Very dim digital readout

srinath · 03:05 AM

In this str-d865 sony amp I just got, the digital readout on the front is very very dim. Anyone know what controls it and how to test and fix it ?
Thanks.
Srinath.

djk · 18th August 2010, 10:03 AM

They are generally backlighted with an ordinary incandescent lightbulb, change it.

Mooly · 18th August 2010, 12:13 PM

If it's vacuum flourescent type then caps on or for generating the -30 or so rail are suspect. Would have to see circuit, but caps are favourite as they are often used in a voltage doubler arrangement.

Similar thread on CD display here... the principle is the same and the voltages used will be similar.
Marantz CD5000 - display very dull - help?

srinath · 18th August 2010, 01:07 PM

Djk: Bulb would be so easy, but schematic doesn't say bulb and I dont believe its thick enough to house even a tiny bulb.
Mooly: That story didn't end too well on the marantz display BTW.

I have found that the face plate is tinted a very deep red, making it 2 X hard to get it to be bright. Maybe they put in clear in the middle after finding out its dim on later models. No idea.
Thanks.
Cool.
Srinath.

Mooly · 18th August 2010, 04:46 PM

Lol, in post 22 he said it fixed it... if the original cap was OK the display wouldn't have altered.

Anyway caps are a big problem... but you really need to see the circuit. For example some Aiwa music centres (Aiwa, part of Sony at the time... hmmm) used two unequal value electroylitics of 33 and 22uf from memory and they failed like they were going out of fashion. These were used to derive the display volts.

The problem is knowing how bright they are when new. Signs of a duff display can be unequal rightness of segments, them looking brighter directly where the heaters pass over them.

srinath · 18th August 2010, 06:52 PM

Oh this thing is dimmest in the center, where it matters most.
Let me read that thread.
Thanks.
Cool.
Srinath.

srinath · 18th August 2010, 06:55 PM

Post 29 he says it only made it just slightly better.
Thanks.
Srinath.

Mooly · 19th August 2010, 05:59 AM

If the illumination is uneven it sounds like the display itself.

gmphadte · 19th August 2010, 11:28 AM

If u bought it old, then there may be dust settled behind the front panel.

Gajanan Phadte

srinath · 19th August 2010, 12:15 PM

It is used, and quite old but there is no dust. The whole thing is very clean.
Thanks.
Srinath.

17th August 2010, 03:04 AM	#1
srinath diyAudio Member Join Date: Feb 2010	Very dim digital readout In this str-d865 sony amp I just got, the digital readout on the front is very very dim. Anyone know what controls it and how to test and fix it ? Thanks. Srinath. Last edited by srinath; 17th August 2010 at 03:05 AM. Reason: typo

18th August 2010, 10:03 AM	#2
djk diyAudio Member Join Date: Feb 2001 Location: USA	They are generally backlighted with an ordinary incandescent lightbulb, change it. __________________ Candidates for the Darwin Award should not read this author.

18th August 2010, 12:13 PM	#3
Mooly diyAudio Moderator Join Date: Sep 2007	If it's vacuum flourescent type then caps on or for generating the -30 or so rail are suspect. Would have to see circuit, but caps are favourite as they are often used in a voltage doubler arrangement. Similar thread on CD display here... the principle is the same and the voltages used will be similar. Marantz CD5000 - display very dull - help? __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

18th August 2010, 01:07 PM	#4
srinath diyAudio Member Join Date: Feb 2010	Bulb ? cap ? Djk: Bulb would be so easy, but schematic doesn't say bulb and I dont believe its thick enough to house even a tiny bulb. Mooly: That story didn't end too well on the marantz display BTW. I have found that the face plate is tinted a very deep red, making it 2 X hard to get it to be bright. Maybe they put in clear in the middle after finding out its dim on later models. No idea. Thanks. Cool. Srinath.

18th August 2010, 04:46 PM	#5
Mooly diyAudio Moderator Join Date: Sep 2007	Lol, in post 22 he said it fixed it... if the original cap was OK the display wouldn't have altered. Anyway caps are a big problem... but you really need to see the circuit. For example some Aiwa music centres (Aiwa, part of Sony at the time... hmmm) used two unequal value electroylitics of 33 and 22uf from memory and they failed like they were going out of fashion. These were used to derive the display volts. The problem is knowing how bright they are when new. Signs of a duff display can be unequal rightness of segments, them looking brighter directly where the heaters pass over them. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*


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18th August 2010, 06:52 PM	#6
srinath diyAudio Member Join Date: Feb 2010	Oh this thing is dimmest in the center, where it matters most. Let me read that thread. Thanks. Cool. Srinath.

18th August 2010, 06:55 PM	#7
srinath diyAudio Member Join Date: Feb 2010	Post 29 he says it only made it just slightly better. Thanks. Srinath.

19th August 2010, 05:59 AM	#8
Mooly diyAudio Moderator Join Date: Sep 2007	If the illumination is uneven it sounds like the display itself. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

19th August 2010, 11:28 AM	#9
gmphadte diyAudio Member Join Date: Jul 2003 Location: Dona paula, Goa	If u bought it old, then there may be dust settled behind the front panel. Gajanan Phadte

19th August 2010, 12:15 PM	#10
srinath diyAudio Member Join Date: Feb 2010	It is used, and quite old but there is no dust. The whole thing is very clean. Thanks. Srinath.

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