Author Topic: Sony STR-DG500 receiver w/ dull vacuum display. Is it worth fixing?  (Read 138 times)

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Offline Ed.Kloonk

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Amp is about 15 years old. I inherited it 2 years ago and in the last year, cos the telly has been on almost 24/7  ;) the display is now only readable if the room is dark. it doesn't really impede any use of the amp, however. It's just hard to know if it's off or on.  :-\

An opportunity is coming up to remove it and everything else from the cabinet (room renovation) and I wonder if it's easy to fix with not much effort or just leave it.

Anyone care to chime in?

So far I have found this..
https://www.eevblog.com/forum/chat/vacuum-fluorescent-display-rejuvenation/

 

Offline Gyro

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Re: Sony STR-DG500 receiver w/ dull vacuum display. Is it worth fixing?
« Reply #1 on: April 08, 2021, 10:36:57 am »
I think that thread pretty much covers all the bases.

Check the VFD supply rail, relevant capacitors, filament voltage etc. Occasionally there's a series resistor in the filament supply that you may be able to lower or bridge out. Other than that, maybe look for a cheap (blown output) parts mule?

Check the user manual for any display dimming function! ;)
« Last Edit: April 08, 2021, 10:40:04 am by Gyro »
Chris

"Victor Meldrew, the Crimson Avenger!"
 
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Offline Ed.Kloonk

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Re: Sony STR-DG500 receiver w/ dull vacuum display. Is it worth fixing?
« Reply #2 on: April 08, 2021, 10:52:07 am »
Oh man, I wonder if someone 'found' a dimming function. All I do is turn it up loud or sometimes really loud.

As for parts, I suspect the ones on ebay are for sale for this reason only. It's all light touch switches and relays so it seems pretty solid.

Crouching down, I've just noticed a very faint, high pitch whine coming from the box, (not the speakers). Noise stops when unit is off. Wonder if that is related. Wonder if it's trying to tell me the PSU has a dry cap.

 

Offline wizard69

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Re: Sony STR-DG500 receiver w/ dull vacuum display. Is it worth fixing?
« Reply #3 on: April 09, 2021, 02:08:57 am »
Oh man, I wonder if someone 'found' a dimming function. All I do is turn it up loud or sometimes really loud.

As for parts, I suspect the ones on ebay are for sale for this reason only. It's all light touch switches and relays so it seems pretty solid.
You have no idea until you ask.    Deoendign on what the part is and whom Sony purchased it from there is the possibility of a lot of NOS around.    I wouldn't discount the possibility of good stuff being on E-Bay, I've made good scores off that place.   Well i did before pricing went nuts there.
Quote
Crouching down, I've just noticed a very faint, high pitch whine coming from the box, (not the speakers). Noise stops when unit is off. Wonder if that is related. Wonder if it's trying to tell me the PSU has a dry cap.

Could be lots of things, possibly even normal.    However you can't dismiss the possibility that the electrolytics (one or more) are bad.    If that is the case the entire amp should be recapped.   Knowing more about the buzz might help

Now to your original question of it being worth it, that is entirely up to you and what you value.   A well designed amp should be well worth fixing.   Frankly it prevents a lot of "electronic waste".    If you are a beginner there is also a huge opportunity to learn, especially in this case the skills needed to track down noisy components and figure out why they are noisy.   
 

Offline james_s

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Re: Sony STR-DG500 receiver w/ dull vacuum display. Is it worth fixing?
« Reply #4 on: April 09, 2021, 02:21:40 am »
I would check the voltages on the display, including the filament voltage, that should give you a pretty good idea of the state of the display. You could also mess with the various functions and get it to light up a rarely used display element, worn VFDs usually have quite a large variation between the brightness of heavily used and lightly used segments. If the whole thing is dim then it's probably low voltage, the whine suggests possibly a bad capacitor and it's about the right age for that to be an issue.
 

Offline JustMeHere

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Re: Sony STR-DG500 receiver w/ dull vacuum display. Is it worth fixing?
« Reply #5 on: April 09, 2021, 02:33:29 am »
My good VFD amps have dimming functions
  It helps cut down on the noise.
 


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