Well I thought I would do some detailed documentation on these HPR builds and I'm going to do some short videos today which I'll share in a Dropbox link at a later time. In the mean time, here's a couple of photos.
One of the things you won't find shown on most layouts is the turret board mounting screws. That is because each chassis is a little different and it is something you need to figure out on each amp unless you're doing a bunch with the same chassis supplier. What I always do is mount all of the transformers, capacitor boards, sockets etc and then figure out where the standoffs for the turret board can go without conflict.
Then I place a scaled print out of the board in the best possible place so it doesn't fall under the chassis lip and so the board components align with the sockets where possible. With the HPR there isn't much leeway for the long axis of the chassis positioning unless you want to go way over the multi value capacitor, but there is some leeway on the short axis depending how close you want to be to the sockets or to the controls. I usually end up putting the board in the middle between the front and back on Fender blackface amps but not always on other amps.
Once I place the print out I take a look on the back side of the chassis for stand off locations that aren't under a trannie or something else. On an HPR there is no choke or capacitor doghouse so that frees up a lot of area. On this particular amp as shown in the photos I've ended up putting the standoffs near the board end on the preamp area and away from the end on the power end. You can see them in the chassis interior photo and the screws for them on the chassis back side photo.
After I figure this out I mount the stand offs on the board, dab a bit of red nail polish on the bottom of each stand off and set it gently into the chassis in the proper positioning. After removing the board I have red dots where I an going to drill for the stand offs. I let the polish dry then center hit the holes with a center punch and then drill them. I mount the board to check for alignment but then take it back out until all chassis wiring not related to the board is completed before putting it back in. This is because if the board is in when you're wiring up the sockets, controls or other non board wiring you are apt to knuckle the board and bend component leads.
You will notice on this particular chassis that the reverb driver transformer holes are not properly spaced and I had to flip that transformer around and mount it differently than in a stock PR amp. In the PDF file I posted in this thread I have a page with the MOJO PR chassis drawing I got way back in 08 when I was first doing these amps and those holes are the same. I don't know if they have changed them since but these chassis (not from MOJO) which I purchased recently have the spacing too far apart as well. Now this is for the current reverb driver transformers that are available. I believe the original trannies were bigger.
One thing you probably can't see in these photos that I do to make things easier is I put a red dot dab of nail polish on the 8 pin sockets at the #1 pin. I do this because the 8 pin symmetry makes it harder to determine which pin is which unlike the 9 pin sockets which have a spacing and I can't read the numbers on the socket very will at my age. Another thing that is hard to see is the two 3 terminal strips I have installed inside the chassis. One is near the multi-cap and the other is on the right side of the PT. The one near the cap is for the heater wire connections from PT to the pilot lamp and the wires going to the sockets and the grounded center tap terminal is for the power section ground point. The other 3 tab terminal strip is for the PT/power cord hot and common wires and the grounded center terminal is for the UL safety ground wire of the power cord.
Topic: Hoffman Princeton Reverb builds (Read 8653 times)