HELP! Rescuing Dad's old PL400 S2 (pics)

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lightfall

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Ok with the multimeter in the 2k ohm position with the negative lead on the collector bus bar the readings for the left 6 emitter resistors on the tie together side shows a reading of 1.28 in the left vertical column of 3, a reading of 1.2 in the second leftmost vertical column of 3, and the right two columns of 3 all read .001.
 
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lightfall said:
Ok with the multimeter in the 2k ohm position with the negative lead on the collector bus bar the readings for the left 6 emitter resistors on the tie together side shows a reading of 1.28 in the left vertical column of 3, a reading of 1.2 in the second leftmost vertical column of 3, and the right two columns of 3 all read .001.
Click to expand...
On the 2nd row from the left did you move your positive lead to the base bus bar for that row?
 
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lightfall

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On the second row from the left with the negative in the collector bar and the positive on the base bus bar I get 1.2.

Attached is a picture of my meter, I don't see a 10 ohm setting, but then again it might be right in my face and I am just missing it.

20141105_202504.jpg
 
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lightfall said:
On the second row from the left with the negative in the collector bar and the positive on the base bus bar I get 1.2.

Attached is a picture of my meter, I don't see a 10 ohm setting, but then again it might be right in my face and I am just missing it.

View attachment 17314
Click to expand...
All 4 rows are checked with the negative lead on the collector bus bar and the positive on the transistor side of the emitter resistors. You should have 4 readings per row...

Move the meter down to the 200 ohm range...
 
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lightfall

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This is how I am reading the collector bus bar to the emitter resistors. I believe it is correct. 20141105_203830.jpg
 
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And you are showing 1.2K ohms. BTW, nice camera work with two hands.....or no hands....


You need to be on the other side of the resistor.....
 
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lightfall

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OK I did that all wrong then. I have been reading from the end of the resistor that is not directly connected to the brown sockets. Also, on the bottom row there is a resistor that is brown but it is smaller. I will take the reading there on the wire that comes directly off of the brown socket into the small resistor at the 200 ohm setting and report back.
 
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New readings:

left row top to bottom: just shows "1"
2nd row: just shows "1"
3rd row: 2.2, 2.0, 1.4, 157 on the small brown resistor at the socket side.
4th row: 1.8, 1.8, 1.0, and at the big resistor socket side 0.5 and on the small one it shows 157 socket side.

All readings at setting 200.
 
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Now you can dismount all the out puts and test them individually on your meter on the diode test mode in accordance with the transistor testing basics thread...

Remember, when holding a TO-3 transistor by it's "shell" with the leads sticking up, and the short side to the left, the lead nearest you is the base lead. The other lead is the emitter and the case is the collector..


Just for kicks, put your test leads on each side of each emitter resistor....I have a feelin some of those are toast....
 
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I will keep the meter in 200 mode and report readings on each side of each emitter resistor. I will also then pop out all of the output transistors and do the readings on them according to those links you sent me before, I expect that will be an interesting / challenging process for me, ha. By the way, was the small transistor on the bottom row the correct one (smaller because it is a pre stage or something with less power?) What is the single large one on the bottom right row that is not present on the second row bottom socket?

Also, since I have a blown supply fuse, suggesting at least one blown output transistor, why did I not see any 400-700 ohm readings suggesting good outputs on any of them as suggested in the troubleshoot manual section 6-1.2?

What did those readings tell you?
 
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It appears you have a blown output in each row....OR some other things are also wrong, that's why you now dismount them and check individually. We just want to check the resistance of each emitter resistor......test lead on each side of each resistor...negative lead on one side, positive on the other...
 
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lightfall

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Just testing the emitter diodes I come up with this:

row 1: .9, .9, .9, 156
2: .7, .8, .8, 157
3: .8, .8, .8 (clearly cracked), 157
4: .9, .9, .8 (cracked), 156, and the additional large emitter resistor is cracked and also reads .9

I am going to pull the outputs now.
 
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emitter RESISTORS......there are no glaringly bad emitter resistors, which shows you a cracked resistor may not necessarily be bad....a teaching moment...
 
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Drivers are a PL rebranded RCA-410

Outputs are a Rebranded Motorola MJ 15024's, the GE's I have no idea...

Drivers were manufactured on the 29th week of 79
And the drivers in the 26th week of 79
 
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