PYE Compressor/Limiter Thread *boards shipping* BOM up!

[sr1200]

Still Nothing on the meter calibration.  Without an accurate schematic, its hard to tell WHAT is exactly wrong.  Though Abe insists that he's gotten those boards to work properly, there might be some fine print there, I was going to put a larger value pot in there to see if that helped anything at some point in the near future.  Right now, it looks like that pot is in parallel with some other resistors that are feeding the meter which doesn't match what i have seen in any iteration of the schematic.

 

[Biasrocks]

Still Nothing on the meter calibration.  Without an accurate schematic, its hard to tell WHAT is exactly wrong. 

Right now, it looks like that pot is in parallel with some other resistors that are feeding the meter which doesn't match what i have seen in any iteration of the schematic.

Bottom line, we need a current schematic.

It's also slightly disconcerting that Abe is largely MIA.

Mark

 

[sr1200]

A member is working on an updated schematic.  no word on when that'll be done since he's reverse engineering it from the board.  With the exception of the meter calibration, there doesn't seem to be anything else "wrong" with the circuit that I've found.  Has anyone else completed one of the newer version boards?

 

[mdainsd]

The schematic is close. Its all cadded out. Now I have to bounce it back against the board to see if I got it right.

Ive found a couple of discrepancies. The one thats got me interested right now. Is the diode array at the end of the SC. Abe has it as a full wave bridge driving the output transformer. But the original schematics have the diodes arranged differently. But if SR1200 has his boards running with the diodes per the silkscreen, I guess possibly the original Pye schematic had an error.

 

[sr1200]

Dont forget that Abe took things out and moved things around... its not EXACTLY the PYE comp.

 

[bruno2000]

The schematic is close. Its all cadded out. Now I have to bounce it back against the board to see if I got it right.

Ive found a couple of discrepancies. The one thats got me interested right now. Is the diode array at the end of the SC. Abe has it as a full wave bridge driving the output transformer. But the original schematics have the diodes arranged differently. But if SR1200 has his boards running with the diodes per the silkscreen, I guess possibly the original Pye schematic had an error.

I, too, am working on a schematic, and will have it done in a couple of days.
Looks to me like the original PYE has the full wave bridge (I have several original schematic scans, and they are all the same), but the schematic I have from Abe (circuit1.jpg) is not a bridge.
This build is certainly a "modified" rendition of the circuit, but it should sound pretty close.
Best,
Bruno2000

 

[mdainsd]

Yes. You are right. I was getting brain fade. Im working on a 670 simultaneously with this Pye build. The Pye schematics do show a bridge. "Circuit1" is definitely wrong, but I have no idea what that schematic references to? The original AC boards? There is a post early on in this thread where Abe made mention of having mixed up this diode arrangement, and found it after some troubleshooting. I think all is well on the 3.14 rev boards SC bridge wise.

Here are the board issues that I know of or have found (again for rev 3.14 boards)

1) C10 having two "+" signs on the silk screen. Plus goes to the right when viewing the board with the AC logo upright.

2) Alternate wiper pads for trimmers not connected. If you use a trimmer with the alternate pinouts, you need to jumper on the back of the board.

3) C7 "+" sign on silk screen reversed.

4) Two additional resistors in the meter circuit. The first one R67 (1K) takes the place of an outboard resistor in the original that needs to be installed if NOT using an additional remote meter. The second one R65 (1K5) unknown reason, I havent quite finished with that one, looks to be in parallel with the meter (Needs to be verified).

5) Neither the core connection or the metal shield connection on the Cinemag transformer are connected to anything. I plan to experiment with that once all is up and running.

 

[bruno2000]

Yes. You are right. I was getting brain fade. Im working on a 670 simultaneously with this Pye build. The Pye schematics do show a bridge. "Circuit1" is definitely wrong, but I have no idea what that schematic references to? The original AC boards? There is a post early on in this thread where Abe made mention of having mixed up this diode arrangement, and found it after some troubleshooting. I think all is well on the 3.14 rev boards SC bridge wise.

Here are the board issues that I know of or have found (again for rev 3.14 boards)

1) C10 having two "+" signs on the silk screen. Plus goes to the right when viewing the board with the AC logo upright.

2) Alternate wiper pads for trimmers not connected. If you use a trimmer with the alternate pinouts, you need to jumper on the back of the board.

3) C7 "+" sign on silk screen reversed.

4) Two additional resistors in the meter circuit. The first one R67 (1K) takes the place of an outboard resistor in the original that needs to be installed if NOT using an additional remote meter. The second one R65 (1K5) unknown reason, I havent quite finished with that one, looks to be in parallel with the meter (Needs to be verified).

5) Neither the core connection or the metal shield connection on the Cinemag transformer are connected to anything. I plan to experiment with that once all is up and running.

I just finished my schematic, and agree with all of these.
#1, the big + is correct.
#2, right, again
#3, yep
#4, looks to be a scaling resistor for the meter.  Yes, it is in parallel.
#5,  this may be so that you could use other transformers.  I sure would ground the core and the case.
As soon as I check my schematic one more time, I'll post it.  There may still be errors, and corrections are welcome.
Best,
Bruno2000

 

[mdainsd]

Potential additional problems. 

The switch board has to be installed upside down tho get the right switch through the right hole in the front panel if using The cool case by Dan. The silkscreening for the switches on the front panel is laid out as one would expect, lower values or off = CCW, higher values or on = CW

Switch board, SWA (DECAY) OK, but SWC (LIMIT) and SWB (RATIO), rotate opposite of silk screening on front panel. So the unit will be in Limit when the switch says off and vice versa. And if the switch for ratio is set per the face plate to 1:1 the unit will be in 5:1 and vice versa throughout the range of the ration switch.

Also, If you spec'd rotary switches with the flat on the shaft, they cannot be installed in that board in a way that would put the flats where they are supposed to be. I worked around by finding a place to instal the switch where the flats are at the top (roughly) of the shafts so that the set screws on the knobs tighten against the rounded part of the shaft...kludge.

I've checked this several times but would like another to verify?

Bruno?

If verified the fix isnt too bad. All the traces on the switch board are available on the backside, so a few clad cuts and re-stuffing the resistors would fix it. However, if I have to correct mine I think I will pitch the switchboards altogether and buy new rotary switches with regular terminals and build them up individually. This will also allow me to put the flats where they belong so the knobs can be secured properly to the shafts.

 

[sr1200]

Dunno about this.  My ratio switch (and all my other knobs/switches) are working exactly as marked on the front panel.  Being upside down doesn't change the direction of the min/max of the pot/switch, switching it front/back would do that.  But you are right about the flats on the switches not lining up.  I wound up grinding down another flat area for the knob to grab.

 

[mdainsd]

Yeah I know that turning them upside down doest change the direction of rotation on a switch or a pot. I did the ring out on the component side of the switch board, where the switches should be mounted.

have you had a scope on it?

Im still rechecking and rechecking...

 

[shot]

I'm about to order transformers for my build. I want to go all Edcor since Cinemag is way to expensive. Maybe some day I'll swap, but for now I have to think about costs.

1. What would be a substitute for the Cinemag on the input? Should I go with Edcor 10K:10K or 10K:600 ? WSM or XSM?

2. Would there be a difference if I put 600:600 transformer on the output instead of 600:10K or 600:15K?



Luka

 

[mdainsd]

Im not good with the transformers. But, to replace the cinemag input transformer, the closest Edcor I think is the WSM15K/15K.

The 1:1 ratio for the output transformers doesnt seem too good. Early on in this thread those ratios were talked about by Abe. It seemed settle at 1:2 up to 1:4 . Im building mine with Edcor XSM10K:600 in those locations.

 

[shot]

Im not good with the transformers. But, to replace the cinemag input transformer, the closest Edcor I think is the WSM15K/15K.

Great! Thanks!

But in one early thread Abe mentioned that he used 10K:600 for the input. I don't know if that performed well since it was an early prototype. Now my gut feeling says this one would be the best solution. I don't know...

The 1:1 ratio for the output transformers doesnt seem too good. Early on in this thread those ratios were talked about by Abe. It seemed settle at 1:2 up to 1:4 . Im building mine with Edcor XSM10K:600 in those locations.

Ok, now there's two different approaches!
You are using 10K:600 for the output... and SR1200 recommends 600:10K (or 600:15K)
And I'm more confused than I was before!

 

[mdainsd]

"You are using 10K:600 for the output... and SR1200 recommends 600:10K"

Same transformer, just turned around. That should help, no?

 

[shot]

Same transformer, just turned around. That should help, no?

True that!
But somewhere round here there was a discussion with measurements provided that reversing transformers is not the same as using dedicated ones. So I was... oh... OK... I'm too picky I know... sorry    8)

 

[sr1200]

The side chain can use these transformers any which way, just trade some noise for some gain in various configs according to Abe.

 

[shot]

Yes, I know that.

But I'm still in doubt what to order for the input transformer.
Should I go with 15k:15k or 10K:600?

 

[mdainsd]

OK, lets see how this goes.....

Attached is a schematic I did for the AC boards. It includes the main board and the switch board.

Page 2 is not attached as that is specific build information for my unit, harnessing etc.

There may be some small errors, but I think I got it. However if you find any, let me know and I will update the drawing AND roll the revision.

Updated to rev b on 8/27/14

 

[bruno2000]

Thanks for doing this.  I made a schematic myself, but was waiting for Abe's blessing before publishing.
You have 2 R80s.  I believe that the one connected to the input pot wiper should be R81 with a value of 20k.
Best,
Bruno2000