G08 problem.

jkoolpe

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Hi all!

Well, after many years of trouble-free problems and several trips to CA Extreme, my G08 monitor finally developed a problem at my Halloween party :( .

At first, I got full horizontal collapse now...the screen was collapsed to the very right in a vertical line. After some connection reseating, I now get no picture and no neck glow. HV is there, though.

I'm just starting to take it apart, but I noticed that there is a small piece of wire on the back of the paddle board that appears to want to connect the "H" and "V" outputs (see picture, upper right side). Is this normal?

The wire does not read continuous on my meter with the "H" output, but it does read continuous with the "V" output. Should I resolder this to the "H" output? Should these two points be connected via this wire?

Other than that, I did find that the upper 6259 transistor reads continuous with the chassis which I think means its blown.

Anyway, I do want to know if this wire between the "H" and "V" is normal. Anyone know?

I have extra 6259 transistors at the ready :) ...

Thanks,

Jon
 

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First, thats the input protection board not one of the paddle boards. the paddle boards are connected to the motherboard near the transistor heat sink. My gut tells me that your outputs are probably ok. Usually when they blowup they dont go quietly, and they pop a fuse. Id guess you may have some connection issues. Make sure the paddle boards and connections to the output transistors are tight and clean. You can bypass that board to test the monitor.
 
Gotcha...I am new to actually working on a G08. I do see those paddle boards...I'll pull the deflection board and see about the connections.

Should the the continuity of the one 6259 deflection transistor to the chassis a concern?

And is that little wire a problem connecting the H and V on the protection board?

Jonathan
 
the 6259 transistor shouldnt have any continuity to the chassis ground at all.hence the pic collapse.
 
Here's a picture of mine -- I was just working on it and fortunately I always snap 'before' pictures of the boards...

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So that little joining wire on my board should not be there!

I have the deflection board sitting on my bench right now and am reflowing the solder to the various connectors, and on the paddle boards. Nothing obvious yet...

On the bottom of the deflection board, the "H" and "V" points are also supposed to be separate, yes (not soldered together)?

On mine, they almost looked joined again with solder, but I reflowed them just now to be sure that they would not be together.

Can anyone confirm that these inputs should NOT be soldered together? :confused:
 
So that little joining wire on my board should not be there!

I have the deflection board sitting on my bench right now and am reflowing the solder to the various connectors, and on the paddle boards. Nothing obvious yet...

On the bottom of the deflection board, the "H" and "V" points are also supposed to be separate, yes (not soldered together)?

On mine, they almost looked joined again with solder, but I reflowed them just now to be sure that they would not be together.

Can anyone confirm that these inputs should NOT be soldered together? :confused:

> So that little joining wire on my board should not be there!

Dunno -- they are not joined on my board. Not sure if that's the universal answer however.

> On the bottom of the deflection board, the "H" and "V" points are also supposed to be separate, yes (not soldered together)?

Hopefully this will help. I have a number of other pictures of this board so if you want a zoomed image let me know and I probably have it -- just tell me which section of the board you want zoomed in. :)

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They should not be connected.

You can bypass the 'protection' board and plug the monitor signal straight into the deflection board (where the protection board plugs into).

The image will be a little larger that it is WITH the protection board, but that would let you know if everything is OK beyond the protection board.

Kerry
 
Thanks guys. I removed the wire.

I looked over all of the boards and didn't see anything obvious. I shored up all of the solder connections anyway.

As soon as I have the new transistors and the rest of my order from DigiKey, I'll replace them and hopefully that'll get me back to working status :).

Jon
 
Tested the Q700-04 and Q600-04 MPU transistors tonight..they all appear to be OK...the readings matched for each pair.

I will still replace the 6259s next, but I was wondering...is the mod in the attached picture to both of my paddle boards normal? I have circled what are deliberately broken traces (not by me) in red, and circled in blue the added wire to the deliberately cut collector leg of transistors Q604 and Q704 that is then soldered to pin 2 on the upper connector of the paddle board.

The cut traces have resistors soldered in line that you can also see in the picture. But oddly, both of these resistors are soldered to the trace coming off of pin #1. The trace coming off of pin #2 is cut and unjoined with the bottom completely (not continuous on my meter).

Is this normal?

Jon
 

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Finally had some time to work on my poor G08...

p1001 is helping me out (thanks Hans! :) ), but if anyone else has ideas, I'm certainly appreciative!

Here is the latest:

I replaced the 6259s with fresh ones, and also replaced all of the MPSU transistors on the deflection board with the Biltonix recommendations from DigiKey. Also recapped the deflection board and reflowed solder for the paddle board connections and everywhere else that looked possibly suspect.

When I fired it all up, I got some smoke within a few seconds coming from the deflection board ...seemed to be located around Q704, but I'm not sure. Turned it off immediately of course. When I now examine the deflection board, I don't see any obvious burn marks. I double checked that I got the right MPSU transistor replacements in the right places, and that I got them oriented correctly...and they are correct as far as I can tell.

I then checked the new 6259s that I had installed, and it appears that one is now reading bad...it's the one in the 700 circuit (upper one located closest to the tube on the heat sink). The readings on my multimeter were definitely not the same as for the other 3 .

I have 8 more at the ready, but I'm afraid to install them now...I did go through the deflection chassis and check all of the resistors (while still on the chassis), and they all gave readings, with a few that were different then the readings as listed in the manual I have (for a ST Captain's Chair although mine is a convert-a-cab upright). None read open.

I did notice that one of the larger resistors on the paddle board (for the 700 series) has a slight bulge in its middle, but it does read at about 1.0 ohms on the meter (while still on the board). So it's not open at least...the reading is very similar to the reading from this same resistor on the other paddle board.

I reflowed some more solder connections again and also noticed that one of the collector pins might have been touching the base on Q604 (with the clipped collector leg that is then wired to pin 2 of the paddle board...I'm told this is a factory mod) so I made sure that this was not happening any more. Also checked all of the connections between the paddle boards and the deflection board they seemed fine.

Should I try again? Or could I have a problem with my HV after all? :confused: . I do hear the HV come on, and I definitely have HV as I have to discharge the monitor each time so it's there.

What to do?!? Thanks in advance!

Jon
 
I would not change out all of the deflection transistors again, just the one that seems different.

Make sure that the transistors in the section where you had a problem don't show up now with collector/emitter shorts.

I'd probably change that resistor that seems bulged. I've seen them literally blow apart after experiencing an inrush current from shorted deflection transistors.

Check the suspect paddle board for shorts/opens on all the small diodes.

Then fire it up again.

Kerry
 
I actually retested all of the original MPSU transistors that I had replaced on the deflection board, and they all test fine (out of circuit). I'm tempted to replace them back onto the chassis first now...

I'll definitely give that paddle board another look over...does anyone have the rating for the larger, resistor on the paddle board involved in the 700 circuit that is applied on the paddle board to bridge between pins 1 and 2 (as seen in my picture in my previous post (post #10)? It looks like a 2 watt size.

Jonathan
 
I took a magnifying glass to the resistor in question on my paddle board (the 2 watt in the picture), and it's definitely cracked.

It reads about 0.8 ohms on my multimeter (when I lift up one leg). If I am reading the color bands correctly (band #1: red = 2, band #2: black= 0, band #3: silver = 0.01 multiplier, band #4: gold), it should be a 0.2 ohm, 2 watt resistor with 5% tolerance (20 x .01 = .2 ohm).

I'm new to reading the resistor color bands...can anyone confirm is this is correct before I order some replacements (such as those here: http://www.ebay.com/itm/2w-Resistor...3?pt=LH_DefaultDomain_0&hash=item519966ea71)?

Thanks,

Jon
 

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Merry Christmas! :)

I'm still working on this poor G08 and had some time today.

Update: I replaced the cracked resistor on the paddle board, re-installed the original MPSU transistors (which tested good out of circuit, replaced the bad 6259 deflection transistor, and even found a bad trace on the HV board (by sheer luck) that I repaired (between pin 1 of the main connector and an adjacent resistor).

When I fired it up now, at first I got a) no smoke (yea!), but b) full horizontal collapse (with the graphics squished into a vertical line in the center of the screen).

So I again looked at the deflection board, and wouldn't you know it...the wire soldered to the collector pin of Q704 had caused the entire collector leg of this transistor to break off! The wire was just hanging there (that goes to pin 2 of the corresponding paddle board)!

OK I thought...all I should have to do is get this wire re-attached and maybe I'll be good. So I resoldered this wire directly to the collector itself on Q704 and reinstalled it. Then when I fired it all up....

SMOKE again! :( And the 4 Amp fuse at Q700 even blew and I took out the same 6259 transistor) :( Another $4 part...but I still have more at least. The resistor teepee was super hot, too.

I'm not sure where to go now except that it sure does seem that there has to be something unhappy in the Q700 part of the deflection board. I'm going over it right now, but thought I'd post on this Christmas Day to see if anyone out there has advice.

BTW, I managed to secure some NOS IC600 chips so if it turns out that this chip is my problem, I even have those at the ready now.

Any help out there? :)

Jon
 
Sounds like your getting dc on the ouput. Unplug the yoke and the output transistors, check the waveform on the connectors for the output transistors. The pins that drive the bases should have some kind of waveform...not dc. Work backwards until you find the short or fried device.
 
Make sure you haven't 'corrected' anything that isn't actually wrong.

The place where the wire jumps from the collector pin of that transistor to the paddle board is normal. The trace for that collector pin is probably isolated from the input on the trace side and there is another jumper wire on the bottom of the board.

The same kind of mod should exist on the 600 side, but the traces are slightly different.

There may be cut traces on the paddle board with a resistor making the reconnection in some other place.

I'm pretty sure the paddle boards are pretty much the same with only a small resistance change there. Maybe the resistor difference is actually on the main board.

The G08 boards I have that are brown-screened on the bottom usually have the cut traces and jumper wires. The boards with the green mask on the bottom are a later revision and the alternate paths were designed into the traces.

Lots of fun.
 
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