CM 8833 II repair + Chroma/Luma added.

[roy_bates]

so,lets start with the warning.

#WARNING# these sets hold massive electrical charge even after its been off for ages,so if you feel the need to fix one of these make sure the screen is discharged BEFORE working on the monitor.

now that is out of the way,let me say this is not meant to be a walthrough or how to repair these,its just what i did to fix one i had.
so..lets begin.

first i removed the faulty LOPT.and cleared the solder points ready for the new one.and replaced all transistors in the area even if they have not failed.including thermal grease.

here is the offending part,ready for the bin.

next,i removed and cleaned the sticking mains switch and cleaned it with switch cleaner and greased the innards ready to be installed...
and re-installed the switch and replaced more transistors and regulators in that area.

then i opened this

then installed it.

and the two wires from the LOPT to the tube neck pcb.

at this point i tuned the screen and focus pots on the LOPT as they are set to minimum at the factory,and all is well.as in WORKING as it should

after setting all this up its time to discharge the screen and dissasemble the monitor one last time for chroma/luma to be added...

more to come...

 

[roy_bates]

sorry about the delay,i was repairing a couple of 128+2's for a friend


anyway...
this is what i did to add chroma/luma.this is also explained elsewhere on this site.
removed jumper(9375)
added resistor(3603) 22K
added transistor(7603) BC548B
added resistor(3604) 10K
removed jumper(9374) added resistor(3620) 10K

next,i removed and replaced all the phono sockets on the back as one of them was a bit mangled.
then i added the following:
added switch(SK5) DPDT(latching)
added jumper(9359)
added resistor(3602) 75ohm
plus i changed all the caps as i added an extra switch for chroma/luma and cvbs(composite)

then i drilled the two holes needed for the extra phono and switch cap to fit through.
connected the speaker pcb back to the main board and slid the back on...

so now to see it working

here is a picture of an amiga via rgb.

and a c64 via chroma luma,i had to make the cables
no worries though, they are simple enough.

pictures don't really do this any justice the picture is really crisp and clear,trust me.
next to fix the flap just like my other one.

and closed,lovely

overall,im very happy with this,i think its got loads more years service in it yet

 

[ElectroBlaster]

I had two of these years ago!

One of them belonged to my father who even bothered to purchase the stand upgrade for it!

I sold them on, the better one of the two a few years back!

Trying to remember who had it?

Excellent work btw! This is what recycling really means, instead of doing what the rat race say you should do lol!

 

[roy_bates]

i thought the stand came with them as standard?

or do you mean something else.

anyway,it does gut me when people toss these.they are really nice monitors,when they are working anyway...

EDIT: although i can understand it as they are expensive to a certain extent to repair if the lopt goes.i try to get them when offered as i can fix them.lovely when they are working.
i would even fix them for other people if they paid for the parts.

 

[ElectroBlaster]

The stand I refer to is a proper foot plate like you got with a PC Crt screens. You can tilt and turn the monitor. Why philips never sold these together is anyone's guess... They certainly did look the part

My father gave me the monitor, its box and then another box with the stand in it! This was back in 1995 I think?

Personally I never saw one before that or since. It was like an optional extra? I stupidly never got a photographic record of all this stuff, boxs etc

Actually I may have done some pictures for when I sold them! I need to find these pictures but will need to hunt them down.

 

[roy_bates]

The stand I refer to is a proper foot plate like you got with a PC Crt screens. You can tilt and turn the monitor. Why philips never sold these together is anyone's guess... They certainly did look the part

My father gave me the monitor, its box and then another box with the stand in it! This was back in 1995 I think?

Personally I never saw one before that or since. It was like an optional extra? I stupidly never got a photographic record of all this stuff, boxs etc

Actually I may have done some pictures for when I sold them! I need to find these pictures but will need to hunt them down.

ah yes i see what you mean,i thought you meant the tilt foot on the bottom.
i think they come as standard(they fold up under the chassis)

 

[Zetr0]

A delightful thread Roy - Thanks for Posting !

 

[keitha]

Nice job

I've still got two

However one has the faulty power switch button (have a small box squeezed in between the button and the wall).

Is the button/switch easily replaceable?

I concur Best monitor ever! And not just Amiga wise.

 

[roy_bates]

the switch may be repairable.its the latch that fails to work on these they get stuck.
its the same sort of latch arrangement in the smaller push switches in the monitor."sort of"
its a small bar that swings from one side of the switch in a groove to the other in a v shaped config and rides back and forth as the shaft goes in and out,if it gets stuck..it just stays in one side and cant travel to the other.(the middle infact,on the half stroke and cant go past that point)
normally it is noticed early on,sometimes it might not stay in when pressed...thats the beginning.it gradually gets worse until it wont work anymore.

replaceable? i dont know if the switch is available anywhere, never looked.
it is however,easy to remove.

i think if the switch can be replaced with a bit of effort with another at the same rating just more available type(more common) and then put the cap on the end.

maybe someone could try to source a direct replacement or a more readily available standard switch and modify it maybe to fit the space it was in.

i remember someone finding a source for the original switch,but that was a very long time ago,im not even sure of the make of the switch itself.

 

[roy_bates]

i forgot to post pictures of the cables i madeicard i had to make them because i simply didnt have any spare not the chroma/luma cables anyway.

so here they are.

c64 chroma/luma cables with sound.

amiga rgb cable for this monitor.

all other cables are standard fare, composite, stereo sound etc can be got cheaper than i can make them.

 

[coltch]

I would love to be able to get my two other 1084S's working but am very dubious about opening them up (one had a squeel and went black screen, the other works then trips the power).

Nice work in rescuing something that would normally be scrapped

 

[roy_bates]

I would love to be able to get my two other 1084S's working but am very dubious about opening them up (one had a squeel and went black screen, the other works then trips the power).

Nice work in rescuing something that would normally be scrapped

i dont think i would scrap any of these.

i would fix the monitor for you if you got the parts.i mean it.

shipping them around though is a bit of a hazard on its own,ive said this a few times because its lots of glass and plastic,its a shame really.

 

[reno78]

Hello,

I'm wondering if anyone in the UK or EU would be willing to sell a ready-made parts kit for this mod, to help out those of us who are not used to ordering components ?

There is an online shop in Hungary which has exactly that, but although I'm happy to pay extra for convenience, their prices are really quite a bit excessive.
With shipping it costs <snip> for 4 resistors + 1 transistor, a DPDT switch + cap and their 4x RCA connector panel. That's around 1/3 of the current going price for the 8833-II itself !

Does anyone know of an alternative, or is the price they ask really worth it ?

Thank you.

 

[roy_bates]

thats really alot of money,parts are only about <snip> tops when i did this

the hardest part is drilling the two holes in the case,that was the only part that made me sweat lol

no,i dont think the price they are asking makes it worth it at all,quite the opposite to be honest,it would hurt me to pay that,i may get in trouble for talking costs but it did bother me reading that comment
i suppose im lucky i can do this without having to rely on sourcing parts from suppliers in packages specific to any one monitor as a kit

 

[reno78]

thats really alot of money,parts are only about £6 tops when i did this

the hardest part is drilling the two holes in the case,that was the only part that made me sweat lol

no,i dont think the price they are asking makes it worth it at all,quite the opposite to be honest,it would hurt me to pay that,i may get in trouble for talking costs but it did bother me reading that comment
i suppose im lucky i can do this without having to rely on sourcing parts from suppliers in packages specific to any one monitor as a kit

Thank you, I'm glad I'm not the only one finding this excessive.

Sorry for the electronics newbie question, but what's your go to place for ordering small quantities of components like the resistors and transistor here ? And would you know the suitable models of DPDT switch, switch cap and RCA panel to do this mod ?

Maybe I should accept to pay for this guy's kit to save me hours of research, but <snip> for the RCA panel alone is really taking the p***, and the last straw was when I found out (and showed him) that Hungarian Post had a <snip> service he could use instead of the <snip> he's asking (for about 50g of parts, lol !) and he flat out refused.

 

[Watson]

OK guys no more mentioning prices, it is against the rules after all.

Thanks.

 

[reno78]

OK guys no more mentioning prices, it is against the rules after all.

Thanks.

Thanks for the heads up, I don't come here often. Would you mind pointing me to the rule or its explanation ? I'm not sure I understand why that would be restricted outside of sell/buy forums.

 

[Watson]

No price discussions anywhere on the forum.

If you want to discuss prices, please do so in private and not the open forum.

 

[moggsie]

Thanks for the heads up, I don't come here often. Would you mind pointing me to the rule or its explanation ? I'm not sure I understand why that would be restricted outside of sell/buy forums.

You should know the rules as you agreed to them when you originally joined. Being an occasional visitor is not an excuse.

Regarding your issue with sourcing components, you have to weigh up whether you're prepared to pay a premium for someone having already sourced everything for you vs finding it yourself and costing considerably less. That's what I did when I modded my CM8833-II 10 years ago. I even put where to buy the components (although some of them may now be out of date). Make the effort, you'll feel better for doing so.

 

[roy_bates]

sod it,i had a thought

if he really wants the parts that bad,i'll supply them at cost ,plus postage,it wont be much

he'll have to send me a pm,i wont be able to do it for while im busy,say around two weeks,or earlier

i dont offer to do this sort of thing often so keep that in mind,and i dont want people sending me messages to get parts,but ill make an exception,take it. i wont offer again,im serious