Problem Crazy Star Wars Vectors on an Amplifone Monitor

[petercasino]

Hello. I've just finished doing a cap kit on an Amplifone monitor. The monitor was untested before the cap kit was done. It's giving a decent picture, but I'm getting some strange vector behaviors as can be seen in the screens below. I've adjusted the screen voltage/focus and the x/y size pots on the deflection board but the strange behavior remains. The pcb was running fine on a WG6100 yesterday. I'm not sure what to do next? I haven't touched the pots on the main pcb, is it worth trying to adjust them? Also, I haven't replaced the fly-back, I'm not sure if doing that would help?

Thanks in advance.

Video showing the issue:

 

[petercasino]

Added video showing the issue:

 

[ColinD]

I'd say LV issue on deflection pcb or transistors. Maybe even a capacitor in wrong. Check the voltage regulation with scope.

 

[petercasino]

Thanks for the tips, I'll take a look.

 

[ColinD]

Looks like the ampliphone runs unregulated, taking a look at the schematics. I'd double check that the game board signal is ok when it gets to the delection board
first. Think you can rule out the HV at this point.

Double check your work, then work through the power supply section checking the 4 diodes (CR14>17) and that the two caps are in the right way round, C17 and C18.

Do you have an oscilloscope of some kind and suitable probes ?

Did you use the same power brick when you tested on the WG6100 ?

Are both x and y affected do you think or just one ? Then it's grunt work going through the transistors and diodes etc. They all can fail or behave erratically.

I may have a couple of delfection boards you could try out if you get stuck but I've never tested them !

2n3904 and 3906 are cheap enough from Farnell. There are some subs for the others, search other threads. MPSU57 and MPSU07 (BD237 / 8 but you will have to swap legs around) and also the bigger ones, something like MJ15003 and 4 but worth double checking ( RGP uses some different ones than these.) Also MJ21196 and MJ21195 have been suggested.

https://www.amazingarcading.com.au/Amplifone_Deflection_PCB_Schematic.jpg

 

[petercasino]

Looks like the ampliphone runs unregulated, taking a look at the schematics. I'd double check that the game board signal is ok when it gets to the delection board
first.

Would that be using an oscilloscope?

Think you can rule out the HV at this point.

Double check your work, then work through the power supply section checking the 4 diodes (CR14>17) and that the two caps are in the right way round, C17 and C18.

Yeah, I've started doing that, the 4 diodes test ok and the caps are all the right way around.

Do you have an oscilloscope of some kind and suitable probes ?

Yeah got an oscilloscope and probes.

Did you use the same power brick when you tested on the WG6100 ?

I did, I've got the WG6100 on a trolley so it's pretty easy to swap

Are both x and y affected do you think or just one ? Then it's grunt work going through the transistors and diodes etc. They all can fail or behave erratically.

I think its y that's affected

Having taken a closer look, there looks like there are bad solder joints on the MPSU07/MPS007 transistors. I think I'll need to reflow them.

I may have a couple of delfection boards you could try out if you get stuck but I've never tested them !

Thanks!

2n3904 and 3906 are cheap enough from Farnell. There are some subs for the others, search other threads. MPSU57 and MPSU07 (BD237 / 8 but you will have to swap legs around) and also the bigger ones, something like MJ15003 and 4 but worth double checking ( RGP uses some different ones than these.) Also MJ21196 and MJ21195 have been suggested.

https://www.amazingarcading.com.au/Amplifone_Deflection_PCB_Schematic.jpg

Ok cheers, I had a look on ebay and those MPSU07's are pretty expensive!

 

[petercasino]

An update: I tested all of the transistors on the deflection board and they seemed to be fine. I reflowed all of the solder joints on the board. On doing that I noticed that one of the diodes was hanging be a thread (CR6 - 1n914) so I replaced it. I plugged the board in and bingo the picture was there. Unfortunately the next time I switched the machine on I got no vectors at all and the following screen



I can hear the vector chatter, but I think that maybe the HV has gone as I can't see any neck glow. I do have a new flyback for this monitor.

 

[ColinD]

So, did the reflow and inspection cure the stray vectors ok ?

It's hard to say from that picture as you appear have glow on the screen. Spot Killer light ok ? Do you have HV Trip LED on ?

Have you read the amplifone repair faq ? (That may help diagnose stuff further) and the Service manual ?

Have you got 180V on the B+ ? Do you have a HV Probe to check the 19.5/25KV HV ?

Do you have regulated +/- 24V on the HV PCB ?

I wouldn't go chopping in a new flyback just yet until you have ran some more checks. Is it a red one fitted ?

 

[petercasino]

So, did the reflow and inspection cure the stray vectors ok ?

Yes, the picture looked great.

It's hard to say from that picture as you appear have glow on the screen. Spot Killer light ok ? Do you have HV Trip LED on ?

Yes the screen glows and there's no sign of vectors. Both Leds are off.

Have you read the amplifone repair faq ? (That may help diagnose stuff further) and the Service manual ?

I do have it, will take a look

Have you got 180V on the B+ ? Do you have a HV Probe to check the 19.5/25KV HV ?

Will check. Yes I have an HV probe, though I've only ever used it to discharge tubes.

Do you have regulated +/- 24V on the HV PCB ?

Will check

I wouldn't go chopping in a new flyback just yet until you have ran some more checks. Is it a red one fitted ?

Yes, good point. The current flyback is black: