PL Model 700 Series II with LEDs that just won't work!

Gepetto

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bhuskins said:
One other thing...

Let's not forget that this amp was wired for 240v for a long time (likely since new) and ran that way on 120v here in the states. I wonder what damage that could have caused to the light boards?
Click to expand...
That won't hurt anything. The other way around would have however. Did you get this with fried LED indicators on it?

I suspect that it was wired for 120, plugged into 240. UAA170 fried as a result. Seems like the op amp survived if you have the last segment flashing. That is the monostable that fires on the overload condition.
 
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Gepetto said:
That won't hurt anything. The other way around would have however. Did you get this with fried LED indicators on it?

I suspect that it was wired for 120, plugged into 240. UAA170 fried as a result. Seems like the op amp survived if you have the last segment flashing. That is the monostable that fires on the overload condition.
Click to expand...
That miswire of the AC in or lightning strike are the only explanations for both meters being defunct.

Replace the UAA170s
 
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Gepetto said:
That won't hurt anything. The other way around would have however. Did you get this with fried LED indicators on it?

I suspect that it was wired for 120, plugged into 240. UAA170 fried as a result. Seems like the op amp survived if you have the last segment flashing. That is the monostable that fires on the overload condition.
Click to expand...
It was an original 240v unit and it definitely looked like factory solder on the transformer primary leads. I highly doubt the unit was ever wired 120v until I did so a couple of days ago.

Just to clarify...all 6 LED bars are testing good...the other light board does not flash like the main board so maybe the opamp is bad on that one?
 
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bhuskins said:
It was an original 240v unit and it definitely looked like factory solder on the transformer primary leads. I highly doubt the unit was ever wired 120v until I did so a couple of days ago.

Just to clarify...all 6 LED bars are testing good...the other light board does not flash like the main board so maybe the opamp is bad on that one?
Click to expand...
Could well be.

You should have seen a healthy signal at the op amp with 200mV in, given the gain that it has in that stage.
 
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If I replace 1 opamp I'd probably replace both...can you suggest a proper one to use from mouser?

what about on the uaa170? Is eBay my only option? Some of the NOS options are as high as $40 a pop! I'd much rather chose a Chinese cheap option BUT I don't want to waste my time.
 
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For what it's worth, the only 1237 IC's that are available for Don's DC protect 400 boards are chinese knockoffs of NEC's........they have worked in everyone I've done so far, that's about 15 in number. I can't say that would happen in your case, BUT, a guys not out much bread by trying. I think they were 1.15 each. Whether or not they will stand the test of time remains to be seen...
 
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Granted it's a crapshoot, but what other options are there. Besides stumbling on a stash of NOS parts , there ya go....
 
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Perhaps there is a new chip that can be adapted to the PL board, the board meaning just the physical portion of the board, not the electronic portion. I know little of :LED driver IC's, but in 35 years I suspect one small IC would now replace most of that board. Perhaps keep the original LED segments and use a modern LED driver...
 
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bhuskins said:
Cheapest Chinese UAA170 eBay option is around $25 for 4 of them
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You can get the original Siemens ones from Germany for ~$5 each. Cheap enough. There are only 2 things on that board, the op amp and the UAA170. You proved the LEDs are good. Time to go for it.
 
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laatsch55 said:
Perhaps there is a new chip that can be adapted to the PL board, the board meaning just the physical portion of the board, not the electronic portion. I know little of :LED driver IC's, but in 35 years I suspect one small IC would now replace most of that board. Perhaps keep the original LED segments and use a modern LED driver...
Click to expand...
They are all awful as well though Lee.
 
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Gepetto said:
You can get the original Siemens ones from Germany for ~$5 each. Cheap enough. There are only 2 things on that board, the op amp and the UAA170. You proved the LEDs are good. Time to go for it.
Click to expand...

German e-bay??
 
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laatsch55 said:
So what's up with that??
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Nobody has used them for a long time Lee so any technology development died quite a while ago. Probably the best contender is the LM3915 and that is a lousy chip too. No really good options out there.
 
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bhuskins said:
I stuck in some temp LEDs and it also tested the same (those in the attached pic are blinking/I have R320 jumped)...I have some on the other end too to make sure it didn't change the behavior.9400110200830611212430

Bad UAA170's? All 4 of them??
or Bad RC4558? Both of them??

and of course the bad LED bars
Click to expand...
Somebody by any chance did not just plug the LED modules in backwards did they??
 
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