ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
The dual ± 15v of the P29 on the PC4 power supply PCB having problem with the +15v even after changing with a new LM7815.
Where should I check for problem?
What kind of problems?
Check,
Transformer
Rectifier
Capacitors
Look for bad solderjoints & PCB cracks.
//Bo.A long list...
Have checked what you mentioned.
No +15volt output.
Could it be the problem of TR11 BD438 which preceded the LM7815?
possible
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I have to desolder it and check.
I have no idea how the problem emerged as it was working normally with minor dB meter problem.
I bought it as a not working unit with no audio output and upon checking the problem was caused by a burnt TR102 PF5103
and at last it was repaired with a substitution of 2N5452-Dual fets for both TR102 and TR202.
And most of the aged components were changed and the IC8 was replaced with the BB OPA2017SM.
The resulting playback is far ahead to the other Beocord 9000 version 4814 which I also owned.
Link to Audio PCB photo：http://archivedforum2.beoworld.org/members/Mikemaxcel/files/Beocord/default.aspx
Upon checking,the BD438 tested OK.
copper track cracked btw the diodes and the B1C1 capacitor.
After solving the problem of power supply,arise another issue--the dB meter,the cassette compartment light,tape type switch on when power-up.
And when pressing the STANDBY button, the counter switches off, the dB meter,the cassette compartment light,tape type keep switching on.
The playback is normal but no dB levels shown.
It seems one of the relays IC(0n off switch) or relays is giving the problem.
Could someone help...