[vcf-midatlantic] newbie

[Corey Cohen]

Persci drives are notorious for needing a lot of work after so many years.  There aren't many fully working drives out there that can exchange disks with each other.   

You will first need to change every single tantalum cap on the 24v rails.  This is not an easy task when you get to the ones on the sensor boards. 

Don't forget to double check the bearings to see if they need replacing or repacking.  

Then you will need to recalibrate the drive using a scope and finally an alignment disk.  If any of the pots don't work consistently across the range you might need to change them.   You also may need to change other parts if they are bad during this process.   I had had everything from bad opamps to bad TTL chips. 

This also assumes you double checked your power supply first to make sure it is fine.  I don't recall and don't have my 277 docs handy but I think it's 24v, -12,+12, -5 and +5v.  I keep a special power-one supply for working on Persci drives since it has all the voltages.  

Well that's about all I can think of off the top of my head.  I can dig up my other docs in a couple of days.  

Cheers,
Corey

corey cohen
uǝɥoɔ ʎǝɹoɔ

> On Dec 26, 2015, at 8:36 AM, Fred Terry via vcf-midatlantic <vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> 
> 
> Hello All,
> 
> I have subscribed to VCF/Mid-Atlantic. I own an IMSAI 80/30 with a Persci 277 drive and a Diablo wide traction printer. These were purchased new in 1978 for the purpose of writing survey and civil engineering software. I successfully used this system for a number of years but retired it for one of the newer DOS based computers.
> 
> After years of storage, I recently dusted the moth balls from my vintage IMSAI only to discover it will no longer boot. I am severely challenged when it comes to trouble shooting problems I am at a loss as to how to revive my computer. I have all the manuals that came with my purchase making a stack almost a foot high but they might just as well be written in a foreign language.
> 
> I hope to find someone in the VCF/Mid-Atlantic living close to me that could shed some light on what my problem might be. All the computer repair people think a S-100 bus is something you ride to work in the morning and raised an eyebrow at the mention of an 8" floppy disc. I didn't realize so much time has passed.
> 
> I live just north of Baltimore in Timonium Maryland only a few miles from I-83.
> 
> Please get in touch if you would want to lend a hand reviving my IMSAI.
> 
> I look forward to learning about the VCF/Mid-Atlantic and perhaps meeting some of the members. This is all new to me so i'll try not to embarrass myself by making stupid comments or something similar. 
> 
> For many years I restored early Corvettes but have emptied my shop and now only make a few reproduction parts.
> 
> Please be in touch,
> 
> Fred Terry
>