here my new profile here
 

here my new profile here:banana:

and someting cool
https://www.facebook.com/pages/Norit...08763672482987
https://www.youtube.com/watch?v=0KbKSW_fkKw
https://goo.gl/maps/R1qYAhCcLnN2

Hey, since you're the VFD master, maybe you can help me with my Pioneer CT-F850. My VFD is completely blank. It was working before the cassette deck was shipped to me, but is not working now. Here's the service manual: http://www.hifiengine.com/manual_lib.../ct-f850.shtml


I've taken some readings from the chips, board, and fluoroscan meter itself.

First off, there are two wires marked 3v AC on the board. Those measure at 1.3v AC between them. They are fed from the power supply board, and measure 1.3v there as well.

The display reads 1.3v AC between pins 1 and 33.
I'm also getting 15v DC (B+) at pins 3, 5, 18, and 32. (measured to the pin marked ground on the board that the display is soldered to)

On the chips, I'm getting 1.25v DC on pin 1, and 15v DC on pin 9. Everything except pin 18 is zero. Pin 18 is roughly 2.4v DC. (The voltage to this pin is adjusted via the VU meter level trimpots)

Any idea what's wrong with this thing? Something took a hit during shipping, but what could cause this?

Basically, if it's an easy fix, I'd like to keep the deck. If the VFD is toast, I'll return it.

Charles.

If I am reading the diagram properly, it looks like the VFD filament comes from the dial lamp winding on the power transformer via a resistor network consisting of R650-R653. Check these for opens/off value. You want to see 3VAC across the ends of the filaments, and you have less than half that. Does the unit otherwise work? Did the unit get shifted into 240V power settings, perhaps?

Yeah, the unit otherwise works, and there's no 120/240 switch on this unit. I've checked the transformer winding outputs and they're the correct voltage. I'll try disconnecting the wires from the VFD and see if they read the proper voltage then. Maybe the 1.3v is because of the load of the VFD. If the VFD cracked or leaked somehow would it still draw current even though nothing is displayed?

I'm assuming supplying 5v DC to the filaments for a second or so wouldn't be a good idea. I don't really have an AC power source that I can generate to test otherwise.

Hmm, I do have another cassette deck that I can temporarily swap the VFD out of. I can try that too.

Charles.

7.2v AC on the transformer windings, 6.2v AC on the supply to the filament, with the filament supply wiring detached from the filament board. Will take apart the other cassette deck shortly.

Charles.

Well nevermind, the VFD is broken, the glass nodule on the back is cracked clean through and there's no vacuum left inside. That's why it's not working.

Charles.

That would explain the low voltage. A filament will draw much higher current in air than in a vacuum, at least until it burns open....

Hey, I got a replacement VFD off of eBay for $25. It was for a CT-F800, but it looked like the same part and I took a chance. It was the correct part! It included the control board and everything, so I just hooked it up and screwed it in place, and it worked perfectly first time. Now all I need to do is re-belt this deck and then adjust it with my test tapes, meters, and signal generators, and it'll be good to go.

Charles.

awesome you got it fixed. I got enough VU meter style VFDs laying around here to choke a horse. Even the one you needed. Anyways...

Here is my latest project that I have been working on:

I have a whole crate of these I got from a contact out of the Ukraine. I am designing a "retro" audio spectrum analyzer using individual VFD tubes.

And... Here it is. First power-up after assembly, but before any code is written yet for the MCUs.

That looks awesome. I really like VFDs.

I'm curious.
How often do people approach you inquiring about your sources?
I got an Itron alphanumeric display here I've spent two years trying to find a replacement for because the evacuation nipple broke off during rough handling.

Almost never. Usually its eBay.

What is the part number/pic of it? I may have it.

What Is THIS DISPLAY
 

Ooohhhh nice display. I'd like to get one myself somehow.