Hi zobsky,
They weren't popular because Nakamichi couldn't focus on producing a line. They flopped between great audio gear and "lifestyle products". Some of their later receivers (after the TA-x series) where decidedly inexpensively made.
I own a TA-2, OMS-7, OMS-4 and BX-300. Really good stuff.
Hi silvercore,
Hi Dave,
-Chris
They weren't popular because Nakamichi couldn't focus on producing a line. They flopped between great audio gear and "lifestyle products". Some of their later receivers (after the TA-x series) where decidedly inexpensively made.
I own a TA-2, OMS-7, OMS-4 and BX-300. Really good stuff.Hi silvercore,
The dreaded "green grease syndrome". Sometimes they got glued together. The proper fix was to disassemble (a feat sometimes) and clean completely, then relubricate. Lubricants with no additives are required. You are correct though, most guys used way too much lubricant and destroyed rubber and other parts.
Hi Dave,
Yes I do, I'll gladly measure it for you. I will email you a picture as well to make your life easier. I don't have a manual for the OMS-4 anymore, could you please email a copy to bhomester at gmail dot com? I'll figure out which jig it is and get you that information. The standard Mabuchi motors are used. I'll try and dig up a generic number for you.
-Chris
Hi Dave,
That doesn't look like any of my gauges for Nakamichi. It's possible that I simply measured from the TT top surface to the mech surface. I could tell more readily from looking at the manual.
I was authorized waranty, but all my manuals stayed with the shop when I sold it. Nakamichi a=had more jigs and test tapes / discs than any other manufacturer. Well, Teac certainly came close I guess.
-Chris
That doesn't look like any of my gauges for Nakamichi. It's possible that I simply measured from the TT top surface to the mech surface. I could tell more readily from looking at the manual.
I was authorized waranty, but all my manuals stayed with the shop when I sold it. Nakamichi a=had more jigs and test tapes / discs than any other manufacturer. Well, Teac certainly came close I guess.
-Chris
Hi Dave,
I have high speed, so no troubles there. Just the alignment pages and schematic to start. Board layouts would be very handy if you have the time at some point.
I have some old disc motors that I want to confirm come from an OMS-4. They have a brass spacer glued to the top. Save this piece (if I'm right) as you will use it on the new motor.
-Chris
I have high speed, so no troubles there. Just the alignment pages and schematic to start. Board layouts would be very handy if you have the time at some point.
I have some old disc motors that I want to confirm come from an OMS-4. They have a brass spacer glued to the top. Save this piece (if I'm right) as you will use it on the new motor.
-Chris
Hi Dave,
No, that was a Sony issue. I have seen the exact same problem wherever that head is used. The unit I just saved was a Denon DCD-3300.
The mechanisms for the OMS 3/4 and 5/7 were NEC units. I am pretty sure NEC was the OEM for the PCB's as well. I am not sure about the OMS-1 and OMS-2. The PCB appears to be NEC also in those.
The clearance was small and the shaft appears to be finished with a slippery surface. Anything at all that gets in there will gum things up. The fix is to make it absolutely clean again, add nothing.
Now that I've figured out what the problem is, I'm going to repair my OMS-4 some time. When I was doing warranty and soon after when they were out, the heads were $500 CDN and change. That's why mine was not repaired. Sony even wanted a fair amount for the head.
Dave, thank you for the effort getting the manual to me. Once I see it I'll remember how I used to set the head height. I believe we used Philips test disc #5 to set the gains, I haven't followed the manual in years for this. Just watch the servo noise while playing a good disc. Set the gain for the minimum noise point between the low frequency and high frequency components. You will hear the servo (focus especially) from the laser assy. Hang you 'scope on the tracking and focus servo outputs.
-Chris
No, that was a Sony issue. I have seen the exact same problem wherever that head is used. The unit I just saved was a Denon DCD-3300.
The mechanisms for the OMS 3/4 and 5/7 were NEC units. I am pretty sure NEC was the OEM for the PCB's as well. I am not sure about the OMS-1 and OMS-2. The PCB appears to be NEC also in those.
The clearance was small and the shaft appears to be finished with a slippery surface. Anything at all that gets in there will gum things up. The fix is to make it absolutely clean again, add nothing.
Now that I've figured out what the problem is, I'm going to repair my OMS-4 some time. When I was doing warranty and soon after when they were out, the heads were $500 CDN and change. That's why mine was not repaired. Sony even wanted a fair amount for the head.
Dave, thank you for the effort getting the manual to me. Once I see it I'll remember how I used to set the head height. I believe we used Philips test disc #5 to set the gains, I haven't followed the manual in years for this. Just watch the servo noise while playing a good disc. Set the gain for the minimum noise point between the low frequency and high frequency components. You will hear the servo (focus especially) from the laser assy. Hang you 'scope on the tracking and focus servo outputs.
-Chris
Chris
Shipping was $16.I'll bet it will cost him more than that. If the laser assy. is any good its worth 26 bucks. Sounds like the belt in the loading assy. is shot also.
Dave
By the way. Is dim LED display segments pretty common in these units? The pic shows track 11,those two segments of the of that particular readout are the only segments that are dim the rest of the segments are full intensity...........
Shipping was $16.I'll bet it will cost him more than that. If the laser assy. is any good its worth 26 bucks. Sounds like the belt in the loading assy. is shot also.
Dave
By the way. Is dim LED display segments pretty common in these units? The pic shows track 11,those two segments of the of that particular readout are the only segments that are dim the rest of the segments are full intensity...........
Attachments
Hi Dave,
After a lot of use, yes. Those digits are the most often illuminated. Happens with the TA series recievers as well.
The OMS-3,4,5,7 are interesting. I think they are the last of the parallel DACs. Soon after they switched to a serial data stream. Nakamichi used a shorting type deglitcher and ended up with a smoother sounding D/A stage.
KSS-123A are $26 USD now? It's not worth it in that case to repair the head, except for duty, exchange and shipping. Hmmmm, I'm fixing mine.
-Chris
After a lot of use, yes. Those digits are the most often illuminated. Happens with the TA series recievers as well.
The OMS-3,4,5,7 are interesting. I think they are the last of the parallel DACs. Soon after they switched to a serial data stream. Nakamichi used a shorting type deglitcher and ended up with a smoother sounding D/A stage.
KSS-123A are $26 USD now? It's not worth it in that case to repair the head, except for duty, exchange and shipping. Hmmmm, I'm fixing mine.
-Chris
Chris
I figured the laser assy.'s were a lot more costlier than that.No sense using a used laser at that price. Your manual is being copied as I speak. Would a pdf file be OK?So... according to a previous post is the KSS-123A or the NEC laser prone to sticking on the post and what are the syptoms of this ocurrance?
My oms-4 has the 123 in it.The unit I just won on ebay is going to be a training aid. And also cosmetic parts donor.
Dave
I figured the laser assy.'s were a lot more costlier than that.No sense using a used laser at that price. Your manual is being copied as I speak. Would a pdf file be OK?So... according to a previous post is the KSS-123A or the NEC laser prone to sticking on the post and what are the syptoms of this ocurrance?
My oms-4 has the 123 in it.The unit I just won on ebay is going to be a training aid. And also cosmetic parts donor.
Dave
Hi Dave,
I misinterpreted what you said then. I thought your were saying that the heads could be bought for $26 USD.
PDF files are fine, thank you. High res. even better so I can zoom in.
Great find to get a donor like than. Mine is cosmetically challenged also as I didn't buy it new.
The sticky lens assembly will track poorly or fail to find focus. The CD would be rejected even though the laser power and offsets are okay. If you were to gently move the assy up or down (cover off the head, use a small plastic stick), you'd see that it wasn't completely free. This will also tend to overheat the focus and tracking servo output transistors. Possibly blowing one of those 4R7 resistors (many in there).
-Chris
I misinterpreted what you said then. I thought your were saying that the heads could be bought for $26 USD.
PDF files are fine, thank you. High res. even better so I can zoom in.
Great find to get a donor like than. Mine is cosmetically challenged also as I didn't buy it new.
The sticky lens assembly will track poorly or fail to find focus. The CD would be rejected even though the laser power and offsets are okay. If you were to gently move the assy up or down (cover off the head, use a small plastic stick), you'd see that it wasn't completely free. This will also tend to overheat the focus and tracking servo output transistors. Possibly blowing one of those 4R7 resistors (many in there).
-Chris
Next ginueapig
Well my second cadaver arrived today. Looks like its not as bad as it was described. The loading assy. belt is slipping bad.It opens the tray but does not fully load a CD far enough to engage clamp ,drop the 4 CD positioning posts and make the closed microswitch. Time to order a new belt.
Dave
Well my second cadaver arrived today. Looks like its not as bad as it was described. The loading assy. belt is slipping bad.It opens the tray but does not fully load a CD far enough to engage clamp ,drop the 4 CD positioning posts and make the closed microswitch. Time to order a new belt.
Dave
Well I tried the heat soak-cold soak x 2 on the belt...It worked !! Neat trick..After reassembly I ops check unit. It plays great ! The cosmetic condition of this unit is outstanding!!! The LED display is perfect. I'm still going to order a couple replacement loading belts. Not to shabby for a $9.95 plus shipping.
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