Cartouche
New member
learning to test horizontal output transistor - odd readings?
I'm trying to test, for practice, these two horizontal output transistors. It's the part# 2SD1938, I believe referred to as a 220 package?
One is new from Bob Roberts, the other I removed from a wg19k7905 I'm attempting to rebuild.
I was under the impression that to test this with a DMM, one places:
1. red to base, blk to emitter = junction drop ~ .7
2. red to base, blk to collector = junction drop ~ .7
3. blk to base, red to emitter = open
4. blk to base, red to collector = open
5. blk to collector, red to emitter = open
6. blk to emitter, red to collector = open
I test the old one, and results are:
1. .07 (way too low, right?)
2. .49 (ok)
3. .07 (should be open, right?)
4. open
5. .52 (ditto)
6. open
I figure, good idea to replace this - 1,3, and 5 say bad transistor.
More importantly, the brand new Bob Roberts one shows:
1. .53 (good)
2. .48 (good)
3. 1.67 (huh?)
4. open (good)
5. 1.78 (huh again?)
6. open (good)
On both transistors, I get readings at 3 and 5 - so am I misunderstanding something about testing these puppies? Or are both transistors be bad?
I'm trying to test, for practice, these two horizontal output transistors. It's the part# 2SD1938, I believe referred to as a 220 package?
One is new from Bob Roberts, the other I removed from a wg19k7905 I'm attempting to rebuild.
I was under the impression that to test this with a DMM, one places:
1. red to base, blk to emitter = junction drop ~ .7
2. red to base, blk to collector = junction drop ~ .7
3. blk to base, red to emitter = open
4. blk to base, red to collector = open
5. blk to collector, red to emitter = open
6. blk to emitter, red to collector = open
I test the old one, and results are:
1. .07 (way too low, right?)
2. .49 (ok)
3. .07 (should be open, right?)
4. open
5. .52 (ditto)
6. open
I figure, good idea to replace this - 1,3, and 5 say bad transistor.
More importantly, the brand new Bob Roberts one shows:
1. .53 (good)
2. .48 (good)
3. 1.67 (huh?)
4. open (good)
5. 1.78 (huh again?)
6. open (good)
On both transistors, I get readings at 3 and 5 - so am I misunderstanding something about testing these puppies? Or are both transistors be bad?