x-y monitor repair

[fa001]

I repaired a Star Wars game by swaping a WG6100 for the dead Amplifone. With the new availablity of the HV transformers, I thought that I would repair the Amplifone.
But as I read the HV transformer replacing directions I see that one is to make HV measurements and set the HV. However I do not have HV measuring equipment.
So my questions are:
a) What are the chances that if I put the new transformer in the voltages will be good and all will work?
b) What are the chances that I can cause more damage if I do not check the HV voltages?

[D_Zoot]

I just got my Cinelabs HVT that I pre-ordered months ago.  I'll be tossing an Amp on the bench this weekend to fit the HVT and see how it goes.

Yes,  you MUST adjust the HV and shutdown on an Amplifone.  Too low voltage will cause PQ problems (blooming),  too high will stress the supply rails on the HV board and could damage components.   Then there's the HV shutdown circuit,  it's there for a reason and must be properly adjusted.

HV probes can be purchased for a reasonable price,  Jameco has them for $80 or so.  You could probably ebay one cheaper.


D

[fa001]

Thanks for the reply. I expected as much.
I did buy the probe from Jameco. That will add to the cost of the project but will also add to the experience. And that is what this hobby is all about.
Now if I can get the monitor working and keep my body working all will be great.
I have not yet received my HVT but supposedly it has shipped.
Please let me know how yours works out.
 

[Level42]

Since I bought a Star Wars with a dead Amplifone recently, I wondered how this worked out. It has the dead-red HVT, so I guess I will need the Cinelabs replacement as well and I guess I'll need a HV probe too .... 

[fa001]

Well, I am a little embarssed to say that even though I have gathered all the pieces, I have not gotten back to this project.  I was waiting to hear of others who did the cinelabs replacement. But have not heard much. And then other projects have jumped the que.

Where are you at? I might be willing to share the HV probe. They are expensive for a one time use.

- Fred

[ChadTower]

The VectorList.

[D_Zoot]

I had forgotten about this thread...


I installed my HVT some time ago,  installation was easy, although on the revision HV board I have, there was a diode that interfered with the fitting the HVT fully down on the board.     The HVT housing was made in a standard mold, so there's an area for focus and screen controls (although this HVT doesn't actually have controls there).   It was this part of the replacement that the diode interfered with as the original HVT doesn't have this.   I simply remounted the diode to the solder side of the board.

Adjustments were quick and easy and the monitor has been up and running since then with no problems.



D

[Level42]

Well, I am a little embarssed to say that even though I have gathered all the pieces, I have not gotten back to this project.  I was waiting to hear of others who did the cinelabs replacement. But have not heard much. And then other projects have jumped the que.

Where are you at? I might be willing to share the HV probe. They are expensive for a one time use.

- Fred

I'm just in the investigation stage. I still have to get my Star Wars Cockpit here to examine what's wrong with it.
It might be something as simple as the infamous brown jumpers or something like that...
Anyway, I'm in Europe so sharing the HV probe would require some overseas shipping.....but might still be worthwhile.

D_zoot: Good to hear you successfully installed the Cinelabs. Were there any other parts damaged on your HV board  or only the HVT ?
Did you do the high voltage safety cut-off adjustments etc ?

[D_Zoot]

D_zoot: Good to hear you successfully installed the Cinelabs. Were there any other parts damaged on your HV board  or only the HVT ?
Did you do the high voltage safety cut-off adjustments etc ?

My HV board was toast.  When the original red went it took out the BU406d and the 7924 (-24 regulator).   All of that got replaced along with the zero ohm jumper and all of the caps.   I did adjust the overvoltage and HV, however I couldn't tell you how far off it was with the new HVT, I turned them down before powering up the board for the first time, let the board run for a while to warm up and set them to specs (I do have an HV probe).

If you have an original HVT that's dead, plan on at least having to replace the BU406d  (make SURE your replacement it's a "D" and not a plain BU406) and you should cap it since it's out and you are working on it.  Regulator failures seem to be hit or miss on these.

Also there are a few mods that should be done to help protect the regulators (mine had already been modded),  instructions for these mods are a quick google search away (google for "amplifone faq").


D