View Full Version : Heathkit H77 Dual Floppy Drive

June 13th, 2007, 04:26 AM
HI, I Have a Heathkit H77 Dual FLoppy Drive selling on Ebay. Item number: 220120015842 Take a look.

June 13th, 2007, 07:16 AM
Hi Dave,

What sort of disk drives are in the unit? Do you know the make & model? I do not recognise them.

I would like to know if they are dual sided or not for sure and if they are double density capable.

What sort of system did your drive assembly attach to?

Would they work attached to a NorthStar MDS-AD3 controller? It looks like it has the standard 34 pin DIP header connector. Is that true?


Andrew Lynch

June 13th, 2007, 03:34 PM
This unit contains 2 Siemens floppy drives. The model number is FDD 100-5. These are 100K single sided drives and have the standard 34 pin edge connector. This drive was plugged to a Heath H89 computer. I'm not sure if they are hard or soft sector drives. I know the old ones were hard sector.
I don't know if they would work on a NorthStar MDS-ADS controller or not.
Since this Heathkit box is just two siemens drives and a power suppy, the answer would be in the specs. for the Siemens FDD 100-5. I've never monkeyed with a working H89 and can't tell you much more.

June 14th, 2007, 08:42 AM
They are SS SD 100K drives. Whoa, that IS vintage.

Dwight Elvey
June 14th, 2007, 10:21 AM
Most H89's had hard sectored controllers but some used soft
sectored controllers with these drives.
These are 35 track single sided but could be replaced with
80 track 96 tpi drives. The 34 pin connector is just a straight
through from the edge connectors. The drives are selected
by jumpers on the drives and not wire swizzling as is
typical on PC's.
If you expect to use these drives, make sure the pulleys
are clean and smooth. Some times a little of the rubber from
the belts will stick to the surfaces. Also, most of the belts
I've seen need tightening as well.

June 14th, 2007, 11:43 AM
Chuckle, close to all the belts I've seen need replacing. Most of the drives I have don't seem to have anyway of adjusting the distance. Makes some sense, longer belt = slower revs.

Hmm, you know, I don't think that is true about the slower revs. Seems like it is only the ratio between the 2 circumferences.

Dwight Elvey
June 14th, 2007, 04:01 PM
I've been known to elongate the mounting holds to get a little
more life from the belt.
You are right, you were wrong. It is only the ratio of the pulleys.
A slipping belt is useless. If you can't replace it, you do what is needed.
Making sure the pulleys are clean and smooth is important. I've
seen several drives given up as hopeless to repair, just needing
these cleaned. Most think of the heads but not the pulleys.

June 14th, 2007, 05:46 PM
Yes, I have had the drives where the "belt" is now a black goo. No belt to be seen. Fun cleaning those pulleys.