|10th June 2014, 06:30 AM||#12|
Pulled out the filter board.
Measuring it is kinda strange.
from what I've observed is nothing is fixed.
So if your measuring resistances of caps, MOVs,
coils and diodes they start somewhere and goes
up or down.
Lytics measure as follows (Blu ELNA 85 C):
C 123 4700uf 25V from .445 MOhms to 14.7MOhms
C 126 470uf 25V from 2.9 MOhms to 2.75 MOhms
C 127 4700uf 25V from 1.185 MOhms to 6.84 MOhms
Films (WIMA) measure:
C124 .1uf/63V 1.156 MOhms
C125 .1uf/63V 2.89 MOhms
Balanced ISO Xformers
Measure from 1 ohm to 2 ohms.
from YEL to BRN 2 ohms
from RED to BLU 1.9 ohms
From RED or BLU to GND 1 ohm
The MOVs in the circuit seem to test okay.\
That is they start around 1 MOhm and peak around 5 MOhm or 6 MOhm.
Their fuses are at .2 Ohms ea.
Havent tested the L7805 yet but it looks
suspect. The rubber is pulled from the heat
The PWR Xfrmr seems okay as it measures
0 to 120V tap 106 Ohms
The Secondaries measure:
10.5V at 1.3 Ohm
9V at 4.7 Ohm
16V at 3.0 Ohm
I'll try to rig up something...
Was going to try and rig up an octopus rig.
Thinking I should try and rig up something
for the Power xfrmr on this filter board
and see how it measures up in circuit.
And then try to guestimate test points
on it and their voltages.
I sure wish some schematic or troubleshooting info would
show up it would point me in the right direction.
|10th June 2014, 10:22 PM||#13|
Filter Board and Power Relays
Shame on me.
Looks can be deceiving.
Made a little test rig, worked through the power xfrmr.
I think it's fine along with most all the associated components.
Thinking the ripple on the DC is too high at 10 percent.
Vin for the L7805 is 14.04 Vdc with 1.4 Vac ripple on it.
Vout for it is 4.96 Vdc.
Using the test rig and lowering the Vac for the board to about
104 Vac adjusts the voltage to 11.96 Vdc to check the relays.
The Filter board is layed out simply and with a little time
its pretty simple to figure out.
I jumpered one of the diodes on the ground side
on one end and to the common ground side of the
relay connection terminal.
Then hooked to the 14 Vdc (now 12 Vdc) terminal connection
that goes to the brains board next to the face plate
and the opposite end I used to actuate the relays.
I can now go back to the T2 board and test those relays.
I know at least something on the T2 board is shorted out.
I'm fixing to replace the 'lytics on the filter board with some
higher temp chem cons.
And measure again.
Film at 10 O'clock.
|13th June 2014, 08:47 PM||#17|
Sync- You have the schematics now.
First, on sheet 7 is the "T2" circuit that checks for valid AC power levels. If that does not see a voltage below 130V AC and above about 70V AC the relay that turns the whole thing on will not energize. Its the starting point. Its very possible that the shunt regulator or the LM339 could have failed. Or there could be an open circuit on the board or on a connection.
Let us know what you find.
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|14th June 2014, 03:37 AM||#18|
it before apply the next series of tests.
Between 30 volts and 60 volts just the T2 board goes from
.2 amps to .6 amps current draw with a 100 watt bulb in series
The cucurrent starts coming on strong around 25 - 35 volts.
Perzzo classifies this short as a "psuedo-zener short", that is
when you start applying power, it reaches a point where it
starts sucking power or turns on like a zener would.
However, it will stabilize at 30 Volts and current will slowly
Also between 30 volts and 60 volts I've let some of the smoke out
of the MJE13005 MJE13003 combo. More from the smaller one
than the larger one.
I don't just want to pull and replace them and have something down-
stream take the new chips out.
Also checking the U406 (MOC3083) with the diode checker has fwd and revers voltage on pins 1 and 2. F 1.025, R 1.014. It was warm.
The Rf input choke was also warm.
The MJE s are pretty tough units rated at 40 watts max.
Wonder why they are switching their lives away?
I can't find the short.
If something is open, then it wouldn't pull current.
Last edited by SyncTronX; 14th June 2014 at 03:49 AM.
|14th June 2014, 04:05 AM||#19|
Are there any caps that get warm on the input/protection pcb?
|14th June 2014, 05:13 AM||#20|
Back to sheet 4, the T2 board. Lets work through that first. Blown MOVs are unlikely actually. The T2 circuit will prevent most of the causes of blown MOV's and we have not seen a failure of that type on any of the products with T2 yet. The MOV's with either be OK or fried. They don't have a middle state where the breakdown voltage is reduced. The symptoms are more those of a failed supply cap or diode. On the T2 board disconnect J402 that goes to the filter board and J404, J406 so it is the only board in the system. The relay will not turn on like this. Check for shorts and supply voltage to see if you still have the problem. I would then power the relays with a 12V supply and see if a problem surfaces. It is designed to run directly off the line and handle in excess of 400V. (Do not touch when energized!) There is a triac, Q405, that powers the control board (I think).
If the LM339 is out the unit cannot start. >.6A into an MOV will get you a lot of smoke pretty fast. The continuous dissipation is closer to .5W so .6X30V is a lot of power.
Can you post a photo of the MJE's so I can see where they are?
Sorry for the less than linear troubleshooting post. I'm still thinking the problem through.
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