SOLVED! - Hantarex Polo 25" repair help

[M K L]

C172 (a cap that is crucial for horizontal deflection and HV) failed and they didn't have a replacement so they did that trick. It's the same thing, just not as clean. Once the monitor is fixed you may want to do it right with a single cap in the proper place.

 

[Keeleon]

So while putting it back together to put it back in the machine for the next test, I noticed the big center pin on the flyback isn't soldered to anything. Theres actually nothing coming through the hole? Is that part actually necessary or might there be some flybacks that don't have it?

Also I never really got an answer as to what I should replace the C137 with. Should I put the 220uf 50v listed in the cap map, or replace it with the same 470uf 35v? Might there have been a reason that was put there?

 

[JukeboxJon]

So while putting it back together to put it back in the machine for the next test, I noticed the big center pin on the flyback isn't soldered to anything. Theres actually nothing coming through the hole? Is that part actually necessary or might there be some flybacks that don't have it?

Also I never really got an answer as to what I should replace the C137 with. Should I put the 220uf 50v listed in the cap map, or replace it with the same 470uf 35v? Might there have been a reason that was put there?

In the k7000 there was one pin on the flyback that many times would not be soldered in, as long as it is not connected to any obvious traces probably normal and not a problem.

Thats why if a flyback had been replaced in a k7000 they just never bothered to solder it back so I would not worry about that. Never cared for the hantarex chassis the polo is ok but ran hot hard to diagnose, however capable of a great picture and had a pretty good tube.

No idea why they would substitute the cap with a different uf rating, you always keep the exact same fraud rating and at least as much volts as the caps you replaced it with if you have a higher voltage rating cap thats fine maybe better. And generally want to keep the size around the same.

 

[Keeleon]

So I put everything back together and put it back in the cabinet. Now when I test for B+ at the corner resister I actually get nothing. I do 0hear a very faint "Ticking" sound coming from what seems like the transformer in the power section. This means its a bad HOT? How do I test the HOT? I jsut check for continuity between the middle and outside legs? I do get a beep when touching the middle to the outside. This means the HOT is bad? Will the HOT I posted earlier work in this? I don't really understand how to check specs on those.

 

[M K L]

Measure resistance across the points where you measured the B+. It's the same as using the center pin of the HOT. If the resistance is low (zero ohm or close) you have a problem.

Use 220uF for C137 (not a priority at this point)

Big center pin is a ground point for the metal spring that holds the ferrite core of the flyback. Some flybacks don't have it so it's not necessary.

 

[Richard48]

So since I seem to be dealing with this a lot more often now, I was thinking it might be economical to buy a bunch of caps instead of jsut buying kits here and there.

It is unlikely to be more economical for a couple of reasons.
1. If you buy in small quantities of each cap (less than 10 each), it will probably cost you about the same as, maybe more than, buying a high-quality kit from a company such as Arcade Parts and Repair.
2. Unless you know a bit more that the average tech about capacitors, you will not be able to determine which of the dozens of caps of the same value and voltage rating are the best for your application.
3. You could spend many hours learning about caps, creating a list of distributor specific part numbers,, and where best to buy them.
4. Unless you are planning to do this as more than a small hobby and for personal use, you have to consider what your time is worth.
While shipping costs from AP&R will likely be a bit more that purchasing the caps from a company like Digikey or Mouser, you will still likely come out ahead because, if no other reason, of the aggravation of figuring out what and where to buy.

Just my 2¢ worth.

 

[Keeleon]

OK, so I took a chance and replaced the HOT with the one I had from my K7000. Not sure if they're compatible since I didn't get a specific answer, but it definitely did something. When I turned the monitor on I got some smoke from the resistor at R167 and it now is all burnt. The screen did actually turn on and has a bright white line across the center. I am reading that this may be because of the remote board maybe? Is there a chance it might work fine if I jsut replace that resistor, or will it jsut do the same thing? What is the value I need to replace it with? IS it something special or jsut a standard resistor? What do I look at now to fix or replace? Does a cap kit address this?



Also am I correct that the POLO 25 doesn't need to be discharged? I'm still gonna do it out of habit, but I was reading that might be the case with this and I wasn't getting a pop when doing it.

 

[mecha]

OK, so I took a chance and replaced the HOT with the one I had from my K7000. Not sure if they're compatible since I didn't get a specific answer, but it definitely did something. When I turned the monitor on I got some smoke from the resistor at R167 and it now is all burnt. The screen did actually turn on and has a bright white line across the center. I am reading that this may be because of the remote board maybe? Is there a chance it might work fine if I jsut replace that resistor, or will it jsut do the same thing? What is the value I need to replace it with? IS it something special or jsut a standard resistor? What do I look at now to fix or replace? Does a cap kit address this?

View attachment 736710

Also am I correct that the POLO 25 doesn't need to be discharged? I'm still gonna do it out of habit, but I was reading that might be the case with this and I wasn't getting a pop when doing it.

they self discharge (or are at least supposed to), but not instantly like the Wells-Gardner K7000 and later monitors do. if you let it sit for about 10 minutes it should bleed off on its own.

R167 is where the vertical deflection voltage runs through. it's a fusible resistor, which means if there's a shorted component in the vertical deflection section it will burn out and go open just like a fuse. this is a safety mechanism to prevent additional damage, so it cuts the 25V supply. chances are your vertical IC is bad, which is the package on the other side of the flyback heatsink wall with the most legs (in the vicinity of R167, actually).

you can use a K7000 HOT in a pinch, even bent off the heatsink wall (so you don't have to mount it with an insulator) but be forewarned it will only run like that for approximately 10 minutes.

just send this to www.arcadecup.com

 

[Keeleon]

Unfortunately I'm already on the fence spending $30 to get this fixed, so sending to a "professional" is probably out of the question lol.

Are you talking about this guy? Is there a way to test it before replacing it?


So I was looking at the schematic and if I'm reading it right, R167 connects to the remote board? Looking at the remote board, I see what looks like a bit of "burny". Is that something to worry about or that makes sense? Could be some of those parts need replacing too?

 

[Keeleon]

you can use a K7000 HOT in a pinch, even bent off the heatsink wall (so you don't have to mount it with an insulator) but be forewarned it will only run like that for approximately 10 minutes.

To be clear, it will only run for 10 minutes because of the K7000 HOT, or because it's mounted without an insulator? I have it in there with a silicon pad strapped to the wall.

 

[Keeleon]

Watching @zenomorp s video here , he says 2 pins on the IC should beep on ground. I get pin 4, but nothing on the trace for pin 1 beeps to ground. Does that mean a problem somewhere? This is after I have replaced R167 and verified R177 is good.

 

[Keeleon]

OK, so for starters, I am a moron. I replaced C137 with a new cap, but forgot to trim the legs, so I had two long pieces of metal shorting to the bottom of the chassis... What a great idea!

After trimming those and replacing R167, it now turns on and stays stable without popping, but I still get vertical collapse. Does this sound like I probably fried my TDA1675A?

 

[mecha]

OK, so for starters, I am a moron. I replaced C137 with a new cap, but forgot to trim the legs, so I had two long pieces of metal shorting to the bottom of the chassis... What a great idea!

After trimming those and replacing R167, it now turns on and stays stable without popping, but I still get vertical collapse. Does this sound like I probably fried my TDA1675A?

you mentioned something about the remote board but I didn't understand what..? you're not running it with the remote not hooked up are you? cause that will cause vertical collapse. as will a bad V. Amp pot, which in my experience are always ridiculous on those remotes. LOL

also there's a possibility the vertical IC is bad

 

[Keeleon]

you mentioned something about the remote board but I didn't understand what..? you're not running it with the remote not hooked up are you? cause that will cause vertical collapse. as will a bad V. Amp pot, which in my experience are always ridiculous on those remotes. LOL

also there's a possibility the vertical IC is bad

To clarify, I am using the remote board, and because the schematic shows R167 going directly to it. I was examining it and saw a charred looking spot and was curious if that was relevant.

I've ordered another IC so it would be great if that fixes it!

 

[Keeleon]

So I recieved a new IC and I'm going to replace it, but I see it doesnt have a silcon pad behind it connected to the wall. Does it just get pasted to that wall as a ground? Or should I put a silicon pad between it?

 

[Keeleon]

Well I took a chance and just pasted the vertical IC in and look at what I got working!

Now just to do some adjustments, but it looks like even just thrown together like this it's pretty accurate and a good picture.

Thanks for the help guys!

 

[mecha]

I've been knee deep in all my work projects for weeks now, I don't remember all the details of your operation here. I'll have to read it later. lol