Amplifone help

shilmover

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Just picked up a SW with an Amp (http://forums.arcade-museum.com/showthread.php?t=144650).

The first monitor I ever fixed was an Amp so it was a while back.

It is a 25" model with the original Red flyback.

Here is the strange thing about the monitor. When I start it up:
- The red led (spot killer?) comes on, then off after a second or so and stays off
- I can hear chatter from the monitor (if I unplug the monitor, there is not chatter). It also seems as though the chatter is changing (as I would expect in a working monitor drawing different vectors.

Any thoughts on where to start? Fuses are all good, nothing seems burned on the boards.
 
Have you got any parts you can change?

My SW CP had a Deflection board problem, and I had a spare.

It's a good fault-finding technique :D

My upright has an Amp in it. Will the 19" boards work on the 25" monitor?

Replace the flyback.
While you are at it recap, and I usually have a set of 3792/3716's onlhand as well.

I will have to order one. Any easy way to test the flyback? i dont mind switching it out, just want to make sure.

Strange thing is that I hooked up my scope to the board and did not get the image I expected. I am going to swap to game board to test...
 
The boards are the same. Try swapping them and see.. If you didn't see game on scope there may be another issue. I have never had a red work on about 6 or so amp sets I have had (not that all would always be bad).. I try out the pcb's when I get them just for a laught then always do a cap kit, always end up replacing the flyback, and many times the deflection transistors... Not much else goes other than one or two of the small transistors or regulators (can't re,ember offhand what they are... Have not had to work om an amp in a looong time) along the edge of the heatsink.
 
P.s. Try the cockpit one in the upright to see if that one is working (hv, then deflection).... If not try upright in cockpit... Should have typed clearer before..Discharge the CRT if it has been on within the lat week..
 
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Actually, it sounds like it's working just fine, but the flyback is just bad. The spot killer is supposed to come on for a second when you first turn it on. The game board hasn't booted fully yet, and isn't producing a signal. Then, when the game board comes up, it's outputting a signal, the spot killer goes off and the chatter starts.

I've never seen a working red Amp flyback.

Replace the flyback, do the caps while you're at it. Also, check the BU406D - it usually gets fried when the flyback goes.

-Ian
 
Actually, it sounds like it's working just fine, but the flyback is just bad. The spot killer is supposed to come on for a second when you first turn it on. The game board hasn't booted fully yet, and isn't producing a signal. Then, when the game board comes up, it's outputting a signal, the spot killer goes off and the chatter starts.

I've never seen a working red Amp flyback.

Replace the flyback, do the caps while you're at it. Also, check the BU406D - it usually gets fried when the flyback goes.

-Ian

Thanks everyone.

I figured it was the flyback (my upright had a red one and I replaced it) but I had not seen it do that before as the one i fixed before was completely dead.

What parts will I need (other than the deflection transistors, caps, 406D)?
 
First thing you need to verify is the deflection board is outputting the proper voltage on (IIRC) pins 7,8 & 9. IIRC pin 7 is ground. You should be seeing something like 32VDC out of the other pins. If anything the first thing to swap into your 19" AMP would be the deflection board. You have to have a good signal before the HV will work right?
And FYI - the wiring harness is infamous for having pins come loose so ensure your pins are solidly mounted in the molex connector. Might even consider a continuity test on the wiring harness. You'll also need to get your hands on a HV probe when working on vectors. You can get the voltage semi close using a DMM.
 
P.s. Try the cockpit one in the upright to see if that one is working (hv, then deflection).... If not try upright in cockpit... Should have typed clearer before..Discharge the CRT if it has been on within the lat week..

Will do. Having a working set should help.
 
What parts will I need (other than the deflection transistors, caps, 406D?

Check the resistors on the deflection board, I've seen those cooked before. Also, check both the + and - 24v lines, you may have a blown 7824/7924, last one I worked on the 7924 was blown apart! But, since you get deflection chatter, they should be working. Chances are, your deflection transistors are also good, but it's good to have some around.

Also, when you're working on the boards, pay close attention to the brown zero ohm "resistors". They're prefixed with W on the board. These are supposed to be jumpers, but they like to fail open or go intermittent. Best course of action, replace them all with some little bits of wire.

-Ian
 
Thanks everyone... Its all starting to come back to me... I remember replacing the "jumpers" :)

So one can get the monitor chatter without HV?
 
Cool. I didnt know that...

So the monitor is trying to draw the vectors, but is not getting any HV therefore not displaying it?

Exactly. The deflection section of a vector monitor is completely independent from the high voltage. So, it's possible to have everything working perfectly, just no high voltage, and thus no picture. In a 6100, the filament voltage is derived from a diode and a couple resistors straight off the power transformer in the game (forget how it's done on the Amp), so you can even get neck glow, deflection and no high voltage. Heh, in one 6100 I fixed for a friend, I managed to repair the HV, so I had deflection, high voltage and no filament - because some previous repairman had replaced the 7.5ohm resistor in that circuit with a 1.2k resistor.

-Ian
 
Thanks for the info Ian.

Sounds like i just need to rebuild my HV board... :)

Any chance the AR board is not supplying voltage to the HV board? I think the same power goes to it and the deflection board, no? Sorry for the noob questions. Have only every worked on 1 Amp and it was completely dead so I had to rebuild everything...

I will test the gameboard, etc tonight...
 
Any chance the AR board is not supplying voltage to the HV board? I think the same power goes to it and the deflection board, no?

Nope. The AR-II only powers the game logic boards. The monitor gets it's power from the center tapped 50 volt winding on the power block's transformer.

-Ian
 
perfect. thanks.

BTW,

The fan is mounted under the PCB. Should I move it under the HV/Deflection board?
 
The fan (I believe) is for keeping the game board PCBs cool... people add additional cooling fans to the HV and Deflection boards for good measure.
 
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