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Messages - Ki Choi

Pages: [1] 2 3 ... 21
1
Tape Project Machines / Re: Nagra T-Audio Metering Bridge D2RS
« on: February 25, 2017, 10:54:31 AM »
The T-Audio meterbridge rarely come up for sale in used market.  Just about the only option is to scan the eBay and buy one from someone who is parting out a T-Audio.  There was a studio surplus seller (salesbaron, i believe) in LA that sold few of them in about three years but I haven't seen one since.

Good luck.

2
Reel to Reel Tape Machines / Re: Nagra T "stutter" issue
« on: January 20, 2017, 02:36:14 PM »
Good work, Doc B!

You have inspired me to play my favorite TP tapes over the weekend on my last remaining Nagra Audio T.

Ki

3
If you haven't figured it out yet, it's rather simple.

You would remove all the cards from the front.

Then remove the bottom cover from the back.

You will see 6 or 8 screws holding the Basis Board.

Remove the screws and the Basis Board will be freed and can be pull out with wire assembly attached to be worked on.

Let me know how it goes.

Ki

4
Tape Tech / Re: STUDER A810 SPOOLING MOTOR CONTROL PCB 1.810.760-82
« on: May 31, 2016, 05:13:57 PM »
I would put the original value 100uF 25V electrolytic caps back in the circuit board and check for traces of overheating / cracks on C26, C27, and C28 .47uF 150V rectangular oil caps.  Replace them with modern film type of same value.  These caps will fail eventually anyway.

Ki

5
Reel to Reel Tape Machines / Re: Lyrec part
« on: April 07, 2016, 09:28:24 AM »
Hi Steve:

I did see the conversation and do talk to Harold once in awhile. Glad he got the part.

Thanks,
Ki

6
Reel to Reel Tape Machines / Re: Upgrading Studer A807 15ips to 30ips
« on: April 04, 2016, 01:20:49 PM »
Actually, you would need a 2 pole motor to reach 30ips.  2 pole capstan motor will cover 7.5, 15 and 30 ips whereas 4 pole motor will cover 3.75, 7.5, and 15 ips.

Ki

7
Reel to Reel Tape Machines / Re: Lyrec part
« on: April 04, 2016, 01:16:41 PM »
"I'm not dead!"

What are you looking for?

Ki

9
Tape Tech / Re: Nagra T Manuals
« on: March 30, 2015, 04:45:17 PM »
Try contacting

Nancy Belt
(615) 451-4168

She is with Nagra USA and used to stock the T key button covers but not sure about the NAB adapters.

Ki

10
Tape Tech / Re: Tape Heads
« on: March 30, 2015, 04:42:40 PM »
Try contacting:

Tom Brucker

Hi Tech Service
2934 Nolensville Pk.
Nashville, TN 37211
615-331-9241
[email protected]

He is the Nakdoc on other tape forum.

Ki

11
Reel to Reel Tape Machines / Re: Studer A810 stuck in "Safe"
« on: August 01, 2014, 12:54:11 PM »
Good to hear happy ending Studer stories.

I still get amused and surprised at the level of design thoughts that went into Studer machines every time I have to deep dive into them with issues.  However there are few things that I wish they had done differently.

From top of my head:

1) Use of the dreaded Frako caps...  I am sure the cost was an important factor for the volume of electrolytic caps they used when tapes were in higher demands but using a little better quality electrolytic caps would have save thousands of hours over the years.  A friend restores old German radios from 30's and 40's. Most of the electrolytic caps are still good in them even today after reforming them but the Frakos and small blue Philips caps in Studers are guaranteed to fail...

2) Use of poor quality inductors...  In most of the capstan control boards for Studers, age will disintegrate ferrite core holding "wax" or plastic material, and they go out of adjustment.  The moment one tries to put an adjustment screw on them, they fall apart... and no replacement inductors available.

3) Poor quality double sided boards ... many have found that removing components without fully melting the solder around the pins and leads while pulling on the part will most likely damage the through hole traces.  It is a bigger problem for A80 boards.

4) Use of rechargeable MPU back up batteries... killer for A810s with 100% leaky batteries that will eat into the socket pins and  the acid fume from the batteries dissolving circuit copper traces on the board while looking ok on the surface.

5) Use of switching power supply design for audio sections... this is true even for the top model - A820s.  One of the reasons why external preamps sounding better.

Oh... I am sure there are more but enough for today!

Ki

12
Reel to Reel Tape Machines / Re: Teac A3440
« on: April 21, 2014, 12:06:36 PM »
Sam is one of the last remaining factory trained TEAC techs.

Sam Palermo, BSEE
Skywave Tape Deck Repair- Chicago area
(630)616-0932 Office/ 708-334-2260 Cell, [email protected]
Past Teac/Tascam Lead Service Technician at Chicago Factory Service still doing repairs.
http://www.thumbtack.com/il/bensenvi...tascam-repairs
Need Tape? http://www.splicit.com/index.html

Ki

13
I got the blank doc as well.  Guess it is true - silence can speak volume.

But for our listening to TP music purposes, 25/91 has no impact and the last official Studer firmware release 01/88 (from first week of 1988) for A810 is still good.  As I understand it, the 25/91 has mainly bug fixes for TLS 4000 interface functions that studios use mostly.

Ki

14
Reel to Reel Tape Machines / Re: PLL Capstan Light on A810
« on: March 17, 2014, 12:31:29 PM »
Hi John:

Glad to help. 

If you do find final fix for the loss of PLL, let us know here.

Thanks,
Ki

15
Reel to Reel Tape Machines / Re: PLL Capstan Light on A810
« on: March 02, 2014, 05:06:11 PM »
Sorry for being late to the post.

There are simple problem areas to look for quick fix fist:

One is to look at the capacitive techo sensor output from the capstan motor. Its functions are described in the section 3.5.9 in the manual.

Second is as Doc B had suggested - there are three electrolytic caps (c12 100uF 16VDC, C16 10uF 16VDC, C18 2.2uF 16V) in the capstan control board need to be replaced.  Even the youngest A810s with serial numbers >6000 are still more than 30 years old.

However, most likely reason for losing PLL signal that I had been experiencing was due to failure of L1 and L2 variable inductors in the capstan control board from machines with serial numbers older (smaller) than ~4000s region.

One of the things that are less than Studer-like was to use these cheap variable inductors with very questionable quality.  These old inductors used some plastic like material to hold the ferrite core in place after being tuned to 5.5Mhz +/- 500Khz.  I found most of the ferrite cores to be out of place due to the holding material that had gone soft from age and no longer holds.

Since I hadn't been able to locate these variable inductors, the only solution was to temporarily position the ferrite core to its proper position and fix it with epoxy glue.  As it dries, I have to double check with a digital scope with counter capability to make sure it holds 5.5Mhz signal.

Hope it helps.

Ki

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