Magnavox T991-01 hiss on sound.(IC Type No)

[BRC2000]

Hi All I have a Magnavox T991-01 on the bench which is probably the only one in the UK. It was made in Greeneville Tennessee in May 1977. It looks unused and after repairing the vert plug in board it is working and producing a very good NTSC colour picture.
I now have the last problem hiss on the sound even when set to zero volume.
I do not have a diagram for the sound board type 210915-3 it only has one IC on it which has the numbers 76-Z date code 7716 on it. I can probably repair it if I had the ICs Manufacturers type number.
The other ICs and transistors in this TV seem have only Magnavox part numbers.
Thank You
Keith

[damen]

Sams shows T991-01-AA in set 1594 folder 1. They say sound board is part number 703639-2. The IC is called out as IC1 and Magnavox's number is 612076-1, it crosses to an ECG742, very popular at the time in a lot of sets.

[BRC2000]

Hi Thank you for your information I will try to get one and hope it will fix the problem.
Keith

[zeno]

We repaired tons of T991, ALL of them we did the following. Pulled
chassis & resoldered the mother board ESPECIALLY at the power supply
& horz area. Dont forget the ground lugs at the steel frame. Pull all modules &
check all PC cons ESPECIALLY at the connectors. If it has a plug in flyback
be sure the pins are clean, they burn. Cold joints were a big problem that
often blew the power supply board & sometimes started chain reaction
failures. When thats all done they were very good sets.

73 Zeno
Stay well & LFOD !

[BRC2000]

Hi ZENO
Thank you for all your information about the T991 I will do as say this week end.
Thanks
Keith

[Naoise]

Originally Posted by zeno

We repaired tons of T991, ALL of them we did the following. Pulled
chassis & resoldered the mother board ESPECIALLY at the power supply
& horz area. Dont forget the ground lugs at the steel frame. Pull all modules &
check all PC cons ESPECIALLY at the connectors. If it has a plug in flyback
be sure the pins are clean, they burn. Cold joints were a big problem that
often blew the power supply board & sometimes started chain reaction
failures. When thats all done they were very good sets.

73 Zeno
Stay well & LFOD !

@zeno @BRC2000

Apologies for bumping an old post; just wondering do you guys have any information about the power circuitry of the T991?

For example, I think the power circuitry is either internal or chassis-mounted with only the power lead visible on the outside and no external power brick - is that correct?

Also, would you have any idea about what the output DC voltage and amperage would be?

Many thanks