PL7000S2

[George S.]

Got the Sendust head installed. Penetration, zenith, height, and guide alignment look good.
The Sendust head has a tape guide the Ferric didn't have.
Going to see if I can allow it to remain rather than disturb the retaining screw and green adhesive.
Only external adjustments on this transport are the head azimuth and supply side guide.

 

[George S.]

Success. Finally able to set Azimuth.
No way the old head was capable of this.
Going to try to align this deck with no component value changes on the boards.
Later.
Listening to King Weed......Smoke Over Doom.

 

[George S.]

Fired up the Han-D-Mag and bulk erased the four cassette types the recording section will be calibrated to.
The tapes vibrate violently within the shell, it's a beast,
The flat bottom is configured for bulk erasing.
Also comes in a 220 VAC version.

 

[George S.]

Progress.
Running through the playback alignment a second time for precision.
Fine tuning the tape path using magnification and scope.
I really prefer adjusting azimuth using superimposed sine waves on the digital scope.
Very easy to observe phase as the waves invert during adjustment. VERY apparent when the channels are in phase, easy to be fooled when they're not.
Ran a frequency response test of the Playback EQ circuit using the QA403 and HPR frequency burst tape.
It's down appx 2 dBV at 10 kHz from were the service manual wants it.
Thinking I might gain that with fine tuning the tape path. I did flip the tape and retest. Spot on, been very impressed with the HPR tapes.

 

[derek92994]

Sure Enjoyed reading this thread. Amazing effort to the finest detail, I'm impressed George.
The mechanism looks tough, and the electronics just plain scary Gotta dig those Nichicon Fine Gold Caps.
I think Sendust type heads are said to be one of the longest lasting.

 

[laatsch55]

Second that. I think seeing the progress on a day to day basis we don't appreciate the effort and tenacity associated with this project. George, I'm fuckin impressed. The amount of research done on your own is a testament to your commitment....excellent example of how to eat an elephant...

 

[George S.]

Playback is aligned a second time.
Testing the Dolby alignment with the HPR Dolby Level tape by measuring directly at the chips soldered in test leads.
The PL manual uses two alignment steps to calibrate the Dolby Board accurately. No tape.
Going to get away from this for awhile, road trip time.
Need to learn more about tape levels.

 

[George S.]

Got the playback levels spot on and verified with the Dolby Level tape.
Measuring voltage directly at the chips worked really well.
The Playback EQ is slightly off spec due to the head swap, I'll look at that again later.
Lots of trial and error so far, here's a few things I've found about the HPR tapes.
1. They are 250 nWb/m, except for the Dolby Level tape, it's 200 nWb/m ANSI=218 nWb/m DIN.
2. They are all 70 us, CrO2 setting.
So how to use these on a deck with a Magnetic Reference Voltage of 160 nWb/m?
The HPR tapes are going to generate higher voltage at the test points proportionate to their higher level.
250/160=1.56
218/160=1.36
These are the conversion factors.
Depending on what tape we're using, multiply the test points spec by the conversion factor.
Now aligning the bias traps and getting into the record alignment.

 

[George S.]

Transport developed a issue with right reel lagging and sometimes stopping.
Cracks in the black hex drivers that engage the tape reels, the shaft spins inside the driver.
I'll glue these to the shaft for now, and look for some replacement pieces.

 

[George S.]

Units are glued up. The hex driver body and cap are glued on the shaft, the spring loaded driver slides freely.
Wish I'd caught the cracks earlier.
The adhesive I'd added earlier to the drums and pulleys looks good.
Maybe someday it'll be easy to replicate the parts.

 

[J!m]

3D scan and 3D print.

Thw future is today.

 

[Gepetto]

Transport developed a issue with right reel lagging and sometimes stopping.
Cracks in the black hex drivers that engage the tape reels, the shaft spins inside the driver.
I'll glue these to the shaft for now, and look for some replacement pieces.

If I knew the dimensions, I could likely 3D print them for you George...

 

[George S.]

Thanks guys. That's something I'll pursue in the future.

 

[Gepetto]

Thanks guys. That's something I'll pursue in the future.

As they say George, Oh Well...

 

[George S.]

I've been looking for another complete set of original transport plastics to use for replication.
The reels drive pulley and clutch, drums, pulleys, hex drive, etc.
I've seen a few transports pop up for sale occasionally. Once I get another, I'll pursue this.
I really need a working unit and learn more about it first.
Will be easy enough to cut those "glue ons" off or they may well just pop off with moderate force.
Step by step, no rush.
Thanks for offering!

 

[George S.]

The tape counters opto sensor is corrupted by the bench lights.
Spent 2 hours chasing unstable voltage to the DC motor, narrowed it to the sensor and rotating vanes.
Shielded it with a piece of paper, got stable motor voltage.
Rock solid voltage at the DC motor and a better operating transport.
Now this thing hauls ass rewinding tapes.

 

[Chris Cables]

Playing the HPR test tapes into the QA-403 to actually see what's on them.
This is working excellent.
It's all rather confusing with the different levels and tapes, but I'm starting to get a handle on it.
I did print out English translations of the German language stickers on the tapes.
Supposedly everything I need is on the six tapes.
I just need to find it and make a note of where it's at from the tape counter.
I also now have the 4 blank tapes I'll calibrate the record portion of the deck to.
TDK D, TDK SA, Sony Duad, TDK MA-X. They're all used, I'll erase them. Should work fine.

Great thread George!

Those HPR tapes are amazing quality for what you actually pay for them! The quality of his previous batches were a bit questionable apparently, but now they're spot on. I'm considering ordering another set for redundancy.



I also need to get some torque tapes in the arsenal at some point. I missed out winning a bunch of about 20 various Sony test tapes not long ago. Lots of types, torque values etc. Looks like they went for €350. I prob would have paid more.



Nikolai Antsanov 'Nick Bohelco' (?) on TH also made a batch of amazing mirror cassetes. I bought a couple from him back around easter this year. They have been indispensible for tracing back an issue on an old Yamaha deck (bent tape guide).

 

[George S.]

So I'm finding some transport issues.
Pulled the opto sensor off the board, cleaned the lenses, reinstalled. Appears fixed.
Having a additional issue with one blank test tape type, TDK SA 90.
The take-up reel clutch is occasionally slipping on this one type. The cassettes appear good with no binding.
I never stretched the clutch springs or changed the felts.
Going to disassemble the transport and look at the felt and spring. Most likely just needs a little stretch for more spring tension.
Supply side clutch appears to operate properly.

 

[George S.]

Great thread George!

Those HPR tapes are amazing quality for what you actually pay for them! The quality of his previous batches were a bit questionable apparently, but now they're spot on. I'm considering ordering another set for redundancy.
View attachment 83963
View attachment 83964

I also need to get some torque tapes in the arsenal at some point. I missed out winning a bunch of about 20 various Sony test tapes not long ago. Lots of types, torque values etc. Looks like they went for €350. I prob would have paid more.
View attachment 83965
View attachment 83966

Nikolai Antsanov 'Nick Bohelco' (?) on TH also made a batch of amazing mirror cassetes. I bought a couple from him back around easter this year. They have been indispensible for tracing back an issue on an old Yamaha deck (bent tape guide).
View attachment 83967
View attachment 83968

Yeah, I copied Nick's work, a excellent design.

 

[Chris Cables]

So I'm finding some transport issues.
Pulled the opto sensor off the board, cleaned the lenses, reinstalled. Appears fixed.
Having a additional issue with one blank test tape type, TDK SA 90.
The take-up reel clutch is occasionally slipping on this one type. The cassettes appear good with no binding.
I never stretched the clutch springs or changed the felts.
Going to disassemble the transport and look at the felt and spring. Most likely just needs a little stretch for more spring tension.
Supply side clutch appears to operate properly.

Sounds like you need some torque tapes in your toolbox too!
>.<