the Poor Man 660 support thread

[noulou]

Just power it up with nothing connected if you want to measure your voltages.

Everything apart from the heater psu is actively regulated.

 

[skal1]

hey thanks for the quick response  ;D


skal1

 

[rrs]

D9 Anode = 392V
D9 Cathode = 211V

D8 Anode = 392V
D8 Cathode = 394V

looks like your first regulator (around Q4) doesn't work

Thanks again I will replace this.

This raises another question though.
I initialy mesured 136V on the connector pin where indicated when first powering up and was correct. Didn't mesure 245V.
After doing this I plugged in the two PM660 boards with valves inserted to mesure the requires R15 resistance. I noticed though after doing this that when I turned one of the threshold knobs that I got a spark on the PSU board around this "Q4" general area so am wondering the cause of the IRF820's failure and could it happen again. I am using the greyhyill rotary non-shorting type.
Mfr Part#: 71BD30-02-1-AJN
Allied Stock#: 948-7249

I don't want to have to replace it a second time as removing the first seems to have not been easy for me or on the PCB.

Also R10 330R on both PM660 boards is burnt out I guess due to the incorrect voltages being pummped through it.

 

[MartyMart]

hey i just finished stuffing psu ,can i power it up with a load or will this cause damage to the psu


regards

skal1

Just remember that with no tubes in, the caps will retain the high voltage for a Very long time !!!
BE CAREFUL
MM,

 

[Purusha]

What about with tubes IN?

 

[MartyMart]

What about with tubes IN?

Dissipation is a bit quicker with them in but ....... S  L  O  W without !!

 

[Purusha]

BTW, how does this unit sound? Haven't had the time to even start mine or read this thread.

Any sound samples out there?

 

[bernbrue]

Thanks again I will replace this.

This raises another question though.
I initialy mesured 136V on the connector pin where indicated when first powering up and was correct. Didn't mesure 245V.
After doing this I plugged in the two PM660 boards with valves inserted to mesure the requires R15 resistance. I noticed though after doing this that when I turned one of the threshold knobs that I got a spark on the PSU board around this "Q4" general area so am wondering the cause of the IRF820's failure and could it happen again. I am using the greyhyill rotary non-shorting type.
Mfr Part#: 71BD30-02-1-AJN
Allied Stock#: 948-7249

I don't want to have to replace it a second time as removing the first seems to have not been easy for me or on the PCB.

Also R10 330R on both PM660 boards is burnt out I guess due to the incorrect voltages being pummped through it.

Keep in mind, that you should not fire up the PSU with the audio pcbs connected before you have done the complete wiring. I burned R10 several times before I realized that the transformers have to be connected first. So I recommend to measure the PSU voltage without anything connected. Then do the complete wiring including rotary switches or pots and transformers, check everything twice and then fire it up.
regards
Bernd

 

[rrs]

OK I have replaced IRF820 and things seem a little better.

heater = 14V
254V = 273V
136V = 147V

Still getting 5.9V at Heater under load with .33R at R15.
Will try using .15R.

 

[noulou]

Leave the machine on for more than half an hour with case closed in order to get warm in there.

The filament voltage will probably rise.

 

[noulou]

I'd love some help with a problem I'm experiencing.

I've got a loud buzzing which I'm suspecting it is the 5687 oscillating.

It changes with varying degrees of threshold change and it completely disappears if I touch the heater B- on the pcb connector with a metal part. (for example metal pliers)

wtf is going on? is it acting like an antenna cancelling rf?

Thanks in advance

 

[bernbrue]

Mhm, never noticed this problem, I would double check grounding.
regards
Bernd

 

[rrs]

Leave the machine on for more than half an hour with case closed in order to get warm in there.

The filament voltage will probably rise.

Thanks will try.

Noulou, thank you for your reply! It's been really helpfull,  wiring was fine but one of my lorlin was faulty. Regarding the meter i originaly put a 22K trim in place of R6 but was afraid to go so low, but you where right two turn of trimmer after my vu finaly read 0.
For those who used sifam AL20SQ like me, substitute R6 22K with a 47ohm or little higher.

Noulou again, thanks!

I am using the same Sifam AL20SQ meter which had the same problem. Have replaced R6 on both boards with 47 ohm resistor but 1 meter (Closest to PSU) is still Flexed hard right. The other channel is at about 3 db GR so will try the 69 Ohm .

Any ideas why one channel is still a problem?

 

[Moby]

I am using the same Sifam AL20SQ meter which had the same problem. Have replaced R6 on both boards with 47 ohm resistor but 1 meter (Closest to PSU) is still Flexed hard right. The other channel is at about 3 db GR so will try the 69 Ohm .

Any ideas why one channel is still a problem?

Did you checked the Edcors. Try to measure them , for start dc resistance...

 

[rrs]

I am using the same Sifam AL20SQ meter which had the same problem. Have replaced R6 on both boards with 47 ohm resistor but 1 meter (Closest to PSU) is still Flexed hard right. The other channel is at about 3 db GR so will try the 69 Ohm .

Any ideas why one channel is still a problem?

Did you checked the Edcors. Try to measure them , for start dc resistance...

How do I go about doing that?

 

[Moby]

I'ts possible that DC resistance is different on one channel ... some people reported that. Just measure are the resistances of the windings. Simply ,, by ohmeter....

 

[rrs]

Thanks Moby

I'm pretty rough on this stuff so if you can tell me what point to measure and what mesurements to look for that well help.
My skills beyond soldering and conecting parts are extreamly limited. 

 

[bernbrue]

Thanks Moby

I'm pretty rough on this stuff so if you can tell me what point to measure and what mesurements to look for that well help.
My skills beyond soldering and conecting parts are extreamly limited. 

Before changing R6 I would adjust RV3 to 2.4V and RV6 to 4.5V for both channels. Since the these trimmers also influence the meters, this might be a chance to get both meters right.
regards
Bernd

 

[Moby]

Thanks Moby

I'm pretty rough on this stuff so if you can tell me what point to measure and what mesurements to look for that well help.
My skills beyond soldering and conecting parts are extreamly limited. 

Try to measure resistance on the 10k/600 (T2) from pin1 to pin2 (around 215ohm) and from pin4 to 2 (around 240ohm). If the resistance is the same on both channels than you don't have a problem with Edcor's  ;D

 

[rrs]

Thanks Moby

I'm pretty rough on this stuff so if you can tell me what point to measure and what mesurements to look for that well help.
My skills beyond soldering and conecting parts are extreamly limited. 

Before changing R6 I would adjust RV3 to 2.4V and RV6 to 4.5V for both channels. Since the these trimmers also influence the meters, this might be a chance to get both meters right.
regards
Bernd

Yep I've adjusted trimmers already but I think I did this without tubes in. Not sure if that changes things expecially as one channel is fine.
The meters take a while to move (around 20 seconds) then slowly make there way into position.

RE: Edcors, Thanks Moby will test further tonight.



Also ..... it was mentiond earlier that when testing the PSU without load that the capacitors hold there charge for a very long time. Well a day after doing some testing I replaced the R15 resistor and while desoldering one of the wires accidently touched the threshold pot giving a decent spark. No power had been connected for about 20 hours.