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
I am trying to repair a Beomaster 5000 that had some failures on the amplifier board. I have two others that I bought for parts.
I started looking at the darlington transistors and I found that they were all bad. When I say bad, I'm saying they failed the normal "transistor test" with a multimeter on the diode setting. For example, the BDV64B (PNP transistor) showed a reading with positive on Base and Negative on Emitter. And for the BDV65Bs, I had a reading with negative on the base and positive on the Emitter.
I took the transistors out of all 3 boards and most of the 12 transistors had failed as described, although a few had some opens that should have had a reading.
What is the deal with this receiver? Are these darlington transistors not tested in the normal way?
I also pulled all of the BF857s and most of these are good.
I've checked the DC power levels and they look good.
Are there other transistors that commonly fail that I should remove and test?
Does anyone have a favorite substitute for the darlington pair?
Appreciate the help!
Jeff
The darlington pair is BDV64B and BDV65B. Mouser has a BDV64BG which I assume works, but they are out of stock until way into 2022...