Messages

1

Reel to Reel Tape Machines / Annis Han-D-Mag: The only choice?

« on: May 09, 2009, 09:40:41 AM »

Hello all,

I am finally close to putting together a full set of tools for proper setup and use of my open reel machines.
I already have a very good Tek scope and have recently purchased an MRL test tape and some proper splicing tape, new empty reels, leader tape, etc. The only thing that I'm now missing is a demagnetizer. I see lots of praise for the Han-D-Mag, but as someone who recently became un-employed I am having a hard to justifying the high $70 cost. Are there no old school units like the Realistic unit or the old Teac E-3 that will work properly? I don't want to damage anything or make it worse but I am really having trouble with parting with my cash for the Han-D-Mag. Any thoughts?

Andrew
 

2

Tape Tech / Re: Studer A-80/RC recording issue?

« on: April 28, 2009, 03:25:13 PM »

Thanks for your responses so far everyone!

Reelnut, I checked the erase head surface and it looks very smooth, so I doubt it's the problem.

Here are my findings:

 I started with the "Stabilizer" card. This essentially is the regulated power supply for the all of the audio and oscillator electronics. 16V AC windings from the power transformer are then regulated into +/- 12V supplies with the required stiffness.
I checked the output voltages of this card and found them to be very close to spec. (+11.8V and -11.6V) I used the provided adjustment pots to make both of these exactly 12.0V and watched the levels closely for 30mins for any changes. There were none. Next I measured AC ripply voltage on both the +12V and -12V supplies and found it to be very low at about 8mV. Just to double check I attached a scope to the supplies and looked for ripple and could see nothing within the noise.
So far so good.
Next I looked at the bias oscillator and attached a frequency counter. The 149kHz measured was within spec of the 150kHz target.
I then attached a scope to look at the bias signal and found a clean sine wave with some small ripples at the peaks and valleys of the sine wave. I don't know if this is normal or not but it does not look like it was noise pickup from the measurement setup. This measurement was done with no input signal to the deck.
Next up was a look at the record amplifiers.
I stared by looking at the record bias points on these cards and found a slightly "noisier" version of the sine signal I found from the erase bias test point on the oscillator card. Some small ripples could be seen on the sloped sections of the sine wave, but in this case it might have been noise pickup from the test leads which run close to the oscillator card itself.
Then I applied some music signal to the inputs of the deck and observed the "pulsing" of the bias waveform as the AF signal was now mixing with the bias signal.
Finally I disconnected the relay output points on both channels, this effectively removes any AF from reaching the record head. Now with only the bias signal reacing the tape I recorded and played back a few minutes of tape. Once again the very low level burbling could be heard if I increased the output level of my system slightly and put my ear to the woofers.
Again I am wondering if this is normal but knowing the pedigree of this deck and the Studer engineers I highly doubt it.
I guess my next step should be to try replacing all of those 30+ year old electrolytic caps on all of the audio and oscillator cards. There's also a pile of tantalums on these boards that should probably go too.
Maybe that's the problem?
 
Andrew

3

Tape Tech / Re: Studer A-80/RC recording issue?

« on: April 26, 2009, 10:41:30 AM »

Thank you ironbut and Ki for your responses.
I'll try to answer all of your questions in order.
The first test I performed was trying the same "record silence" test at 15ips.
The rumbling sound is identical in level and pitch, suggesting that this is record section issue and not a mechanical issue.
I think the repro section is not the problem as there is no rumbling noise when I play back a fresh section of blank tape.
Could this also suggest that a demag will not help? It seems that the rumbling is being recorded onto the tape.
The only reason I though it might be oscillator or power supply related is that the same type of rumbling can be heard in both channels. It seems unlikely that the same problem would manifest itself in both record amplifiers, but I guess it's possible.
My next step will be to measure the record bias current on both channels to see if it's stable.
I can also check the oscillator frequency it make sure that it is also stable.
I'll report my findings once I have completed the measurements.
Ki, I can't remember exactly how many hours are on my machine, but I think it was somewhere around 5000.

Andrew

4

Tape Tech / Studer A-80/RC recording issue?

« on: April 25, 2009, 11:23:28 AM »

Hello everyone,

A few years ago I was lucky enough to pick up a 1/4" Studer A-80/RC in nice shape for a song.
It had a problem with the capstan servo which made it look like the capstan motor was dead.
A few days of diagnosis and a $0.60 IC later it was working very nicely.
I have only used this deck for playback but recently decided to try making some recordings.
Unfortunately the first recording test showed nothing going on the tape on one channel.
I traced this to a bad relay on one of the record amplifiers which I have just replaced.
Now I get recorded signal on both channels and it sounds very good even though I have not calibrated it yet as I am waiting for a test tape to arrive.
In order to quickly assess recorder frequency response I recorded a CD with sine frequencies at steps from 20-20,000 Hz.
On playback of this tape I noticed a couple of things which may or may not be normal.
At high frequencies, above 8kHz or so, there is noticeable fluctuation on the VU meter of one channel only.
I guess a good check for this would be to swap the record amplifiers and see if the condition moves with the amplifier.
Also, I noticed some low level rumbling, popping, or crackling (though crackling seems to suggest high frequencies!) when I come close to the speakers. As a further test I played back a blank tape and the output was completely clean with only a little hiss present. I then recorded with no signal to the input of the deck and this VERY low level low frequency rumbling could again be heard in both channels. Could this have somehting to do with the bias oscillator or is it normal?
Or could it suggest the deck requires demagnetizing?
I am not sure I could detect it on musical program but I am wondering if there is anything in the system I should look at.
Thanks for any advice!

Andrew

5

General Discussion / Re: Group Buy of Multi-format Alignment Tape?

« on: April 15, 2009, 01:43:59 PM »

I'd be interested, depending on the price.
MRL has some 2-speed cal tapes, but they are either NAB OR IEC and they are only 2 tones each, 1kHz and 10kHz, IIRC.
That of course would be of no use to correctly set repro EQ.
Thanks for offering to look into this!

Andrew

6

Tape Tech / Re: How to remove RS-1500/1506 Control "marker" rings?

« on: April 13, 2009, 07:28:17 PM »

Lovely...why didn't they just use another set screw for this???
Oh well...I'll clean it up as best as I can.
Thanks!

Andrew

7

Tape Tech / Re: Technics 1500 Schematic wanted

« on: April 13, 2009, 07:27:18 PM »

Hi Andrew, unfortunately there is about 120 pages to the service manual but if there's a particular item you want, I'd be happy to email it to you.
BTW welcome to the forum.

Thanks for the welcome Steve!
I'm specifically interested on the playback and record electronics setup.
I have a PDF copy of the RS-1700 service manual, but of course it refers to the RS-1500 service manual for making these adjustements!
Can you believe purchasing the RS-1700 service manual and finding out that you now need to buy another one to actually work on your deck!?

Andrew

8

Tape Tech / How to remove RS-1500/1506 Control "marker" rings?

« on: April 13, 2009, 04:16:40 PM »

Hi everyone,

I'm in the process of refurbing my RS-1506.
In order to really clean everything properly I would like to remove the bottom faceplate.
To do this the knobs from the controls and the switch caps need to be removed.
Easy so far, but there are "marker" rings under a couple of the pots, these are used to mark a reference setting or position for the control pots. The knobs themselves are held on with allen or hex screws, but I can't see how to remove these "marker" rings.
Any suggestions are appreciated!

Andrew

9

Tape Tech / Confused about alignment tapes!

« on: April 13, 2009, 03:31:25 PM »

Hi everyone,

I'm hoping some of our knowledgeble members can help me out.
I have a Studer A-80/RC 1/4" stereo deck which is used predominantly for playback of old RCA 2-track pre-recorded tapes.
I also use it for the occasional live FM broadcast taping.
I also have a Technics RS-1506 used for 1/4 track tape playback.
In the past I have had the machines aligned by a friend, but I have a full measurement setup and would like to do this job myself.
I don't have a demagnetizer yet (I know, I know) and I want to purchase an MRL test tape to setup these 2 decks.
On the A-80 I usually record on Quantegy 456.
Which reference fluxivity should I go for from MRL?
Also, and this might sound like a really stupid question, can the MRL tapes be used to setup either 2-track or 4-track configurations?
Obviously I would like to align the head for both 2 and 4 track playback on the RS-1506.
Your input is appreciated!
Thank you,

Andrew

10

Tape Tech / Re: Technics 1500 Schematic wanted

« on: April 13, 2009, 03:17:46 PM »

Here ya go Charles. Let me know if you need anymore of the page. One of these days, I'll probably scan all the schematics and post the links. I think the prices some of the manual guys charge for the 2 service manuals is nuts.http://www.mediafire.com/imageview.php?quickkey=agchcwns12z&thumb=4

Hi Ironbut,

I would LOVE to have a copy of the 1500/1506 Service Manual if you get it scanned.
Thanks!

Andrew