Upgraded 1.2TL xovers new way & circuit error found

RichCanDo

michaeljhsda2 wrote: »

"Another way it could be wired properly, is to have resistor lead connect to Pin #2 trace (no jumper req'd), other lead of resistor connects to other end of 12uf cap & input side of circuit."

I think this scenario is probably it. Perhaps Ben could comment on this. Ben?

If you have the crossover out, easy to check. Just look for 2 solder connections on the trace with Pin #2. One connection is the 12uf, other is either a jumper or lead of resistor. If only one solder connection, you need to connect the resistor to it somehow.

michaeljhsda2

another view

michaeljhsda2

RichCanDo wrote: »

If you have the crossover out, easy to check. Just look for 2 solder connections on the trace with Pin #2. One connection is the 12uf, other is either a jumper or lead of resistor. If only one solder connection, you need to connect the resistor to it somehow.

I wish it was out now cuz it's a pain to take in and out

RichCanDo

"I wish it was out now cuz it's a pain to take in and out"

I had mine in and out many times also. In your last photo I see the inductor lead was relocated to the resistor hole. That resistor is the one under the board now. Look to see if the lead is insulated so it cannot touch the large trace which has the tie wrap going thru it. It should connect to a small trace under the resistor body.

michaeljhsda2

I'm taking the xover out now. Back in a few.

RichCanDo

I'm looking at schematics of my center CS1000p and f/x1000 surrounds to learn what it will cost to install new caps and resistors in them. Today I will probably install left over Dynamat on 5 speakers for guitar amp & speaker cabinet.

michaeljhsda2

Just pulled the xover and the lead of the resistor is not going into the same hole as the tie wrap...the photo is deceiving.

michaeljhsda2

It looks as though nothing is jumping over, be it a resistor or cap. Camera battery is recharging...more pics to follow.

RichCanDo

Look at the two photos I have marked with notes in Post #1. It explains the connections. You can compare your board connections to it. Your parts may have been relocated, and connections made to different locations, but all still connect the same way. In any case, there has to be 2 solder connections in trace with Pin #2. OR, just a jumper and other end of jumper connects to both the cap and resistor leads.

michaeljhsda2

I'm going to put the jumper in the hole of the "R" and then into the hole that is open as that looks like where it's supposed to go. The "R" has solder in it but nothing is attached to it.

vmaxer

RichCanDo wrote: »

Yours are missing the jumper also. Your board looks just like mine did. Your jumper may be under the board but I doubt it is.

What are the serial #'s on yours?

My serial numbers are L 6226 and R 6203...It sure seems odd that Polk would miss this

RichCanDo

michaeljhsda2 wrote: »

I'm going to put the jumper in the hole of the "R" and then into the hole that is open as that looks like where it's supposed to go. The "R" has solder in it but nothing is attached to it.

Wrong holes. Those 2 holes are on the same trace. The jumper connects the 2 traces together. But before you connect it, you need to know what is on that long trace. On stock board only one lead from the mica cap and one lead from 22.5 ohm resistor connect to that long trace. If that is what you have, connect jumper. Your photos show 2 connections on that trace that are not stock connections. So you have to know if connections are correct.

RichCanDo

vmaxer wrote: »

My serial numbers are L 6226 and R 6203...It sure seemd odd that Polk would miss this

My 1.2TL #'s are 6119 & 61xx. Only a few replies so far with serial #'s, but looks like from my #'s and above have no jumpers. 50xx had correct factory jumpers.

michaeljhsda2

RichCanDo wrote: »

The jumper just connects the 2 traces together. But before you connect it, you need to know what is on that long trace. On stock board only one lead from the mica cap and one lead from 22.5 ohm resistor connect to that long trace. If that is what you have, connect jumper. Your photos show 2 connections on that trace that are not stock connections. So you have to know if connections are correct.

There is nothing whatsover hooked up to the long trace. It looks as though one lead of the 12uf cap is in the smaller trace where the tweeter is at and the other end goes to the complete opposite end of the board one trace block before where the resistor on the bottom is at.

michaeljhsda2

RichCanDo wrote: »

My 1.2TL #'s are 6119 & 61xx. Only a few replies so far with serial #'s, but looks like from my #'s and above have no jumpers. 50xx had correct factory jumpers.

My serial numbers on my original 1.2 TL's are 61xx and they have jumpers.

michaeljhsda2

Rich see post #48 for an important edit.

michaeljhsda2

Holes B, C and D have nothing in them.

RichCanDo

I edited the post you quoted above to state the 2 holes you were going to use are on the same trace.

Pin #2 connects to a small trace. 12uf cap connects to this trace also. At the far end of the long trace are 2 factory connections. The 22.5 ohm resistor and the 750pf cap. That is all parts on this trace. (The 750pf may have been removed)
On other end of trace, the jumper connects, it jumps to trace Pin #2 & cap is connected to.
I now see we are working with your TL'S? I thought these were Jerry's we were talking about. In post #29 the pic you posted shows 2 solder connections on that long trace that are not stock for 1.2TL's.

michaeljhsda2

RichCanDo wrote: »

I edited the post you quoted above to state the 2 holes you were going to use are on the same trace.

Pin #2 connects to a small trace. 12uf cap connects to this trace also. At the far end of the long trace are 2 factory connections. The 22.5 ohm resistor and the 750pf cap. That is all parts on this trace. (The 750pf may have been removed)
On other end of trace, the jumper connects, it jumps to trace Pin #2 & cap is connected to.
I now see we are working with your TL'S? I thought these were Jerry's we were talking about. In post #29 the pic you posted shows 2 solder connections on that long trace that are not stock for 1.2TL's.

No we are working on Jerry's 1.2's that were converted to 1.2 TL's by Ben

michaeljhsda2

There are a total of 4 solder (holes) in the long trace....however, absolutely nothing is connected to them even though you see solder in them.

RichCanDo

Holes "C" and "D" are where the mica cap used to be. It was removed as not needed with upgraded caps. But hole "B" should have one lead of the 22.5 ohm resistor in it. If not in that hole, it should be connected to trace Pin #2 is on and to the input side of the circuit.

Do you have a 22.5 ohm resistor on the board? Maybe it was removed with the bypass cap.

RichCanDo

michaeljhsda2 wrote: »

There are a total of 4 solder (holes) in the long trace....however, absolutely nothing is connected to them even though you see solder in them.

OK! Makes sense. My guess is the resistor was removed with the bypass cap. Let me know if you find the 22.5 ohm resistor in the board.

michaeljhsda2

Holes E and H have a jumper

RichCanDo

michaeljhsda2 wrote: »

Holes E and H have a jumper

Correct. That is the only jumper I had. Easy to see where things go in photos I have in Post #1. Did you find the 22.5 ohm resistor? There should be 5 resistors on the board. (More if 2 were used to make one value)

michaeljhsda2

Rich, I just talked to Ben and everything is where it's supposed to be on Jerry's 1.2's (now 1.2tl's) xover board.

RichCanDo

michaeljhsda2 wrote: »

Rich, I just talked to Ben and everything is where it's supposed to be on Jerry's 1.2's (now 1.2tl's) xover board.

I would expect it to be correct if Ben did the work. I was waiting to learn if you found the 22.5 ohm resistor on the board or if it was removed. Now I am going to bed. Been awake all night.

michaeljhsda2

RichCanDo wrote: »

Holes "C" and "D" are where the mica cap used to be. It was removed as not needed with upgraded caps. But hole "B" should have one lead of the 22.5 ohm resistor in it. If not in that hole, it should be connected to trace Pin #2 is on and to the input side of the circuit.

Do you have a 22.5 ohm resistor on the board? Maybe it was removed with the bypass cap.

Is it the brown one?

RichCanDo

michaeljhsda2 wrote: »

Is it the brown one?

No, not the brown one. The 22.5 ohm would be directly above it, about even with the closest edge of the inductor. Now under your caps. The body near the removed 750pf bypass cap. You have 3 resistors where the brown one is, plus one under the board. The 5th and last is the 22.5 that bypasses the 12uf cap using the missing jumper. If the 22.5 is not under the caps flat on the board, it was removed with the bypass cap and should be replaced to match schematic.

In post #13 above, Brian provided the function of the 22.5 ohm resistor; "Adding that resistor in parallel with the cap gives the tweeter more signal at the low end of its range. It may appear harsher, but I think it helps to create a solidified center image."

In post #40 of this thread http://www.polkaudio.com/forums/showthread.php?t=54124&page=2
Ben provided "FYI for you guys doing upgrades to 1.2's.
While talking to Joe, and finding out which tweeter was the offensive one. Tweeter 3, second from the bottom is kinda a full range tweeter at lower levels. There is a 22.5 ohm resistor parallel to the capacitor that makes it take longer to burn in at lower levels. This is the only cap in the crossover that does not have the currant travel directly through it."

RichCanDo

Lasareath wrote: »

Here are mine, The original and then the upgraded one.

Elliot didn't have a 22.5 Sonicap so I bought a Mundorf.

22.5? This is one of the resistor values. Looks like you have a .22uf Mundorf cap. - Schematic calls for .25uf. I received (2) .22uf Sonicaps that each measures .225uf. If I remember correct this was as close to .25uf as they could get. - .225 is the -10% low limit spec for the .25uf. I sent Sonicraft the schematic and was told this cap value was not critical where it is in the circuit. I may add another cap to it to get closer to .25uf next time I order parts to upgrade my center speaker.

dorokusai

Mark – I’ll have to start at his message and this but two things are worth noting:

1. The tweeters on the 1.2/TL are all supposed to be hooked up in negative polarity. That was one of the interesting things about moving to the TL tweeter on the 1.2.

2. The 750pf caps are not bypassing the 12uF cap – they act as a single value (12.000 750uF if I have my zeros right). But the addition in any case is not important in terms of the crossover point. The 750 is added to impart a lower DF and other qualities to the 12uF that it did not itself possess. A 12uF silver/mica would have been the most straight forward way to get these qualities but the cost and voltage sensitivity of the silver/mica caps was prohibitive so we never even tried that. There might be suitable HQ 12uF cap that could replace both nowadays. PP or styrene perhaps?

As to the jumper question – we wrestled with tweaking this section and may actually have had an option in the board that we chose not to use in the end. Matt seems to remember something like that as well.

More later. - POLK