Search found 20 matches

by gkmaia
Sun Oct 13, 2019 6:03 am
Forum: HELP!
Topic: Ensoniq EPS issue
Replies: 3
Views: 97

Ensoniq EPS issue

I bought a second hand EPS (not the 16, the standard one). Got the ALL leds no display issue. Power supply is fine. The keyboard to main pub cable has been re-crimped. MC68000 MPU seems to be managing the control, address and data bus. MC68440 DMAC seems to be also doing its job pulsing addresses to...
by gkmaia
Sat Aug 31, 2019 8:48 am
Forum: HELP!
Topic: M-Audio Prokeys 88SX board needed
Replies: 0
Views: 455

M-Audio Prokeys 88SX board needed

I got an M-Audio Prokeys 88SX which has a faulty SAM9708 IC and I am just trying to find if anyone here has one of these that is maybe not working and would be interested in selling the main PCB.
by gkmaia
Wed Jan 23, 2019 9:32 am
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 4812

Re: D-50 sounding distorted, noise & creaking

I did manage to create a clean patch by "init" the partials. It sounds clean and perfect.

But as soon as I start messing with chorus look what happens... seems chorus flanger options 3 and 4 are completely busted.

by gkmaia
Thu Dec 27, 2018 9:52 pm
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 4812

Re: D-50 sounding distorted, noise & creaking

Try contacting the seller in the ebay link. Read the description. Maybe the item didn´t sell or the seller still has one available. Good luck. http://forum.vintagesynth.com/viewtopic.php?f=5&t=102457&hilit=crackling&start=45#p806128 I am wondering what would happen if I just remove the Chorus chip ...
by gkmaia
Thu Dec 27, 2018 9:14 pm
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 4812

Re: D-50 sounding distorted, noise & creaking

Try contacting the seller in the ebay link. Read the description. Maybe the item didn´t sell or the seller still has one available. Good luck. http://forum.vintagesynth.com/viewtopic.php?f=5&t=102457&hilit=crackling&start=45#p806128 Thanks Mooger5. I will do that. I ordered all new RAM ICs as I hav...
by gkmaia
Thu Dec 27, 2018 2:42 am
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 4812

Re: D-50 sounding distorted, noise & creaking

No luck. Unfortunately. These are the last updates: - New PCM54 DAC installed - Chorus IC & Chorus RAM IC removed, checked and cleaned at 20X magnification. - Checked all traces from-to Chorus and Chorus RAM ICs. And they are all fine. No shorts or fails. - Chorus IC & Chorus RAM IC welded back and ...
by gkmaia
Sat Dec 22, 2018 8:45 pm
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 4812

Re: D-50 sounding distorted, noise & creaking

Looking at the chorus IC pin table would you know what results to expect on a logic probe?

Image
by gkmaia
Sat Dec 22, 2018 7:57 pm
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 4812

Re: D-50 sounding distorted, noise & creaking

What about the chorus chip? I am not sure yet. Waiting my sram socket to arrive so I can attach it with a socket instead of soldering directly to the PCB. After that I will turn it on again and test it. But till then just waiting. It would be good to know more how to test the chorus IC with a probe...
by gkmaia
Sat Dec 22, 2018 6:25 am
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 4812

Re: D-50 sounding distorted, noise & creaking

Here, a similar problem is described and solved. Hope it helps. http://forum.vintagesynth.com/viewtopic.php?f=5&t=78276#p741443 Thanks Mooger. I've been following this thread. I got the reverb and SRAM ICs out of the PCB today. Put it back and did a good check on pads and traces. All 100%. Just wai...
by gkmaia
Fri Dec 21, 2018 8:28 am
Forum: HELP!
Topic: D-50 sounding distorted, noise & creaking
Replies: 22
Views: 4812

Re: D-50 sounding distorted

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. I may have found the source of my problem but I don't actually know how to pin point it. If I edit a patch and change the all chorus balances...
by gkmaia
Wed Dec 19, 2018 8:31 pm
Forum: HELP!
Topic: REPLACEMENT for HEX D type flip flop with clear
Replies: 7
Views: 1455

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: 1455

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: 1455

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: 1455

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: 4812

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...