Wharfedale w90 - matching transformer bypassed ?

[zobsky]

Hi,
When opening my W90s with the intent to replace the ancient capacitors (after refinishing them), I discovered that the matching transformers on both of them were effectively bypassed. I don't believe the previous owners ever did anything with them so I'm curious why the matching transformer is effectively just a solder terminal (all connections are on one lug).

I'm also attaching an image of another W90 with what I believe to be the correct connection.

Can anyone shed light on this . Maybe @klipschorn ?

 

[zobsky]

These are late 1964/early 65 W90 with one ported woofer and the other aperiodic

 

[zobsky]

One possible fix but I'm still trying to understand while this speaker was wired as shown with the matching transformer operating as a glorified terminal lug

 

[RVT1K]

Is it possible that the transformer is defective and that is why it was bypassed?

I would have thought one speaker would sound different??

 

[zobsky]

Is it possible that the transformer is defective and that is why it was bypassed?

I would have thought one speaker would sound different??

Those were my initial thoughts too except that -

1. Both speakers are wired identically
2. I don't see any evidence of solder on the currently unused transformer tabs
3. I don't see any evidence of an extra wire ever originating from the negative (-) speaker binding post
4. I was able to test for electrical continuity between all 3 tabs.

I wonder if the factory had an inexperienced and / or stoned tech assemble this pair.

I guess I could try and tack solder the correct config and validate.

 

[zobsky]

Found a wiring diagram in another AK thread

 

[RVT1K]

Those were my initial thoughts too except that -

1. Both speakers are wired identically
2. I don't see any evidence of solder on the currently unused transformer tabs
3. I don't see any evidence of an extra wire ever originating from the negative (-) speaker binding post
4. I was able to test for electrical continuity between all 3 tabs.

I wonder if the factory had an inexperienced and / or stoned tech assemble this pair.

I guess I could try and tack solder the correct config and validate.

I misunderstood your first post and thought the two photos were of each speaker.

I agree with wiring them as per the diagram and seeing what happens. Worst case is you go back to the original configuration.

 

[zobsky]

Yes, I'll tack solder them temporarily with the original caps (soon to be replaced) and report back.

 

[zobsky]

My mod works (not really a mod as I'm fixing a factory wiring error ). I'll share pics and impressions later after addressing both cabinets

 

[zobsky]

Here is how to fix . Sounds better balanced after fixing the wiring. Moving on recapping next

 

[Dave1027]

Wonder why they tied the two pots together? Seems odd.

 

[zobsky]

Wonder why they tied the two pots together? Seems odd.

They're only tied on the ground leg. On the +ve leg, they both feed off individual high passes fed from the matching transformer output

 

[zobsky]

Crossover caps updated . Sounds a bit smoother in the midrange and more defined treble (compared to the 60 year old electrolytics). I wouldn't call it a day/ night difference like some other posts report.

 

[Dave1027]

They're only tied on the ground leg. On the +ve leg, they both feed off individual high passes fed from the matching transformer output

Yeah. I did not see the very small wire connecting to ground in that other pic. Those square brown caps are odd. What kind are those?

 

[zobsky]

Yeah. I did not see the very small wire connecting to ground in that other pic. Those square brown caps are odd. What kind are those?

They are a pair of 4uF Russian NOS paper in oil caps paralleled to make 8uF for the tweeter high pass