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Forum Free Registration Closed
Granada Television Brochure, 1970s
Long Gone UK TV Shops
Memories of a Derwent Field Service Engineer
PYE Australia Circa 1971
Radios-TV VRAT
Fabulous Fablon
Thorn TX10 Chassis
Crusty-TV Museum, Analogue TV Network
Philips N1500 Warning!
Rumbelows
Thorn EMI Advertising
Thorn’s Guide to Servicing a VCR
Ferguson 3V24 De-Robed
Want to tell us a story?
Video Circuits V15 – Tripler Tester
Thorn Chassis Guide
Remove Teletext Lines & VCR Problems
Ceefax (Teletext)
Suggestions
Website Refresh
Colour TV Brochures
1970s Lounge Recreation
CrustyTV Vintage Television Museum
Linda Lovelace Experience
Humbars on a Sony KV2702
1972 Ultra 6713
D|E|R Service “The Best”
The one that got away
Technical information
The Line Output Stage
The map
Tales of a newly qualified young engineer.
Tales of a Radio Rentals Van Boy
Sanyo SMD
Disastrous Company Rebranding
1969 Philips G22K511
Memories Of The TV Trade
Crazy house
Dirty TV screens
Dual Standard and Single Standard CTV’s
Radios-TV on YouTube
The Winter of 62/63
A domestic audio installation
1979 Ferguson Videostar Deluxe 3V16
Music centre modifications
Unusual record player modification
B&K 467 Adapters
Mishaps In The Trade
1971 Beovision 3200
Mullard 5-10 amplifier.
Feedback circuits are complex and could be introducing phase changes but not enough to break into oscillation.
Good call to remove that first.
Frank
Or it's oscillating supersonically. I was presented with a hybrid guitar amp many years ago that the owner - following advice on a forum, I might add - decided to replace the numerous op-amps in with higher-spec ones.
When brought to me, he said that on the decay of a note, it had a "paper-on-comb" quality as it decayed but otherwise it seemed fine.
Putting a 'scope on the amp output immediately revealed the problem - a sea of green, with the amp oscillating at 100KHz. The new op-amps, with a much larger gain/bandwidth product, had made much of the poor layout and design of the pre-amp PCB and so were oscillating. Putting the original op-amps back cured it.
Posted by: @cathovisorI was presented with a hybrid guitar amp many years ago that the owner - following advice on a forum, I might add - decided to replace the numerous op-amps in with higher-spec ones.
Oh dear. What I call the "Top Trumps" school of engineering- on paper, the context-devoid parameters of one item exceed those parameters of another, ergo It's Better...
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