Otari MX-70 Audio Card Issues

[DerrickH]

Hey Everyone:

I've got 3 cards on my MX70 that are all showing the same problems. When you run a test signal through the machine, I show a signal on the meters and can hear the signal through the card's output jack no matter what mode I'm in (even in repro).

When I go to put the signal to tape, it appears like it's recording, but it doesn't record the signal.

I've replaced IC 29/30 and the relays. IC6 is the I-0125, not the latest, but should not be causing this issue. I'm wondering if it could be the program array chip (IC28).

Anyone else have these issues? Also, if anyone has any functional IC6's or IC28's they want to sell, please let me know.

Derrick.

[blue_thunder77]

You could try swapping the IC6 and/or the IC28 from a working card and see if that solves the problem. At least you'd know for sure where the problem lies. Have you tried swapping the card locations to be sure it is the cards themselves that are causing the problem? If the card works okay in a different channel, it could be a problem with the switches in the remote or a problem on the main board.

I had a similar problem with mine, but it went away when I replaced the IC29.

[DerrickH]

I think that IC29/30 are there to help protect IC28 to some degree. I have tried switching card locations, but I'm concerned about blowing good parts trying to troubleshoot these couple of cards.

Since I originally posted this, I got so fed up with this deck I spent 24 hours round trip picking up a real nice MX-80 32-track that also came with a nearly new 24 track headstack! It's real nice. Lots of other bonuses as well.

I'm planning on parting the MX-70 out or selling it outright if someone is interested.

Thanks for your response.

[@?,*???&?]

I am 90% positive your problem is the main output chip at the back top of the card. The old I-0050 chips are prone to burn. The replacement I-0178-B. The replacement burns at a much cooler temperature.

I had to replace over half on the machine I have. The I-0178-B chips are still readily available from Otari, but are $84 each and have to be shipped from Japan.

Functionally, all my cards worked, but many of them had no or low output levels or output with significant noise.

[DerrickH]

Most of the chips are the I-0178B, a few I-0125,and (2) I-0050. I think it's the program array chip (IC28), but I don't want to take a chance blowing others just to test it.

On that MX-80-32 I just picked up, all 32 channels are the I-0125 flavor with no problems. That machine seems so much more reliable than the MX-70. Anyone else observed that?

[telecasterrok]

Hey Everyone:

I've got 3 cards on my MX70 that are all showing the same problems. When you run a test signal through the machine, I show a signal on the meters and can hear the signal through the card's output jack no matter what mode I'm in (even in repro).

When I go to put the signal to tape, it appears like it's recording, but it doesn't record the signal.

I've replaced IC 29/30 and the relays. IC6 is the I-0125, not the latest, but should not be causing this issue. I'm wondering if it could be the program array chip (IC28).

Anyone else have these issues? Also, if anyone has any functional IC6's or IC28's they want to sell, please let me know.

Derrick.

Hi Derrick - I have the exact same problem with 2 channels on my MX70. Did you figure out the solution?

[DerrickH]

Hey Everyone:

I've got 3 cards on my MX70 that are all showing the same problems. When you run a test signal through the machine, I show a signal on the meters and can hear the signal through the card's output jack no matter what mode I'm in (even in repro).

When I go to put the signal to tape, it appears like it's recording, but it doesn't record the signal.

I've replaced IC 29/30 and the relays. IC6 is the I-0125, not the latest, but should not be causing this issue. I'm wondering if it could be the program array chip (IC28).

Anyone else have these issues? Also, if anyone has any functional IC6's or IC28's they want to sell, please let me know.

Derrick.

Hi Derrick - I have the exact same problem with 2 channels on my MX70. Did you figure out the solution?

Never bothered since I had picked-up the MX-80. Sorry.