the Poor Man 660 support thread

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rrs said:
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. :eek:
Click to expand...

Jeez !!
That's why you can now buy "capacitor powered" hand tools !
Charge them for 45 seconds and you get about 15 minutes of decent power.

Be careful mate !
MM.
 
buy a cheap Multimeter for EUR 10,- and have it connected to the high voltage part all the time you work on it ...
at least I do it this way, and since I'm still alive this can't be wrong ;D
 
[silent:arts] said:
buy a cheap Multimeter for EUR 10,- and have it connected to the high voltage part all the time you work on it ...
at least I do it this way, and since I'm still alive this can't be wrong ;D
Click to expand...

You're too modest Volker , since you build and repair this stuff for a living ... we expect you to LIVE  !!

The rest of us "mortals" just keep one hand in a back pocket  :-\

MM.
 
OK this has really got me down.

Realized I had a couple of transformers mixed around. Fixed up and turned on with much anticipation.
Meters went to correct place or close to.

Was very excited at this time ...BUT!!
After a period of time both went all the way right.

Now I am back to where I started. Am testing with everything connected and fried R10 on both pcb's again.
PSU measurements with no load are now.

Heater --14V
245V ----278V under load at around 300V
136V ----150V under load around 160v
other voltages are normal.

Measured
D8
403V - cathode
278 - anode

D9
278 - cathode
150 - anode

:'(

Any advice on what I have blown this time. Hopfuly this was due to something I did while swapping the Edcors. Power wasn't on but considering how much charge that may have been left?????
 
Burning R10s:
double check if your "compression / threshold" control and T3 is wired correctly.
mine smoked while testing without the controls connected.
double check T2 & T4.
the high voltages are fed through the center tap of the primary (Edcor Pin2)
you should measure (nearly) equal voltages on Pin1 & 4 of those transformers.
 
Hello everybody.
first PSU fire up and it did seem to work.
then I went on to check various voltages around it (off load)and I managed to short circuit PIN 2 and 3 of Q4...
:mad: :mad: :mad:
of course that blew Q4 and Q1. replaced those (plus Q2 and Q3 just in case) and now I have really low voltages at the output.
220V instead of 245V and 110V instead of 136V off load and 60V instead of 245V and 30V instead of 136 on load.

so then I disconnected R8 from the circuit and measured voltages(off load of course) and I have:
  -Q4 PIN 2 ->378V
  -Q4 PIN 3 ->254V 
  -Q3 PIN 1 ->101V (across the zener diode)
so everything seems to be fine at the first stage.

then I replaced Q5 and D10 reconnected R8 in the circuit but yet the voltages are as mentioned above..

are we suspecting R9 and R10? shall I replace the resistors in around Q5?!

any help will be much appreciated.

AW.


 
Thanks Bernd,

I have replaced R9/R10......

i have checked C7 and C9, they seems OK
i have measured their capacitance:
C7 : 92 uF
C9 : 82 uF
C5 : 86 uF

still the same.
??? ???

Maybe the problem i have is caused by C9 and C5 that are not at their best performance ??

Someone can shom me the  way ??

Ragards
 
rrs said:
OK this has really got me down.

Realized I had a couple of transformers mixed around. Fixed up and turned on with much anticipation.
Meters went to correct place or close to.

Was very excited at this time ...BUT!!
After a period of time both went all the way right.

Now I am back to where I started. Am testing with everything connected and fried R10 on both pcb's again.
PSU measurements with no load are now.

Heater --14V
245V ----278V under load at around 300V
136V ----150V under load around 160v
other voltages are normal.

Measured
D8
403V - cathode
278 - anode

D9
278 - cathode
150 - anode

:'(

Any advice on what I have blown this time. Hopfuly this was due to something I did while swapping the Edcors. Power wasn't on but considering how much charge that may have been left?????
Click to expand...

OK
Have replaced IRF820, IRF840. and still no joy.

D8
Cathode 182
Anode 153

D9
Cathode 110
Anode 53

245V Pin  = 390V
136v Pin = 211V

I really need some help please.
 
rrs said:
I really need some help please.
Click to expand...
Static check Q1, Q2, Q3... R1, R8... If there's something wrong with Q1/2/3, you'll maybe have to disolder them... If you do, check all the resistors all around here...
Check once, twice... your ground connections.

Hope you'll find something wrong there...
 
lolo-m said:
rrs said:
I really need some help please.
Click to expand...
Static check Q1, Q2, Q3... R1, R8... If there's something wrong with Q1/2/3, you'll maybe have to disolder them... If you do, check all the resistors all around here...
Check once, twice... your ground connections.

Hope you'll find something wrong there...
Click to expand...

Hi

How do I do a static check?

I did also replace Q2,Q3 but Q1 I cannot get as easily but will have too order I guess. If I work out how to check I'll find out if I have to do that.
Also desoldering is destroying the PCB pads as they are lifting off the PCB too easily and am having to wire directly.

I did have the PSU working perfectly for a while so I'm sure resistors are correct values. But will re check.
 
Static check ... mmmm ... I don't really know if it's the correct word in english... Anyway, power off, all caps empty, test all the connections possible. On your tester you should have a diode mode... check the differents points of Q1/2/3. You should find 2 diodes values on each one (around 600mv) as a transistor is basicaly two diodes connected on the Base point. If there's something wrong with a value, you'll have to disolder the transistor to check if it isn't the all around components that make the error  :'( :'( :'(. Yes, the boards are really painfull to disolder... but I have to, and I did it but you've got to be calm and patient... Use a few solder sucking wick and the help of a disoldering pump...
If Q1 is dead I'm sure there will be someone to help you here to get one at a fair price...
 
Tested Diodes and Q1,2,3 and all measured around .600 so that's good. 47R/2W resistors measured ok also.

Is there any further measurements to try. Could they measure well but still be faulty??

I would really appreciate any further input.


[Edit]
OK found the culpritc ....1N4764 (D7) replaced and now voltages are correct.  ;D

And now to hookup to the two PM660 boards. I'm crossing my fingers.
 
Hopefully one of my 6BC8 died yesterday, i say hopefully because it make me realize that RV3 and RV6 was wrongly adjusted, -2,04V and -4,05V instead of -2,4 and -4,5!
I finaly had to retrimm my AL20 variable resistor (470r trim) and end up with something like 127R and not 47R like i said in my previous post, so my apologies here.

Volker,Analag, thank you again for this nice comp! ;D ;D ;D

Best regards, Adrien.

http://s218.photobucket.com/albums/cc214/klaus2you/DIY/
 
Volker,

thank you for the kind words! Regarding the PSU transformer you're right, i mount it under the PSU pcb encapsulated into a shielded can. The switches are Elma's.
I really like the way you design boards, clever work ! I wait for your analag tube eq and your 500 format box and hope i'm not going to miss the order thread this time.

Thank you again Volker,Analag ;)

Adrien.
 
klaus2you said:
i mount it under the PSU pcb encapsulated into a shielded can.
Click to expand...

Great idea!

What transformer was this, a toroid I'm guessing, made by whom? Where did you get the can?

I've always had difficulties finding transformer shielding cans.
 

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