Hi Fivos,

Thanks for your comments!

Indeed, what the Arduino is doing is rather simple: it cheats the machine into thinking it is always threaded (end thread switch). Once you have this signal under Arduino's control, you can operate the loading motor for a defined amount of time (you can fix it by software or make it externally adjustable with a tiny mod).

The amount of unthread is critical because if you apply too much, you lose track of the begin tape sensor. This is dangerous as you can miss the begin section and break/stretch a tape.

I think that altering the syscon code is a major challenge. These ICs used to be mask ROM so they can't be changed. One funny approach would be swapping the whole IC with a custom programmed one :-)

The SL-C20 shown on YouTube was not really bad in terms of drum wear but at the time of recording it was the only available one I had at home. Badly worn ones would benefit most from this experiment.

I am thinking in a new mod. Not sure it will work but if I succeed I will also make it public in this forum.

Greetings,

Gabriel

Gabriel

That's very interesting. I have a Sanyo VTC 5350 (PAL+SECAM 5300) which doesn't have picture search like the 5400. Is it possible to create a similar mod that would enable picture search when pressing the FF and REW buttons during PLAY mode instead of going into full FF/REW like the 5400 does? It has an LM6402A IC on the syscon board.

Fivos

Hi Fivos,

If I have correctly understood: you suggest adding picture search (CUE/REV) to a machine not previously having it from factory.

I am not an expert on that series of Sanyos but it seems to be quite tricky because of the following facts:

-These additional functions are some "intermediate" speeds between normal playback and FFWD/REW. The challenge is entering the machine into a new state with a given mechanical arrangement.

-The arrangement for REV/CUE is being laced, pinch roller applied to tape. Capstan should run to a defined speed (both forward and reverse!) and the servo should lock to that condition. So at least the servo IC (and its reference signals) have to be involved.

-Reel operation has to be readjusted, but this would be the easiest point (slippage "clutch" of the take up spool allows some tolerance).

-Muting circuits should also be revised as the machine by default mutes audio and video when FFWD/REW (I've done funny experiments in the past playing with Sonys muting signals).

There might be more factors constraining this modification so I don't see it feasible given a reasonable budget of time and effort.

Greetings,

Gabriel

Gabriel,

Yes. I was talking about adding that feature to a machine that doesn't have it. My VTC 5350 keeps the tape always laced, even during fast forward and rewind. So I guess it's only a matter of speeding up the capstan and reel motors and muting the audio to enter the CUE mode. Strangely enough, the schematics for the VTC 5300 clearly mention the CUE and REV functions in the syscon board schematic. There are a few missing connectors on the board however there are still markings for them (S13, S14 and S15). So I guess the same board was used in the 5400 with just the additional connectors for the additional CUE/REV and audio dubbing functions? Have a look at the pictures.

https://ibb.co/QPrBKgD

https://ibb.co/4JqDmpt

https://ibb.co/r5LFBNr

Fivos

Hi Fivos,

That's a good insight. However, I don't get the whole picture with only one picture of the schematics (if you have the complete manual, feel free to send it to me). Anyway, a first approach would be:

-We will ignore any drum speed change (and we shouldn't!) so there is a high chance that the result is going to be a jumpy out-of-sync image.

-How is reacting this machine when you press FWD/REW while you keep pressed Play? This behavior is important.

-We need to see if pushing the buttons create a High or Low level to the uC.

-The Arduino would be in charge of:

*Suppress the FWD/REW signals towards the uC unless a genuine "only" FWD/REW condition is met (machine will operate normally)

*Detect a combination of Play+FWD or Play+REW (logical --> Play AND Fwd OR Play AND Rew)

*Make the capstan rotate quicker and this is not easy as the capstan is servo locked. Instead of applying brute force (directly applying more bias/voltage to its analog control signal) we can take advantage of the servo itself by modifying the CTL signal to be at a lower frequency. This should be done at the point where it has been previously amplified (TTL compatible wave). A single divide-by-four or similar has to be implemented on this signal. We don't already know the catching range of the capstan servo, so this might work or not (because if an out-of-range output/clipping signal is detected, the machine will tend to shut down).

*Check for a complementary unused "Reverse" signal in your capstan. Probably it is there, forced to a fixed logical level high or low as that model (in theory) only rotates the capstan in one direction, unless it is used for an extra function (drive the reel via belt?).

*Apply slightly more torque to the reel motor (if existing). We might implement this with some hybrid analog arrangement. I recall the torque modification on the VTC5000 with a diode so we should follow a similar strategy.

*Audio muting signal has to be observed, if active high or low. We also have to manipulate this signal the same as the FWD/REW so we might need external pullup/pulldown resistors and a dedicated I/O from the Arduino.

It is an interesting beautiful project but I would strongly advise not to modify things unless you know what you are touching. Chances of short circuits, overloads and magic smoke increase as we modify stuff.

The only thing I can remotely do for you is writing some code. But bear in mind this is a looong iteration hit-and-miss cycle.

Greetings,

Gabriel

Hi all,

Has anyone got the white plastic rewind idler arm for a Sony C7 for sale please?

Regards

Rich.

Rich,

I could send you one but it would cost a bit in postage from Australia and it would not get there quickly in the current circumstances.

regards Noel

Hello Guys,

Hope everybody is going well with the though time we have…

I used my lockdown time to record the hold Betamax tape I have.

I have a Betamax SL-F1F coupled with a TT-F1F.

The video was quite noisy almost at the same position for all tapes, so I decided to try to clean the video heads.

Unfortunatly, since this operation there is no more video at the output of the SL-F1F.

The sound is playing with no problem, but the screen remains black.

Do you have an idea of where the issue could come from ?

Do I have broken the heads ?

Can we found a repair center or some replacement part for this kind of material.

Thanks for your support and so detailed website.

May I have seen it before….

Olivier

Olivier,

The sort of tape issue you indicated originally is sometimes due to corrosion or contamination on one part of the head drum assembly causing the tape to lift a little away from the heads at that point decreasing the magnetic coupling causing drop-outs.

Yes you have probably damaged the heads. Try the play then pause function to see if you get any picture. A dirty ACE assembly causing loss of the tracking pulse can cause loss of picture but it still comes up using pause function.

If you have damaged the heads it should be observed by inspecting the heads with a magnifying glass to see they are broken.

Video head cleaning is a delicate art. Yes - getting replacement heads is difficult if not unlikely as the machines are nearly 40 years old.

regards Noel

Dear Palsite friends,

Just wanted to share with you all a new development based on Arduino. This time, a remaining tape indicator (as the one found on the SL-C9 ) is implemented on an LCD display.

Testing machine is again my SL-C20, with slight modifications for this purpose.

Here's a link of a video I recorded today:

https://youtu.be/iFgD-W-IKwU

I hope you like it.

Greetings,

Gabriel

Gabriel.

Nice work. I just received a couple of Arduinos from eBay to learn with. (About time - all the stuff I build is hardware based logic.)

cheers Noel

It's been a while since my last post. My SL-HF100 was only working in black and white. Eventually I sourced another donor machine and swapped the problem board over, colour restored!

It now leaves me with a couple of spares machines 2 Hf100s and a C20. I've been seeing if I can make another running machine.

The C20 has given up the cassette carriage, loading gear and drum motor.

I've got an HF100 running quite well, colour picture and HiFi audio working OK, however the edge track audio is really quiet on its own recordings. Recordings made on other machines play back loud and clear.

Is it likely to be the head or is the audio recording level adjustable?

Thanks

Clive:

Congrats on getting your HF100 back to perfect.

They can pose tricky at times with various problems they throw up after time.

AS for the Low mono edge sound. That too is common and the mono sound on these was never that great (maybe comparing to the beta Hi-Fi makes it worse).

It could be the stationary audio head but on a few later Sanyo's issues there with recording was down to the controlling IC.

I believe it is adjustable on the Hf100 (it's on the very top board under a sliver can.It could also be that head azimuth is slightly out too. Be careful though as moving that will put out the tracking alignment a bit.

Clean that head too, to be sure it's not dirt contaminated.

I have a HF100 here in near perfect shape bar one area on the servo board affecting the reel spool torque.

It speeds up when the machine get's warm and if you turn down the torque ,when using from cold it won't turn at all.

You don't have a spare good servo (SS) board for that model do you?

Cheers...................Kevin

Clive (and Kevin)

After head clean rules out dirty heads there are other things to consider.

1/ The azimuth would not be the issue here because it does not affect a machine recording and playing back to itself - just the use of tapes from other machines which you said was good - though it does affect the higher frequency level/response more.

2/ The first thing that is an issue on all SLHF100 and later front loader machines is loss of back tension spring tension. Typically they can drop back to below 30gm when the factory setting is 35gm. I mostly find that breaking the green glue seal and moving the spring to its most rearward step on the saw tooth lever of the black back tension arm (which you view through a hole) gives you back the correct setting, Be careful not to let go of the spring or you will hve to pull out the reel assembly to put it back. Use nail polish to fix it in place at the new position. A back tension test tape is useful but most people don't have them

3/ Record bias level issues. This is not common but the transformer can fail. If total failure happens then you also lose erase of the previous recordings which you would notice for both picture and sound.

A lower level bias will affect the quality and level of recorded audio from this machine. If the record level settings on this machine have been fiddled with that might also be your issue.

A service manual alignment would be the only way to be sure.

4/ Usually it is go/no-go issue but check the tracks on the AV connectors on the base board to ensure they have not been damaged. The board often breaks there because people lift the front of the machine while connectors are still poking out at the back.

Kevin - Re that problem with the reel motor pickup torque - I have never noticed that happening on any SLHF100s I have repaired. The OP amps on the board can have contamination affecting their inputs from leaking capacitors which I have seen as an issue on SLC9s and I have seen that affect the pulse width circuitry.

regards Noel

Noel

Where or board are the failing op amps on the C9 ? ?

Webber,

The SONY SLC9 capacitor leakage issue/corrosion issue was at/under IC001 and IC004 on the SS11 board.

regards Noel

Noel

What is the type of failure that occurs?

What symptoms?

Hi Noel:

Thanks for the detailed info as always.

I should've mentioned the back tension too (as I usually do) and had a feeling the azimuth wouldn't be the culprit there but worth mentioning all the same.

As for that Reel drive torque issue. You state you've never seen that well I have two issues here on different HF100 servo boards. One with the one I mentioned previously and the other the reel spools don't turn at all. So no doubt a similar condition. The rest of the machine ahs been checked with a good board and all works fine.

I have checked and changed many components /transistors, e.t.c to no avail.

It's been one of those issues that n matter what it does'nt want to reveal itself after many frustrating hours. (Thankfully that doesn't occur too often eh!)

I do now have access to another good board and will be glad to see this one returned to the recipient in 100% order :)

I appreciate, as always, the input from you though.

.......Kevin

Weber,

The SS11 board IC001 and IC004 ICs are 8 pin containing twin two input OP amps used to buffer the Fg control pulses for the reel motors which as you know are DC controlled in the SLC9 model.

So when they have issues loss of proper pickup or back tension reel control results.

regards Noel

Kevin,

Your email prompted me to remember that the reel motors on the front load Sonys can all suffer the sort of problems documented on the SLHF950 chassis repair information.

The spindle pivot for the magnetic shaft wears and the magnet eventually closes the gap to the winding and then runs the insulation off and spreads copper between adjacent winding shorting out the particular coil.

You mentioned that you think its the control board but that might only be the symptom caused by the increased motor drive current requirements.

Back to what you said - It speeds up when it gets warm - but that does not happen with the above condition. The capstan motor keeps the speed constant so you should only be noticing and increase in forward tension, not the machine speeding up.

I spent hours fixing such a fault once and it was due to a leaking transistor which tested OK but failed intermittently in operation due to heat related excessive Icbe current.

Use some coolant spray on the transistors in that part of the control circuit to track down which one if that is what the cause is.

BUT REALLY - neither explains exactly why reduction in forward tension (a reel function) allows the speed of the capstan to reduce. Are you sure the capstan roller is holding the tape hard against the capstan shaft?

SOME FOOD FOR THOUGHT!

regards Noel