Could it possibly be the db25 cable?
I think its supposed to be straight through minus one or two wires being flipped but I think straight through works anyways.

Definitely check the cable! I have had similar issues, purchased a straight DB25 and it was fine. Maybe more info there:

MPU-401 and MIF-IPC-B question

Thanks for the replies - I'm using a DB25 extension with a gender changer (which I ordered after reading your post Boohyaka), which I assumed to be fine but I might need to check it over...I'll report back.

EDIT: I checked the cable and all pins are connected straight through.

Does the MPU-401 need to be connected for the card to function correctly, or can I test without it connected?

Additional info - the MPU-401 I have is a pretty old unit with a ROM version that's almost certainly pre 1.3. Could this be why it isn't playing nice?

Oh wow is that one of the older 401 revisions with a eprom chip separate from the mcu?

https://forum.vcfed.org/index.php?threads/loo … ing-card.45735/

According to this thread version 1.5A is the highest?
So might be worth upgrading.

AppleSauce wrote on 2022-03-22, 13:39:

Oh wow is that one of the older 401 revisions with a eprom chip separate from the mcu?

It is, one of the "Roland DG" branded models.

AppleSauce wrote on 2022-03-22, 13:42:

https://forum.vcfed.org/index.php?threads/loo … ing-card.45735/

According to this thread version 1.5A is the highest?
So might be worth upgrading.

Thanks for the link. I read that thread also and am considering it, but I'd need to buy a programmer to try it out so I'm trying to exhaust my other options first...

I highly doubted I really needed a programmer for a long time...finally went ahead and it's been so useful! It probably ended being one of my wisest investment in this hobby 😁
went with one of those TL866II+ kits off eBay and it's been awesome

Boohyaka wrote on 2022-03-22, 14:09:

I highly doubted I really needed a programmer for a long time...finally went ahead and it's been so useful! It probably ended being one of my wisest investment in this hobby 😁
went with one of those TL866II+ kits off eBay and it's been awesome

Looks like I'd need to spring for the GQ-4X to program a 2732 without difficulty. What have you used yours for?

I've managed to find someone able to supply a chip with the newest ROM version on it. It might not fix the problem but I guess it's a start.

In Boohyaka's linked thread, keropi said that the ROM version should not be a factor.

keropi wrote on 2022-02-12, 16:08:

Do not worry about ROM versions stalk3r , it is not an issue
I also have such a box with a lotech clone card, just needs a 1:1 pin DB25 cable and you are good to go

Sounds like there could be some other fault with the unit then - not sure how best to proceed given that information...

It might not get much visibility in this thread, but I'm going to attach the service notes for both versions of the MPU-401 here as I wasn't able to find them anywhere else online. Hopefully they can be of use to someone.

charlatan wrote on 2022-03-24, 00:16:

Sounds like there could be some other fault with the unit then - not sure how best to proceed given that information...

It might not get much visibility in this thread, but I'm going to attach the service notes for both versions of the MPU-401 here as I wasn't able to find them anywhere else online. Hopefully they can be of use to someone.

Oh man thanks for that , I've tried to find the service manual just out curiosity to see how the original mpu works for ages but never had any luck , only the AT version was floating about , so cheers again.

charlatan wrote on 2022-03-24, 00:16:

Sounds like there could be some other fault with the unit then - not sure how best to proceed given that information...

It might not get much visibility in this thread, but I'm going to attach the service notes for both versions of the MPU-401 here as I wasn't able to find them anywhere else online. Hopefully they can be of use to someone.

Yeah after going back and rereading the thread it seems all his troubles began with the mif ipc card and persisted.

So now that I think about it maybe the actual 401 unit is not at fault , is it possible some of those SN74 glue logic chips on the interface card could be faulty?

Maybe they got some esd in transit or something , since I'd assume that texelec at least tests their cards before they sell.

https://www.lo-tech.co.uk/wiki/Lo-tech_MIF-IPC-B

That texelec page has a buncha service manuals and diagrams for the interface card.

Looking through , though I'm no expert when it comes to circuits , it looks like the 74HCT04N chip controls the IRQ selection and the 74HCT688N chip controls I/O address selection?

Maybe the fault lies in one of those chips?
Or maybe I'm grasping at straws?

charlatan wrote on 2022-03-23, 23:51:

Looks like I'd need to spring for the GQ-4X to program a 2732 without difficulty. What have you used yours for?

Dumping/testing/upgrading bios on many devices, mainly MIDI expanders and motherboards.... and also programming an XT-IDE chip to put as optional bios on a network card (mind was blown when I learnt that was possible, then figured out it actually made sense 😀 )

AppleSauce wrote on 2022-03-24, 05:45:

Yeah after going back and rereading the thread it seems all his troubles began with the mif ipc card and persisted. […]
Show full quote

charlatan wrote on 2022-03-24, 00:16:

Sounds like there could be some other fault with the unit then - not sure how best to proceed given that information...

It might not get much visibility in this thread, but I'm going to attach the service notes for both versions of the MPU-401 here as I wasn't able to find them anywhere else online. Hopefully they can be of use to someone.

Yeah after going back and rereading the thread it seems all his troubles began with the mif ipc card and persisted.

So now that I think about it maybe the actual 401 unit is not at fault , is it possible some of those SN74 glue logic chips on the interface card could be faulty?

Maybe they got some esd in transit or something , since I'd assume that texelec at least tests their cards before they sell.

I do keep coming back to that card as the source of the issue (wishful thinking?) and I should mention that TexElec has been helpful and happy to provide a replacement, despite believing something else is likely at fault. I guess that'll take a couple of weeks to arrive.

I'm glad those service notes were helpful and that I wasn't the only one having a hard time finding them...

Boohyaka wrote on 2022-03-24, 07:26:

charlatan wrote on 2022-03-23, 23:51:

Looks like I'd need to spring for the GQ-4X to program a 2732 without difficulty. What have you used yours for?

Dumping/testing/upgrading bios on many devices, mainly MIDI expanders and motherboards.... and also programming an XT-IDE chip to put as optional bios on a network card (mind was blown when I learnt that was possible, then figured out it actually made sense 😀 )

Didn't think about that; I have a board here I could probably save. I ended up ordering the model I mentioned so we'll see how that goes 😀

Can someone please answer this for me - should the PC behave normally when only the MIF-IPC/-A/-B is connected, without the MPU-401? Maybe it would be worth swapping those ICs out.

Can someone please answer this for me - should the PC behave normally when only the MIF-IPC/-A/-B is connected, without the MPU-401?

I don't see why it wouldn't. From what I can tell these cards are extremely basic anyway. When they run fine you completely forget they exist. No need for specific drivers. They just work from DOS, and in all Windows versions they are automatically detected and supported. I never tried it to be fair but I can't see how it could be a problem if the DB25 cable is off.

Boohyaka wrote on 2022-03-24, 12:07:

Can someone please answer this for me - should the PC behave normally when only the MIF-IPC/-A/-B is connected, without the MPU-401?

I don't see why it wouldn't. From what I can tell these cards are extremely basic anyway. When they run fine you completely forget they exist. No need for specific drivers. They just work from DOS, and in all Windows versions they are automatically detected and supported. I never tried it to be fair but I can't see how it could be a problem if the DB25 cable is off.

That's what I thought and it seems logical. Since I wrote that, I took a closer look at the card...

The wiki page states that IC3&6 should be 74LS08N and IC5 should be 74HCT04N. On my board, IC3 (Address Decode & Data Buffer) and IC5 (IRQ Select) are switched around.

charlatan wrote on 2022-03-24, 12:17:

Boohyaka wrote on 2022-03-24, 12:07:

Can someone please answer this for me - should the PC behave normally when only the MIF-IPC/-A/-B is connected, without the MPU-401?

I don't see why it wouldn't. From what I can tell these cards are extremely basic anyway. When they run fine you completely forget they exist. No need for specific drivers. They just work from DOS, and in all Windows versions they are automatically detected and supported. I never tried it to be fair but I can't see how it could be a problem if the DB25 cable is off.

That's what I thought and it seems logical. Since I wrote that, I took a closer look at the card...

The wiki page states that IC3&6 should be 74LS08N and IC5 should be 74HCT04N. On my board, IC3 (Address Decode & Data Buffer) and IC5 (IRQ Select) are switched around.

Oh wow that doesn't seem right at all can you send a picture of the card so we can see the ic chips?

I guess whoever assembled the card had a bit of a la la land moment and missed the fact they installed the chips in reverse order.

Shame its not socketed it would be much easier to fix vs desoldering parts.