Re: G08 Rebuild issues

Have uploaded my assortment of Electrohome XY monitors to: (typo fixed!)

FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment/Monitors/ElectrohomeXY

 
These include four variations of the GO5 and two variations of the GO8
series. Some I have scanned, others are 'found' - where I may have
scanned or downloaded over the years.

John :-#)#

John Robertson wrote:
> OK, here are the adjustments from the Electrohome G08-105 XY November
> 1982 monitor manual.
>
> ----------------------------------------(quote)-----------------------------
> 4.0 Service Set Up Control
> NOTE: These controls have been factory adjusted. If adjustment
> is necessary check set up procedures in this manual.
> 4.1 G2 Adjustment R930
> ....
> 4.8 E.H.T. Duty Cycle R918
> 4.9 E.H.T. Frequency Adj. R917
> 4.10 E.H.T. Sensing Control R933
> 4.11 E.H.T. Regulator Adjustment R945
>
> .......
>
> 6.0 E.H.T. Alignment _/(follow this sequence EXACTLY! - JR)/_
>
> 6.1 After 10 minutes warm up, adjust voltage regulator for 100V,
> -6V/+2V via R945. _/(JR - I think this is a typo, R310 is the
> regulator adjustment on version -003)/_ Measurement is made between
> anode of D902 and ground.
>
> 6.2 Jumper TP1 to ground with jumpers hook up oscilloscope to
> collector of Q902 and adjust R918 for duty cycle of ~ 20 usec on ~ 35
> usec off.
>
> 6.3 Adjust R917 for anode voltage of 21 KV +/- 300V then remove jumper
> at TP1 and adjust R933 _/(R920 for rev -001 - JR)/_ for 0V +/- 15 MV
> at TP1.
>
> Note: Adjustment made with zero beam current.
>
> ------------------------(end quote)---------------------------
>
> If you do not have these tools or the knowledge of how to use them
> then send your HV unit to someone who can set it up safely.
>
> I've scanned in the manual and will post it to my FTP site (Tech Tools
> List) later today, and I'll provide the link then.
>
> John :-#)#
>
> Grant Thienemann wrote:
>> Crap yeah I was messing with R917 an R919 on this schematic:
>>
>> http://www.arcade-museum.com/manuals-monitors/Electrohome%20G08_Schematics.pdf
>>
>> Any help so I can get this set correctly would be fantastic!
>>
>> Thanks
>> Grant
>>
>> On Thu, Dec 27, 2012 at 1:19 PM, John Robertson <pinball@telus.net> wrote:
>>
>>> Grant Thienemann wrote:
>>>
>>> Hey Guys,
>>>
>>> Apparently there are two pots on the High Voltage board, what I did to
>>> fix the problem was rotate them both all the way counter clockwise
>>> till they stopped, turned on the machine, I finally had a game image
>>> YES but the screen was small and I had the same issue as before, I
>>> started rotating both pots very slowly one at a time till the G08
>>> sounded right, and the game looked great.
>>>
>>> I don't think I even needed to rebuild my monitor now that I knew
>>> about those pots, but I did all the "upgrades" I could find online for
>>> this monitor and its running VERY well. I don't even here the vector
>>> chatter that I've heard other people talking about.
>>>
>>> The only other "mod" that I'm doing is that my Sega Star Trek has two
>>> backs on it, and I've left the top one off that is for access to the
>>> monitor. I figure that will keep the monitor running as cool as
>>> possible.
>>>
>>> Thanks guys!
>>>
>>> -Grant
>>>
>>>
>>>
>>> !!!DANGER DANGER DANGER!!!!
>>>
>>> This is potentially a very BAD idea - adjusting various potentiometers in HV
>>> circuits without the correct test equipment hooked up. Not knowing which of
>>> the four or so pots on the HV section that you played with, I would say you
>>> may have created problems/dangers (X-Rays!) for yourself that you may not be
>>> aware of.
>>>
>>> The four pots I find (schematic version G08-003) are R310 (100VDC setting),
>>> R933, R918 and (danger) R917. At the moment I do not know what R933, R918
>>> and R917 do, but R917 has a safety mark beside it indicating that it is a
>>> critical adjustment that likely sets the X-Ray protection circuitry up
>>> correctly. You REALLY do not want to mess with that with out the correct HV
>>> probe and other factory recommended adjustment tools handy!
>>>
>>> If I have time later today I'll dig into these adjustments, but it would
>>> help if we knew WHICH pots you adjusted!
>>>
>>> Chances are you are safe, but if you set the HV higher than factory AND
>>> turned back the X-Ray shut-down your tube could be emitting X-RAYS - soft
>>> X-Rays to be true, but considering people play the game only inches from the
>>> screen the risk is reasonable that you do nto want to expose yourself or
>>> loved ones/friends to the risk!
>>>
>>> If you adjusted a pot that had any glue or nail polish, etc. to 'lock' it in
>>> place, then do NOT turn the game on again until you have test gear lined
>>> up!!!
>>>
>>> John :-#(#
>>>
>>> On Wed, Dec 26, 2012 at 8:09 AM, Grant Thienemann
>>> <grant.thienemann@gmail.com> wrote:
>>>
>>>
>>> ok I 'll check both of those, if you think of anything else please let me
>>> know!
>>>
>>> On Tue, Dec 25, 2012 at 5:45 PM, Mark Jenison
>>> <eliminator4player@gmail.com> wrote:
>>>
>>>
>>> This is another one of those "I've seen this before, wish I had written down
>>> the fix..."
>>>
>>> Offhand, I'd look at the ribbon cable between the xy pair. Then the yoke
>>> connector.
>>>
>>> On Dec 25, 2012 4:36 PM, "Grant Thienemann" <grant.thienemann@gmail.com>
>>> wrote:
>>>
>>>
>>> Hey Guys,
>>>
>>> I did the cap kit on my G08 today, and when I hooked the monitor back
>>> up to my Star Trek I get scrolling vertical lines. I noticed there
>>> were two pots on the HV board, and I know I accidentally moved one of
>>> them when I was rebuilding the chassises, what do those two pots do?
>>> Its like the horizontal or vertical sync is off, but this is a vector
>>> not a raster.
>>>
>>> Also just messing with it a little bit the more I change the pot the
>>> more the vertical lines change. Any help would be fantastic.
>>>
>>> Thanks
>>> Grant
>>>

-- 
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
                 www.flippers.com 
"Old pinballers never die, they just flip out"
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