I’m working on a MCD7008 that I picked up, it had distorted output. After doing some research it looked like it was most likely the muting transistors right before the analog outs, or the .47 uF caps on the laser board. After a bit of reading it seemed like the thought was while you had it open might as well recap the board, replace the lamps and belt.
Well I did the full recap, replaced all four muting transistors with proper replacements, and then thought I’d put it back together and power it up to make sure all was kosher before moving onto the lamps and belt. Well wouldn’t you know it isn’t powering up now. I’ve checked all connections multiple time and all is good. I’ve gone over all of my soldering work and it looks good (I solder often and I’ve been doing it quite awhile).
I figured the next step would be to measure voltages, especially on the ps/relay board as the relay wasn’t clicking.
Here are a couple of photos showing where I measured and the results.
The markings on the schematic fall on the same place as the board layout.
On the anode side of D1 (red) I get 121vac
On the leg of R1 (green) I get .9Vac and 0Vdc. As the voltage passes through D1 isn’t it rectified to DC?
On the cathode and anode of D2 (blue) .5Vac 0Vdc
On SP6 and SP8 (light blue) which are pins that go to the input of the transformer I get .5Vac
The yellow marking are pins that go to the power switch board. I removed the cable and connected my meter to both sides of the cable going to the switch. I measured for continuity and had continuity regardless of how many times I pushed the power button, always had continuity.
I measure the resistance of both resistors on the board and using the diode reader on my meter measured both diodes in circuit and the measured okay. Should I remove them from the circuit and measure them with my Peak Atlas meter?
I’m stuck, I have a feeling that my issue is on the ps/relay board, but not sure where to go from here. I don’t fully understand the flow of the electricity on the boards to know where to measure next. Could it be the relay? Isnt the power switch responsible for tripping the relay? I have continuity in the switch though. I just find it odd that it powers up just fine prior to me capping it and now it won’t power up.
Thank you sooooo much in advance!
Dan
Well I did the full recap, replaced all four muting transistors with proper replacements, and then thought I’d put it back together and power it up to make sure all was kosher before moving onto the lamps and belt. Well wouldn’t you know it isn’t powering up now. I’ve checked all connections multiple time and all is good. I’ve gone over all of my soldering work and it looks good (I solder often and I’ve been doing it quite awhile).
I figured the next step would be to measure voltages, especially on the ps/relay board as the relay wasn’t clicking.
Here are a couple of photos showing where I measured and the results.
The markings on the schematic fall on the same place as the board layout.
On the anode side of D1 (red) I get 121vac
On the leg of R1 (green) I get .9Vac and 0Vdc. As the voltage passes through D1 isn’t it rectified to DC?
On the cathode and anode of D2 (blue) .5Vac 0Vdc
On SP6 and SP8 (light blue) which are pins that go to the input of the transformer I get .5Vac
The yellow marking are pins that go to the power switch board. I removed the cable and connected my meter to both sides of the cable going to the switch. I measured for continuity and had continuity regardless of how many times I pushed the power button, always had continuity.
I measure the resistance of both resistors on the board and using the diode reader on my meter measured both diodes in circuit and the measured okay. Should I remove them from the circuit and measure them with my Peak Atlas meter?
I’m stuck, I have a feeling that my issue is on the ps/relay board, but not sure where to go from here. I don’t fully understand the flow of the electricity on the boards to know where to measure next. Could it be the relay? Isnt the power switch responsible for tripping the relay? I have continuity in the switch though. I just find it odd that it powers up just fine prior to me capping it and now it won’t power up.
Thank you sooooo much in advance!
Dan