the Poor Man 660 support thread

[khstudio]

kevin, I got your message.  my edcore power transformer does not get very warm. But the fil. resistor and ic's do. I did put some mu metal between the pt and audio transformers due to low level hum .
Looks like you did a mod to the time constants. Im curious what you find.

Hi Mark,
... good to here from you man.  ;D
Well, that's good news about your EDCORE PT not getting hot.

I'm having some VERY strange issues & have spent DAYS, trying to figure it out... this project is killing me.
Any chance you could measure your unit too? (check back a few posts if you want or can)

The time constants do make a BIG difference... I can explain more, in detail if you want.
Give me a call anytime. I'm usually up late.

Kevin

 

[khstudio]

I think I've narrowed down my problem to the Cathode voltage / current draw of the 5687 tubes (R10/330r)
The voltage I'm reading here is different for Each channel. The voltage at R10/330r also changes when I change my threshold control. I've thoroughly checked all connections & my Threshold pot, wiring, even swapped out tubes & rechecked all TX's... it all looks good.

Here's what I'm getting:

CH1 - Threshold, Pos 1, Voltage at R10 = 17.6v  (approx)
CH1 - Threshold, Pos 2 (or so), Voltage at R10 = 11.9v  (approx)

CH1 - Threshold, Pos 1, Voltage at R10 = 11.8v  (approx)
CH2 - Threshold, Pos 2 (or so), Voltage at R10 = 15.8v  (approx)

LoLo-M Posted = 12.06v @ (R10/330r) But didn't mention where his Threshold was or if the voltage changes when moving the threshold

YES I know, this is strange.
I've checked so much stuff & can't find it so I'm re-flowing solder joints just to make sure.

 

[khstudio]

Well... no luck.      Still left with the same problems (listed above)

Re-solder everything but the PCBs.
Besides that, the only 2 things I haven't tried is swapping Transformers & the Threshold pots.

 

[lolo-m]

The voltage I gave for the 5687 where with no signal applied. There shouldn't be any change in pure DC with or without signal. When I say pure DC I mean that some testers are not only measuring DC... The "threshold" pot only change the amount of signal you send in the SC AMP not its bias... I hope it helps ...

 

[Moby]

I think I've narrowed down my problem to the Cathode voltage / current draw of the 5687 tubes (R10/330r)
The voltage I'm reading here is different for Each channel. The voltage at R10/330r also changes when I change my threshold control. I've thoroughly checked all connections & my Threshold pot, wiring, even swapped out tubes & rechecked all TX's... it all looks good.

Kevin are the values you posted with or without test signal applied? If you are measuring with  test signal applied, I still suspect on PSU or transformer. Can you measure the current at T4's PL8? Than, disconnect the plate voltages and try to measure PSU without tubes (left the heaters on). Also, try to measure PSU with some shunt loads close to real situation .  Voltage should be constant with changing current. If yes, than we will know that there is no problem in that stage.

 

[khstudio]

The voltage I gave for the 5687 where with no signal applied. There shouldn't be any change in pure DC with or without signal. When I say pure DC I mean that some testers are not only measuring DC... The "threshold" pot only change the amount of signal you send in the SC AMP not its bias... I hope it helps ...

No signal applied!!!

This is the problem (read below)
The cathode voltage @ R10 changes with the threshold setting... YES I rechecked ALL connections to & from that control & the resistance of it.
Also, my 330r resistors are getting slightly discolored.

I think I've narrowed down my problem to the Cathode voltage / current draw of the 5687 tubes (R10/330r)
The voltage I'm reading here is different for Each channel. The voltage at R10/330r also changes when I change my threshold control. I've thoroughly checked all connections & my Threshold pot, wiring, even swapped out tubes & rechecked all TX's... it all looks good.

Here's what I'm getting:

CH1 - Threshold, Pos 1, Voltage at R10 = 17.6v  (approx)
CH1 - Threshold, Pos 2 (or so), Voltage at R10 = 11.9v  (approx)

CH2 - Threshold, Pos 1, Voltage at R10 = 11.8v  (approx)
CH2 - Threshold, Pos 2 (or so), Voltage at R10 = 15.8v  (approx)

LoLo-M Posted = 12.06v @ (R10/330r) But didn't mention where his Threshold was or if the voltage changes when moving the threshold

YES I know, this is strange.
I've checked so much stuff & can't find it so I'm re-flowing solder joints just to make sure.

 

[khstudio]

I think I've narrowed down my problem to the Cathode voltage / current draw of the 5687 tubes (R10/330r)
The voltage I'm reading here is different for Each channel. The voltage at R10/330r also changes when I change my threshold control. I've thoroughly checked all connections & my Threshold pot, wiring, even swapped out tubes & rechecked all TX's... it all looks good.

Kevin are the values you posted with or without test signal applied? If you are measuring with  test signal applied, I still suspect on PSU or transformer. Can you measure the current at T4's PL8? Than, disconnect the plate voltages and try to measure PSU without tubes (left the heaters on). Also, try to measure PSU with some shunt loads close to real situation .  Voltage should be constant with changing current. If yes, than we will know that there is no problem in that stage.

I'm just starting a session now so I'll test this later tonight.
Thanks.

 

[[silent:arts]]

...
Also, my 330r resistors are getting slightly discolored.

there is something wrong with your threshold switch assembly / connection, or the interstage transformer.
this resistor is known to burn without connected transformers / threshold switches (as mentioned before)

 

[khstudio]

OK... I'll try swapping the trans next, then pull my stepped gain switch & sub in a dual pot for testing.

Thanks Volker

 

[khstudio]

Could someone else PLEASE test their voltage @ R10 = 330r ?

One side if it is grounded so we don't want that side.

Also, please move your threshold (for that channel) while measuring to see if the voltage moves!!!

I need to see this voltage while the threshold is in the OFF position, Middle & Full ON!

UPDATE on my Unit:
I un-plugged PL7 (threshold) & plugged in a new Molex connector with open wire.
I then attached 2x 10k resistors from the outer 2 to the Center (GND).
This way I gives the GRIDs a DC Ground reference so they don't run away.
It also allowed me to rule out the Threshold POT so I could take new measurements @ R10 = 330r

Here's what happened...
BOTH channels now measured the same but were VERY high = around 20+ Volts.  

OK, so now I tried just "Shorting" them (no 10k)
I did this do "Simulate" the threshold in the OFF position... which SHORTS the Grids to Ground...
Now the voltages @ R10 = 330r when even higher = 22v +   :

This makes NO sense.

Here's what I got before:

No signal applied!!!

I think I've narrowed down my problem to the Cathode voltage / current draw of the 5687 tubes (R10/330r)
The voltage I'm reading here is different for Each channel. The voltage at R10/330r also changes when I change my threshold control. I've thoroughly checked all connections & my Threshold pot, wiring, even swapped out tubes & rechecked all TX's... it all looks good.

Here's what I'm getting:

CH1 - Threshold, Pos 1, Voltage at R10 = 17.6v  (approx)
CH1 - Threshold, Pos 2 (or so), Voltage at R10 = 11.9v  (approx)

CH2 - Threshold, Pos 1, Voltage at R10 = 11.8v  (approx)
CH2 - Threshold, Pos 2 (or so), Voltage at R10 = 15.8v  (approx)

LoLo-M Posted = 12.06v @ (R10/330r) But didn't mention where his Threshold was or if the voltage changes when moving the threshold

 

[lolo-m]

Kevin, you seam to have DC on your threshold pot (you shouldn't). Try to measure if there's some...
The 5687 I use are old (not NOS at all)  but there's a huge difference between you measures and mine so...
Try to measure too your audio transformers to see if EDCOR didn't make any error in the wiring ( I don't remember who was saying it did happen ). With an ohm meter, the difference between one half and the other on the primary (1-2, 2-4) and secondary (5-6, 6-8), shouldn't be more than 10%. If it's more there's a problem on the transformer.

 

[khstudio]

Well, when I disconnected PL7 (like I mentioned above) the threshold Pot & transformer before it isn't even connected.
I basically removed them (PL7) and added 2 Grid to Ground resistors for testing & ruling out the threshold & TX before it (T3)...
I also tried just grounding the grids (which the Threshold Pot does anyway in position 1.
When I did this I measured = 20+ Volts @ R10 = 330r.

TUBES I'M USING = PHILIPS 5687WB (NOS) From Antique Electronics Supply

I measured ALL the TX's & they seem to be OK:

Can anyone else measure their EDCORE Transformers?
Or is it posted somewhere?

 

[khstudio]

Just got off the phone with Brian from EDCORE.

I asked him about the Current draw of the Heaters & the AC to DC amp rating.
He discussed it with one of the other guys there & they both said it should be fine.
They said as long as the current draw, being on the AC or DC side, isn't higher than the TX's rating, you're good.

The CORRECT OHM READINGS of the 10k:600 & 600:10k Transformers:

10k side = 470 ohms (approx)

600 side = 120 ohms (approx)

CT to outer windings are approximately HALF!!!

NOTE about the XSM & WSM series Transformers - Used Backwards!!! :
Brian said that SOME of their TX's have "Compensation" designed into the for minimal loss...
BUT, the XSM & WSM series Transformers DO NOT HAVE THIS & CAN BE USED BACKWARDS.
The Windings are identical!!!

This is good news & nice to know.  ;D

 

[khstudio]

I measured ALL my TX in my unit & they ALL measure correctly.

I am NOT going to be able to fix my unit unless someone can help me out.
I've done all the testing & troubleshooting I can at this point & have posted, in DETAIL, what I found.

Rowan, Volker... any ideas... PLEASE.

 

[emrr]

I wonder if people would stop unloading their unbuilt PM's in the black market if there was more apparent support from the designer?  I know [silent:arts] is doing what he can.  I certainly note enthusiasm waning.  How hard is it to provide a voltage chart?  Conversely, is it really that hard for those with built units to make a voltage chart, given that an official one seems unforthcoming?  I told Kevin he should make a chart himself, and I encourage those with built units to compare notes and create one for the good of the project.  I would think a request from the creator to keep the schematic private would also come with a certain level of continuing support and commentary, which I've not seen.  Perhaps I've simply missed it. 

 

[kambo]

I wonder if people would stop unloading their unbuilt PM's in the black market if there was more apparent support from the designer?  I know [silent:arts] is doing what he can.  I certainly note enthusiasm waning.  How hard is it to provide a voltage chart?  Conversely, is it really that hard for those with built units to make a voltage chart, given that an official one seems unforthcoming?  I told Kevin he should make a chart himself, and I encourage those with built units to compare notes and create one for the good of the project.  I would think a request from the creator to keep the schematic private would also come with a certain level of continuing support and commentary, which I've not seen.  Perhaps I've simply missed it. 

1+

i have just bough the boards from black market, but i think i gonna sell them.... i have other projects to finish... 

 

[[silent:arts]]

I still wonder why others build it to success ???
ok, it should have been mentioned it is not a beginners project.

it is getting scary.
won't do this anymore.

my PM670 is lent, thus I can't do any voltage chart.

at the end, you don't buy support with PCBs.

Volker

 

[idylldon]

Could someone else PLEASE test their voltage @ R10 = 330r ?

One side if it is grounded so we don't want that side.

Also, please move your threshold (for that channel) while measuring to see if the voltage moves!!!

My voltages are:

Left:  Threshold off = 11.94
        Threshold on (24 position switch all the way CW) = 12.06

Right: Threshold off = 11.70
         Threshold on (24 position switch all the way CW) = 10.97

It doesn't appear that helps much as one channel is different from the other.  Also, when measuring those voltages my multimeter seemed to affect the VU meters on the PM 670.  I don't have a great multimeter (keep meaning to get a Fluke when the funds permit), so perhaps it's just loading down the circuit a bit when I probe.

Also, where are you measuring your PL1 voltages and what does your "Threshold Position 2 (or so)" actually mean?  

Cheers,
--
Don

         

 

[khstudio]

I still wonder why others build it to success ???

Volker

At this point... me too. :-\

ok, it should have been mentioned it is not a beginners project.

Maybe I should make a list of everything I've successfully built over the past 8 years... & NOT just projects from this forum
but Several (18) Guitar amps, built from scratch with NO support forum or parts list... just schematics with voltages written on them... and they ALL work. I record them all the time

You tell me... Am I too much of an amateur for this project?

I must say, I do appreciate all you've done for this project... but I also must say that when things go wrong (as in my case) simple things like voltage charts help determine what & where the problems are.
Another problem is, hardly anyone that has completed their unit is visiting this thread & in turn able to help me out.
Thank GOD for lolo-m, Doug & my good friend GUS. ;D

it is getting scary.
won't do this anymore.

Can't say I blam you

my PM670 is lent, thus I can't do any voltage chart.

That would be cool

at the end, you don't buy support with PCBs.

I don't know how to respond to that one.

What I can say is... I shared a project with this forum (EQ-3D) & Hundreds were sold & are working.
I made ZERO $$$ off the project but supported it & shared everything I had.

In this case, the Designer is nowhere to be found & it seems like you're left holding the bag.

 

[khstudio]

Could someone else PLEASE test their voltage @ R10 = 330r ?

One side if it is grounded so we don't want that side.

Also, please move your threshold (for that channel) while measuring to see if the voltage moves!!!

My voltages are:

Left:  Threshold off = 11.94
        Threshold on (24 position switch all the way CW) = 12.06

Right: Threshold off = 11.70
         Threshold on (24 position switch all the way CW) = 10.97

It doesn't appear that helps much as one channel is different from the other.  Also, when measuring those voltages my multimeter seemed to affect the VU meters on the PM 670.  I don't have a great multimeter (keep meaning to get a Fluke when the funds permit), so perhaps it's just loading down the circuit a bit when I probe.

Also, where are you measuring your PL1 voltages and what does your "Threshold Position 2 (or so)" actually mean?  

Cheers,
--
Don

Thanks man.  ;D

YES... this DOES help. Your voltages are within reason close to the 12v that lolo-m got.
So this backs up the approximate "Range" I should see on my unit.    

what does your "Threshold Position 2 (or so)" actually mean?

It means = the 1st step ON.

Also, where are you measuring your PL1 voltages

If you're referring to the Control Voltage... that's pin 2 , or the Center of the 2x 15k sections on the GAIN pot.
The outer pins (1 & 3) are the GRIDs of the 6BC8's.

I explained how to test the Control Voltage a few posts or so back.

Thanks again.