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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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16th Sep 2021, 6:23 pm | #21 | ||
Dekatron
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Re: Bush vintage radio DAC90A.
Quote:
John.
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16th Sep 2021, 6:30 pm | #22 | |
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Re: Bush vintage radio DAC90A.
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16th Sep 2021, 6:34 pm | #23 |
Octode
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Re: Bush vintage radio DAC90A.
The reason for testing is incase I need to buy a new one, it allows time to do the rest of the work.
I have a basic emissions and shorts tester which showed a fault with a valve in a DAC90 without the A, it had no cathode!
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16th Sep 2021, 6:37 pm | #24 | |
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Re: Bush vintage radio DAC90A.
Quote:
I'd agree, valve faults are rare in radios, and in-circuit measurements will reveal if there is a problem. Just treat each valve as another circuit component, albeit one which is less likely to be faulty (which means you'd suspect other items ahead of the valve). Last edited by kalee20; 16th Sep 2021 at 6:37 pm. Reason: fixed quote |
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16th Sep 2021, 6:53 pm | #25 |
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Re: Bush vintage radio DAC90A.
UL41 anyone.
Lawrence. |
16th Sep 2021, 7:11 pm | #26 |
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Re: Bush vintage radio DAC90A.
I see your UL41 and I'll raise you ECC85! But there isn't one of those at least in a DAC90.
There are relatively few famously short-lived valves. Who knew, back in the days of new sets, when valves were specifically excluded from warranties? David
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16th Sep 2021, 7:23 pm | #27 |
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Re: Bush vintage radio DAC90A.
Back in my TV servicing days, at least the Mullard top ten/twenty were in my service van.
Lawrence. |
16th Sep 2021, 9:18 pm | #28 | |
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Re: Bush vintage radio DAC90A.
Quote:
Yes, I've never met screws on the last generation of DAC90A front knobs, those with the perspex backing disc. I've a feeling screws were used on the intermediate knob type, the chunky ones that don't taper toward the front: probably I've a set that uses them hiding somewhere, but can't at present find one to check. |
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17th Sep 2021, 9:22 am | #29 |
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Re: Bush vintage radio DAC90A.
I may be mistaken but I'm sure there is a version of the DAC90 that employs a PX4. The model number is DAC90P. I have one somewhere but it would take months to find it. I suppose they substituted the PX4 due to the UL41 playing up. John.
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17th Sep 2021, 9:47 am | #30 |
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Re: Bush vintage radio DAC90A.
Could a PX4 even physically fit in a 90A? Maybe a 90? The filament would be a major mismatch let alone the gain and the load impedance required.
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17th Sep 2021, 10:28 am | #31 |
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Re: Bush vintage radio DAC90A.
This thread is getting silly and recent posts are of no help to the OP.
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17th Sep 2021, 10:36 am | #32 |
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Re: Bush vintage radio DAC90A.
Start with checking any caps that have been changed for correct values, after that checking resistance of mains dropper .
After changing UL41 grid coupling , then remove replace cap across mains input with the correct type. Then , having made sure o/put transformer is ok, measure voltages, starting from the smoothing cap. NOTE, this set has a "LIVE" chassis. If in doubt use an isolation transformer. If you have no experience in valve set repairs, pass on to someone who can safely service it.
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