Powering your Apple IIe - (3) Optimizations

This is just about some enhancements I made to my previous projects (1) and (2). They were implemented on my other platinum IIe. I improved on the system cooling by over 45% and also on the AC power wiring arrangement to better accommodate systems with different peripheral cards. Lastly, I did it with the illuminated switch!

Better Cooling

Regarding the auxiliary cooling fans used in my previous projects, there are many makes and models with different dimensions, rotational speeds and noise levels. I believe two smaller "40DD" (i.e. 40x40xDDmm) fans give the best look. If opening 12 (the one above the PSU cutout) is occupied, a "6025" fan is the biggest that will fit (barely) in that space behind the RQ-85B PSU. Otherwise you could use a "7020" fan for maximum cooling (A "7025" will not fit because the back of the IIe is not exactly vertical).

 

The two 40x40x15mm fans in my last project (2) have a total axial flow of 13.0 CFM (cubic foot per minute, equivalent to 0.368 m³/min) compared to 23.5 CFM (0.666 m³/min) of the single 60x60x25mm fan in my original project (1). I finally opted for the look and switched to two 40x40x25mm fans with a total axial flow of 19.1 CFM (0.541 m³/min). Nevertheless, bigger fans give better air flow on top of the PSU and also tend to have a lower pitch noise which is more pleasant to the ears.

 

I used two high strength neodymium magnets (from hardware store) taped to the fan assembly to adhere it to the IIe’s steel bottom pan. This gives the fan assembly freedom of movement in case you need that space for temporary work or as a relief when the fan assembly is accidentally hit by external object. Those IIes with aluminum (non-magnetic) bottom pan are out of luck here (as in my original project (1) ;-).

Illuminated Switch

I make sure I get the right switch with the neon discharge lamp inside this time. The easiest way to check if the switch was illuminated is to connect it to the household AC power source and turn the switch on (please be extra careful here!).

 

I used the two terminals behind the “off” position for switching and the two behind the “on” position for illumination.

Better Wirings
I chose to have the AC power wires go over the peripheral cards instead of to have everything hide at the back behind the peripheral cards. The ferrite bead was placed down the AC power wires and above the PSU to avoid physical interference with the peripheral cards. To prevent EMI crosstalk due to their proximity to the peripheral cards, the AC power wires were shielded with copper foil and sleeved with heat shrinks wherever necessary.

Some extra length of bare copper wire was left at the Earth terminal of the C6-inlet to ground the copper shield. The solder joint was heat shrunk as usual.

 

My other platinum IIe had connector openings 8 and 9 free so the C6-inlet was installed in opening 9. Crimp-spade connectors were used on both the N (Neutral) and L (Live) power wires for connecting to the illuminated switch. Copper foil was wrapped around the power wires from the C6-inlet to just before the connectors.

The bare copper wire from the E (Earth) terminal on the C6-inlet was soldered to the copper foil and the power wires from the C6-inlet to the crimp-spade connectors were sleeved.

 

The crimp-spade connectors were connected to the switch and copper foil continually wrapped around the AC power wires until there is sufficient length to cross over the peripheral cards in the lower-numbered slots. The copper foil was then metered to make sure it was earthed properly. This section of the AC power wires was sleeved afterward.

The AC power wires were then wrapped around the ferrite bead and everything sleeved. I double checked that there was no exposed copper foil anywhere.

I reinstalled all the peripheral cards and everything got slightly but surely more space than in my last project (2). Using openings 8 and 9 (between slot 1 and 2) also improved the layout of the AC power wirings and cablings as there was less physical interference with the peripheral cards.

My other platinum IIe finally got her “new lease of power”. I hoped everything was done right this time!

Thank you again for visiting!

Dream your Apple II dream!

Powering your Apple IIe - (2) A customized C5/C6 connection

The Meanwell RQ-85B PSU installed in my enhanced IIe in my last project is humming happily thus far, so I decided to dig out my other two platinum IIes to do the same since I find it difficult to trust those 30-year-old power supplies inside them.

Problem - Simple But Only Functional

After playing around with my enhanced IIe for a few months, I realized the dangling switch and power connector at the back is functional but could be a nuisance during storage and also not aesthetically appealing. Also, although it is an easy and simple solution, there is always the possibility the power cord could be accidentally tripped during operation and the live connections pulled loose.

Searching for a Connection

To make the setup truly clean and tidy, the power connector and a switch needs to be installed flush with the back panel like the original. However, there just isn’t much room behind the RQ-85B PSU for a C14-inlet (like that in the original PSU) let alone adding a power switch. Then it occurred to me the smaller C6-inlet on my laptop’s power brick could be just the right ticket.

This is the power cable of my laptop with a C5-plug and the back of the Apple IIe platinum. According to the IEC60320 standard, the C5-plug/C6-inlet combination is rated at 2.5A, and thus over 250W in North America. So it is more than sufficient for our purpose.

Finding the Right Parts

There are various C6-inlets (commonly known as the “Mickey Mouse” connectors because of their shape) on the market and this particular rear-side screw-on panel-mount C6-inlet (sometimes referred to as Schurter 0724) with solder terminals for wires fits my purpose well. Because of its slim housing, plan was made to install it in one of the connector openings at the back of the IIe.

This C6-inlet in its original form will only fit into the largest opening (labelled 12) on the platinum IIe. However, after removing some of the housing material from three sides (one aligned and two angled cuts as shown in the above picture) it will also fit nicely into one of the smallest openings (labelled 5, 6, 8 and 9).

This is the top and bottom of the C6-inlets after and before modifications. The C6-inlet housing is made with a relatively stiff black thermoplastic. You have to be careful here particularly with machine tools because removing too much material will either damage the C6-inlet’s housing or make it a poor fit which means being easily pulled loose by the power cable.

The above is the KCD1-102 19 x 13mm boat rocker single-pole switch I sauced. There are many makes and they are in general rated at over 1000 Watts and 100,000 mechanical cycles. I believe a double-pole version with the same dimensions (KCD1-104) was actually used by Astec and Dyna Comp in their IIgs PSUs (Apple model no. 699-0126). Initially I planned to use the double-pole version (which is safer) but later changed to the single-pole version for specific reason.

The KCD1-102 switch in its original form is a tad too big to fit into any of the connector opening except the largest (i.e. 12) on the back of the IIe but I wanted to install it into one of openings 5, 6, 8 or 9 next to the C6-inlet. Fortunately, this could be rectified by removing the right amount of material from its four corners (four angled cuts as shown in the above picture). The KCD1-102 switch housing was made with a softer black thermoplastic so a hobby knife will suffice here. This was where, from my experience, the double-pole version fell short because its housing was thinner (due to the bigger switch mechanism and illumination, if any, inside) and thus readily damaged before enough material was removed. Note that the switch I used here was not the illuminated version so one of the solder terminals was removed since it was not electrically connected and only there for mounting.

You may also want to install an electromagnetic interference (EMI) filter, in this case a ferrite bead (or ring, like that inside the original PSU, which was missing in my last project), to comply with local electromagnetic compatibility regulations; and even a fuse or circuit breaker in case you don’t trust the RQ-85B PSU’s own short circuit/overload/over voltage protection circuit.

I had two 12V 40mm x 40mm x 15mm fans handy so I tied them and two fan grills together with cable ties for cooling the PSU. The dimensions of the two together match that of the PSU cutout at the back of the IIe very well.

Piecing Them Together

When soldering AC power wires to the C6-inlet, take great care of the polarities. Also, you won’t want exposed dangerous voltages inside your computer, so heat-shrinks are a must.

To better secure the C6-inlet to the back of the IIe, I made two notches on both sides of the housing (as shown) for later use. The cable tie in the above picture was only used as a guide for removing material at the right positions.

In the first of the two platinum IIes, the CGA video and mouse connectors have occupied openings 8 and 9, so the KCD1-switch and C6-inlet will have to be installed in openings 5 and 6 (farther away from the PSU). Before installing, check again no metal part inside the C6-inlet’s housing is exposed because of our modifications as you won't want any to touch the IIe's metal back panel. Unfortunately, the mounting holes of the C6-inlet does not match those of the smallest connector openings (i.e. 5, 6, 8 and 9; for DE-9 connectors) so I used plenty of hot glue to keep the C6-inlet in place. Alternatively, you could drill two holes on the IIe’s back and mount the C6-inlet with screws (or the other way round but I found drilling the C6-inlet somewhat difficult because of the holes’ positions in relation to the layout of the C6-inlet).

A larger heat-shrink was used to cover the entire back-end of the C6-inlet as a secondary safety measure against exposed metal parts inside. Two cable ties was tighten back-to-back around where the notches were on the C6-inlet and acted as a restrain to prevent it from being pulled loose by the power cable.

The KCD1-switch was then installed in opening 5 and secured with hot glue. The wirings were connected to the switch with crimp-spade connectors (6.3mm female) and jackets for it made uninstalling the switch easier than with soldering. A single-pole switch should always be installed on the Live (NOT Neutral) power wire because it is the one that carries dangerous voltage. The Neutral power wire normally carries current back to the source and is usually connected to ground (Earth) at the main electrical panel or meter for simple household installations. Nevertheless, it could at times also carry significant voltage since “real world” circuits are never perfect.

The AC power wirings were then wrapped around the ferrite bead as close to the C6-inlet and KCD1-switch as possible to minimize EMI crosstalk due to extended length of wirings inside the IIe case.

Heat shrink was used to cover the ferrite bead to prevent damage to the wirings due to abrasion with installed peripheral cards. The KCD1-switch was also covered to avoid any exposed dangerous voltage or the connectors loosening.

Notice that connector openings 5 and 6 are directly behind slot 4. So this renders the slot not available for most peripheral cards except may be a few with very short back-end (e.g. Uthernet I & II, some smaller Apple II Raspberry Pi adapters, or some kind of flexible slot extension, etc.)

I successfully reinstalled all the peripheral cards but found the cablings and AC power wirings at the back a bit crowded mainly because of the ferrite bead. If you have, in the lower-number slots, peripheral card with long back-end or connector(s) on the back-edge, you may want to try a different wiring strategy here given the roomy interior of the IIe.

Case Solved

Here is the external look of my project. Hmm, a power switch with illumination would give it the perfect look … if only I were careful in sourcing the right switch in the first place :-(

As a final check, I deliberately pulled the power cord out forcefully and the C5/C6 connection detached instantly without problem. So I deemed this setup safe enough for my ordinary use.

Following is the cost estimate of the parts used. For most electronic hobbyists, many of the parts may be readily available on their shelves and this would make a fun afternoon project.

	Parts	Qty	Est. Cost (USD)
1.	Fan & Grill	2	8
2.	C6-Inlet	1	2
3.	KCD1-102 Switch	1	1
4.	Ferrite Bead	1	0.5
5.	AWG-18 Silicone Wires (ft)	10	6
6.	Heat Shrinks (ft)	1	0.5
	TOTAL		18

Still living the Apple II dream!