Otari MTR-10 Power Problems

I have an Otari MTR-10 that wasn't working when I got it. It had a bunch of broken solder joints on the connectors and it worked for a while. Then all of a sudden the transport controls just stopped working.

The PSU has a bunch of different voltages coming out of it. It also has an led indictor for each voltage that shows if it's on or not and they are all lit. I've read that bad PSU caps are a frequent cause of failed gear, and was wondering if anyone thought that might be the case here. Is it possible that they are working enough to light an LED but not actually power the transport? There was no smoke or anything when it stopped. I turned it off one day and turned it back on later in the day and it wasn't working.

This thing is really complicated(20 or so different schems) and I don't think I'm qualified to dig into it much. So my question is, would it be worth my time/money to replace all of the large electrolytics in it? There are two 15000uf 16V, one 6800uf 35V, one 1000uf 63V, one 4700uf 50V, and one 4700uf 35V.

Here is the schem for the PSU. Ignore the red lines as that was the section that originally didn't light the LEDs, but now does. That is what was fixed by repairing the faulty solder joints.

http://fucanay.fischerworks.com/schems/otari_psu_schem.gif

Any advise welcome.

Matt

[quote author="fucanay"]
Is it possible that they are working enough to light an LED but not actually power the transport?.....So my question is, would it be worth my time/money to replace all of the large electrolytics in it?
[/quote]

Hi,

Any significant drop in individual power supply's voltage will affect the LEDs brightness (especially when the zeners are inserted in LED's circuits). To be sure, you might use a DVM and check all voltages at the output connectors. IMO, the power supply for the transport control is +5V and for driving the motors are +24V and +30V.
Changing caps in the power supply used for the audio circuitry (+/-26V) thus doesn't make much sense.

Regards,
Milan

I'm afraid that really doesn't sound like caps gone open... I think the problem is elsewhere.

Peace,
Al.

Looks like it's time to spend a few hours with my DMM. This machine is really hard to work on because a lot of the circuits are on boards that slide into the front of the chassis, so it's impossible to test voltages. I was really hoping it was a PSU problem because it is easily accessible.

I'll keep you all posted on the progress, or lack of progress.

Thanks

Matt

Be warned before you start, Otari machines in my experience frequently have transport controller boards that go bad. -Most ofter I've had to replace the entire card and at today's prices, that's more money than a replacement machine...

Hope it's not the same for you, but the symptoms are the same...

Keith

[quote author="SSLtech"]Be warned before you start, Otari machines in my experience frequently have transport controller boards that go bad. -Most ofter I've had to replace the entire card and at today's prices, that's more money than a replacement machine...

Hope it's not the same for you, but the symptoms are the same...

Keith[/quote]

I pulled that card out and there is some weird things going on with it. Number one, there are legs lifted on two resistors. The other is there is a zener of some sort from a resistor to a pin on the connector contact. Really strange.

I haven't really dug into this thing that much still. Been too busy working on GSSLs and G1176s, but I am determined to fix this damned thing someday. Even if it comes down to replacing every damned part in it, although I think think I'll try to use some reasoning before I go that far.

I told ya I'd keep ya posted on the lack of progress. :green:

FYI: Thread title updated to reflect actual content.

Matt

Well, it is not the transport card. In fact it was yet another molex connector on the PSU that was killing the whole damned thing, I don't know if they used the worst solder, connectors or people installing them, but almost every connector on the PSU had to be resoldered.

It works again, now I need to se about aligning the thing. I've never done it before, so if anyone has some good resources, let me know.

Matt