This site is for the DAP310, but as you probably know, Mike and Kay Dorrough created a magnificent follow up to the 310 called a 610. A regular customer asked me to look at one for him. I’ve repaired a couple of them, but this one is exhibiting very strange problems. If you have repaired one of these, please send me an email. I’d like to pick your brain a little bit. UPDATE: See my update in the comments section of this post.
I have experience working with a 610, what’s the specific issue with yours, they had quite a few bugs.
So I now have pretty extensive experience working with the 610, as well. Except for the digital portion of the compressor cards, the circuitry is not very complicated. The killer is trying to read, understand, and follow the schematic diagrams. Step 1 is to make sure you have the right schematic for the version of the unit you have. Step 2 is to learn the routing of the signal through the unit. Compared with the 310, it’s actually quite easy to fully disassemble. Servicing the front panel is a bear. Unfortunately, the plastic surrounding the meters on the front panel is brittle. The front panel circuit boards are mounted to standoffs formed in the plastic. It takes a lot of work to stabilize and strengthen the standoffs such that they will support the circuit boards.
Once you get through the schematic and layout, servicing the 610 can be rather straightforward. Be sure to shotgun all of the 12uF Tantalum capacitors. They are time bombs. If they haven’t failed, they will. Check for modifications of the timing circuits around the compressor card connectors. Thoroughly clean and apply DeOxit to the headers and sockets that connect the compressor cards to the motherboard. Try to get some DeOxit into the front panel switches and work them a number of times. Like the 310 switches, they get dirty and create havoc.
There’s a lot to go wrong with a 610, and it’s hard being confident that everything is fixed when it is returned to the customer. I’m still chasing a problem with one of the compressor boards in the unit I have on the bench. If and when I find the problem, I’ll update this post. In the mean time, if you have one and need more information on them, contact me privately. I’m happy to share what I’ve learned. If you have one you want to trash, I could use some spare parts.
Hopefully all’s well that ends well. Both 610s have been repaired and returned to the customer. Believe it or not, a big challenge was the connectors that connect the compressor boards to the motherboard. They were very difficult to clean, but once they were cleaned, they worked well, and the compressor cards stabilized. As expected, the response times were modified, but they were returned to factory specs. When all was said and done, they weren’t that hard to service — after I understood the layout.
Unfortunately, the plastic faceplate, for lack of a better description, is very brittle. The studs that hold the display board to the front panel are cracking. Removing the display board is risky. Maybe one day someone will 3D print a replacement.
If you have any questions about the 610, send me an email, and I’ll try to answer them.