HH IC100L amp from 1977

[N_Cook]

Been used as 1ch amp for 20 years but now wanting ch2 up and working.
Someone in the 80s must have tried repairing, replacing a TBA231 with a
741 where it was a blown associated 741 , still there,now changed, that
was probably the problem. TBA231 unobtanium (sensibly)
datasheet
http://www.bg-electronics.de/datenblaetter/Schaltkreise/TBA231.pdf

Have tried cobbling together 2 x LM301 wired onto a DIL socket and have
the ch2 working but fixed volume. Vol pot is fine.
What would be the generic name for this sort of vol control, wiper to
gnd and track ends of pot via loads of Rs and Cs to the dual TBA B side
output and inv i/p of A and inv i/p of B , be called?
The ch1 vol control is the same wiper gnd and that is working order and
the wiring looks the same .

 

[N_Cook]

The volume is fixed, at probably 50 percent
There are 6.8uF electrolytics in the circuit. Would the circuit
configuration be bass-boosted at low volume, to avoid the need for a 4
terminal pot?

 

[Reinhard Zwirner]

N_Cook schrieb:

Been used as 1ch amp for 20 years but now wanting ch2 up and working.
Someone in the 80s must have tried repairing, replacing a TBA231 with
a 741 where it was a blown associated 741 , still there,now changed,
that was probably the problem. TBA231 unobtanium (sensibly)
datasheet
http://www.bg-electronics.de/datenblaetter/Schaltkreise/TBA231.pdf

Hi,

a few minutes ago I sent you an e-mail and offered one piece for
free. Unfortunately, the mail bounced. What a pity ... <shrug>

Bye

Reinhard

 

[N_Cook]

All electros have good ESR.
The grounded wiper circuit is probably like the vol controls on this HH
schematic

http://s197.photobucket.com/albums/aa211/bajaman002/HHVSMusicianamplifier1of2.jpg

The IC100 amp involves a pair of 4.7 ohm resistors around the TBA opamp
pairs of each ch

 

[N_Cook]

Disconnecting the R-C of 100nF+4.7R (lag input A x2 pins of the TBA231
and B the same) from the 2x LM301 p1-p8 f-comp pins, returns something
like normal vol/tone function in comparison to ch1.
Will have to take some ch1/ch2/f comparison readings

 

[Arfa Daily]

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:lthib2$cg3$1@dont-email.me...

Disconnecting the R-C of 100nF+4.7R (lag input A x2 pins of the TBA231 and
B the same) from the 2x LM301 p1-p8 f-comp pins, returns something like
normal vol/tone function in comparison to ch1.
Will have to take some ch1/ch2/f comparison readings

Have you not seen the post from Reinhard offering to send you the correct
opamp to save all this pissing about ?

Arfa

 

[Adrian C]

On 25/08/14 19:51, Reinhard Zwirner wrote:

N_Cook schrieb:
Been used as 1ch amp for 20 years but now wanting ch2 up and working.
Someone in the 80s must have tried repairing, replacing a TBA231 with
a 741 where it was a blown associated 741 , still there,now changed,
that was probably the problem. TBA231 unobtanium (sensibly)
datasheet
http://www.bg-electronics.de/datenblaetter/Schaltkreise/TBA231.pdf

Hi,

a few minutes ago I sent you an e-mail and offered one piece for
free. Unfortunately, the mail bounced. What a pity ... <shrug

Bye

Reinhard

His current email is on http://www.divdev.fsnet.co.uk/

Not everyone who posts to usenet uses a real email address in headers,
including me.

I'm actually a multimillionaire that owns a jet boat, an airliner and
half a country. Just don't want Nigerian scammers fishing for some of that.

--
Adrian C