Re: 25" Amplifone Brightness Problem

Wow! I have some good stuff to go on now.

1) Forgot to mention that the diode was put in backwards for the -24v
    voltage regulator. -32v showed up. Possibly my VR is bad?
2) The 4001 diode that was in backwards was tested and was .56v in one
    direction. I have extra so I'll just replace this anyways.
3) The guy that was using my DMM to test these regulated voltages told
    me today that he accidently shorted pin 2 and 3 together the first time
    he tried to test +24v. He then figured out to test at other points on
    the trace farther away from each other. The test then showed +26.5v.
    Sounds good. Should I replace this VR just in case?
4) I followed the Michael Kelley FAQ that didn't mention something found on
    another "How To Install a new HV" FAQ. That other FAQ mentions putting
    down black electrical tape below the new HV unit to insulate it from the
    pads and traces (the new HV unit is a metal case). I have the smaller
    beige board so had to put the HV at an angle to keep it off the hard to
    find 1500 diode nearby. The HV unit does slightly overlap the mounting
    base of the focus assembly. I should really insulate this if I can.
5) I need to check to make sure my neck socket is on the correct pins.

I really hope whatever I did didn't ruin anything beyond repair!

Any other suggestions based on this information?

Greg

On 2002.03.07 09:28 "Rosenzweig, Joel B" wrote:
>> I once experienced a problem that sounds just like yours, though I'd need a
>> picture to certain. The description "it was almost all white with a bright
>> spot in the middle" is exactly what I had experienced. It turns out that I
>> had not properly aligned the neck socket to the pins on the tube. I was off
>> by one pin! Doh! It was miraculous to me that any picture showed up at
>> all. Fortunately, no damage was done and putting the socket on the correct
>> way made everything normal again.
>>
>> Joel-
>>
>>
>>
>> -----Original Message-----
>> From: Gregory Erway [mailto:erway@rochester.rr.com]
>> Sent: Wednesday, March 06, 2002 10:12 PM
>> To: vectorlist@synthcom.com
>> Subject: VECTOR: 25" Amplifone Brightness Problem
>>
>>
>> Well I dove into the 25" Amp tonight and installed the new Wintron HV
>> unit. I also installed a Zanen cap kit on the HV and deflection boards.
>> Tested all resistors to within 10% in circuit on the HV board. Did NOT
>> test any of the transistors but since I had them I replace the 2 voltage
>> regulators and BU406D. I have a beige board but it is the small version
>> that is like the blue updated version. There were 4001s and 50 ohm
>> resistors on the board (although only 1 was 5w the other was 10w). I
>> did test the old BU406D that I took out and it tested fine. I have a feeling
>> the HV unit (red) may have been functional. But the insulated voltage
>> reg was completly missing and one resistor had a leg lifted as though
>> someone had been testing something. I mentioned before that the tube
>> had a 1/8" or so phos burn in the center. Now I may know why.
>>
>> I turned on the game (we did check +/- 24 at the regs before putting the
>> BU406D back in and every thing was in range. -24 was more like -32)
>> and we got a picture. But it was way too bright. You could see all the
>> traces being drawn and it was almost all white with a bright spot in the
>> middle but the picture being drawn on almost the whole screen. Possibly
>> the width was wider than the tube and the vertical height was shorter than
>> the tube. I tried adjusting the brightness (screen) on the focus assembly
>> but we didn't think it was helping at all. We later verified that it did
>> help
>> some but it is at it's lowest seeing now. Focus may or may not have helped
>> we just couldn't tell. The PCB was tested in a friends UR 5 months ago.
>> It worked fine (although he thinks it was too wide on his WG monitor too).
>> If it is on for a while you start to get more color and can see multiple
>> colors.
>> We did not touch R17 since it was sort of glued with red fingernail polish
>> or something so it wouldn't turn. We figured we would set the HV. I
>> used the voltage prob and only got 15.5k I turned R7 and got the pot to
>> it's limit and only got up to around 17.5k. Anode poped off a couple times
>> on me but I think I have it on good now. Also we tried to put the game
>> PCB in test mode to maybe get a pattern to adjust width but it seems to
>> go into test and say "No Errors" and then after 1/2 sec to 1 sec it would
>> go black on the screen (except for the white dot in the middle). In game
>> mode the game seemed to work fine.
>>
>> I just don't like seeing that bright dot in the middle. In reality the
>> damage was
>> already done. But still it bothers me. Seems like a Z deflection problem
>> maybe? If there are any hints you could give me on what to look for that
>> would be great. I also have no FAQs on the deflection boards. Are there
>> any? I should also mention that I did NOT replace the 0-ohm jumper
>> since it was labled differently on my board from the FAQ (and it was white
>> and not brown). I also did not test the 555 timer since I don't have a
>> scope.
>>
>> If the statment that 99% of the time when the red HV goes it takes the
>> BU406D with it is true (from the FAQ). Then is it also true that if the
>> BU406D tests fine when removed then 99% the HV unit is still good?
>> I don't want to run the red in there for obvious reasons. But I might not
>> toss it if it's good. Guess I need a ringer.
>>
>> Thanks for reading this. I know it's long but wanted all the information
>> available for anyone that might have an idea what my problem is.
>>
>> Thank you in advance for any help.
>>
>> Greg
>>
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Received on Thu Mar 7 07:11:42 2002