Reviving a PERQ 1a

Fortunately my love of classic computers, expecially classic PERQs, well exceeds my dislike of certain organisations :-) It's probably too late to say this, but you shouldn't remvoe the lcoking clip from the postioner on the SA4000 winchester drive until it's spinning. It's too easy to move the heads as you pull the clip out, and doing tha on a stationary disk is not the best idea. Although to be fari, these drives are pretty solid, and it's hard to wreck them. The power supply is one of those infernal Boaschert 2-stage ones. However, it doesn't seem to need a dummy load to regulate correctly. You can run it with no load and it should be fine. atmittedly the PERQ 1 was the last (of 4) PERQs that I obtained, but I also had to start PWERQ repaires with no knowledge :-). I apologise if I mention things that are obvious. Some things seem obvious to me, but I then find after much emailing to and fro that this was the problem. Tke the casing off first. I guess you've done that., though. If you haven't, the front and rear panels come off first, then the sides. THis frees the top cover over the floppy drive, etc. There are interlock switches that prevent the machine pwoering up with the front and rear panels removed. They;re those standard white ones found in a lot of machinesm, and you can pull thje actuators out a little way to turn them on, so you can run the machine with the cover removed. The PSU is under the main card cage, and is a right pain to get to. Basically you have to remvoe the card cage. So to save a bit of time, you can test it without removing it : Unplug the ribbon cables from the front of the CIO board. The top one goes to the floppy drive (SA850 pinout), the bottom one ot the wincheter. Lable them if you are not sure. Then pull the boards out of the card cage. You don't bneed to remvoe them all the way, jsut make sure they don't connect to the backplane. There are 3 boards i na normal PERQ, form the left they are the CPU, then the memory (and video) and finally the CIO board (input/output, disk controllers, etc). If you are very fortuantel there's a 4th vaord on the right of these. That's the OIO (Optional Input/Ouptu). It adds a 16 bit parallel interface (a bit like a DEC DR11-C [1]), and oen or both of ethernet (which is not standard on PERQ 1 and 1a models) and Canon CX laser pritner interface. There are other boards that could be inthat slot (like a QIC-02 tape interface or a Datacopy 300 camera controller), but you are very unlikely to see those. Now disconenct the DC power cables from the floppy drive nad winchester. Unplug the AC cables to the motors if you like, in fact the Winchester motor cable should have been unplugged when the spindle locking scrrew was fitted. HAve noting plugged into any of the D connectors o nthe backplane At this point there.is nothign conencted to the DC output of the PSU. Connect mains, with the interlocs pulled out, the breaker closed, flip the little switch on the front./ The fans should start up. If that's OK, check the DC voltages on the labelled traces on the backplane. It's rarew for them to be out of tolerance. Eitehr they are OK, or they're all missing. If nthe latter case, you have to work o nthe PSU, whioch I can explain when you need to do it. For the moment I will assume the PSU is OK. Power down. and remvoe the mains lead. Put the logic boards back in, connect the keyboard ot the appropriate conenctor on the backplane. On the underside of the keyboard is a 3 digit 7 segment display. Power up again and press and release the reset button on the back of the keyboard. Look at that display. if it gets to 010, then the CPU has passed power-on diagnositcs, and is attmpting to load microcode from disk. If not, you haev some logic faultfinding to do. Power down, reconenct the drive data ables to the CIO board and the drive power cables. Conenct the monitor to the correct conenctor, and power up again. Again blip the reset button. Watch the display. At 030, you should see memory test patterns on the CRT screen. If not, maybe there's a monitor problem. If you are lucky, the machine will complete the boot not, you might have to re-install thigns from floppy. I've left out a lot of what to do when it doesn't work. What I epxext is you do the above 9which is safe, and will protect the mahcine from amjor damage), adn then get back to me when you ahve problems -- like the PSU is giving no outputs, or the DDC (7 segment display) sticks at 009, or whatever. THen I can help uou further. -tony