I created and etched a circuit board from the old “Phaser 80” schematic.
It works with an old TCA350 BBD chip.
The schematic indicated a very rare VL01 BBD (10-pin chip), which is very similar to the TCA350Z / TCA350Y, only the pin orientation is completely different!
It’s not working properly at the moment!
I only now noticed that the A109D operational amplifiers (similar to the µA709) are not supplied with voltage.
When I created my board according to the schematic, I initially thought that all connections were fully indicated in the schematic, but that doesn’t seem to be the case at all!
In the data sheet of the A109D it says that pin 11 is plus and pin 6 is the negative connection, which is not yet connected to me.
Question 1: (The most important question)
The phaser generally works with +24V and +12V! Should I supply the negative connection of the A109D Bi-polar Operational Amplifier (µA709) with negative voltage or can I also connect it to ground for testing without causing any damage?
I’m totally confused, in the PDF of the Phaser 80 wiring diagram, I don’t see anywhere that a negative voltage is generated/drawn anywhere!
Question 2:
I think the TCA350 doesn’t need an additional plus power supply, right?
There is another question in the pictures! I hope there is someone who is a bit bored, has time and can help!
Hope it’s understandable what I want
Here are links to the sound plans for the Phaser 80 and Formation 1 if anyone is interested!
Vermona Phaser 80 wiring diagram:
tl;dr: Probably connect A109D pin 11 to +24 V and pin 6 to ground, TCA350Z pin 4 to +24 V and pin 7 to ground. Test on a breadboard.
I believe IS1 and IS2 constitute an oscillator, with IS1 wired as a comparator and IS2 as an inverting amplifier. Since the latter is inverting its output will be “negative”, by which I mean on the opposite side of whatever voltage is acting as ground. In this case that’s the +12 V rail. So a “positive” signal is +12–24 V and a “negative” signal is +12–0 V. Since the op amp has to take inputs in both ranges (from the comparator) and produce outputs in both ranges, that means the op amp has to have +24 V and 0 V on its supply pins. So pin 11 connects to +24 V and pin 6 to ground. The datasheet says (I think, I don’t read German) maximum voltage is +18 V and minimum is -18 V, but that really means the maximum difference is 36 V, so 0 V and 24 V should be fine.
There’s a datasheet for the TCA350Y on page 170 of this http://www.introni.it/pdf/ITT%20-%20Integrated%20Circuits%20for%20Consumer%20Applications%201977_1978.pdf , I don’t know how it compares to the TCA350Z, looks like they have the same pinout. Pin 7 is VDD (they show -22 V and recommend -20 to -24 V) and pin 4 is ground. In your case “ground” becomes +24 V and VDD then is 0 V (the circuit’s ground), which is more or less what’s shown — I don’t know why pin 4 has a resistor between it and the power rail. I can only assume the VL01 took the same voltages, I can’t find any information about it. Anyway, it’s clear the Phaser 80 and Formation 1 circuits are close enough to identical so the TCA350Z connections in the latter should be what you need.
BUT: I think the above is right, but… I strongly recommend testing this circuit on a breadboad, or at least relevant sections of it, rather than trying to go directly to PCB.
… Is it true that the A109D has a maximum operating voltage of +18v, which also prevented me from connecting it to the +24v rail, but thanks to your insightful, good explanation, I now dare to connect it to 24v, as well as the connection from pin I will connect 6 (negative connection) to ground!
I couldn’t find any information about the old “VL01” on the Internet, even in the Internet archive!
Yes, the TCA350 Z AND Y have the same pin. Inside the Z there is one more transistor working compared to the Y, as far as I have observed. Surely Z came out later and got a little update.
I’ll try it like you said on my board, at my own risk!
I think I’m too lazy and too impatient to build everything on the breadboard again in order to test it.
But I’ll be careful. I have duplicates of all the semiconductors!
Thank you very much Analog Output for taking your time and thinking!!!
Yeah, keep in mind there are no absolute voltages. Voltage values are always relative to other voltages, it’s the difference that matters. When you say +18 V you normally mean relative to ground. But op amps have no power connection to ground, only to two voltages, so they don’t “know” what those voltages relative to ground are, only to each other. What the spec sheet means is they can be, in this case, up to 18 V above and below… anything, or in other words within 36 V of each other. They could be +1000 V and +1024 V and the op amp wouldn’t care. Of course that means the inputs would have to be in the same range, and the output would be in that range as well. Likewise the delay chip is specified for (about) -22 V and ground, but that could equally well be ground and (about) +22 V as in this case.
… I did it, result:
I get +19.4V on the +12V track !
If I remove IS1 (IC1) there is still +13.2V on the 12V track, if I also remove IS2 it is 12V again! IS3 has no influence on the changed voltage in any constellation! If only IS1 and IS3 are installed it stays at +12V!
I checked all connections and values again, everything was ok!
I speak and read German well. I had read the service booklet, it’s true:
IS1 and IS2 form a triangle generator, with IS1 acting as a comparator and IS2 as an integrator. The amplitude is determined by resistors R2 and R9.
I will continue to search, try and get advice from the internet. I don’t want to give up the phaser, if only because I want to find the error!
Maybe I’m misunderstanding you, but if you have a +12 V power supply connected to the line shown in magenta, then there must be +12 V at any point on that magenta line. It cannot be any other value. ADDED: Unless the +12 V rail is shorted to some other voltage source.
… BEFORE the 1n4001 diode there is actually +12.5V on the 12v “magenta” track!
BEHIND the 1N4001 (cathode) there is an actual +11.8V!
When IS2 is installed I get +19.5V on the 12v track, without IS2 installed normal 12v again!
If I pull out pin 10 (output) from the IS2 everything is normal! I measured around +20.2 volts at the extended output! Strange behavior!
Whether my OP’s are outdated and defective?
I will buy some more from another source on the Internet.
Per your schematic, there is no diode anode on the magenta track. There is a diode cathode.
The voltage from cathode to ground must be exactly the same as that of your power supply. The voltage from anode to ground can be expected to be about 0.7 V higher.
If you have a +12 V power supply connected to a trace on a PCB, then every point on that trace will be at +12 V — unless there is something so very, very wrong that the power supply can’t maintain +12 V and sags to something lower.
Or if the 12 V supply is being shorted to some higher voltage point. Then you can get a higher voltage, but that means something is very wrong with your circuit. If it really is the IC then something is extremely wrong, because it means some sort of short is occurring inside it to the negative power pin. Did you get your op amps from a reliable source? It sounds like they may be fakes.
I also attached the 1N4001 to the 12v and 24v voltage inputs for protection; it is not on the circuit diagram. Only visible on PCB layout!
There is ALWAYS a constant 12v volt in front of the diode at the input plug, even if the rest of the board has 19.5v.
My thought is that something is short-circuited in the A109D because the chips are so old, possibly due to poor and damp storage over many years, if not it must be my fault. I have already ordered new NOS Op’s and hope for improvement later.
I’ll check everything thoroughly again this evening for the fourth time.
The chips are original and come from the former GDR, not China!
It’s certainly totally irrelevant, but I get the voltage from the notebook power supply, which outputs 20v, where the output is connected to a step up converter, which outputs 24v and a parallel step down converter which regulates it down to 12v. This is just a temporary quick fix from me!
Hello,
I have made some progress in researching the causes!
I DISCONNECTED EVERYTHING that was connected to the 12v and 24v!
And everything that is now connected to the +12v and +24v tracks are the decoupling capacitors (C1 and C3 each 1000u and C2 and C4 100N capacitors):
… Now I ONLY plug in the 24v power supply: What happens is that I get about 5v on the 12v rail, which must have gone through the 1000uf capacitor, because if I also remove the 1000uf, the only 12v that remains clean is the 47N capacitor is connected but doesn’t cause any trouble!
After about 10 minutes the 12v is free of voltage again, I think the capacitor has completely emptied in that time!
I replaced the 1000uf capacitors twice with others, no change!
Does anyone have any idea what I can do to prevent 24v voltage from reaching the 12v rail? A blocking diode or z-diode can help???
Here are pictures of the original power supply!
The power supply seems to output 24V and is then brought down to 12V with a Z diode and another Z diode from the 12 V track is used to generate ground, is that correct?
Error found! Stupid of me, I had installed additional 1N4001 diodes on my PCB (see also picture), as reverse polarity protection I thought I removed them, now everything works great!
!
