The Workbench

Re: MX6000 shuts down

tournedos — Wed, 04 Jun 2008 02:59:15 GMT

I resoldered a number of solder joints I didn't do last time (including one bad left by myself). The set has now worked fine for hours - even after I assembled it and the room is quite hot. Looks good

Re: MX6000 shuts down

nobby — Mon, 02 Jun 2008 03:56:43 GMT

Re: MX6000 shuts down

tournedos — Mon, 02 Jun 2008 03:45:27 GMT

Not yet, I haven't had the energy to lift the set off the stand so I could pull the chassis completely out. Will do later and report on the results...

Re: MX6000 shuts down

nobby — Mon, 02 Jun 2008 02:58:12 GMT

Did you check the place I pointed to?

Re: MX6000 shuts down

tournedos — Sun, 01 Jun 2008 15:11:23 GMT

Well, in any case I tried to see & listen. There's a definite buzz at the tube neck area (I guess from the deflection coils) but other than that I don't hear anything funny.

However, since I opened the back cover and pulled the chassis half out to be able to see what's going on, the set has stayed on for an hour straight. I guess I'm back at the cracked / dry solder joint theory...

Re: MX6000 shuts down

nobby — Sun, 01 Jun 2008 13:54:48 GMT

Hmmm ... never seen this failure mode on any of the MXs that I have ever seen ....

Re: MX6000 shuts down

Die_Bogener — Sun, 01 Jun 2008 09:53:23 GMT

Hmmmm, listen to the high voltage transformer. It should be a very smooth humming sound.... summmmmmmmmmmmmmmm

If you hear something like summmm-tick-summmmmmmmmm-tick-tick-summmmmmmmm-tick....... the transformer has problems and needs replacement.

This is a very common problem. I've had already several damages on these transformers, almost every MX5000, 30-40% of the MX5500 need a new one, 10-20% of the MX6000 too.

Martin

Re: MX6000 shuts down

tournedos — Sun, 01 Jun 2008 09:22:39 GMT

Last error = no

The set remains in standby after shutting down, so I suppose the CPU is running and would be able to store the error code if it was really shutting down due to power fail signal?

The last time the set shut down, I think I heard a not too loud "pop" sound maybe five seconds in advance. I think it's possible something might be actually arcing... I didn't find any tell-tales about that on the circuit boards the last time, though.

Re: MX6000 shuts down

Die_Bogener — Fri, 30 May 2008 12:50:24 GMT

Have you checked the selftest? There should be an error message stored in the cpu.

Last error ....... ?

Re: MX6000 shuts down

tournedos — Fri, 30 May 2008 07:11:56 GMT

Aww, crap. The shutdown business is back again. 15 minutes from a cold start, and back to standby. Audio mode works fine however (the tv stays on for at least an hour), so I'd expect the problem to be at the line output stage?

I didn't replace any of the high voltage plastic caps nor the big diodes, all electrolytics are new however (except for the high voltage ones) and were spec'd at 105°C. Any ideas?

Re: MX6000 shuts down

tournedos — Tue, 13 May 2008 14:00:50 GMT

Well, this has been a good start for the week!

I got back from the trip with just a bruised shoulder (shotgun cough) and a biblical hangover - the country is almost affordable at the current rates!
after replacing TR11 (BC557) and some more resoldering, the MX sprung to life, and I've been watching it for two hours straight now!

Looks like 60 euros for a clean MX6000, motor stand and Beo4 wasn't such a bad deal after all

I will be returning on the general forum with some programming questions; the Beo4 and myself don't seem to get along too well. Thanks a lot to you all for your help!

Re: MX6000 shuts down

nobby — Thu, 08 May 2008 14:19:27 GMT

Trace them back ... probably only 11, 10 and 9.

You lucky thing ... Iceland!

Neil

Re: MX6000 shuts down

tournedos — Thu, 08 May 2008 13:55:16 GMT

nobby:
Also check the drive transistors for the BUT12

TR11 indeed seems to be shorted. Guess I'll just have to test just about everything

(once I come back from my long weekend in Iceland, that is )

Re: MX6000 shuts down

nobby — Thu, 08 May 2008 03:19:08 GMT

Also check the drive transistors for the BUT12

Re: MX6000 shuts down

ipaul — Wed, 07 May 2008 15:50:12 GMT

Try checking the diodes on the secondairy part of the supply for short-circuit, especially the 2 doides mounted on the cooling plate (don't have the numbers at hand here).