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| Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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28th Oct 2017, 12:04 am
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#1 |
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Tetrode
Join Date: Sep 2017
Location: Dorchester, Dorset, UK.
Posts: 81
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Bush DAC90 problems.
Looking for any tips on replacing the Bush DAC90 scale lamp it is rated at 3.5v 0.3Amp they seem to be hard to come by so I am looking for any suitable alternatives
Thanks Mike p.s this is for a Bush DAC90 not a 90A |
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28th Oct 2017, 2:22 am
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#2 |
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Heptode
Join Date: Jan 2004
Location: Stockport, Greater Manchester, UK.
Posts: 827
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Re: Bush DAC90 bulb replacement?
Suitable ones are still available from bicycle shops, most component supppliers and online auction sites and marketplaces.
(Please see: https://www.vintage-radio.net/forum/...ad.php?t=77763) |
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28th Oct 2017, 3:15 am
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#3 |
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Tetrode
Join Date: Sep 2017
Location: Dorchester, Dorset, UK.
Posts: 81
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Re: Bush DAC90 bulb replacement?
all sorted thanks Mike M1ALT
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28th Oct 2017, 12:05 pm
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#4 | |
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Heptode
Join Date: Oct 2012
Location: London, UK.
Posts: 500
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Re: Bush DAC90 bulb replacement?
Quote:
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28th Oct 2017, 1:28 pm
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#5 |
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Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,988
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Re: Bush DAC90 bulb replacement?
DAC90 = 6.2v 0.3 Amps
DAC90A = 3.5v 0.15 Amps Taken from manufacturer's sheets. John. |
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1st Nov 2017, 8:43 pm
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#6 |
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Tetrode
Join Date: Sep 2017
Location: Dorchester, Dorset, UK.
Posts: 81
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Bush DAC90. Tuning Capacitor Help.
The tuning capacitor is fixed in place with three bolts which also act as a ground to the chassis connector. In the middle of the bolt is a non metal spacer which have long since perished looks like some sort of cork washer about 5mm tall, now is this insulated spacer of importance to prevent a short? or am I making things look harder than they are? knowing how they were originally fixed would help
Thanks Mike |
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1st Nov 2017, 9:25 pm
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#7 |
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Banned
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
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Re: Bush DAC90. Tuning Capacitor Help.
The flexible mountings are to prevent microphony due to the speaker vibrating the tuning capacitor and altering the tuning in sympathy.
The frame and hence the moving vanes are grounded to the chassis, the fixed vanes are insulated from the frame. |
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3rd Nov 2017, 11:54 pm
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#8 |
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Tetrode
Join Date: Sep 2017
Location: Dorchester, Dorset, UK.
Posts: 81
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Bush DAC90 valves U76 question?
Whilst checking the valves on a Bush DAC90 instead of a CY31 fitted at valve 5, a U76 was fitted was this o.k for this set? from the web I have found that The U76 was designed for television use.
This set I am restoring I no nothing about, if it worked?, modified? mucked about with? I am going by the trader service sheet 950 and the service instruction sheet. All I have found is it once had a drop or a wack cracked case busted tuning wire both now restored usual caps I have replaced going long nicely until turning my attention to the valves. Some help on this would be very helpful Thank you Michael |
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4th Nov 2017, 12:03 am
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#9 |
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Banned
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
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Re: Bush DAC90 valves U76 question?
As a direct replacement, U76, which has a 160mA heater, is not good to replace a CY31, which has a 200mA heater.
Check that there is not a shunt resistor across the U76 heater. |
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4th Nov 2017, 12:55 am
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#10 |
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Hexode
Join Date: Nov 2013
Location: Lancing, West Sussex, UK.
Posts: 286
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Re: Bush DAC90 valves U76 question?
A Mazda U201 is a more usual replacement for a CY31.
Regards Trevor. |
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4th Nov 2017, 1:43 am
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#11 |
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Tetrode
Join Date: Sep 2017
Location: Dorchester, Dorset, UK.
Posts: 81
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Re: Bush DAC90 valves U76 question?
No shunt resistor so it seems who ever may have tried a U76 then gave up or someone nicked the CY31 who knows? I think I had better search around for a CY31.
Last edited by cernem1alt; 4th Nov 2017 at 2:02 am. Reason: more text added |
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4th Nov 2017, 3:37 am
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#12 |
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Heptode
Join Date: Jan 2004
Location: Stockport, Greater Manchester, UK.
Posts: 827
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Re: Bush DAC90 valves U76 question?
Nah, just fit the shunt and set the mains tapping 10V lower than your mains unless the U76 has actually failed. CY31s are neither cheap nor particularly reliable.
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4th Nov 2017, 11:36 am
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#13 |
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Hexode
Join Date: Nov 2013
Location: Lancing, West Sussex, UK.
Posts: 286
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Re: Bush DAC90 valves U76 question?
Langrex have CY31 in stock.
Regards Trevor. |
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4th Nov 2017, 10:26 pm
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#14 |
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Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: Bush DAC90 valves U76 question?
Shunt needs to be 750R 2W or so. (Two 1k5 1W in parallel?)
__________________
....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
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6th Nov 2017, 7:01 pm
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#15 |
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Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,289
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Re: Bush DAC90 problems.
Three threads relating to the same radio merged.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
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6th Nov 2017, 7:52 pm
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#16 |
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Tetrode
Join Date: Sep 2017
Location: Dorchester, Dorset, UK.
Posts: 81
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Re: Bush DAC90 problems.
Sorry
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12th Nov 2017, 9:12 pm
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#17 |
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Tetrode
Join Date: Sep 2017
Location: Dorchester, Dorset, UK.
Posts: 81
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Re: Bush DAC90 problems.
What replacement speaker do others use for a DAC90? I see its 2.5-3 ohm.
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12th Nov 2017, 11:36 pm
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#18 |
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Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: Bush DAC90 problems.
Anything that will fit! It won't make much difference whether it's 3,4 or even 8 ohms!
__________________
....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
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