HeNe Video Disk PSU ?'s

Hi, I'm still new here. I'm going to try limiting the questions on this to just this side project. I'm still waiting on a lens assembly shipping from Hong Kong, so the laser diode project is on hold

I have a HeNe tube(NEC GLT 165) complete with it's original PSU & power transformer, all of which I removed from an antique laser video disk player. It was years ago when I put all these parts in a box and I don't remember writing any notes on which wires go to what, so a small challenge here. Also, I think the transformer might've 'bumped' the PSU circuit board, as it's cracked right down the middle! Just a little soldering is all it needs

Please don't ask if the tube is cracked:bowdown:



The PSU board has pins numbered 1~13. After spending several days searching LPF & Google, I found the best info on Sam's laser FAQ's. There, a list of some Pioneer schematics showing PSU connections look very promising, but nothing matched-up exactly.

Pins 1 & 2 on my PSU & on the Sam's site are the same, power from transformer to PSU. On what I have, these two were and still are connected.

Pins 4 & 5 AC mains in. What I have is a short piece of lamp cord with the indentation from a strain relief. This looks like where the wall outlet is connected, & Sam's schematics agree on the pin numbering.

Tracing pins 4 & 5 on the PSU board shows that the AC mains input is completely isolated from the rest of the board. After running through a fuse and a filter section, outputs on pins 8 & 9. Pin 9 has a wire that is tied to another wire that is connected to pin 6. I believe I tied these two wires together, and that they went to the main power switch. Sam's schematics agree with that, only one small problem is that pin 6 does not go anywhere and no other wires are currently connected to this pin. So I'm assuming a wire came loose from here while in the box.

Good news is that pin 8 is connected to the input side of the transformer.

The transformer is a multi-voltage input type, that is - there's a selector switch to plug into one of four mains voltages. 110, 120, 220 & 240. There's also another fuse block wired inline with the selector switch. This makes three fuses total for the entire system I have here. I temporarily cut the selector switch wiring and tested all positions. There's one wire on the switch that is not connected to anything, but it gets connected to one each of all the other wires depending on which position the switch is in. So I'm guessing this should be connected to pin 6 on the PSU?

Pins 3 & 7 are not used. Pin 13 is one of the wires to the laser tube, the other wire of which goes directly to the flyback.

Now for what I had thought were the real issues here. Pins 10, 11 & 12. The Sam's schematics were only partially helpful as they don't cover this exact model, but as they all agree with each other on pin usages as well as with my PSU, then I'm hoping that these next few assumptions may hold true for all of these PSU's.

Pin 10 is shown on the schematics as a ground. On mine, there's a black wire connected to that.

Pin 11 is shown being connected to an interlock switch on all schematics, with the PR 8210 schematic also stating that this is connected to 12 volts positive. The PR 8210 also shows that the interlock is bypassing a resistor that has '270' written next to it. Maybe 270 ohms? So the voltage to pin 11 drops when the interlock switch is flipped. But for my purposes, I don't need an interlock and am assuming that I can connect +12 volts to pin 11. I'm thinking of using a separate wall wart for this instead of messing around with the other outputs on the transformer. It has five wires taped-off. On my PSU there's a purple wire on pin 11, going nowhere special

On Sam's, another page to do with setting-up a new tube, as part of an alignment procedure - there's a reference made to 'shorting pin 12 to ground' using a jumper so as to get the PSU to stay on with the disk player opened-up. I'm thinking this was in reference to all of the Pioneer players, and maybe will also hold true for my PSU. The schematics show this wired to a 'lid switch', then to another module. On my PSU, there's a red wire with a position sensing mechanical switch at the other end. So I'm thinking of connecting this to pin 10, and also connecting the 12 volt negative to this pin.

I'll also wire-in a power switch between pin 9 & the selector switch. But I thought I'd wait on all of this until I should get any feedback from this forum. Hopefully, I made this clear enough that not too many questions need be asked about what I'm doing here...:thanks:

A link to the psu scheme on sams laserfaq would be nice, this way we know better what you talk about. You can also try to make a circuit diagram of your psu, maybe it's not that hard to figure it out, but I can't do it fully in my mind But it sounds like you're on the right track.

Bluefan said:

A link to the psu scheme on sams laserfaq would be nice, this way we know better what you talk about. You can also try to make a circuit diagram of your psu, maybe it's not that hard to figure it out, but I can't do it fully in my mind But it sounds like you're on the right track.

Click to expand...

Ok, but it'll take a minute to find those schematic links. As for drawing-up a circuit diagram, well I could but I'd rather not at the moment. But I could post better pics with the pins in question high-lighted. I don't know why I didn't think to do all this to start with, but you're absolutely right. I should've linked my references, thanks!

Alrighty, that was a workout cruising around the index structure of Sam's laser faq's. I finally resorted to doing a site search from google, but finally found the relevant page: Notes on the Troubleshooting and Repair of Optical Disc Players and Optical Data Storage Drives

I forgot it was actually an offsite link I had found here that referenced the Pioneer schematics: Laser Disc Player Tech Center

This is from the PR 8210 pdf:


That showed the pin 12 voltage. Also note how pin locations are different from my PSU yet the numbering stays the same. On my PSU, the board is labeled with pin & component numbers. These next two pics are of the PSU board that I have, with pins highlighted & labeled. Then I even went and indicated basic components on the backside view. Just a little more effort to get some values and drawing the circuit is a done deal.



Flipped left-to-right:

Dont forget to get the x/y mirrors outta there

ped said:

Dont forget to get the x/y mirrors outta there

Click to expand...

You mean these?


All this is maybe 8 years ago, both the teardown and construction. This contraption was fun! The mirrors tilt using 8 ohm coils & perm magnets. So hooking the mirrors right to the speaker terminals on my stereo system is no problem. I used a laser module from a $30 level that I bought expressly for taking the laser out of. It's brighter than any typical pointer. I also used the battery compartment and power switch from that level. The whole thing is put together with a chunk of pine 2x4. You get a nice audible feedback on the power limit when the mirrors start hitting their mounts! Dialed back a bit, and left to run for hours never hurt these things. One of these days I might put the mirrors on ebay, but it's easy enough to just stick back into my time machine/storage bin

I'll wait another day on the HeNe laser, if no-one says it'll blowup going by what I've suggested trying, then I'll go ahead and wire it up! I was hoping somebody with some experience using this kind of PSU might put their two cents in.

There the fellas!

Get some deep house with cranking basslines and watch thos babies fly haha.

ped said:

There the fellas!

Get some deep house with cranking basslines and watch thos babies fly haha.

Click to expand...

lol - Oxygen Restriction by The Shamen from Entact

Ok doke, I'm feeling brave. Setting up a video camera for this and I'll let you know what happens!

Well that went well!:beer:

Here's a link to the video on youtube:
Firing up the HeNe

Well now isn't that just great! Now that I finally get this laser to work I don't want to turn it off! - What's the duty cycle on this thing?

Not sure - I can't find a rating in hours for a typical low mW HeNe tube - but they run an awful long time (10's of years). Depending on the service it saw - its probably got thousands of hours left.

Sam's FAQ had a reference in the for sale section for that very tube - 0.8-1.5mW output.

I would think you have more concern for the caps in the PS going out before the tube does... You may want to look at recapping the PS if you intend to keep it for some time - or simply buying a Melles Griot type power supply and connector for the tube... then you can save your *vintage correct* PSU for special occasions, and run the standard power brick for daily use.

Escher said:

Not sure - I can't find a rating in hours for a typical low mW HeNe tube - but they run an awful long time (10's of years). Depending on the service it saw - its probably got thousands of hours left.

Sam's FAQ had a reference in the for sale section for that very tube - 0.8-1.5mW output.

I would think you have more concern for the caps in the PS going out before the tube does... You may want to look at recapping the PS if you intend to keep it for some time - or simply buying a Melles Griot type power supply and connector for the tube... then you can save your *vintage correct* PSU for special occasions, and run the standard power brick for daily use.

Click to expand...

Well I hadn't really thought it out enough for what the duty-cycle might be. If this was for a video disk player, I would think it was built to run continuously for the duration of several movies at a time. So it ought to be capable of running all day without a problem.

Is it possible I've been scammed all these years with my diode lasers? I'm just going by eye, not having any better device at the moment but this HeNe is noticeably brighter than my 5mW and a bit brighter than my laser level module. Or it just looks that way. It does seem to put it's light into a smaller dot, maybe it's a smaller amount of energy lighting-up an even smaller area? Well I'm not going to worry about what the actual power is. It won't light black or blue paper no matter how long I try. It looks very nice, and I expect it will make a nice pattern on the wall if it's rigged like I'm planning.

Just how likely is it that any of the caps will fail?

And, is it safe to run the PSU until a cap fails? You've got me worried! I wont mind buying a set of caps if it stops working, but if I run the chance of blowing other components when I really would prefer to work on other projects & not diagnosing this one, well I guess it wouldn't hurt to change those.:undecided:

I'm going on what I know from my other hobby - guitars and tube amplifiers... In vintage tube amps the main thing you get replaced is the caps if they dry out or fail... if the PSU is working, then you are probably fine for a while.

As to the operating power - that may have been a measured output of that particular laser over at Sam's site - it was in his classified section. But, I know the laserdisc players and CD players that originally used these type of tubes didn't use very powerful ones. Under 5mW is very typical... Both HeNe's I have owned were about the same size and both in the 3-5mW range... its typically (again from what I have read here and at Sams FAQ) that the power is related to tube length... and this tube looks to be inline with a 5mW or so...

I'm sure the guru's will chime in soon if I have misspoken, but that is my take from my research to date... I'd also recommend scouring ebay for similar tubes and what their output is - may give you and idea as well...

Escher said:

I'm going on what I know from my other hobby - guitars and tube amplifiers... In vintage tube amps the main thing you get replaced is the caps if they dry out or fail... if the PSU is working, then you are probably fine for a while.

As to the operating power - that may have been a measured output of that particular laser over at Sam's site - it was in his classified section. But, I know the laserdisc players and CD players that originally used these type of tubes didn't use very powerful ones. Under 5mW is very typical... Both HeNe's I have owned were about the same size and both in the 3-5mW range... its typically (again from what I have read here and at Sams FAQ) that the power is related to tube length... and this tube looks to be inline with a 5mW or so...

I'm sure the guru's will chime in soon if I have misspoken, but that is my take from my research to date... I'd also recommend scouring ebay for similar tubes and what their output is - may give you and idea as well...

Click to expand...

Cool, thanks. Overall length is about 10 inches. I'm thinking that in the case of this particular laser, under 5 mW would be better as I'm thinking of using this as a casual light-show display to take to a party. I'm thinking of making a wood glass & steel display box. It sure would be neat to build a PSU using vacuum tubes!

Reminds me of another project. I have a tube amp from the fifties, a Bogen DB20 that worked great when I first used it. Then it blew a power supply cap. I replaced that cap but it still wont work and I haven't felt like going through the whole thing just yet because I don't have a speaker good enough for this to drive. I'll still fix it because it sounded better than any other amp I've ever heard. Absolutely zero static or hum at full volume(for the speakers used, wired in series = 16 ohm).

Sometimes when an amp blows a cap, it will take out a grid resistor as well. You may have lost a resistor when the cap blew..

Check out Les Paul Forum | Gibson Epiphone – MyLesPaul.com and search their "squalk box" forum for info on screen grid resistors... Great bunch of amp guru's over there.

Escher said:

Sometimes when an amp blows a cap, it will take out a grid resistor as well. You may have lost a resistor when the cap blew..

Check out Les Paul Forum | Gibson Epiphone – MyLesPaul.com and search their "squalk box" forum for info on screen grid resistors... Great bunch of amp guru's over there.

Click to expand...

I'll take a look, thanks.