Hantarex Polo Revisited...

[grantspain]

a bu508 a has a metal back,you sure it not a bu508af or else?
if it has a metal back then you must install a insulation sheet between the back and the heat shield

[grantspain]

desolder pins 1 and 3 of the flyback transformer(make sure they are completely desoldered and not touching the trace)so it is isolated from the circuit
then use a 40 watt light bulb with crocodile clips connect one side the the chassis frame and the other to R227 nearest pin 3 of the flyback
when you switch on you can meter the b+ at r227(bulb side) and it should read around 110-115v dc steady
if it reads really high then there is a crack on your board and is normally around any fixing point or where the heat shield clips in
if it reads good then for sure its a dead flyback

[gokun]

a bu508 a has a metal back,you sure it not a bu508af or else?
if it has a metal back then you must install a insulation sheet between the back and the heat shield

not as far as I can tell, but the writing is faded and hard to read...I will just desolder it to get a better look tonight after work.

desolder pins 1 and 3 of the flyback transformer(make sure they are completely desoldered and not touching the trace)so it is isolated from the circuit
then use a 40 watt light bulb with crocodile clips connect one side the the chassis frame and the other to R227 nearest pin 3 of the flyback
when you switch on you can meter the b+ at r227(bulb side) and it should read around 110-115v dc steady
if it reads really high then there is a crack on your board and is normally around any fixing point or where the heat shield clips in
if it reads good then for sure its a dead flyback

Will do! just gimme a couple days to get it done. Thanks!

[gokun]

a bu508 a has a metal back,you sure it not a bu508af or else?
if it has a metal back then you must install a insulation sheet between the back and the heat shield

ok,I removed the HOT and have it in front of me as I type this...the only markings on it say BU508A and underneath that it says S0010. And it does not have a metal back. There was, however, a nice little black spot(burn?) on the insulation behind it when I took it out if that helps at all.

At any rate, still working up my courage to test the flyback; will post the results as soon as I do. Thanks!

[Kevin Mullins]

You need to test that HOT ..... forget about testing the flyback.

[gokun]

You need to test that HOT ..... forget about testing the flyback.

Already did several times...it is bad. But unfortunately there is more going on with this one than just that 0_o

[grantspain]

a faulty flyback can cause the hot to blow constantly,also there has been instances of bad batches of transistors as well
the light bulb test should prove where to look

[gokun]

ok, finally got back to this...found r227 again(and felt really stupid for not being able to find it before...sigh...it's only like a HUGE white box screaming "look at me! look at me!"....but I digress)....
where was I.....oh yes....
so was getting ready to do the last test you recommended with the flyback...got pins 1 & 3 desoldered really good and prepared my lightbulb with alligator clips....
but since I had relocated r227 finally, I decided to test it with a fresh head....turns out it is bad....no biggie as I found replacements available that I can order....but it raised a question in my head I would like to ask you....
Is it safe to do the test with that resistor being bad? Also would I get an accurate reading if I did? I'm assuming no on both, but would like to know for certain before I do anything. Let me know; thanks a bunch!
oh! one last thing...that is a 10W 4ohm resistor, correct? The writing on it is kinda crappy and hard to read(seems to be a trend on this monitor) and I still suck at reading the schems...thanks again.

[grantspain]

its a 10 watt 4.7ohm,never had one go faulty myself but had a lot of polo with trace breaks around this resistor
you can safely check the chassis still its just if the resistor is open circuit then you will need to read the B+ before the resistor and you will get a high reading

[gokun]

k; thanks! will let you know the results this evening sometime...

[gokun]

ok...holidays are keeping me too busy...sigh...but finally got back to this again...
so here we go...
desoldered pins 1 and 3 of flyback, reinserted hot(you'll recall I had removed it to verify the numbers on it, etc-this is the same bad one as before), then connected my lightbulb up(I used a 60w bulb actually...bulb in socket with gator clips...clip the black to the chassis frame and the white to r227 nearest pin 3 on flyback as advised)...powered on and went to take readings...
upon power on you can still here the initial sound(the deguass? that's what it sounds like...) then of course nothing...so start checking for b+ at a couple spots I had traced to be in front of r227(you'll recall r227 is bad also) and oddly enough, I get nothing at all...so just to be thorough tried it on the blown r227 too....nothing at all...
Also it has stopped making that faint ticking I mentioned in an earlier post...so I dunno...
I'm thinking I've missed something or took the readings wrong or something...
whatcha think? would a pic of my setup help at all to make sure I'm connecting the bulb properly, etc? I can provide one if you want...
...totally open to ideas, suggestions, etc and as usual have no intentions on giving up on it just yet, so totally willing to try whatever I need to...thanks!

[grantspain]

does the lightbulb light up,if not then you need to trace the b+all the way back,meter at tp6 for +145 dc-if not present you need to check d116

[gokun]

ok, no light up on bulb and voltage not present at tp6...will check the diode and let you know...it's late now unfortunately and I'm getting the damnable flu it seems  ....so anyways, gonna sleep tonight and finish up with checking that diode tomorrow. thanks, as always, for the input!

[grantspain]

2 very important things to remember,
1-diodes should be read out of circuit(lift one leg from the trace)
2-the primary stage of the power supply is deadly so be real careful around there

also double check you have isolated the flyback completely from the traces and the light bulb meters continuity across the circuit

atm this looks to be a missing +145 dc voltage
you will also need to check +85v at TP7,+27 v at TP8,+15v at TP9
also important to note that some revision of polo chassis had a safety resistor installed on both the +145 and +27,check if this is the case with yours-most likely a flame proof 1watt 2.2ohm-if this is the case and it is open circuit YOU MUST install the exact same type or you may get a minor fire

make sure you meter is set at DC volts,i am sure you know.

[gokun]

outstanding! lotsa stuff to check...will let you know my results soon as I get a chance to sit down with it again.

[gokun]

Wow was away from this one for quite a while....sorry it's been so long, I been caught up with other crap unfortunately...sigh...hate it when that happens....anyways....long story short, I ended up replacing(including stuff from the original problem probably as my notes kinda suck in retrospect)...

All caps were replaced...r227 and a couple other resistors replaced(r227 was the only one that was not the 'regular' kind), replaced the HOT, replaced east/west diodes, replaced the flyback(found one for $20 shipped-too good to pass on), and I "re-fixed" some of the repairs that were in place when I got it, and I did find a broken trace eventually too while doing the re-fixing so took care of that while I was there. What else....hrmmm...I seem to recall doing something else but it's not in my notes...at any rate, I think I covered the main stuff I did...oh wait! I adjusted the bridge coil thingy! that was it I think....so yeah that's probably it because the top of it was broke and I remember getting paranoid while adjusting because my hand was uncomfortably close to that damn anode wire...basically just threw parts at it, which I realize is not ideal, but that's still the novice level I'm at...so after all that, it worked again...

and then my wife made me get rid of it because I had no use for it anymore...sigh...so after all my troubles I end up giving it to a friend who is trying to build a mame cab from scratch...so there's my good deed for the month-lol!

At any rate, I learned a LOT more about troubleshooting and such so I consider it overall a successful project despite all the problems I had...so now I'm looking around locally for another broke one to play with(but something much smaller this time so my wife don't get so mad about it being on the floor for 3 months-lol!)...I figure the only way I'm gonna get better at this stuff is to keep doing it.

And finally, I would once again like to thank grantspain for all his help this time, as well as every other time I've had a problem with a monitor. Could not possibly have learned or done this much without your help dude so many, many thanks!
PS
I did at least play 1 game of turkey hunting on it before I gave it away...it actually callibrated better than the monitor that came with the turkey hunting cab-lol! so at the end of the day I guess I did get to really enjoy the monitor once before it left me.

[grantspain]

well all that work and you have to get rid of it,on the big positive side you have learned a great deal about monitors-that in itself is priceless
glad it worked anyway