1084ST Won't power on.

KBQ

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Bit of an odd one this.

Old Commodore 1084ST. Left running all day, generally showing signs of being a bit knackered (flyback whine, blurry corners) but fully working. But just now when I've had my back turned, died!

Now it just shows a vertical white line, which once a second collapses into a white dot, then expands to a line again. Monitor power LED turns on and off with this, and it also makes noise like it's powering on and off.

I know this is a rare variant, but I guess CRTs are all similar enough... I can't find any manuals online. What part failure is this, normally?
 

roy_bates

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AmiBayer
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you have vertical and horizontal collapse,maybe even flyback failure...


you might have bad solder joints,but dont get your hopes up.
 
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KBQ

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Well I think the most important symptom is rapid powering on/off at 1 second intervals. Is that the flyback?

Kindof bummed out because I just bought this with an A500. A500 was DOA but I thought the monitor would at least be nice.
 
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roy_bates

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AmiBayer
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i wouldnt know what the exact problem was unless it was siting on my bench right in front of me.:)

the power light going on and off would be an overload somewhere probably on the high voltage rail.
could very well be the flyback possibly other parts as well.

i wouldnt turn it on again if i was you,it wont get any better.


EDIT: there is a way to find out if its the flyback but suggesting it to people who may have no electrical knowledge can be a danger in itself.
 
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KBQ

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I know enough not to blow myself up, I can solder and do work on things myself.
 

roy_bates

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AmiBayer
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lol,ok you discharge the flyback remove it then check the voltages on all the rails.

if they look good and the power light stays on with the flyback removed its most likely the flyback.
i dont have a service manual for this monitor though,but i would imagine the main rail is around 125 volts dc when stable.
i think the tube itself is a philips but the chassis isent.

you dont want to messing around in the back anywhere near the flyback itll generate around 25k volts when working.
 
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KBQ

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Taking it all apart now. How do you remove the small board on the back of the tube? I would leave it in place, but there are some wires directly soldered to the main board so I need to take them both out together.

I tried pulling - firm but gently - and it did not move. I don't want to break the glass.

EDIT: Gave it a firmer yank after wiggling it about. There was hotglue where I couldn't see. All unplugged now.
 
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KBQ

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Oh now I'm reassembling it (minus flyback) and I realize I've done something incredibly dumb...

The board on the tube neck has two identical 4 pin connectors. One goes to the video in socket, the other goes to a small pcb which plugs in the far corner (right hand side closest to you from the back) of the main board.

I've only gone and unplugged both without marking which is which!

Looking at each plug, one is R,G,B, Ground.

The other is white, red, blue, Ground. white and ground use the same insulation.

neck board ports, each have one pin go to ground. But the interesting port's traces have only two wires go directly to an IC, the third to wherever. So that one must be for the second cable...

This is not as hard as it seems! I could get back into this.


_________

1:36AM update:

SUCCESS! after a snack break I finished reassembling the monitor, without the flyback transformer. Turned it on, and it stayed on!

Of course I turned it off after a couple of seconds because I have no idea what running it without such a vital part could do to it. But now we know flyback is kaput, time to find a replacement. I'll be happy to be rid of that horrible whining sound it makes.

It's identifying marks are:

top of flyback : 26 18 R
above focus control: CMP-15A

and a sticker:

SAMPO 9241
FEA188
42-025-01
MADE IN TAIWAN

Ten pins underneath in a horse shoe shape, and an eleventh in the middle.

Feeling positive about this! I'll also need a HOT right? How do I identify that?
 
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roy_bates

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AmiBayer
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it wont hurt it to run it without the flyback.

the hot usually will be a large transistor on a large heatsink near the flyback


was that what was written on the flyback? the sticker you mention.

if you can,take a clear picture of the underneath of the flyback directly into he pins and label please.

EDIT:i did quite a bit of searching and investigation,the replacement for the flyback(LOPT) is a HR7495
one down,now if you can tell me whats written on the hot transistor...
 
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roy_bates

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cant see the pinout or any specs for that lopt you listed.yes i did see it.
same here couldnt find any hr 7495 anywhere...

send them an email asking if they have any hr 7495 lopts or if they can get any.as they deal with hr deimen who actually make them.
im a 1000% it is a HR 7495

also send them the sampo fea188 42-00250-01 code for compatibility, lopts are all different and not universal so you have to absolutely sure its the right one.

ill see if i can find that part you listed as a hot transistor...


EDIT: here is a pack of five transistors...

http://www.ebay.co.uk/itm/S2000A-DU...A-PACK-OF-5-/230678119283?hash=item35b57cc373
 
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KBQ

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Shot an email to them and I'll see how this goes.

Believe it or not buying this monitor was supposed to save money! Oh well, can't back down now.
 

roy_bates

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i have a lot of crts and i like using them.and i enjoy servicing them.

one risk in having one is getting parts for it when it fails,ill keep an eye on this thread as i can actually get parts for nearly or all of my monitors..but i dont have this particular one it never took my fancy.
and i have all the service manuals for the ones i have(filled with notes that i put in them on parts references)...i also cant find one for your monitor and i did look...

...sometimes you have to be very persistent in looking and hunting for parts they can be very hard to get sometimes,and if your very unlucky,impossible.

i have been known to put a monitor in storage for months sometimes over a year while i search for parts for them...its the truth.


as a rule of thumb,if i cant get the service manual or parts i wont bother with it.
if it worked when i get it after the above its on borrowed time.and i accept that when it stops working.
 
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KBQ

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Well I'm having a bit of back and forth with Donberg at the moment, not all that impressed.

Sent them an email saying what flyback I was replacing, the HR7495 replacement I'd been recommended but is not in stock, but I found another one that is in stock that looks like it might be right, can you confirm it'll work?

get an email back, with a price offered for the HR7495, and how would I like to pay?

Sent them another email, debit card please...

Get another email back, telling me to go to the online shop, where they will "send me the link to payment".

Err, it's not listed in the online shop, and how could they send me the link to pay for it there, when their online shop doesn't have accounts?

Looks like this is going to be a long game of email pingpong. Maybe if I type louder they'll hear me a bit better.
 

roy_bates

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ive bought lots of parts from donberg...

just explain how you want to pay,they do accept paypal.

if there is no link tell them.you should of had a link to a basket with options to pay and where its going after...from what i remember.


they are very helpful as long as your clear and to the point,at least thats how ive found them to be.

it still requires alot of patients.

depending on the part a reply could take days.
 
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KBQ

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I did explain how I wanted to pay. They asked, I answered, then I got "To pay by credit card please go to our online shop then we can send
you the link for payment"

Which makes no sense, because if they were "sending me the link for payment", they'd be emailing it to me, and that can be done weather of not I have their website open. It's definitely not something on their website.

I've been as clear as I can be. I've got an X that needs a Y. I was recommended this Y, which your store doesn't have. Can I use this other Y which your website DOES have?

Only needs a yes or no answer. Instead I get arsed about.

I would give them a ring, probably easier than trying to get sense out of the work experience girl manning emails today, but virgin cocked up my phone install so it doesn't work.
 
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roy_bates

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AmiBayer
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ok ,i havnt seen the messages so i can really comment.


like ive said ,only problem is you have to be patient...i have noticed there are two women manning the emails.
maybe one got confused about what you wanted,i dont know.

if they can get the part and you want it,stick with it.
 

KBQ

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Right rang them over skype (there went six quid buying credit) and I've supposedly ordered it, at least the woman who picked up the phone has taken my address and card details. Fingers crossed. Also got the hot off ebay.
 

roy_bates

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ok lets see what happens

which one did you get?
 
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