Compact Cassette - JVC TD-V661 [A] Recertify
Images of unit A
Japan Victor Cassette Deck Model TD-V661
JVC TD-V661 is a stereo cassette deck with Dolby B/C and HX-Pro noise reduction, it was first sold by JVC in 1993 with a recommended retail price of USD $420.
The main features of the JVC TD-V661 are: 3 heads and off-tape monitoring, digital linear tape counter with 4 digits, automatic tape type selection and capable of handling normal, chrome and metal tapes, dual capstan transport.
Typical front loading cassette deck with the cassette compartment located on the center of the deck. Tape eject is operated mechanically and the cassette needs to be placed with the side to be played facing forward in the cassette well.
Level meters used on the TD-V661 are generic digital peak reading meters. Full-logic transport controls used on the TD-V661 let it respond to the slightest finger contact for fast and effortless transport function selection.
To ensure the best response from the wide variety of tapes available adjustment of, bias and sensitivity, to optimum levels can be performed prior to recording.
Dolby C-type used in the TD-V661 provides 20 dB of noise reduction above about 1,000 Hz, fully doubling the amount given by B-type. The Dolby HX PRO system provides precise bias control during recording to reduce distortion and improve linearity in the high-frequency range, the result is recorded sound that is highly faithful to the original. The 19kHz multiplex pilot slgnal present in FM stereo broadcasts can cause false triggering of the noise reduction system. The switchable MPX filter of the TD-V661 filters out the pilot signal, and assuring proper Dolby processing of FM stereo programs.
For undisturbed listening a jack connector for a pair of stereo headphones is supplied. Connection to other audio components for playback can be achieved by a RCA cable and recording from a source by a RCA cable.
Power Up - Test Operation
Power Up and test play.
These tests are made using scrap tape, and a pre-recorded tape. The deck functions as expected, the tape path looks clean, and the rollers look okay. A short test recording indicates that the machine is functional for recording and reproducing and that the noise reduction systems operate. Looking at the owner’s manual I can see that fundamentally the machine is meeting operational requirements.
Check for Wow and Flutter
For a rough check, I use a 1 kHz -10db test tape. At this stage I am listening by ear for obvious worn belts and pinch rollers. Of course, the condition might have been indicated in the test play step above.
Remove the cover and look for worn belts, hardened grease, and worn rollers in the tape drive. Often a simple application of a tiny bit of rubber cleaner/dressing can allow you to avoid replacing rollers and such. Any lubrication should be very slight.
Please note that these are generalized instructions. This machiene was rebuilt with new belts, pinch roller, and a new motor. In addition, these decks have an inventory of spares remaining, several moptors, a complete set of pinch rollers, new belts. For any antique devices you want to keep running in your system, these level of spare parts is worth considering. In the case of these machines, i cannot find replacement parts today. These machine were rebuilt 4 years ago.
Test Criteria and Certification Standards
The Following criteria will form the topics for re-certification
Criteria
- Mechanical Alignment speed and path and wow and flutter
- Playback Electronics Alignment to standard
- Recording Alignment to Standard
- Required minimum performance specificatio as listed in Equipment User Manual
- Standards Applied which are described in other articles on this website
- The equipment described here is calibrated to the specification [or better] in the user manual
- The Standards used here apply system wide
Standards
— Test Tapes —
Tape types:
Type I – Maxell UD
Type II – TDK SA
Type IV – TDK MA
Head Height Standards Tape [G-2]
250 nwb/m level tape G-3
200 nwb/m level tape G-5
200 nwb 1kHz 0db test tape S-2
12 kHz Azimuth Test Tape G-7
Wow and Flutter / Speed Standards Tape G-4
— Test Hardware —
M300 Jig
T-100 Computer Measurement Software
Behringer UCA-222 Audio Interface [see]
Leader LFM-39-A Wow and Flutter Meter [see]
Hantek DSO 2D15 Digital Staorage Oscilliscope
Leader LMV-181-A Level Meter [see]
Software Spectrum Analyzer [website]
OWON XDM1041 Digital Multimeter
Magnetic Imaging Ink
—
TD-V661 Owner Manual
TD-V661 Service Manual
Mechanical Alignments
Tape Path Alignments
Before beginning recertification, this deck was mechanically rebuilt. Motors were replaced, New Belts were installed, and new pinch rollers were installed. The power supply, and functional components were tested. All the controls were cleaned and the machines were checked for functions such as play stop wind and record.
One should never commit valuable test tapes to a machine that has not been mechanically aligned and tested for operation, and cleaned and demagnetized.
M300 Test Jig
The M300 is a master plane jig used for cassette tape alignment1. It’s designed to establish track height, parallelism (tilt), and head penetration1. The shape of a cassette shell is specified by standards set by the Philips patents, and this jig is designed to ensure the heads and other parts of the deck match this standard
Instructions for the use of the M300 jig are in the service manual for this deck
Some photographs of this jig in deck A are shown below also.
Head Height Standards Tape
There is an adjustment for the head height, and there is a standards tape for that. Putting that standards tape in the machine, adjust the height adjustment screw as shown in the service manual. The tape is shown below.
Unit A = -6db Left, -6db Right
Unit B = -6db Left, -6db Right
That compared to the test tape standard is a good value, and importantly, is equal in both channels indicating that the tracks are centered. This tape has been verified as a system standards tape, no additional track placement test are required
The reference numbers from a Nakamichi are show on the tape from the factory. The tape was tested at the 02:00 minute mark.
This tape has been imaged to confirm the tracking and measured with a visual scale.
This tape is in addition to the M300 Jig adjustments above, or can be in place of that step
Magnetic Tape Path Imaging
It is possible to make a image of the actual tracks recorded on tape. Below is a picture of this track on JVC A deck. See the Test tools segment on magnetic Imaging for the materials and instruction on hw to make these images. If there is any question about the head alignment and track placement on tape, this procedure will provide the neccessary confirmation of the actual track placement. For a clearer image click on the image below.
Wow and Flutter
I will use the standards test tape, and the T-100 software system to check wow and flutter on both machines. See the test equipment article about the T-100 software test system and the Behringer UCA 222 interface.
Also this is the point at which a speed adjustment is usually made. This can be accomplished using a frequency counter with appropriate preamp. On the JVC A and B deck, no speed adjustment is available in the traditional sense. This is because the Capstan motor is a direct drive unit, which drives both capstans in a closed loop with a belt. The Capstan Motor is a frequency servo closed loop and there are no adjustments to the servo.
The wow and flutter measurements in this case are simply a chack. Results outside the specification indicate a mechanical problem that would need to be addressed before continuing.
Note that if you are using a standards tape, the residual w&f on the tape must be considered. Additionally, the cassette shel can have an impact on the readings.
Because of these two considerations, I have used the Leader w&f meter and the record playback method. See the complete user manual in the Test area of this website
JVC Unit A Wow and Flutter
Wow and Flutter Using the Leader LFM-39-A
It is also possible to check wow and flutter using the Leader Wow and Flutter Meter. This method involves recording a standard signal, which is available on the unit, and playing it back to measure the result. This method provides a more universal method because the standard testing tape has a residual w/f recorded on it when it is made.
We have verified that the Leader is accurate based upon testing with Leader supplied Test tones and Calibration instructions. For this reason we will use the Leader LFM-39-A as the system standard . We will use the method of recording the signal out from the Leader and playing it back to measure w&f specification. This can be done in real time on a three headed deck. The displayed figure is math corrected by using the RMS vale of the number.
Below is the result on unit A and B when the Leader is used in the spec in the service manual
Tape Speed
We set tape speed with referance Wow and Flutter Test Tape G-4 [Shown above] and read the frequency with an OWON XDM1041 Digital Multimeter. The tape standard frequency is 3150 hZ and 3149.2 is close enough. There is no actual speed adjustment on this machine, so this is really just a verification. It will be useful when we set speeds on the other machines in the system.
Azimuth
Using a frequency response standards tape, adjust the azimuth screws so that the wave shown on the Oscilloscope line up. Start at the lowest frequency on the tape and proceed upwards. At the very highest frequencies it might be a little unstable, but get the average to fall into the waves
Finally, use an azimuth standards tape to set the final azimuth.
Note: the final azimuth tape you use will become the system standard and all decks should be set to this same azimuth. This may be a problem and careful attention needs to be paid to select the actual standards tape. very few machines have an easily adjustable azimuth setting and all tapes could be different if no standard is set, or if different standards were used.
Fortunately this issue is not as serious as one might first expect, variations of azimuth result in some losses at high frequency, but of course this is a vintage analog format anyway so that is not the end of the world. [Read about analog versus digital on this website]
Below are two example tapes.
System Standards Azimuth for Cassette Tape
We have found a System Standards Azimuth Tape. In order to verify the azimuth on this machine, we used a standalone Oscilloscope, Hantek DSO 2 D 15 and lined up the traces . This azimuth setting will be used system wide. Below is the images of the tape and the scope trace. The Azimuth adjustment screw is indicated in the Service Manual.
The Electronic Performance and Alignment
Playback Alignment to Standard
Playback Frequency Response / Equalization
The first alignment that must be performed is that of playback equalization. This is required because all subsequent adjustment are based upon the playback being set correctly.
Playback equalization can only be set by using a known standards test tape. Using this tape and electronic spectrum analysis software we can assure that the subsequent adjustments are made based upon a correct playback system.
The Service Manual indicates where these adjustment are.
We have obtained the TEAC Multi-Frequency tape MTT-117 SP which contains 40, 315, 3.15k and 14k signals recorded in a single tone. Using a spectrum analyzer, we can set the playback equalization for a flat response by looking at the spectrum of this tape played back. The TEAC MTT-117SP cassette test tape is a system standard for all cassette playback equalization.
Below is the left and right channel spectrum. We used a Software spectrum analyzer and the Behringer UCA 222 along with our mil spec laptop. The computer laptop we used is described in the computers section of this website.Together, the UCA-222 and the Spectrum Analyzer software and the Lenovo Carbon x1 Laptop are a system standard.
The figures below show the connections and graph
Playback Level
Playback level setting is the basis for the setting of the recording level and that in turn sets the distortion at maximum recording level.
Playback level is set by using a standard level tape. In the case of this deck, and of all decks in the system, we have decided that 200 nwb/m magnetic flux = -2db on these machines. This is perhaps an arbitrary setting to some degree. The service manual for this deck wants to use a particular tape from JVC and they want to set that tape at -7.5 dBs. The consensus is that that tape is a 160 nwb/m tape and using our 200 nmb/m tape will be the same level.
We will use the Leader VTVM to set that level using the same setup as shown in the service manual.
The Leader LMV-181A, and the 200 nwb tape G-5 are system standards.
Recording Alignment to Standard
Calibration Adjustment
On this machine the next adjustment is the caibration settings. This is done by putting a type I tape in the machine with the calibration, level and bias, set at zero. Then the calibrate mode is run and the internal adjustment pots are use to set the VU meters to the index marks. There is no special equipment needed for this step.
In my opinion, the Bias and Level Calibration need to be RECHECKED after any change is made to recording Gain or BIAS setting. I think this is a msitake in the Service Manual… It is not impossible to find errors in service manuals.
Bias Adjustment
Bias adjustment is most easily accomplished using a white noise signal and spectrum analyzer. We used the software analyzer and the UCA 222. Simply tune the bias control for the flatest response. This is best done at -20db signal level. Below is the spectrum ..
Note that this Bias adjustment was used because it has the flatest response. It is possible to decrease Bias somewhat and elevate the high frequency end of the response curve, but this is done at the cost of linearity and increase of harmonic distortion. Also note that the curve was recorded at a low level. Higher recording level will saturate the tape and cause increasingly lower high frequency response.
For this set of machines and calibrations Standard Tape is \
Type I – Maxell UD
Type II – TDK SA
Type IV – TDK MA
Recording Level
Recording Level adjustment is used to place the recording levels equal to playback levels. On this deck just put in record mode, and flip between source and tape monitor. Tune the recording level so that there is no change or equal level between source and tape. We used the Level Meter to verify this setting for both Type II and Type I tape standards.
If you changed the Recording Level, It seems like you should go back and check the Calibration Settings at this point.
That's it so bolt the cover back on
That’s it so bolt the cover back on, and try to record something and musically verify the tuning. and of course there’s always ….
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Okay - Here's a Bad Video of this playback
Revisions
This is REV 1 – Original Article compiled over the course of actually doing the recert.
This is REV 2 – Changed some colors added some quotes for attention
This is REV 3 – Added video and fixed end menu and links
Conclusions
Concluding comments
1. There are two TD-V661’s in the system -Unit A and Unit B – The test results and illustrations are similar for both units.
2. This page was done engineering notebook style – Someday in the future it might be added to and typed up
3. See our list of req test equipment for detail on the gear used
4. Take a look at some of our other re-certifications
Here’s a summary
- Recertification Process: The page details the recertification steps for the JVC TD-V661 cassette deck, including power up tests, recording and playback functionality, and noise reduction system checks.
- Technical Checks: It describes technical procedures such as checking for wow and flutter using a 1 kHz test tape, inspecting the tape drive for worn belts and rollers, and applying rubber cleaner/dressing.
- Alignment Adjustments: The page outlines adjustments for head height and azimuth using a standards tape and an oscilloscope, ensuring tracks are centered and equal in both channels.
- Final Steps: It concludes with setting the playback level using a VTVM and a standard level tape, and emphasizes the importance of keeping test tapes and gear handy for future adjustments.
The page adopts an engineering notebook style and includes references to the TD-V661 Owner and Service Manuals. It also mentions that there are two units, Unit A and Unit B, and provides test results for both1. The page is part of a larger site focused on audio equipment testing and recertification.
okay – this is an example page – the menu will update automatically when they are edited – no need to come back into the page. This is REV 3 and it is final i think
Carl Valle 2024 06 19
Testing the Record/Repro performance right now. Recording on Metal tape there is no difference between tape and source recording form the T-4140 tuner. Amazing performance actually, for cassette.