Share your knowledge on these two classic MPCs
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By thedailyhustle Fri Mar 02, 2007 8:08 am
I desoldered the original inverter box from the 60II el inverter pcb. I have a mpc3000 invertbox I want to solder in for replacement. I know the pin designations for the 3000 component, but I cannot be certain from the service manual picture.

I believe I know where the ground and ac out holes are but what about the 5vdc in hole? I tried the 2 seemingly possible wiring combinations with no luck... The contrast knob wiring is ok and backlight wiring didnt seem to get jjarred or anything. I want to be sure of wiring the inverter to pcb before I check the backlight joints..

inverter component pins
____________________
| o 2 gnd o 1 dc in \
|
|
| o 3 ac out
|____________________

el inverter pcb from 60 service manual..

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can anyone please tell me which one for certain is the correct 5v dc input for the inverter? I will contact vst tomorrow. The diagram they included shows the 3000 filter pcb and not 60 el inverter pcb so I have a gap in information.


ALL HELP APPRECIATED
Thanks.
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By mikedean Fri Mar 02, 2007 12:30 pm
5 VDC is coming in on connector P1 through R1. The AC ouput is going out through P2 to the LCD backlight. Ground is the large trace which you have labelled correctly.
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By SimonInAustralia Fri Mar 02, 2007 2:33 pm
I opened my MPC60II and measured the points you highlighted with a multimeter.

These are the voltages that I measured on my MPC60II...
Image
...if the MPC3000 inverter only needs ground and 5VDC, I guess you ignore those top 2 MPC60 inverter pins, and just take the 5VDC from the input connector from the power supply, and wire the AC output to the output connector or to where the MPC60 inverter output was connected to.

This might get you going, and maybe VST can provide more details of exactly how they wire and mount the MPC3000 inverter into the MPC60II.

Maybe they do not use the circuitry on the MPC60II intverter PCB, if it only needs the connections that you mention.
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By thedailyhustle Fri Mar 02, 2007 5:27 pm
Thats what I was thinking, directly connecting to the connectors bypassing the circuitry. Thank you so much for your guys help. I will contact VST today and Ill let you know how it goes.
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By thedailyhustle Fri Mar 02, 2007 7:59 pm
MIKEDEAN: Did you directly wire the 5vdc in from the connector lead to the inverter? Did you bypass the circuitry and directly wire the dc in and ac out to their respective leads on the bottom of the two pin plastic connectors? Please confirm as soon as possible...

A vst tech said that there is a resistor that acts as a fuse in case of ac out shorts. He didnt think bypassing the circuitry was necessary. He also thought a drop in voltage to the input pin was normal he though it should be about 4v He didnt really give me a for sure definitive answer. When I asked about directly wiring to the input connector lead he said he hadnt heard of that...

Ill be able to check it out again tonight. I am hoping I can get this working.

Thanks to all of you for your help, and thanks Simon for whipping out the multimeter, as I didnt have one on hand to check voltages.
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By mikedean Fri Mar 02, 2007 8:59 pm
thedailyhustle wrote:MIKEDEAN: Did you directly wire the 5vdc in from the connector lead to the inverter? Did you bypass the circuitry and directly wire the dc in and ac out to their respective leads on the bottom of the two pin plastic connectors? Please confirm as soon as possible...

A vst tech said that there is a resistor that acts as a fuse in case of ac out shorts. He didnt think bypassing the circuitry was necessary. He also thought a drop in voltage to the input pin was normal he though it should be about 4v He didnt really give me a for sure definitive answer. When I asked about directly wiring to the input connector lead he said he hadnt heard of that...

Ill be able to check it out again tonight. I am hoping I can get this working.

Thanks to all of you for your help, and thanks Simon for whipping out the multimeter, as I didnt have one on hand to check voltages.


No, what I did was mount the new inverter upside down with some hot glue in my case and ran jumper cables to th pads on the circuit board. I glued the new part just next to the circuit board since there is plenty of room in there.
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By thedailyhustle Fri Mar 02, 2007 10:14 pm
Here is how I will wire it. Is this correct?

Image

MIKEDEAN: I think I understand now. GND and AC out locations are proper. Wire/jumper the lead from r1 resistor to dc in on inverter block, correct?


Thanks once again.
Last edited by thedailyhustle on Sat Mar 03, 2007 12:38 am, edited 3 times in total.
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By mikedean Sat Mar 03, 2007 7:36 am
thedailyhustle wrote:Here is how I will wire it. Is this correct?

Image

MIKEDEAN: I think I understand now. GND and AC out locations are proper. Wire/jumper the lead from r1 resistor to dc in on inverter block, correct?


Thanks once again.



When you remove the old part just follow the traces to where they go as far as the conectors P1 and P2 since you know what P1 and P2 are 5vdc and ac out. This way you can identify which pins on the old part go to gnd, 5 vdc and ac out. Then you can just run jumpers to the original pads.
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By thedailyhustle Sat Mar 03, 2007 10:45 am
It wasnt that simple in my case. I had figured where the gnd and ac out pads were by following traces, but there are two possible pads for dc out. I tried both pads and got no light from the backlight foil! Unless you are saying to wire both pads to the dc in of the inverter box, which I did not do. The VST tech i spoke with last said to run the wire from dc in on inverter to the 2nd pin off the R1 resistor right after the 5vdc in connector on the pcb. This worked, the backlight foil now lights up...

Now to further complicate my seemingly simple backlight problem.

The lcd/backlight foil is emitting the noise. When the foil is withdrawn from the display the noise stops. The el backlight foil is brand new from telesis.

Does anyone know what could be causing this noise when the backlight foil when inside the lcd display assembly???
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By thedailyhustle Sun Mar 04, 2007 3:48 am
I think its the el foil vibrating inside. I put some foam strips along the edges and it quieted down the noise about half way. I'll have to attempt to queit it down more later. For now its alright. If i get sick enough of it, Ill just disconnect the backlight, but its about 75% quieter now than before the inverter.

Peace