Pentranic 1432 display issues [RESOLVED]

[Arm123]

I recently purchased a Midway "Invasion: The Abductors" at an auction.  Installed in it was a Pentranic 1432 33" monitor.  It seems to have an issue i am trying to solve.  I have tried adjusting all the display controls in the cabinet.
 
There seems to be some kind of "tearing" at the top of the image...



Its as if some rows of pixels are missing.  I have tried moving the image around to different portions of the screen.  It results in the same tearing effect.  I am not concerned about the crappy positioning (my fault) of the bottom corners, it is fixable via the cabinet display controls.

I am wondering what my options are ?  Any suggestions are appreciated.

Thanks.

[grantspain]

when you say all the adjustments does that include the one's they like to hide on the main chassis

[Arm123]

when you say all the adjustments does that include the one's they like to hide on the main chassis

Yes indeed, I opened up the monitor housing and messed around with the controls that i can see.  I see controls for R, G, B, contrast, brightness and focus (which seems to blur and sharpen the image).

I cant locate the service manual for this baby...  and its pretty dusty inside.  I cant see any other controls in the chassis.  I’m going to clean it out and see if i can locate any other controls.

Any suggestions are appreciated.

[StephenH]

Here is the schematic:

http://www.alsmarketing.net/schematics.htm

[Ken Layton]

Contact Rick N at monitor manufacturer, Nieman Displays. He has experience with Pentranic monitors.

[Arm123]

Thanks alot for the responses guys.

Ill muck around with it this coming weekend.  See if i can sort it out.  If not, ill make an atempt to contact Rick N at Nieman.

Thanks again for the diagrams StephenH   

[rockin_rick]

My polo looks like that when horz freq is adjusted.  It goes from good/correct, to that, to horz blanking visible on screen, to garbage.  When it looks like that it is on the very edge of going bad.  FWIW

Good luck,
Rick

[meequalgreat]

yeah I had this same problem until I found my horizontal adjustment knob, which was on the chassis away from everything else.

[rockin_rick]

I'll just add that the h freq only effects the curl of the screen, not the missing top pixels.  I'd assume that your top line of pixels are missing due to another setting (perhaps v phase and/or v size?)

Rick

[Rickn]

Yes- the Horizontal hold to fix the curl a combination of Vert pos'n and VHold for the missing "Pixels' and if that does not do it there is a small Tantalum capacitor to change C318.

Good Luck

Rick Nieman
Rick@Niemandisplays.com

[Arm123]

Hey guys.  Thanks for the replies

I have spent the better part of a Sat. trying to get this thing to display a descent image.  I did, indeed, find two more controls buried in the monitor chassis.  One was a 'zoom' control and the other seemed to 'shrink and expand' the bottom portion of the screen.

The only way i can get the top part of the grid to display is to shrink the image to the 1/4 the size of the screen in the middle.  Once i try to expand that image, the top part of the grid seems to roll over behind the image.

After a spray of compressed air, I took a look inside the chassis to see if i can see any burnt or swollen caps.  I couldn’t see any.







After playing with the extra controls, i found in the chasis, this is the best image i could come up with (as far as the top of the grid is concerned).  No missing pixil rows anymore.  However, the image seems to bend over its self.



Iv played and played with the Vert pos'n and VHold.  Im guessing the only option is to replace that cap specified by Rickn ?

Any input is more than welcome.

[Rickn]

No- not a "Zoom" control, more likely B+ , the other control is vertical linearity,

Send me an e-mail to Rick@Niemandisplays.com

Copy/Paste this post in the e-mail to remind me - I will send you a service manual


Thanks again

Rick

Rick@niemandisplays.com

[Arm123]

Email sent...  thanks Rick 

[Arm123]

Hey guys...

Well, i haven’t touched this particular unit for a few months.  I just turned my attention to it today and powered it on.  I saw a horizontal line threw the middle of the screen...  the picture seemed to be ‘compressed’ to one line.  Then I smelled something burning, so I powered down and waited 10 min.  Powered back on and nothing...

I do hear a faint, short wine or buzz repeatedly and no picture or power on.

What, if anything, can I do about this ?  Any thoughts are welcome.

Thanks.

[Rickn]

Likely the Horizontal output transistor.

Check to see if it is shorted.

Good luck

Rick

[Arm123]

Thanks Rick.

I will locate, replace and pray 

[Arm123]

I checked the HOT and it wasn’t shorted...

I replaced it anyways.

Im still hearing a short repeated 'beep'...  more like a hummm, over and over.

Ill have to do some more investigating.

[qrz]

 a flat line is usually the loss of vertical deflection. occasionally, there may be a cold solder joint feeding the horiz yoke that will cause a flat VERT line . but,  this is VERY infrequent.
if the horiz output xistor fails , there will be NO high voltage and thus,  NO DISPLAY at all ..

the vert output IC may be "toast" and perhaps the supply res and diode on the 20-30v source.
screen pic does show some foldover , so there are caps that should be changed as well ....

qrz

[grantspain]

not your model BUT many machines in the u.k used pentranic monitors(i am sure its ch1450),there was a lovely design fault whereby the frame i/c had a crappy heat sink and after time it would develop bad solder joints and in turn start to overheat the smoothing cap which would then break down completely and then in the extreme would cook the diode
the symptoms would start with a frame foldover gradually progressing to a full frame collapse

[Arm123]

Hey guys..  thanks for the insight.

if the horiz output xistor fails , there will be NO high voltage and thus,  NO DISPLAY at all ..

Indeed, there is no display anymore.  But after changing the HOT i can assume its not that.  So i think im going to try to locate the vertical output IC and replace it.  See what the result is.

not your model BUT many machines in the u.k used pentranic monitors(i am sure its ch1450),there was a lovely design fault whereby the frame i/c had a crappy heat sink and after time it would develop bad solder joints and in turn start to overheat the smoothing cap which would then break down completely and then in the extreme would cook the diode
the symptoms would start with a frame foldover gradually progressing to a full frame collapse

Just a couple questions if you dont mind educating ---my bottom---   

For future reference....

Whats the "frame i/c" ?

And whats a "smoothing cap ?"



Thanks guys.

[grantspain]

us brits use different terms than our american cousins
frame i/c=vertical output i/c
although this is the same
smoothing cap=electrolitic capacitor acting as a voltage smoothing component on the frame(sorry vertical)i/c voltage input pin

[Arm123]

lol..  thanks mate.

I need to get the lingo down, so i can communicate with those who use a 'foreign tongue’ such as your self        J/K

I was pretty sure of the first one, because of a similar term 'frame buffer' that I do know.

The last one, I was clueless and wanted to confirm.

Thanks again.  Ill keep plugging away at this puppy until something positive happens.

Ill keep you all posted.

[Arm123]

Ok, I got around to looking at this thing.  Being summer and all, I want it fixed.

I went threw the board, found a bad solder joint on one of the coils near the PS section.  Re-flowed that, and started testing the caps.  Checked C516 start up cap as well as C551 and c313.  All seem to check out except the large startup caps (100uf 200v) they were leaking heavily, down to less that 20uf (probably what was causing the folding?).  I replaced them.

Then I checked Fet Q501 and start-up resistor R510.  The resistor is fine.  However, the Fet seems to only read on 1 of the 6 diode test combinations (should be 2 readings).  Which leads me to believe that its bad.  I have also tested for continuity, and get none in any combination.

I can’t seem to find a replacement for it.  Looked threw a dozen local shops to no avail.

I also replaced the HOT and an5521 frame IC for good measure.  Would you guys bother to fire this up with out replacing that Fet ?

[Arm123]

Just did some continuity comparisons with the old and new an5521.  The old one is indeed toasted, so that makes me feel a bit better.

I’m just concerned about the Fet possibly being bad.  Any second opinions ?

[grantspain]

i was kinda expecting IC2 HA11235 and a few of the caps nearby to be the culprit in your case

personally i do not think the FET will be faulty,unless you really screwed the B+ right up-still doubt it though

[Arm123]

Hmm.. 

I know that an5521 was bad because i found a short on pins 1 and 2.  None on the replacments.

IC2 ill have to see if i can find a replacment HA11235 to at least compare it with.  Ill also check thise caps around it.

About the Fet...  I cant seem to find a replacment.  I just did a standard transistor / diode test on it and only got 1 positive result out of 6 test combiations.  There 'should' be 2 positive results.  Do you think its bad ?

[grantspain]

i can call pentranic to find an equivilant
i am pretty sure you will get a diode reading from source to drain only

[Arm123]

Thanks Grant, makes me feel better.  Ill try and fire this thing up.

I cross referenced that 2SK1507 to 2SK2645 or NTE2989, just incase anyone wants to know.

[Arm123]

Well...  I tried to fire up my Pentranic after make my mods and it didn’t work     Still, same chirping.

I put my ear to the chassis and the chirping seems to be coming from the top right of the board.  Where the FET and sub power board are located.

Since i still have not replaced the FET transistor, i think ill do that and check on a few other components in that area.

[grantspain]

just helped a chap with a 988 chassis and was getting a similar problem,when you swapped out the horizontal output transistor(if it had a metal back) did you refit the insulator sheet

[Arm123]

Hey there Grant.

The original HOT did indeed have a metal back.  However, the equivalent replacement did not.

Still, i used the insulator backing...  Same issue with both HOT's.

Im actually convinced that the original HOT is still good / working.

[grantspain]

i still think its something to do with ic2

[Arm123]

yup, ill change it and the surrounding caps...  Just didnt have the parts on hand, so i left it for last.

[gokun]

Hey man I just fixed mine!
take a look at my post about the last batch of stuff I replaced and see if it helps you...
I never did replace those 2 resistors I mentioned might be causing the no power deal btw....they were fine.
Also I found an exact match for my FET if you need a 1507 I have 2 spares. Anyway, good luck and I will continue to follow your thread and try to help where I can.  Good luck!

[gokun]

Just curious if you had any luck with this yet?

[Arm123]

Just pulled the trigger on the parts i needed...  IC2 and the FET, waiting for delivery.

Ill make sure to update with my progress, or lack there of  ;-)

[Arm123]

Replaced the Fet and IC2.  I checked both of the 'pulled' parts for shorts and they came up clean.  So im not optimistic, that they were bad...

I also checked D502 and it turned up as working.

Just for the hell of it, i replaced Q302.

I really hope this works   

[gokun]

Hope springs eternal-Let us know how it turns out!

[Arm123]

Tried it yesterday and its still chirping.

I'm sad, but i guess i must keep searching for the culprit.

I may have to send this one off the Rick N

[gokun]

well crap in a hat....are you sure the flyback isn't blown out? or maybe some part on the subpower board? just thinking out loud....subpower board being bad can cause lotsa crappy problems...and continually cause components to blow out(I learned that one the hard way0_o)

[Arm123]

Just found D506 open...  Let us prey   

[Arm123]

Ok...   I just went over to where this beast was stored and fired it up, after replacing D506 (15df8) with a NTE577.  I finally got an image !

Here is the result...



As you can see the flyback 'screen' control and geometry pots need adjusting.  However, there appears to be a portion of the screen that is 'compressed' to one line.  The middle section of the screen is missing and compressed.

Im thinking this has something to do with vertical deflection ?  So i am going to check IC3 (an5521) and IC701 (LM1203N) for shorts and bad solder joints.

Anyone see anything like this before ?  Could it be a pot on the board that needs adjusting ?  Iv never seen a control on any chassis that had such an affect on the picture before.

The saga continues ....   

[Arm123]

Im wondering if i damaged IC3 (an5521) by trying to start the monitor to test it...   because D506 was open ?  I checked it for shorts but found none.  Maybe its just malfunctioning...

[gokun]

Well, congrats on making some progress first of all! I know first hand how frustrating this crap can get...somewhat like a dog chasing it's tail at times...while on fire...
anyhoo, I played with all my knobs on your behalf(now that sounded bad!) and I cannot get it to make that white line like you have so I'm guessing you're right and something else is amiss...
correct me if I'm wrong here(cause I probably am) but it kinda reminds me of vertical collapse(right term?)or rather the start of it...that's really the only time I've seen or heard of the line in the middle symptom...but bare in mind I'm still very new to all this so definately wait for grantspain and the others to chime in before you listen to me ...still I think you're on the right track, and the parts you mention are likely places to start, so don't give up and keep us informed! Good luck!
[EDIT]
as for the IC, I think it is possible to damage it like you mention...speaking personally, I am very very paranoid, so I would probably replace it just to be safe...after all, it couldn't possibly hurt.

[Arm123]

Thanks gokun.

It is a pain in the --I'm attempting to get by the auto-censor and should be beaten after I re-read the rules-- because this showcase cabinet is 50 miles from me.  So i can only take the chassis home and make mods, then go test every other weekend.       At least im closer than i was before, so i cant be too unhappy.

I am just wondering if this looks like bad case of 'fold over'  to anyone, or the start of vertical collaps ?

Just wanted to get some opinions.

[grantspain]

what voltage do you read on d506?
have you checked d399,401,407,r336,c393,326
could be the ic3

[Rickn]

Replace C318 it causes some real weird problems at times.

Rick N

[Arm123]

Grant and Rick...  thanks very much for your input.


Grants suggestions:

Even though i looked over those diodes before, I checked D399, D401, D407.  Then i checked C393,and C326.  All was well.  However, C510 (right next to C326) had a cold solder joint on one leg and pulled right out with little to no force.  So i touched that up.

I did find something interesting with R336 though.  On the schematic, its supposed to be 1W 4.3 ohms, but mine reads as 100 ohms. Is that odd ?

I could not take any voltages at D506, because the tube is not at this location, but i will tomorrow.



RickN's suggestions:

I pulled off that TAN C318 and gave it a look.  It looks brand new, and reads above spec. when tested.  Should i replace it anyway for good measure ?



Thanks again guys, im just trying to gather up a parts list here, because i have replaced so many things on the chassis and had to order out (mouser) for the parts.  So its getting pretty costly...

At this point the only toasted components that i have found are D506 and IC3 (an5521).  I may just replace IC3 again and test tomorrow.  Wish me luck   

[Arm123]

I changed C318 (TAN 2.2u 16v) and IC3.  Still the same image persists.  I started looking around at some other parts.

Found a couple of odd things while poking around....

C333 (330u 25v) failed, replaced it
C907 (4.7u 75v BP), in its place was a 10u 50v BP part
C392 (22u 50v), in its place was a 22u 25v part
R336 (1w 4.3ohm), in its place was a 1w 100ohm part

Does anyone find the above strange ?  After all, the schematic states different parts.  Should i change the parts back to the origonal stated by the schematic diagrams ?

[grantspain]

r336 should not be 100ohm-25" tube is a sort link,29" is 1ohm 2 watt,33" is 4.3ohm 1 watt
there are a few other tube size dependant components

[Arm123]

Yup...   this chassis is for a 33" tube.  I saw that R336 was dependant on tube size.  So i will be putting in the correct part value (4.3 ohm 1w).

Someone obviously went threw this chassis and make some wrong component substitutions.  So this will make fixing this thing that much harder.   

[grantspain]

yes thats always a danger,someone may have had a go at this before you-i have had similar problems over the years
follow the schems not whats on the chassis

[Rickn]

So before you go changing all those parts to what the schematic says... need to clarify. Did the noard work right at one point and then develop this problem?? That is without having anyone monkey around with changing parts- if so do not rush to change them.

I will be back in the shop tomorrow or Tuesday and try to find time to check a 32" board to verify what the values are.

If you do not hear from me by Wednesday, then e-mail me direct to remind me.

Rick@Niemandisplays.com

[Arm123]

Thanks Rick...

Since i have aquired this monitor, its never worked properly.  It did have a better image than this, before it totally failed.

Im just checking and making notes thus far.   So i wont actually change anything till i hear back from you.

[Rickn]

just checked the values of the components on a good board (never been changed0
Your board has the right values C333= 330u, C907= 4.7u, C392= 22u, R336=4.3 ohm.

When you changed c318, did you realize it is polarized and must be inserted correctly?? Also, you mentioned C333 had failed- check R401 and the check the 18 volt line to be sure it is 18 volts.

Good luck

Rick Nieman
Rick@niemandisplays.com

[Arm123]

Happy Monday Rick   

Actually, your saying that the schematic values are correct and the parts in my chassis are wrong (ie 336 has a 100 ohm, i will change it to 4.3 ohm).

I will also check R401 and TAN C318, im certain i installed it with the correct polarity.

Thanks for confirming.  I have actually made note of several parts that differ in value from the ones in the schematic.  Im going to post them here, just for fun, once im done adding the correct value parts.


Thanks for double checking.

[Arm123]

So far i found the following parts with the wrong values...  i corrected them.


R336 found 105ohm, replaced with 4.3 ohm
R369 found 1.6 ohm, replaced with 3.3 ohm 5 w
C907 found 10uf / 50v BP, replaced with 4.7u 75v BP
C392 found 22uf / 25v, replaced with 22uf / 50v

[grantspain]

does it work?

[Rickn]

Your board is right... the schematic is generic. All boards are subjcet to change by the manufacturer tomatch tube and yoke types.

Rick

[Arm123]

does it work?

Unfortunately, i cant test this until Saturday...  This blows   

Iv made notes, of what the previous values, of the components i replaced.  So, i can go back to the seemingly 'incorrect' values.

[Arm123]

I just pulled L501 and the outer plastic casing crumbled off and looks burnt.  This is probably what i smelled when the monitor initially failed.

Im not sure how to test this with my DMM...  any ideas ?

[Rickn]

Yeah, sounds like that could be part if not the whole problem. To measure it you will need an inductance meter. Probably dont have one... right.

Any chance you have an adjustable DC power supply... if so you can lift the coil and substitute the 18volts for 18 volts supplied by the flyback.

Richt now all the components on this line R401,D304,C333,L401,C402 are suspect.

RickN

[MonMotha]

I just pulled L501 and the outer plastic casing crumbled off and looks burnt.  This is probably what i smelled when the monitor initially failed.

Im not sure how to test this with my DMM...  any ideas ?

You can do a partial test by just using the resistance (ohms) setting.  After letting it settle for a few seconds, it should read something very low (usually less than 1 ohm, but sometimes up to 10 or more, depending on construction).  If it reads as an open, it's toast.  If it reads low ohms, that doesn't guarantee it's good, but if it reads as an open, then it's definitely broken.

[Arm123]

Rick, are you sure you dont mean L401 on the 18v line off the flyback ?  Cuz im looking at the schematic and dont see how L501 (my burnt part) connects with R401,D304,C333,L401,C402

In any case, thanks Rick.

I don't have an inductance meter, Iv never had an inductor part go bad on me before.  Ill have to buy one.

I was in the process of testing all the components on that line with L501.  Ill just replace L501 anyways and check the components you mentioned.

Your the best Rick..  thanks for being so patent with me  ;-)

[Arm123]

I just pulled L501 and the outer plastic casing crumbled off and looks burnt.  This is probably what i smelled when the monitor initially failed.

Im not sure how to test this with my DMM...  any ideas ?

You can do a partial test by just using the resistance (ohms) setting.  After letting it settle for a few seconds, it should read something very low (usually less than 1 ohm, but sometimes up to 10 or more, depending on construction).  If it reads as an open, it's toast.  If it reads low ohms, that doesn't guarantee it's good, but if it reads as an open, then it's definitely broken.

I checked the burnt part and let is sit for a couple minutes.  I get 0.00 ohm with no fluctuating...  Fried ?

[MonMotha]

0.00ohms is the expected ideal value for the resistance of an inductor.  It may still be bad (could have failed partially-completely shorted), but it could also be fine as a measurement of 0 ohms does not indiciate a failed or good inductor.

If you had measured an open (infinite ohms), then you would know it had failed from that test.  You'll need an inductance meter to test further.

[Arm123]

no worries...  ill just replace it for good measure.

[Arm123]

Checked all the parts on the same line of L501 and L401.  Everything seems to check out ok.

Im thinking its L501 thats burnt, because i get no fluctuating readings like a few other inductors iv tested (fluctuating from 0.0 ohm to 0.5 ohm).

Ill have to make my way down town to see if i can fetch these parts.

[Arm123]

"It works! Ha ha, it works! I finally invented something that works."
—Doc Brown


Well, I spent 7 long hours on this thing.  Finally got it working 

I started out by putting in the old parts that i replaced (HOT, RGB amp, FET, IC2 etc)...  to see what was actually initially at fault.   My initial replacements of IC3 and D506 were the only components that were causing the thing to not fire up.  However, after a couple minutes of running, the old HOT shorted.  So that was finally needing to be replaced.

Still the problem persisted, and i was out of ideas.

I decided to replace R336, with the same value fromthe reference schematic, and see what would happen.  To my suprise, i got rid of the 2 lines and the image was filling up the whole screen !  However, the chassis was screaming at me and i could not get it to sync horizontally.  It was almost there, but not all the way.  So i replaced R369 with the proper value, and all systems were a GO !

So i guess this turned out to be a hack job by someone else to account for the failing symptoms of a dying part ?  Who the hell knows.

I just want to say thanks to all that took the time to read this thread and suggest something.

Thanks to all   

[grantspain]

i am really glad you got this fixed,it has been an epic crusade
 

[Arm123]

i am really glad you got this fixed,it has been an epic crusade
 

Thanks very much for your help along the way Grant.

This has been my hardest fix ever !  I wanted to cop-out and send the thing over to RickN, but i resisted the urge.

I did buy an inductance meter, and tested those parts mentioned above.  They all checked out ok, even the burnt one.

Just for a summary of info, this is what ended up fixing the trouble....


Screen curl:
C516
C551
C313

Vertical collapse:
D506
IC3 (an5521)

Strange lines mid screen:
R336 found 105ohm, replaced with 4.3 ohm
R369 found 1.6 ohm, replaced with 3.3 ohm 5 w


The picture has a very small / fine wobble to it,  which you can barley see.  I think ill replace all those old IC's and the FET with new ones for good measure.

[gokun]

NICE!! Congrats!!

[Pinball Wizard]

Well I'm fighting the same chirp noise as you were. HOT checks out good, IC3 isn't shorted and neither is d506. What should I be looking for?