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

[bhuskins]

Somebody by any chance did not just plug the LED modules in backwards did they??

No I checked that all are going the same way and the clipping indication is working if you remember so they should all be in correctly.


What should I use from mouser to replace the RC4558?

 

[laatsch55]

There should be a new version. Have you searched for a 4558?

 

[laatsch55]

Brent..those NOS AA170's will be here March 7th. Did you want 2?

 

[bhuskins]

There should be a new version. Have you searched for a 4558?

Yes there are plenty of options...that's the issue. Too many to choose from and not sure what might be different between them.

 

[bhuskins]

http://www.mouser.com/ProductDetail...=sGAEpiMZZMtCHixnSjNA6Mrdwin7F8A2L3HgyjSimP4=

That's what I'll pick up today unless someone tells me
otherwise.

 

[laatsch55]

Joe's the op-amp guy...but you should be able to download a data sheet for the original and a new one to check pinouts etc...

 

[MarkWComer]

I wonder if that's "our" Mark58Comer that asked about them in the comments section?? They do look pretty damn cool.

Yup. Dat wuz be me.

 

[MarkWComer]

So- I'm watching this thread with interest. The right channel meter on my PL400/II momentarily disappears from time to time, just a short-term MIA that recovers quickly. I have the service manual, was considering replicating the PC board and getting all new components (some of which are apparently obsolete and unavailable). The momentary disappearance really doesn't bother me much as long as it does come back, but I consider this the harbinger of an eventual complete failure. I chose the Series II model over the original PL mainly for the quick attack of the LEDs over the inertia of mechanical meters, and also for the fact that those old galvanic meters are a Holy Grail pursuit when they do fail.

Now- given that there's this: https-::learn.sparkfun.com:tutorials...r-hookup-guide I was wondering about making a pair of them and replacing the meter boards completely, and how much headache 'n' aspirin will be required to get them accurately calibrated. I also like the option of having a line display as opposed to a dot display (no offense to the Cylons out there...).

Aside:

1. If I'm gonna take that route, I'd like to have blue or green LEDs all the way up to 0db, a yellow one at 0db, and red for the upper limit (just seems logical to adapt this color scheme).
2. Do all of the galvanic meters have the same electrical characteristics? (IE: ohms per volt and deflection per mA?) If a meter with the same characteristics and physical dimensions for the bezel mount, it shouldn't be necessary to have an original "Phase Linear" brand mark on the scale. The problem would be whether the scale was delineated for "VU" and not some other measurement.

From the world- famous Wikipedia:
A volume unit (VU) meter or standard volume indicator (SVI) is a device displaying a representation of the signal level in audio equipment. The Acoustical Society of America standardized it in 1942 (C16-5 - 1942) for use in telephone installation and radio broadcast stations. Consumer audio equipment often features VU meters, both for utilitarian purposes (e.g. in recording equipment) and for aesthetics (in playback devices).
The VU-meter (intentionally) "slows" measurement, averaging out peaks and troughs of short duration, and reflects more the perceived loudness of the material than the more modern and initially more expensive PPM meters. For this reason many audio practitioners prefer it to its alternatives, though the meter indication does not reflect some of the key features of the signal, most notably its peak level, which in many cases, must not pass a defined limit.The original VU meter is a passive electromechanical device, namely a 200 µA DC d'Arsonval movement ammeter fed from a full wave copper-oxide rectifier mounted within the meter case. The mass of the needle causes a relatively slow response, which in effect integrates the signal, with a rise time of 300 ms. 0 VU is equal to +4 [dBu], or 1.228 volts RMS across a 600 ohm load, or about 2.5 milliWatts. 0 VU is often referred to as "0 dB".[SUP][1][/SUP] The meter was designed not to measure the signal, but to let users aim the signal level to a target level of 0 VU (sometimes labelled 100%), so it is not important that the device is non-linear and imprecise for low levels. In effect, the scale ranges from −20 VU to +3 VU, with −3 VU right in the middle. Purely electronic devices may emulate the response of the needle; they are VU-meters inasmuch as they respect the standard.

 

[Nick Danger]

Check out this thread too, Mark: http://forums.phxaudiotape.com/showthread.php/5940-A-WOPL-quot-Frankenstein-quot/page7

 

[MarkWComer]

Check out this thread too, Mark: http://forums.phxaudiotape.com/showthread.php/5940-A-WOPL-quot-Frankenstein-quot/page7

Yes, cool and groovy, but want something to mount internally in the PL cabinet with LED segments. I see the driver/output/construction and it doesn't look difficult to put together, but this isn't exactly what I'm looking for (even though it's essentially the same thing I'm looking for).

Actually, I did read through this thread when I noticed my right channel meter cutting out.

 

[grapplesaw]

So Lee you might as well get these to go along with the uaa170

they are supposed to be TI originals its a 50 lot rc4558p. I think they would work with a dip socket a well

http://pages.ebay.com/link/?nav=item.view&alt=web&id=181668460140

So so how are we making out with the repair?

Do do we have power to the Uaa170 or not?

we got to solve this one.

 

[laatsch55]

It has been determined that all IC's will be shotgunned on the PL 37 LED boards....Brent tested the LED segments and they are good....not much else on there...the GES 97's tested good and he replaced all the caps...

 

[laatsch55]

So Lee you might as well get these to go along with the uaa170

they are supposed to be TI originals its a 50 lot rc4558p. I think they would work with a dip socket a well

http://pages.ebay.com/link/?nav=item.view&alt=web&id=181668460140

So so how are we making out with the repair?

Do do we have power to the Uaa170 or not?

we got to solve this one.

How many of the segments did you get Glen??

 

[grapplesaw]

How many of the segments did you get Glen??

Lee I have not bought yet
option 1 is get a group of 4-6 people together and buy a lot of 185 pieces of 10 led segments cost $1-$1.25 per piece
option 2 is buy a 20 lot of 10 led segments cost $1.75-$2 each

I will buy the 20 lot if no takers on option 1

 

[Gepetto]

Joe's the op-amp guy...but you should be able to download a data sheet for the original and a new one to check pinouts etc...

LM358 will work in place of the LM4558 in that application. It is a jellybean op amp that is needed for this application.

 

[grapplesaw]

LM358 will work in place of the LM4558 in that application. It is a jellybean op amp that is needed for this application.

Here is some more information on Op-Amps, meaning of jelly bean and different types of op amps

http://tangentsoft.net/audio/opamps.html


here is some very nonessential reading, but geeky

http://www.electrosmash.com/jrc4558-analysis

 

[Gepetto]

Here is some more information on Op-Amps, meaning of jelly bean and different types of op amps

http://tangentsoft.net/audio/opamps.html

Important to note, the light board application is not an audio op amp application.

 

[laatsch55]

Cool link Glen, thanks..

 

[grapplesaw]

Important to note, the light board application is not an audio op amp application.

Right Joe, I guess I did go off the topic a bit.

 

[laatsch55]

Figured that...