Source of crosstalk help......

Go To Last Post
16 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I cannot find the spot in the signal flow where the crosstalk between channels is happening......

 

Maybe here?

 

Anybody?

 

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Come on Jim!

 

What is it (the box)? From the wiring and the size of the caps, I'd guess audio, but that is just a guess. 

 

What kind of cross-talk? Under what conditions?

 

Signal flow goes from input to output, no? I'd guess it is along that signal  path, somewhere. [ Thats as good as your original information :) ]

 

West Coast Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Last Edited: Sun. Mar 3, 2019 - 03:18 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Today's headline:

"West Cost Jim suckered by East Coast sarcasm"

wink

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The Oreo cookie in the bottom right corner.

 

--Mike

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Someone stole the 12AX7s.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Reposition that yellow wire.

Ross McKenzie ValuSoft Melbourne Australia

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

valusoft wrote:

Reposition that yellow wire.

Since you did not call out which yellow wire I repositioned each one but with no noticeable change.

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Re-loom and separate the wiring to each potentiometer ?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Would be interesting to compare the size if it were converted to 0402 smd parts & a flat flex cable.

When in the dark remember-the future looks brighter than ever.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The 1st question I'd ask is whether the cross-talk appeared recently or was it always there?

 

If it started to appear then dry electrolytic or other faulty caps on the supply may be a cause.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I'm guessing that you unplugged the USB Bluetooth Host Adapter from the front panel while you worked on the circuit.

 

JC

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Here is a circuit that is about the size of the tip of your thumb that does 100x what the old board in the picture does.  I'm guessing by the size and smell of the 1 watt resistors that this box is from the 1965-1978 era.  It (probably) does some kind of signal filtering.

 

I'm sure glad that I don't have to work on this kind of board anymore.  It's hard to believe that men actually made a family wage by poking, prodding, probing, and replacing the individual components on these kind of boards.   Well, stuff like this actually put men on the moon, so who am I to say anything.  Still, you'd have to pay a lot more than minimum-wage to repair this thing.

 

While in the modern era, here is a complete front end of a stereo system circa 2015-2020.  It has a cage for a 32 gigabyte SD card [$8-$10 USD] that holds 1000 full albums in high-fidelity MP3 format (320 bps).  There is a stereo headphone amplifier and a mono speaker amplifier included.  Debounced push-buttons that control the song selection and volume get connected to the row of pins.  It is the size of the tip of your thumb and costs about $1 on eBay.  Runs fine on a 4V rechargeable Lithium-Ion 18650 battery (@ $4 USD).   Listen with KOSS ear-buds that will set you back about $3-5 USD.   A stereo and sound library for 1/100 of what equivalent equipment would have cost 50 years ago.

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

joeymorin wrote:

Today's headline:

"West Cost Jim suckered by East Coast sarcasm"

wink

 

I admit I did leave a lot to be desired in the form of information.......

I started repairing musical instrument amplifiers and other stage gear nearly 25 years ago as a hobby, and it turned into a nice little side business once in a while.  I restore cabinets, re-apply Tolex and repair  electronics as needed.

 

Truth be told there is no crosstalk.  Very little hum, or any other unwanted gremlins.  What is in the pictures is the audio "processor" for a 1967 VOX British amplifier

https://en.wikipedia.org/wiki/Vox_(musical_equipment)

 

The processor has a tremolo effect and three pairs of inputs,  Normal, Brilliant, and Bass all of which are now operational.  Theres an in-built distortion loop and other effects that are selected with an external foot switch control box.

 

It's owner is a personal friend of mine who says that the amp was owned by Henry Gross from Sha Na Na.  I am not gonna argue.  The electrics were in pretty bad shape as some fool removed the original power rotary switch and put in a useless on/off/on switch which I removed and replaced with a new rotary switch, and I was able to find an OEM knob for it. I added a three prong grounded power inlet, and removed the 'Death Cap'.

 

No tubes in this one.  All solid state.

The main filter caps were shot.  Really old metal cans that were about 25mm in diameter and almost 100mm high.  the replacements were a fraction of the size. - You can see one of the replacements in the lower right corner of the picture.

 

The owner did the Tolex himself, and did a pretty decent job for a first timer:

 

He's very happy with the sound and I am happy the project is off my list of 'to do's'

 

ka7ehk wrote:
Come on Jim!

I feel bad(almost).  I did intentionally post with very little information as possible to see what 'original' advice I would get in return.......  Nothing malicious intended, just something different than our normal MOSFET to AVR questions and the like.

 

JIm

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

Last Edited: Mon. Mar 4, 2019 - 02:33 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Reminds me of my own foray into the repair business for "the professionals". Did one for a friend of Suzie Quatro in the early 70s.

Ross McKenzie ValuSoft Melbourne Australia

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

A friend has a business doing repairs to music equipment. I frequently get called in to help with switched mode supplies and 80's synths.

 

One project we did many years ago was the electronics for a guitar to emulate the Kiss guitar in 'I was made for loving you'. It was basically a ton of 'grain o wheat' light bulbs (no leds - there was no white leds in the 70's) wired into a number of segments. Then I did a little micro with some mosfets to switch it and a battery pack. The problem we had was the clicking induced into the pickups. Try as we might, we couldn't eliminate it. Later we read the original suffered from the some trouble and the music would drown it out. 

 

https://www.youtube.com/watch?v=...

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Kartman wrote:
and the music would drown it out
music? what music? you call that music? wash your ears out! devil

Ross McKenzie ValuSoft Melbourne Australia