Troubleshooting: Hantarex Polo/2 15/25 kHz no picture (euro)

[tobiasbpdk]

Hello there.

I have a euro Beatmania 3rd Mix (mini). The chassis is a Hantarex Polo/2 15/25 kHz (in 25 kHz mode). The tube is a Samsung A48KRD89X01. The game is from around 1999.

There were never any issues with deteriorating image quality. Then one day, there was no picture. The game currently plays blind (I hear the game audio). I have checked that the chassis gets the 220V. I have also made sure the fuse is good. I see no neck glow (in a lot room, I should probably have turned off the lights).

I have done quite a bit or research, but the different Hantarex polo models is confusing (to me). It seems like the first step in troubleshooting, would be to measure the B+ voltage.

I have some photos of the monitor in a Google Photos album here.

Questions:
A: Where should I measure B+ on my chassis?
B: What should the B+ voltage be? I have found a single source saying 171V for 25 kHz (euro).
C: Would it make sense to do a full recap hoping that would solve the issue?
D: Does anyone have links to documentation for this chassis?

Thanks.

 

[princess prin prin]

Measure B+ at R153 in the corner near the flyback. On a 20" I would expect it to be lower than what you said. Recapping doesn't sound like a good idea.

[tobiasbpdk]

Measure B+ at R153 in the corner near the flyback.

Thanks. I'll get the monitor installed again and measure B+.

[tobiasbpdk]

For documentation purposes, this is what R153 looks like. Which leg (left/right) should I measure at? I don't have the monitor installed yet, so can't do the measurement yet.

What should the next steps be if:
A: There is 0V at R153?
B: There is some reasonable voltage at R153?
C: Voltage at R153 is far away from the expected voltage?

For C, I believe the voltage can be adjusted via a pot reachable through the cage around the power supply.

[princess prin prin]

If the B+ voltage is present it will be on both legs with little difference. The left leg (closer to corner) is coupled to pin 3 of the flyback. Use that first. Before doing anything, measure the resistance from the leg to ground and only power the monitor if it's very high (a few Kohms at least). If it's low or zero there is a shorted part (e.g. T22). If you lift the leg of R153 from the PCB and attach a 60W lightbulb (old incandescent type) to it (and to ground) you can power the chassis outside of the cab and see if the power supply section is working or not. Yes, the trimmer RV1 in the power supply adjusts the B+ voltage. If you intend to adjust it, take a pic of the rotor position first as the B+ level is uncertain and the trimmer is most likely factory set to the correct voltage.

[tobiasbpdk]

I have found the following schematics: https://media.recreativas.org/manuales/hantarex-polo-2-esquemas.pdf

 I'm unable to locate R153, even though I can find T23, R152 & R155? (Main board). However, R153 IS listed as a spare part on page 7.

Do you think the schematics are for a different chassis?

[princess prin prin]

Those are the only Polo/2 dual freq. schematics I've ever seen. They're for chassis intended to drive tubes with 110-degree deflection angle, i.e. 25" and bigger (yours is a 20" 90-degree).

R153 is in the last bit of schematics (before spare parts list) to the left of the flyback (TH3), in parallel with L12 and C110 and going to pin 3 of the flyback.

[tobiasbpdk]

They're for chassis intended to drive tubes with 110-degree deflection angle, i.e. 25" and bigger (yours is a 20" 90-degree).

Would the difference between a 110-degree and a 90-degree chassis just be the component values, or would the circuits be different as well?

R153 is in the last bit of schematics (before spare parts list) to the left of the flyback (TH3), in parallel with L12 and C110 and going to pin 3 of the flyback.

Ah. I see it now. Thank you!