Marantz CD4000 dim VFD display repair
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- čas přidán 27. 08. 2024
- We take a look at a Marantz CD4000 with a very dim display. Dim as in WAY too dim to read. If you jam your face up against the screen and switch the lights off you get something so it is 'working' but it is impossible to use. So what is to be done?
Written up here:
www.retroginge...
When measuring the filament voltage, you should set the multimeter to AC, as that is probably what it gets. When in DC-mode you won't get a usable reading.
Glad to see that blasting the filament can brighten the display. Note: With a little editing, your 25 minute video could have been reduced to 2 minutes.
fr kinda bummed i sat through this whole thing. btw, is that a squarepusher CD?
When measuring the filament voltage, if you choose AC you need to put your probes on each filament end, if using DC on your multimeter you need to put the negative probe onto the chassis and the positive probe to one of the filament ends, it's usually around 30 volts DC.
On my HP power supplies and bench DMM's, the filaments are ran at 5Vac.
I have been seeing 6V AC being used for filament voltage.... 30V seems like a lot even for an output triode tube!
@@PeterMilanovski the 30v is not across the filament, that is the offset voltage from ground. The VFD needs around 30v to work. Look at the datasheet to the chip driving the VFD, most I seen has split supply rails of +/-16v.
@@Ozzy3333333 ohhhh ok, sorry... When I was reading this thread it sounded like someone was saying that the heater needs that much...
The heater element usually needs around 6V AC and you then need around -31V for the rest...
I have quite a few equipment that has VFD displays and some of them are not as bright as they used to be, which explains why I was here!
I went around looking at all my VFD displays with my thermal camera.... Can't believe that I didn't think of doing this ages ago and I saw some interesting results.....
The hottest display was on my Panasonic VHS which always shows the time regardless of whether it's on or off!
The heating filament is always on if the VCR is plugged in and turned on!
My pioneer DVD/HDD recorders VFD display is cooler but a lot dimmer!
My Sony ES amplifier, it's filament can be seen glowing red faintly, I have owned it since new and it has always done that, it's display is beginning to fade also, I have had it since 1997....
So far, from what I have gathered from what I have seen.... Some VFD displays can benefit from heating up the filament, but you have to make sure that it's getting the correct voltage for the filament and the control voltage which is usually -31V..... Or whatever it may be going by the service manual....
Those are the 3 different things that must be done to make sure that the VFD display will work properly.... Just doing one and not the others is not the correct way.....
There are vacuum tubes from the 1920's that are still functioning properly today..... If it was made well, and something else doesn't destroy it, it's going to last a lifetime!
That's my take on this matter so far....
Docela mizerný video
Upps its looks he even does not know how to meassure vfd voltages.
I have a Fostex D1624 mk2 rare as a hens tooth and the display went dead hasn't leaked and most probably eproms with fimware did find burnt out ferrite smd beads the thing is so over engineered. i just seen the first version on ebay i backed out on bidding at £52 it sold for £53
Done myself a favor i will never consider anything with a florescent display
Mate! Missing out by £1 has happened to me SO many times its annoying. I hear you, they look amazing when they are fresh but are such a pain when they fade... Just not robust enough long term