CurtPalme.com Home Theater Forum

haireez · Posted: Mon Mar 28, 2016 10:50 am Post subject:

Thanks to everyone for your contribution and concern. The set that I got from Curt was perfect and I'm extremely thankful to Curt for selling me at a very good price eventhough the shipping cost is very expensive to Singapore.

Just for clarity, I made a mistake when I assemble the unit to the ceiling. Everything is perfectly new and there's no leaking on the bellow. What happen is that I made some modifications to the top 3 fans + another fan that I installed on the rear heatsink (it was very quiet with my existing Vision 1). After installation, I start the machine and found the fans were extremely nosiy eventhough it has the same setup with my first Vision 1. Due to this, I took my existing Vison 1 modified fans and installed it right above the projector and disable the fans in the projector. I did not realised that the fans did not actually cooling the HDM and that why it shorted it. Julian was spot on when he was curious on why the HDM overheat.

By the way, I will buy some materials during the weekend and hope that the new HDM can be repaired. It is way too costly to ship one back to Curt (US)and ship it back to Singapore.

haireez · Posted: Mon Mar 28, 2016 1:51 pm Post subject:

Guys,

Here are some updates:

D21 - Not tested yet
D22 - Good as only 1 direction has reading.
R93, 96 & R1001 - Bad (no continuity & no reading)
R62 - Actual value 10.6ohm (specs: 10ohm) Not too sure good or bad.
R91- Actual value 1.6ohm (specs: 1ohm) Not too sure good or bad.
R98 - Actual value 220ohm (specs: 22ohm) not too sure why high but no continuity & I think it's bad.
Q20 - it's been removed from the board but not too sure how to check. Definitely no continuity between D & F. Appreciate if someone could show me how to check Q20.

Do take note that I remove one side of the resistor (de-solder) before taking measurement using a digital multimeter.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

What are the colors of the tolerance bands on the resistor?

Silver, 10 percent.
Gold, 5 percent.
Black, 1 percent.

If the measured value is within the tolerance indicated by the tolerance band (fourth band) then the resistor is good.

A 1 ohm resistor measuring 1.6 ohms would be bad.

But before you assume it's bad, short your meter's probes together and ensure that the resulting reading is actually zero ohms.
If it's higher than that, then subtract that amount from any reading you make to get the true value.

haireez · Posted: Mon Mar 28, 2016 2:29 pm Post subject:

Hi CM,

You're right as when I probe them together, I'm getting 0.6ohm reading. So practically, R62 & 91 are good.

How do you measure Q20 then?

tschaeikaei · Joined: 08 Apr 2013 Posts: 489 Location: Germany/Saarland

Ok, that sounds to be is less broken than it could have been.
Don't mind that 1.6 Ohms, it's pretty normal for a multimeter to be way off in the very low resistance ranges.
For a proof simply short the probes together. Do you read 0.0 Ohm? Mine are always like 0.2 or 0.3, somewhere in that range.

tschaeikaei · Joined: 08 Apr 2013 Posts: 489 Location: Germany/Saarland

Oh, yes i do get the photo. You additionally use the original belly fans blowing down on top of the ceiling mounted pj?
They should be fitted tight to the chassis, the airpressure through those little holes in the sheet metal won't let enough
air pass through to cool the HDM and FGM.
If you want to discuss cooling, we should most likely use another thread, this one could get messy otherwise.

haireez · Posted: Sun Apr 03, 2016 1:06 pm Post subject:

Hi Julian,

Latest update as per below:

D21 - value is 685 on diode mode
D22 - value is 683 on diode mode.
Bought a new BYV26B and result is 690 on diode mode. I think both are good unless you feedback otherwise. I bought new and can change it if need to.

R93, 96 & R1001 - All are bad. I bought 1ohm resistors for R93 & R96 but couldn't get 1/3 watts. They only have 1/4 watts. Anyway, I have bought them and do let me know if I can replace them.

As for R1001, they only have 1/4 watts and not 1/3 watts. Can I use this value of 1/4 instead of 1/3 watts?

R62 - Good - no need to replace.
R91- Good - no need to replace.

R98 - Bad, schematic drawing indicate as 10ohm but actual resistor colour code as Red Red Black Gold which is 22ohm. Anyway, I have bought 10ohm 1/2 watts as per drawing requirements but not too sure whether I should buy the actual resistor on the board. May need you to advise me on this.

As for IRF730, the shop doesn't have the exact mosfet but recommended me to use SSP6N60A (526) instead but I'm not too sure whether it's compatible.

I will wait for your advise before I proceed with the repair. If not compatible, let me know so that I could purchase them from Element 14 but it might take awhile before I could get them.

tschaeikaei · Joined: 08 Apr 2013 Posts: 489 Location: Germany/Saarland

Don't use that transistor. Check ebay for IRF730 or get one somewhere else.
The one you bought has different specs.
If you found a 22Ohms resistor as R98, replace it with a 22 Ohms. Do not use 10 Ohms,
we do not know which other parts are different between your HDM and the schematic.
1/4W is even not good. If you don't have the exact replacements, do not use the HDM.
BYV26B (and C) are 415mV drop. Could be you have another series or manufacturer than i have, the datasheet says 1.3V max.
I'd say the diodes are ok.

You can replace the 3 parallel resistors with a single one of 0.41 Ohms 1 W. That should be even harder to get and don't use the wire wound type.
Only metal film.
You can also use 4 1/4 W resistors in parallel, but make sure you get 0.407 Ohms resistance over all.
Don't measure, use Ohms law.
Your meter is not accurate at all in this low mode, especially not under 1 Ohm.

Regards, Julian

haireez · Posted: Mon Apr 04, 2016 11:04 pm Post subject:

Thanks Julian,

I've already ordered from Element 14 yesterday for the correct value and will install once I have the materials.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

If you have to ask how to measure and check a transistor, then I would suggest, gently but strongly, that you do not attempt to repair the HDM yourself and just buy a tested good spare.

I predict spot burned tubes in your future.

Know the limits of your knowledge.

If you want to do something that requires greater technical knowledge, take a few night classes in electronics, THEN attempt repairs once you have an understanding of the circuits, their function, and the function of the components that comprise those circuits.

I am only trying to save you from the wreck that I think you are dead set on driving into.

Buy a good spare board. Stick it in and forget about that. Learn more about electronics, then fix your bad board when you are ready to do it in a knowledgeable fashion.

haireez · Posted: Tue Apr 05, 2016 2:37 pm Post subject:

Hi CM,

Truly agree with what you are saying and that's why I'm getting the exact value & specifications to replace the suspected components. If Curt is here locally in Singapore, I would definitely send my HDM for him to repair.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

The problem is that you need to understand electronics well enough to be able to determine WHY the components failed.

You get a flat tire, you patch it, or replace it, you go driving, you get another flat tire. You keep replacing tires and they keep going flat.

You're not paying any attention to the box of nails somebody dropped in your driveway.

Parts that fail always fail for a reason.

Just replacing the failed parts doesn't necessarily mean that you have addressed the CAUSE of the failure.

Simply replacing blown parts is not the answer. You have to figure out WHY they blew up, and fix the CAUSE of the problem,
and since you've said you've had overheating problems with this for a while, as I remember, then the parts you're trying to change out are only a symptom of a larger problem you're not seeing.

Until you fix the root cause, the new parts will overheat and blow up, too.

haireez · Posted: Wed Apr 06, 2016 11:48 am Post subject:

As mentioned in my upper thread (photos above), the real rootcause of the issues is known. It's due to my negligence of testing the external belly fans and placing it on top of the projector which did not provide cooling to the projector. During this testing process, I disabled the belly fans inside the projector (see photos above).

I didn't realise that the direction of the external test fans that I placed on top of the projector did not provide cooling to the HDM or the focus board.

I did the test in order to understand why the existing fans is so noisy and to make comparison with another set of belly fans from my 2nd set vision 1. In conclusion, it's not an existing overheating problem that I don't understand but the reason above is the root cause. Hope this explanation is clear enough.

mp20748 · Posted: Thu Apr 07, 2016 6:35 am Post subject:

haireez · Posted: Sun Apr 10, 2016 2:25 am Post subject:

Guys,

Just to give latest update on the HDM status. I have replaced the necessary components and the HDM is working perfectly without any issues running for more than 9 hrs yesterday. Special thank to Julian for his sincerity in trying to help the so called ' NEWBIE' (EVENTHOUGH I HAVE BEEN WITH CRT SINCE 1995) and it's only people like him will encourage the CRT hobby to continue in existence even in a small and dying community. There's not many people in Singapore still having a CRT right now. I won't be surprise if the number is less than 5.

As for other comment's, thank you for your concerns on safety's aspect. However, I believed that in order to encourage more CRT owner to engage or seek help in Curt's forum, I would appreciate a positive communications rather than demoralising others and eventually, less and less people visiting Curt website.

Once again, I truly appreciate Julian for his patience in guiding me to resolve my HDM issues. Thumbs Up

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Nobody's trying to demoralize anybody. We've made an attempt to keep you from blowing yourself up, OR your projector, that's all.

It was almost a "I'm having trouble with my transmission, can you tell me how to fix it?" scenario.

This was not really all that different from someone with a computer problem saying "I think something's wrong with my computer and I'm sure it's one of those doohickeys on the motherboard. Can anyone tell me which one I need to replace, and how to do it?" .

Not quite that bad...but the general idea is similar.

I'm a decent technician. But I don't mess around with repairing parts of circuits that, if they should fail, will cause damage that I am not willing to absorb. Like line burned CRTs. I'll toss the HDM in the trash and get another one before I'll mess with those high voltage deflection circuits.

haireez · Posted: Mon Apr 11, 2016 9:59 am Post subject:

By the way, does anyone knows how to adjust start pulse? The step by step how to do it?

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

That was covered in the first few posts in the first page of this topic.

haireez · Posted: Mon Apr 11, 2016 1:49 pm Post subject:

It doesn't moved. Maybe need to get the correct frequency band. Thanks.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Yes, you must find the right frequency band. It'll probably be 2 or 3. 1 will be for very low resolutions, 4 will be for extremely high resolutions. (Or refresh rates.)