AR-10pi environmental control

[Illf8ed]

With the woofer switch set to pi, far left position the woofer and the high range driver switch on either -6db or 0db, far left or far right, the woofer stops operating.  It is the same on both speakers.  What’s going on?

[Illf8ed]

Sorry messed up the sentence.

With the woofer switch set to pi....and the high range on either -6 db or 0 db, the woofer stops operating.

[DavidR]

Attached is a crossover diagram.

I'll take a look at the schematic and see what could cause that.

[DavidR]

Does it matter where the midrange is set?

[rjr513]

Looking at the schematic i would suggest spraying the woofer enviromental switch with contact cleaner then spray with deoxit I'm suspecting internal switch contact issues... look at last page of pdf of switch contact movements

AR10pi-CircuitNotes Version 1.1 Sep2014.pdf

[Illf8ed]

The mid range switch position does not effect the issue. 
I did spray Deoxit on the woofer switch with no improvement, but will try again.  The odd thing is both speakers are doing the same thing.  Also with the hi range in the middle position the woofer works on any switch position.....maybe Deoxit the hi range switch?

[rjr513]

Would not hurt cleaning all those slide switches,Also have you removed the Woofer to look at the exitsing crossover for possible modification by the previous owner since both speakers are showing same symtoms?Compare the wiring with some of the crossover photos already supplied on this forum by other members

[Aadams]

31 minutes ago, rjr513 said:

exitsing crossover for possible modification by the previous owner since both speakers are showing same symtoms

Have these speakers been recapped? 

  If you are not sure you can post photos of the crossovers, someone here will know the answer.

Aadams

[DavidR]

I'm not thinking its a dirty switch as the woofer is only affected when the tweeter is in -6dB and 0dB but not -3dB and the midrange position does not affect it in any position AND only when the woofer is in the Pi position. XFMR issue is a possibility or someone messed up with the 20uF cap wiring.

[Illf8ed]

If the wires are supposed to be colored, someone has rewired these.  
you can also see two wires that have come unsoldered.  One from the transformer, the other from the top end of the speaker.  I need to figured out where these connect.

 

[Aadams]

Those are original Spragues. Crossover has not been recapped.

[Illf8ed]

OK got it.  One disconnected is the - lead from the mid dome and connects to terminal 9 on the post.  The other disconnect is the + lead to the transformer.  The schematic show just “2”.  Doesn’t look like a post connection.  Where does this solder?

[giovanni56]

58 minuti fa, Aadams ha detto:

Quelli sono Sprag originali. Crossover non è stato ricapitolato.

The capacitors are original Sprague, but the wiring harness wires are not original. The wiring harness has been redone. The AR10's are among the earliest produced, they have the external protection fuse next to the input terminals.

[DavidR]

Hope this helps

[DavidR]

I attached 2 pdf files that should help.

10Pi_schematic.pdf 10Pi_xover schmtic.pdf

[Illf8ed]

I really appreciate the schematics and photos.  As suspected above someone in the past rewired these and not to original connections.  I want to go back to color coded 18 AWG TEC OFC tinned wire and redo the internals.  The risk is going to be running into the reason the past owner did what he did.  Has there been any issues with the auto transformers failing?  The other components in the crossovers should be available if needed.  Induction coils rarely fail.

My speakers are 02010 and 02013 serial numbers.

[Illf8ed]

This is R15 in the crossover.  White crusty on the outside.  Should this be replaced?
 

[DavidR]

I replaced mine with Mills resistors. Dead on values.

[ar_pro]

It's a mystery why anyone would choose to re-wire the entire harness with the same color-jacketed wire. 

Also, some of the soldering work looks less than stellar, which could certainly cause issues.

As a rule of thumb, members generally favor replacing any original Callins black & red capacitors, and maybe (maybe not) replacing the Sprague caps.

Unless they've been monkeyed with, the coils are probably fine. Resistors are easily tested, and cheap to replace if necessary. Within reason, it's hard to guess what would cause damage to the autoformer. The level switches and their pc board can be tested out of circuit for reliability.

If you replace the harness, do yourself a huge favor, and stick with the schematic colors. 

[Illf8ed]

Also difficult to understand some of the connection modifications.  For example terminal 8 on the auto transformer is soldered to terminal 4 on the tab strip.  Then terminal 3 and 4 on the tab strip are bridged with a short piece of wire.   I found a company called Pace that sells marine grade 18 AWG tinned oxygen free copper wire that looks like the right material and comes in the nine colors needed.   Good thing I have speakers already in my system.  These AR-10pi are just for fun...and they get funnier as I dig in.

This is why the schematics and crossover photos above are greatly appreciated.

[DavidR]

FWIW even my 10Pi had incorrect wire color to a small degree from the factory. They used red wire from the center terminal strip to one end of the 100uF cap. Its supposed to be blue and is why I put a piece of blue tape on it. Also the wire from the xmfr to one side of the 2500uF is supposed to be yellow but was red. Must have had extra red wire on hand. When I recapped it I addressed some of those quirks.

Is the replacement wire silver wire by chance? No reason to have messed with what AR used. Heavier wire in a speaker xover is some what useless.

[Illf8ed]

I have not yet ordered any wire.  I looked inside my LST-2 cabinets to see what type wire AR used.   By the wire code it was tin plated oxygen free copper, 18 gauge AWG.  Pace wire is marine grade and fine strand.  

Just measured that white crusty R15 resistor.  It’s supposed to be 15 ohm, but measures 1.9 ohm.  The other 10 ohm resistor measures 11.4 ohms, I may replace that also.

[DavidR]

I highly recommend the Mills resistors.

[Illf8ed]

Ordered the Pace wire and some 3/16” female spade connectors.  I decided to go ahead and clean these up.  Will also order 15 ohm and 10 ohm Mills resistors from Parts Express.  The 10 ohm are unfortunately on back order now.

[Illf8ed]

Pace marine grade wire came this morning in nine colors.  I spent several hours re-wiring the internals of one of the 10pi.   It worked first try and I’m sitting listening to Crosby, Stills and Nash “Guinevere”.  Very nice even without any stuffing in the re-wired box.   Takes a bit more push from my Pioneer SX-1010 than the ESS amt1b.  I may become an AR convert.  Switching between the ESS and the 10pi I can hear the hole in the midrange of the ESS although the ESS highs are much clearer-cleaner than the AR speakers.

Another Thankyou to DavidR for sending the color coded connections and to R. Lowe with assistance from Tom Tyson for creating the three drawings.