Hi,
I have an amplifier that won't dissengage the bypass of the graphic/auxillary RCA jacks when it's button is pressed.
Similarly it won't dissengage the tone controls when the Power amp direct path is chosen.
Both of these have small electromechanical relays to operate the switching of this path.
It's 1991 model amp.
What's the likelihood that these functional failures are because of the relay versus the connections to trigger the relay.
Also the board is quite dusty..
So... Electromechanical versus electronic versus connector issue.
Perhaps a good clean first ?
Perhaps the connectors from one circuit board to another?
Any ideas ?
I have an amplifier that won't dissengage the bypass of the graphic/auxillary RCA jacks when it's button is pressed.
Similarly it won't dissengage the tone controls when the Power amp direct path is chosen.
Both of these have small electromechanical relays to operate the switching of this path.
It's 1991 model amp.
What's the likelihood that these functional failures are because of the relay versus the connections to trigger the relay.
Also the board is quite dusty..
So... Electromechanical versus electronic versus connector issue.
Perhaps a good clean first ?
Perhaps the connectors from one circuit board to another?
Any ideas ?
Attachments
Flexible switch mechanism.
Japanese.
Possibly Sony.
Dry joints at switches and connectors.
Replace relays after checking they are actually shot.
Rest will not need much beyond cleaning and contact spray.
Those flexible flat strip operated switches can be troublesome, and are not easy to get.
Japanese.
Possibly Sony.
Dry joints at switches and connectors.
Replace relays after checking they are actually shot.
Rest will not need much beyond cleaning and contact spray.
Those flexible flat strip operated switches can be troublesome, and are not easy to get.
Thank you for the reply..
Yes I figured this to be the case.
The owner had it from new and had the user manual.
About a month ago I noticed the adaptor button started to switch off the sound when I engaged it rather than letting the music continue despite nothing connected there. So I figured that relay had started to work .
This last week I noticed that the music also stopped when I engaged the extended direct drive circuit in both balanced and unbalanced modes so I was hopeful the relays had in fact started to make contact or actually engage when I selected the direct drive
Sure enough just yesterday I connected the unbalanced RCA direct drive inputs and it worked !!
Yes an intermittent problem that needs a proper sorting but I was thrilled that the direct drive circuit worked.
Thanks for the feedback..
One more question and this is one of voltage gain versus current stage.
This amplifier quotes 106dB s/n when using the aforementioned unbalanced direct drive inputs... Due to the shorter signal path but it then goes on to say in the brochure that this high s/n is maintained as the volume is reduced from rated power to more usual listening levels due to the unity gain current drive and the variable gain voltage stage.
It appears to me that the extended drive just bypasses the preamp and this gives it the higher s/n and that the constant s/n is not die to the direct drive at all but rather the way the two stage amplification is setup.
Would it be true then..that when using this amplifier in non direct drive, the s/n will be constant all the way down the volume reduction albeit at a slightly less high level?
The circuit board was rather dusty when I opened it up late last year.