9100Bs freshly acquired, weird variations

[tubenewb]

Hey there! New here, and new to vintage HPs. I have come into possession of two 9100Bs and a 9125. They’ve long been neglected, and I’m cleaning them up in anticipation of attempting to get one running.

So the question I have is that the power supplies are different. One is as you would expect, big thick wires, standard look. The other back panel is abbreviated, with a single plug, no s/n plates, and a much thinner wire running between the plug and power supply. The plug is also a different shape and has a 115/220V switch.

I’m quite confused. Any thoughts are welcome.

https://i.redd.it/5s51k5y7a3g21.jpg

https://i.redd.it/r96dutzojlg21.jpg

https://i.redd.it/wzojz20pjlg21.jpg

[jackrubin]

HP switched from the earlier (pin-style) oval connector to the "standard" IEC connector during the 9100 production run. You can find illustrations of both types on page 29-30 of the 9100 Service Manual (09100-90034), available at hpmuseum.net.

My experience with HP machines of this vintage has been that HP used an adhesive to attach the s/n and name plates to these machines that tends to dry out and fail. On my 9100A, I had to reglue the serial number plate (loose, but held on by the power cord). The front identification plate fell off and was lost.

Enjoy your new machines!

[tubenewb]

(02-14-2019 11:50 PM)jackrubin Wrote:  Enjoy your new machines!

Thanks so much. I'll check out the manuals and maybe get up the courage to plug one in and see if it works. I need to find screws to affix the power supply.

[tubenewb]

(02-14-2019 11:50 PM)jackrubin Wrote:  Enjoy your new machines!

Jack, do you know of any special considerations for plugging these in if they've been dormant for over a decade?

For example, with tube gear, it's recommended that you use a variac or light bulb to limit inrush voltage. Can I just plug this in and cross my fingers? ?

I finally got some proper thread and length screws to affix the power supply to the case.

Thanks!

[teenix]

(02-20-2019 03:15 AM)tubenewb Wrote:  Jack, do you know of any special considerations for plugging these in if they've been dormant for over a decade?

For example, with tube gear, it's recommended that you use a variac or light bulb to limit inrush voltage. Can I just plug this in and cross my fingers? ?

I finally got some proper thread and length screws to affix the power supply to the case.

Thanks!

I'd at least open it up and check for cleanliness inside. Accumulated grime, dirt, old spilled liquids etc.

cheers

Tony

[tubenewb]

(02-20-2019 04:23 AM)teenix Wrote:  I'd at least open it up and check for cleanliness inside. Accumulated grime, dirt, old spilled liquids etc.

cheers

Tony

Oh yeah it's a bit dusty but I've cleaned out the cobwebs and such. Nothing significant that should short anything out, anyway

[John Keith]

(02-20-2019 03:15 AM)tubenewb Wrote:  Jack, do you know of any special considerations for plugging these in if they've been dormant for over a decade?

For example, with tube gear, it's recommended that you use a variac or light bulb to limit inrush voltage. Can I just plug this in and cross my fingers? ?

Using voltage-limiting tricks is generally not recommended for digital equipment or anything with a switching power supply. If you are experienced with electronics you can replace the large electrolytic capacitors. If not just flip the switch but be ready to turn it off quickly if any strange noises or odors occur.

[tubenewb]

(02-22-2019 07:37 PM)John Keith Wrote:  

(02-20-2019 03:15 AM)tubenewb Wrote:  Jack, do you know of any special considerations for plugging these in if they've been dormant for over a decade?

For example, with tube gear, it's recommended that you use a variac or light bulb to limit inrush voltage. Can I just plug this in and cross my fingers? ?

Using voltage-limiting tricks is generally not recommended for digital equipment or anything with a switching power supply. If you are experienced with electronics you can replace the large electrolytic capacitors. If not just flip the switch but be ready to turn it off quickly if any strange noises or odors occur.

Good to know, thanks. I’ll give it a shot this weekend. Wish me luck.

[dramsey]

Bear in mind the little CRTs in the 9100s will take some time to warm up enough to display an image...

[tubenewb]

(02-27-2019 05:26 AM)dramsey Wrote:  Bear in mind the little CRTs in the 9100s will take some time to warm up enough to display an image...

Well, I plugged it in and it did nothing but hum (from the power supply). I did, amazingly, run into someone who was trying to get this particular unit working years ago. They were having trouble with the replacement of a germanium diode (?) on one of the power supply boards. I see the replacement but it didn't work, apparently. That's where they left it, over a decade ago.

[KeithB]

If you can't find a geranium, you can use a Schotkkey.

[Massimo Gnerucci]

(02-27-2019 02:02 PM)KeithB Wrote:  If you can't find a geranium, you can use a Schotkkey.

Here it is!


SCNR :D

[teenix]

(02-27-2019 05:29 AM)tubenewb Wrote:  

(02-27-2019 05:26 AM)dramsey Wrote:  Bear in mind the little CRTs in the 9100s will take some time to warm up enough to display an image...

Well, I plugged it in and it did nothing but hum (from the power supply). I did, amazingly, run into someone who was trying to get this particular unit working years ago. They were having trouble with the replacement of a germanium diode (?) on one of the power supply boards. I see the replacement but it didn't work, apparently. That's where they left it, over a decade ago.

Probably wise to be careful poking around in there too. The cathode ray tube operates from very high voltage (around 3500V), not to mention the mains power. Both will be nasty to the unwary. Some capacitors may remain charged at a high voltage even after power off.

cheers

Tony

[tubenewb]

(02-27-2019 07:30 PM)teenix Wrote:  Probably wise to be careful poking around in there too. The cathode ray tube operates from very high voltage (around 3500V), not to mention the mains power. Both will be nasty to the unwary. Some capacitors may remain charged at a high voltage even after power off.

Thanks for looking out, Tony. I was splitting apart old all-in-one Macs (Plus, SE, etc.) when they were still in use and VERY conscious of the charges on those CRTs and related caps.

FWIW, here's a photo of the work the last crew did that didn't seem to fix the problem. (that TI in place of the germanium)

[teenix]

(02-28-2019 02:05 AM)tubenewb Wrote:  Thanks for looking out, Tony. I was splitting apart old all-in-one Macs (Plus, SE, etc.) when they were still in use and VERY conscious of the charges on those CRTs and related caps.

FWIW, here's a photo of the work the last crew did that didn't seem to fix the problem. (that TI in place of the germanium)

Cool, you should be a wiz then :-)

If it is the TIP29B you are referring to, it is a 1.0 A, 80 V 30W NPN Bipolar Power Transistor marked as Q1 in the circuit diagram for that board. Still cheaply available for around $1. It is part of the oscillator circuit around the transformer which looks like it has had better days.

Q1 is listed in the service manual on the HV PCB (09100-66522) as...
TSTR: NPN Si (this would seem to be silicon, not germanium)
MFR. 86658 (???)
PART NO. obd (???)
Not much to go on.

Looks like the circuit track has lifted off the board too.

cheers

Tony

[tubenewb]

Yeah I think this TI was put in place of the (whatever) that was there before. I've seen a similar replacement on a 9100a teardown on Flickr.

https://www.flickr.com/photos/141701495@...776277466/

https://www.flickr.com/photos/141701495@...776277466/

https://www.flickr.com/photos/141701495@...776277466/