Search found 40 matches

by gkmaia
Wed Dec 19, 2018 8:31 pm
Forum: HELP!
Topic: REPLACEMENT for HEX D type flip flop with clear
Replies: 7
Views: 2120

Re: REPLACEMENT for HEX D type flip flop with clear

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 elect...
by gkmaia
Wed Dec 19, 2018 7:59 pm
Forum: HELP!
Topic: REPLACEMENT for HEX D type flip flop with clear
Replies: 7
Views: 2120

Re: REPLACEMENT for HEX D type flip flop with clear

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 thoug...
by gkmaia
Wed Dec 19, 2018 2:39 am
Forum: HELP!
Topic: REPLACEMENT for HEX D type flip flop with clear
Replies: 7
Views: 2120

Re: REPLACEMENT for HEX D type flip flop with clear

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.
by gkmaia
Tue Dec 18, 2018 9:56 am
Forum: HELP!
Topic: REPLACEMENT for HEX D type flip flop with clear
Replies: 7
Views: 2120

REPLACEMENT for HEX D type flip flop with clear

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. ht...
by gkmaia
Sun Dec 09, 2018 9:32 pm
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 6522

Re: D-50 sounding distorted, noise & creaking

Well, the synth has been in storage for the last 20 years. Did you install a fresh battery and do a reset already? Have you checked the PSU voltages? Looked for bad capacitors? Those routines always come first. We just assume upon reading the OP the obvious stuff is already done. Be sure to AC coup...
by gkmaia
Sun Dec 09, 2018 5:18 am
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 6522

Re: D-50 sounding distorted, noise & creaking

SMD joints too? I dont have the service notes here atm but testing the chips should be easy. Just follow the input and output lines and watch with a scope or a logic probe the pulse streams. Thats the digital data or 1s and 0s in electric form. For instance that 74hc chip has four lines going into ...
by gkmaia
Fri Dec 07, 2018 6:57 pm
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 6522

Re: D-50 sounding distorted, noise & creaking

Touched up all welds on the board and same issue.

Ordered a new PCM54 + 74HC ICs and will replace them. Lets see what happens.

In the mean time any other ideas?
by gkmaia
Fri Dec 07, 2018 4:33 am
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 6522

Re: D-50 sounding distorted

madtheory wrote:The DAC is actually in two parts, a 16 bit DAC and a ladder DAC for the other 4 bits (20 bit in total). You'd need to check the components in the ladder DAC.
IC10 = 16 bit DAC
IC11 = 4 BIT DAC

Any idea how to test these ICs?
by gkmaia
Fri Dec 07, 2018 4:28 am
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 6522

Re: D-50 sounding distorted

Mooger5 wrote: I believe there should be a +5V pulse signal at TP1 and 2...
I am getting a +4V on each TP1/2
by gkmaia
Thu Dec 06, 2018 6:10 am
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 6522

D-50 sounding distorted, noise & creaking

Hi, I just toke my D-50 out of storage after 20 years and the sound is completely distorted, noise & creaking. Software test - Reverb and Chorus passed - All buttons and sliders passed - D/A Adjustment. VR1 on the main board adjusted for minimum distortion done Hardware - weld - Touched up all welds...