the Poor Man 660 support thread

[served]

Can you send some voltage information?
I could compare them with mine.
Mine is acting similar to this.

 

[vari-mu]

5 years! ...
As I was wiring in a switch for the meter to go between gain reduction and output , my troubles started.  The right side worked fine, but the left side did not. It showed very little gain reduction for a minute then the whole thing got much lower in volume ...

  HI Freddy G
Perhaps you have "died" transistors Q1, first in one channel, then in another.
Switch the cathode  resistors from  emitters  to the ground.
Try other variations on the scheme.
Load Rz 1-2k on the secondary output is required.

Good luck!

 

[vari-mu]

Hi.

I have a strange issue with my previously working 660.
Its built like it should.
It compresses and works like it should, but.
There is strange distortion in the sound if I push it.
If I feed it with sine, I get a crossover-distortion-like picture.
What could cause it?

    HI served !
  In the picture we can assume that only works one shoulder.
Check the circuit input transformer T1 - 2X15k attenuator.
The signal must be on the grids of each shoulder.
To measure relative CT
Good luck!

 

[served]

Hi.

I have changed the input transformer. And replaced the input attenuator with two 15k resistors.
This will give me no attenuation.
I have messed around with the biasing. I have cleaned the boards and replaced all the components.
Waiting for new tubes to see if this could solve my problem.
I will probe the signal to see if both of the shoulders are working.

Will report back.

 

[Freddy G]

  HI Freddy G
Perhaps you have "died" transistors Q1, first in one channel, then in another.
Switch the cathode  resistors from  emitters  to the ground.
Try other variations on the scheme.
Load Rz 1-2k on the secondary output is required.

Good luck!

Thank you vari-mu! I will try this.

 

[served]

What value resistor should replace the VU meter?
I am suspecting that my meter has too high resistance.

I have signal on the both shoulders.
Measured from the T1 CT. Until the tubes, the signal looks like a perfect Sine.

Changed the tubes abit. Things went worse.
With the Input and treshold maxed. Output is -7db and looking like this.

 

[served]

Took some voltage readings related to ground.

There is very high voltage drop on that meter.

 

[vari-mu]

What value resistor should replace the VU meter?

  Served , change 22 ohm resistor R6  instead of 22kohm .

 

[served]

What value resistor should replace the VU meter?

  Served , change 22 ohm resistor R6  instead of 22kohm .

Replaced the R6 with trimmer. You are correct. Reduced it and everything started to improve. I will run the scope and generator tomorrow. Can't wait!

 

[served]

Sifam AL39 should be around 6,6k

So if you would like to run the unit with out the VU.meter add a 6,6kohm resistor parallel with R6.
No more distortion and the sound is just perfect!
Best compressor I have heard so far!

 

[rrs]

Hi All.

Hoping someone can help me out with a little issue with my PM670, Its serving me well for around 7 or 8 years now ( with a better power supply) but last week it let me down.

To describe what has happened the lights on the meters are not on and the audio seems to be in complete bypass. This is in both channels and I am also using the relays boards on the in and outputs .

I immediately checked power supply and all voltages seem fine but did notice 2 wires around the heater seem significantly discolored or burnt. The valves appear to be glowing but the unit isnt as hot as it usually is.

Also on the Power PCB Heater + and - terminals seem to connect (as in i can beep them with my multi meter)



Any input would be great.

 

[duantro]

Hi All.

Hoping someone can help me out with a little issue with my PM670, Its serving me well for around 7 or 8 years now ( with a better power supply) but last week it let me down.

To describe what has happened the lights on the meters are not on and the audio seems to be in complete bypass. This is in both channels and I am also using the relays boards on the in and outputs .

I immediately checked power supply and all voltages seem fine but did notice 2 wires around the heater seem significantly discolored or burnt. The valves appear to be glowing but the unit isnt as hot as it usually is.

Also on the Power PCB Heater + and - terminals seem to connect (as in i can beep them with my multi meter)



Any input would be great.

Where are your meter lamps connected, and what voltages are they? Are you running a scamp board or anything that uses the same voltages as the lamps in the meters?

 

[rrs]

Thanks duantro
I have the SCAB board and am using the Sifam AL20 meters which goes to the meter connection in the Channel PCB (136v measured).

The connections on the Sifam AL20 lamp go to the SCAB and RELAY Board. No voltages mesured. The SCAB board measures 17V where the Power input connects though.

 

[rrs]

Also notice reglulators lines up at the back all show + or - 17 appart from the last one U102 showing 0.

 

[duantro]

Also notice reglulators lines up at the back all show + or - 17 appart from the last one U102 showing 0.

Looks like you may have found the problem. U102 connects to the bypass relays. I'd check it with a meter to see if it is bad. also check c106 and c107 on scab board aren't bad.

Regarding your burnt looking heater wires, I'd suggest a heavier gauge wire here. They're pulling some current. I had a heater wire burn in half, before I did this!

 

[rrs]

Ok thanks will do

 

[rrs]

BIG Thanks duantro

Replaced LM7812  (with L78S12 because i had it) and two capacitors back up running  a treat.

Such a nice nice compressor always a pitty to have it out of action.

 

[djfatum]

amazing project 8)

 

[tommypiper]

amazing project 8)

Gorgeous build.  Who made the front panels?

 

[weiss]

wow, and then two of that kind  ;D