Recently did the full Leestereo restoration of a lovely BA3K for a customer. Unit was working perfectly for some weeks until it died.
Kudos to Ben for yet another invaluable resto reference!
Background: the unit was of unknown origin and service history. It's a global voltage model that had been set to 220V by someone in the past. It was sold to my customer within Australia so no idea how long it had been run on 240V but set to 220V. The native voltage here in Australia is 240V. Not overly uncommon to see this after units have been imported from Europe. Of course, I altered the jumpers to 240V as soon as it hit my bench. It was all original internally and no sign of previous work, all was factory.
Symptom: It blew the main fuse and after the customer replaced it, no power at all, no blown replacement fuse. No hard use, happened at power on.
Diagnosis: I removed the F-2511 protection board and found R01 (3.9Ω 7W) had gone high (470MΩ), R02 (3.9Ω 7W) was fine. I replaced them both anyway. Unit powered on but failed DBT instantly, even with the power amps disconnected. I suspected the bridge rectifiers but both sets D01/02 and D03/04 tested fine. Also, all the fuses on the protection board were fine. All semis on F-2511 are original and tested fine. Began testing the transformer for resistance and shorts to ground. Found the +/- 46V secondary taps were both shorted to ground. That’s the blue wires from the transformer to pins 5 & 6 of F-2511.
Before I embark on a search for another transformer or doner unit at crazy money, wanted to sanity check with you folk and see if others have had similar experiences with the BA-3000?
Kudos to Ben for yet another invaluable resto reference!
Background: the unit was of unknown origin and service history. It's a global voltage model that had been set to 220V by someone in the past. It was sold to my customer within Australia so no idea how long it had been run on 240V but set to 220V. The native voltage here in Australia is 240V. Not overly uncommon to see this after units have been imported from Europe. Of course, I altered the jumpers to 240V as soon as it hit my bench. It was all original internally and no sign of previous work, all was factory.
Symptom: It blew the main fuse and after the customer replaced it, no power at all, no blown replacement fuse. No hard use, happened at power on.
Diagnosis: I removed the F-2511 protection board and found R01 (3.9Ω 7W) had gone high (470MΩ), R02 (3.9Ω 7W) was fine. I replaced them both anyway. Unit powered on but failed DBT instantly, even with the power amps disconnected. I suspected the bridge rectifiers but both sets D01/02 and D03/04 tested fine. Also, all the fuses on the protection board were fine. All semis on F-2511 are original and tested fine. Began testing the transformer for resistance and shorts to ground. Found the +/- 46V secondary taps were both shorted to ground. That’s the blue wires from the transformer to pins 5 & 6 of F-2511.
Before I embark on a search for another transformer or doner unit at crazy money, wanted to sanity check with you folk and see if others have had similar experiences with the BA-3000?
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- however this is where a DBT or perhaps better a Variac would come in handy. But first completely isolate the transformer from all connections, other than incoming AC from a DBT and/or Variac, then measure/monitor secondary voltage behaviour.
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