I meant a ground connection to the tuner power supply board and I can't really see where the one you're holding is connected, but suppose it's grounded nonetheless.
Let's assume the protection board is intact (but I suggest you overhaul it anyway) and go back to square one.
Here's what I suggest:
- Swap the DBT light bulb to 100W b/c the 70W is too bright for me (maybe others too) to get an indication from the pix.
- You have a mixture of old Sanken and new On Semi output transistors pairs in the back of the unit - swap them all to match.
- Make sure the connections at the bottom of the driver amp Molex footer are all springy and make good contact with the pins. No solder blobs should be in there restraining the contacts.
- The only components I could not check on the excellent pictures of your driver amp are the LED's orientation and the STV-3HY's polarity. LED's go anodes (+) to the outside, cathodes (-) facing each other. STV-3HY's go yellow dots (cathodes) facing the outside. Can you verify?
- Make sure to hook up the top Molex header (2 channels and ground) to the driver amp. Set the bias trimmers on the driver amp to minimum and measure bias current. You should have about 17mA. If you get less, set them to 17mA which should be about a quarter turn. Notice the DBT and the LED's and make sure they do not light up. If they do, it's a too-much-bias-current warning.
- See if you can get the protection circuit to click the relay and exit protection mode. If not, measure DC voltage on the gray/blue wires coming out of the bottom of the PS board near the driver amp, with, and then without, the driver amp. Put the F04/F05 fuses back in when you remove the driver amp. Leave them there while not measuring bias.
I hope we see some progress b/c there's no apparent reason for the protection circuit to protect with nearly zero VDC input to it.
Let us know how it goes.
This is getting weird....While I was reading your guide I got the green light 3 times but I haven't done anything different...just reconnected the board, fuses and it worked.
I was able to bias the right channel, waited 20 minutes, changed the fuse to F04 and meter on F05 to bias the left channel and again I can't get the green light.
Tried everything again but still nothing...Re-checked DC offset on the right channel and it was at -15mv, took it down to almost 0...DC on the left is at -1, 0mv
I thought that maybe the fuse holders weren't making good contact, checked that but nothing.
Could it be possible that the 70W DBT doesn't let the amp power correctly?? Remember I'm on 220v grid not 120v...
1. Gonna try with a 100W tomorrow
2. My outputs are all new. Here a pic
3. Connections checked, everything is tight and makes good contact, no solder blobs
4. LEDS are ok, cathodes facing each oder. STV-3HY yellow dot facing outside
5. With the bias trimmers at minimum I got 2mA. When I got the green light I started trimming the right channel slowly within the 4 minutes till 28mA (2 quarters turn aprox). The LEDs didn't light up and the DBT was barely on