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REPLACEMENT for HEX D type flip flop with clear

Posted: Tue Dec 18, 2018 9:56 am
by gkmaia
Hi,

I got to replace my TC74HC174F-TE hex D type flip flop with clear for a new one on my roland D-50. The 4 bit DAC IC.

From TI I should be using the following,but it is 4mm wide and I need 5.3mm wide.

http://www.ti.com/lit/ds/symlink/sn74hc174.pdf

For that there is the following Toshiba option.

https://docs-apac.rs-online.com/webdocs ... c0c3be.pdf

Can anyone confirm that it's logic will suit?

Re: REPLACEMENT for HEX D type flip flop with clear

Posted: Tue Dec 18, 2018 10:19 pm
by Mooger5
What matters is if the pins reach the pads. I´d go for a NOS part or one that is closer to the original.

Re: REPLACEMENT for HEX D type flip flop with clear

Posted: Wed Dec 19, 2018 2:39 am
by gkmaia
Mooger5 wrote:What matters is if the pins reach the pads. I´d go for a NOS part or one that is closer to the original.
Cannot find NOS. Pretty damn hard to find these old Roland D-50 parts.
The only manufacturer that produces one with 5.3mm and 16 pins is Toshiba and it is still a back order.

Re: REPLACEMENT for HEX D type flip flop with clear

Posted: Wed Dec 19, 2018 11:32 am
by Mooger5
But isn't it just a 16 pin SOIC chip? That's a standard. Some manufacturers might make the body a lttle narrpwer, but the pins will have the necessary length to touch the pads on to which they are to be soldered.
Search Ebay for 74HC174 SOIC. There are plenty.

Re: REPLACEMENT for HEX D type flip flop with clear

Posted: Wed Dec 19, 2018 2:15 pm
by meatballfulton
Mooger5 wrote:But isn't it just a 16 pin SOIC chip? That's a standard. Some manufacturers might make the body a lttle narrpwer, but the pins will have the necessary length to touch the pads on to which they are to be soldered.
Search Ebay for 74HC174 SOIC. There are plenty.
Mooger5 is correct. As a veteran electrical engineer, I can assure you that all the 74xxx chips from various mfr are pin compatible. That was the whole idea of the 74xxx series.

Only the letters are important...HC parts are electronically different than LS and S parts, for instance. In some cases they are interchangeable, in others they are not, depending on the design of the circuit they are used in.

Re: REPLACEMENT for HEX D type flip flop with clear

Posted: Wed Dec 19, 2018 7:59 pm
by gkmaia
Mooger5 wrote:But isn't it just a 16 pin SOIC chip? That's a standard. Some manufacturers might make the body a lttle narrpwer, but the pins will have the necessary length to touch the pads on to which they are to be soldered.
Search Ebay for 74HC174 SOIC. There are plenty.
Not really.

Not sure what Roland thought at the time when designed the PCB but the pins of a SOIC 4mm wide wont reach the pads on both sides at the same time.

I have with myself a pack of TI SN74HC174D and their pins wont reach the pads. I really need a SOIC-W with 5.3mm body.

The Toshiba TC74VHC175F seems to have the same logic but it is a 74VHC175 instead of 74HC174.

That is my question then, will the Toshiba do the job?

Re: REPLACEMENT for HEX D type flip flop with clear

Posted: Wed Dec 19, 2018 8:31 pm
by gkmaia
meatballfulton wrote:
Mooger5 wrote:But isn't it just a 16 pin SOIC chip? That's a standard. Some manufacturers might make the body a lttle narrpwer, but the pins will have the necessary length to touch the pads on to which they are to be soldered.
Search Ebay for 74HC174 SOIC. There are plenty.
Mooger5 is correct. As a veteran electrical engineer, I can assure you that all the 74xxx chips from various mfr are pin compatible. That was the whole idea of the 74xxx series.

Only the letters are important...HC parts are electronically different than LS and S parts, for instance. In some cases they are interchangeable, in others they are not, depending on the design of the circuit they are used in.
I think I found my answer. I will need a SN74HC174NSR from TI. That is a EIAJ package type. Will fit the board.

Re: REPLACEMENT for HEX D type flip flop with clear

Posted: Thu Dec 20, 2018 1:24 am
by Mooger5
You´re right, there´s SOIC-W and SOIC-N. As the spacing between the pins is the same I wrongly assumed the pads would allow for either package. Maybe there wasn´t the level of miniaturization of SOIC-N in 1987 yet...