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Author Topic: Otari Troubles...  (Read 10299 times)

Offline Grant99

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Otari Troubles...
« on: September 12, 2009, 11:24:37 PM »
Just recently got my Otari back from having the mods done. So I finally hooked it up to my new tube repro preamp (for the first time, rec'd it about a month ago I think).  Well...the great music was not to be; all I get for sound is some  hiss and very low level hum.

Now.  I'm just a layman & not technical at all but 25+ years of riding (& wiring) ancient motorcyles has taught me one thing for sure: when you have a problem, ALWAYS start looking at the most simple, obvious thing (duh!) before you move on to something more complicated.  So here are a couple of simple, dumb questions:
1) The Otari was rewired for direct output from the heads...so this output comes out of the LINE OUTPUT jacks on the back panel, correct?
2) I tried using both the RCA output and the XLR output; no difference, no sound output.
3)Was the deck actually test-run before it was shipped back to me?
4)My thinking is that I need to isolate the problem; i.e. is it the deck or is it the tube repro, correct?
5)So to do the above (4), can I test the output from these jacks using a voltmeter or ohmmeter, to verify if there is output from the deck?  What should I be looking for?
6) If I verify that the deck's output is OK is there a way to test the tube repro?  As I only have the Otari how about running the output from my turntable into it (Grad Sonata - 5MV version).  Is this doable?

Any suggestions will be appreciated...I really hope my problem is due to something obvious that I have overlooked...thanks in advance










Grant Thrasher
audio/LP/tape hobbyist
Otari MX-5050 BIII, VPI-19/SME IV, MFA Magus/MFA D75 amp/McAlister EA-8 amp/Stax OA2 & SR-404/Coincident Millenium Spks/Nak Dragon/Marantz PMD520/Sony KA1ESA

Offline ironbut

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Re: Otari Troubles...
« Reply #1 on: September 13, 2009, 12:44:40 AM »
Hey Grant,
You said that you tried the RCA and XLR outputs of the Otari. You may be hooking the deck to the outputs of the Repro. There are no XLR inputs but there are balanced outputs on the Repro. The only inputs are a pair of RCA jacks with a ground lug in between them.
steve koto
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Offline Tim

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Re: Otari Troubles...
« Reply #2 on: September 13, 2009, 12:50:09 AM »
Put an ohm meter across the line out jack.  If the play head has been wired to it, you should get a low resistance.  Perhaps in the 100 to 500 ohm range.  If you don't get this, see if there are any other added jacks on the deck that could be head outputs.   Or perhaps an added switch to convert the jacks into a head output. 

Connect the output of a turntable to the input of the your tube repro .  It should work with it, although the low and high frequency balance will be off.

Tim Leinbaugh
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with RTR specialty.

Offline jcmusic

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Re: Otari Troubles...
« Reply #3 on: September 13, 2009, 07:27:03 AM »
Grant who did the work on it? I would get in touch with them to find out if it was tested.

Jay
Redpoint Model D TT/Soundsmith Sotto Voce Cartridge Otari MX 5050 BII/BH Tube Repro deHavilland Model 222
 Ah Njoe Tjoeb 4000, Rogue Magnum 99, Korneff 45 SET Amp, Klipsch K-Horns Bass Bins/2" Tractrix Horns 2" BMS Drivers, Vintage Tubes.

Offline Grant99

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Re: Otari Troubles...
« Reply #4 on: September 13, 2009, 07:56:11 AM »
Grant who did the work on it? I would get in touch with them to find out if it was tested.

Jay

The work was done at Bottlehead.  When I spoke to Dan (I'm pretty sure it was him) he indicated the head output would be wired to the XLR terminals already there; I assumed he meant the line output ones.

Sorry Steve, to clarify, I meant that I tried both the RCA & XLR outputs of the repro preamp.

Regarding the repro, could it have developed a tube issue in shipment?  It does seem to up power OK & I get the usual  hissing sound when a tube component is on...but I do have an old tube tester...would it be worth testing the tubes?

Another note: when the line inputs are turned up, the meters go up at a constant level, even when there is no signal from any source going into the deck.  This doesn't seem right.  When I first powered up the deck, the meters were pegged as far as they could go.  Could this be indicative of some kind of short?

I just can't help thinking it's something basic that I've overlooked so I thought I'd post here first, to go through the first steps, then give them a call if I'm stuck.  I will check the Otari output with a ohmmeter and report back later...thanks everyone for the suggestions.
Grant Thrasher
audio/LP/tape hobbyist
Otari MX-5050 BIII, VPI-19/SME IV, MFA Magus/MFA D75 amp/McAlister EA-8 amp/Stax OA2 & SR-404/Coincident Millenium Spks/Nak Dragon/Marantz PMD520/Sony KA1ESA

Offline Grant99

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Re: Otari Troubles...
« Reply #5 on: September 13, 2009, 08:12:06 AM »
Put an ohm meter across the line out jack.  If the play head has been wired to it, you should get a low resistance.  Perhaps in the 100 to 500 ohm range.  If you don't get this, see if there are any other added jacks on the deck that could be head outputs.   Or perhaps an added switch to convert the jacks into a head output. 

Hi Tim, thanks for the response...I forgot to ask...when checking resistance...where am I checking it...between the the hot pin and the ground pin?  Just wanted to be sure, thanks again.
Grant Thrasher
audio/LP/tape hobbyist
Otari MX-5050 BIII, VPI-19/SME IV, MFA Magus/MFA D75 amp/McAlister EA-8 amp/Stax OA2 & SR-404/Coincident Millenium Spks/Nak Dragon/Marantz PMD520/Sony KA1ESA

Offline docb

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Re: Otari Troubles...
« Reply #6 on: September 13, 2009, 09:39:53 AM »
Hi Grant,

Sorry for your troubles. This will be most easily dealt with by phone, as the forum makes for a pretty balky way of communicating back and forth. Shawn and I will both be in the office tomorrow during regular business hours and we can call you at a time that is convenient.

In the meantime make sure that your XLR to RCA interconnects from the head output to the Tube Repro are wired pin 2 hot at the XLR end - in other words when you disconnect the cable from the system and measure resistance you should find continuity from the center pin of the RCA plug to pin 2 of the XLR plug and continuity from the outer ring of the RCA plug to pin 3 of the XLR plug. If you need a different cable because yours happens to be wired pin 3 hot, monoprice.com has very nice cables for great prices.
 
If you can hear tube rush with the volume turned up it sounds more like an issue upstream of the Repro than the Repro itself. I like your idea of connecting the Repro to a phono cartridge to test it to be sure. The Repro was tested here (as was the Otari - kind of hard not to when you have to check alignment ;^)>  ) and it ran in my system for a couple of weeks. So the only potential issue with it might be that something was knocked around in shipping. Try removing and replacing the tubes and then running it for an hour or so and make sure that all the tubes get warm to hot. The two tubes closest to the red output transformers get super hot, don't burn your fingers. The two tubes nearest the input jacks get very warm, but not as hot as the other tubes.

By the way the phono idea works both ways. You can also connect the head output of the Otari into a known good phono preamp and check it's function.

You might also want to cycle the 2-track/1/4 track head selector switch back and forth. Sometimes they get set between the two positions.

Regarding the meters, since they are not connected to the Repro circuit they may just be picking up noise from the open input of the now disconnected internal electronics. Turning the level controls down will cure that. The meters can be used by using a y connector from the output of the Tube Repro and running the extra outs back into the line input jacks of the Otari, then switching the Otari to meter the line inputs.

I will be off to the Wooden Boat Festival today, but we will be around all day tomorrow.

Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline High and Outside

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Re: Otari Troubles...
« Reply #7 on: September 13, 2009, 11:36:51 AM »
Put an ohm meter across the line out jack.  If the play head has been wired to it, you should get a low resistance.  Perhaps in the 100 to 500 ohm range. 

If you do this, be sure to demagnetize your heads afterward. The DC that the meter uses to measure resistance is small, but might be enough to leave the head magnetized. You don't want to play tapes over a magnetized head as that can damage the recorded signal on the tape.
Paul Stubblebine
Managing Director, The TapeProject

Offline jcmusic

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Re: Otari Troubles...
« Reply #8 on: September 13, 2009, 01:15:45 PM »
Put an ohm meter across the line out jack.  If the play head has been wired to it, you should get a low resistance.  Perhaps in the 100 to 500 ohm range. 

If you do this, be sure to demagnetize your heads afterward. The DC that the meter uses to measure resistance is small, but might be enough to leave the head magnetized. You don't want to play tapes over a magnetized head as that can damage the recorded signal on the tape.
Now that is the best advice I have seen all day!!!

jay
Redpoint Model D TT/Soundsmith Sotto Voce Cartridge Otari MX 5050 BII/BH Tube Repro deHavilland Model 222
 Ah Njoe Tjoeb 4000, Rogue Magnum 99, Korneff 45 SET Amp, Klipsch K-Horns Bass Bins/2" Tractrix Horns 2" BMS Drivers, Vintage Tubes.

Offline Grant99

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Re: Otari Troubles...
« Reply #9 on: September 14, 2009, 05:52:37 AM »
Hi Grant,

Sorry for your troubles. This will be most easily dealt with by phone, as the forum makes for a pretty balky way of communicating back and forth. Shawn and I will both be in the office tomorrow during regular business hours and we can call you at a time that is convenient.

Thanks for the input/suggestions, I get  home from work around 6:00 p.m. (EDT) which I believe is 3:00 p.m.  your time and can be reached then.
Grant Thrasher
audio/LP/tape hobbyist
Otari MX-5050 BIII, VPI-19/SME IV, MFA Magus/MFA D75 amp/McAlister EA-8 amp/Stax OA2 & SR-404/Coincident Millenium Spks/Nak Dragon/Marantz PMD520/Sony KA1ESA

Offline Grant99

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Re: Otari Troubles...
« Reply #10 on: September 15, 2009, 10:52:30 AM »
As a follow-up on this one, the cuprit appears to be a toasted 6922 tube on the repro, "modified" by either the U.S. Postal Service, or  Canada post.  I substituted another 6922, still only some hum &  no output, so in my discussions with Dan he is conjecturing that the bad tube has cause some secondary issues.  But I'm going to sub. the other tubes in a few days (when they arrive) just to see.  If it is still a no-go with all new tubes then it's getting shipped back to Bottlehead-town for a full analysis.

I also tested the cables (XLR-to-RCA) for continuity per Dan's suggestion, to confirm the pins are correct, they check out OK.

BTW, I did run the Otari's output into my phono stage, you could hear the deck's output, although not great sounding, presumably due to RIAA eq. & output differences.  On the other hand, running the output of my turntable into the repro yielded no output from it, only more of that low level hum.  So I think my Otari has a clean bill of health, except for those VU meters showing constant signal when there isn't one; I'm a bit concerned about this.  I'm going to try and dub FM or an LP and see if the Otari records OK.

Again, thanks everyone for their help on this one, this is what makes this audio hobby a great one.
Grant Thrasher
audio/LP/tape hobbyist
Otari MX-5050 BIII, VPI-19/SME IV, MFA Magus/MFA D75 amp/McAlister EA-8 amp/Stax OA2 & SR-404/Coincident Millenium Spks/Nak Dragon/Marantz PMD520/Sony KA1ESA