could you please tell me how you wire your time constant 2x 6 lorlin because i think i fuct up there, just unsure of the connection between the board and the lorlin (+,-,ground).

the problem with my vu meter is that it has too high internal resistance.
In the circuit the vu meter is in parallel with R6, a 22K resistor.

you can calculate parallel resistances using this:
http://www.sengpielaudio.com/calculator-paralresist.htm

In mine I had to substitute R6 with a 68 Ohm resistor in order for the current flowing through them to be normal.

If your meter is pegging to the right you should also try a smaller value R6.

The attack switch is wired as follows:

At the pcb connector, the left leg goes to fully cw at the switch. (end of resistor network)
The middle one goes to the wiper.
Right one goes fully ccw. (start of resistor network)