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Posted

Before anyone asks - those are pain killers on the left, vitamins on the right. grin.gif

Below is a pic of the rough layout.

The boards will have a gap between them, the left amp pcb shifted back so the overall tube footprint forms a rectangle.

The psu pcb will be stood off higher than the amp boards with about a half inch of overlap above the amp boards.

Still waiting on the heatsink delivery.

The new soldering station showed up on the doorstep yesterday along with a lighted gooseneck magnifying glass.

Started stuffing boards with resistors last night. Now it's time to find the ideal soldering temp, then go to town with Mr Kester.

post-2625-0-93443000-1345578358_thumb.jp

  • 1 month later...
Posted (edited)

So, it's been a month since I posted on my necrofied thread.

Amp and PSU boards are stuffed, undergoing soldering.

The populated CCS boards are now mounted on the heatsinks, the chassis top-plate has been drilled swiss cheese style.

The bottom "drawer" has the trafos mounted along with the input & output jacks and IEC module.

Still waiting for my 50K Alpha Quad to arrive....

I'll post pics soon when I find my camera.

My daughters have a nasty habit of borrowing it and not bringing it back. Hmmm?

Edited by livewire
Posted (edited)

#1) Lower cost. The 1968s are becoming rare and their price reflects that.

#2) Availability. If my CCS burns up in the future, hopefully the 10m90s wil be in abundant supply. The 1968s wont be.

#3) Reliability. I've heard of strings of 1968 transistors burning out. Not one, but a bunch of them.

#4) Ease of construction. Drilling, tapping and aligning (6) 4-40 holes into the heatsinks is much less work than the 30 required for the A1968s.

#5) HeadAmp uses them.

The current version of the BHSE uses a similar CCS. Seems to me to be a natural evolution in circuit design. And a good one at that.

Edited by livewire
Posted (edited)

Livewire, just for knowledge what were the changes you had to make to the circuit to accomodate the use of the 10m90s in place of the 1968? I beleive that in the KGSShv the were some difference for both the resistor and diode values.

Edited by Victor Chew
Posted (edited)

Since the newer CCS circuit layout has not been published by the designers, I wont divulge the schematic without their consent.

Nattonrice did post some pictures of his KGBH build in the HC DIY forum. One can see which parts have been omitted on the amp boards.

Gone are the 1968s, the 500 ohm pull up resistors, the two series LEDs and the 400K resistor that connected to the bases of the 1968s.

I can be stupid when it comes to linking threads.

To see his pics, look in the 'DIY amp and such build gallery' thread, page 212 - post #4239

Edited by livewire
  • 1 month later...
Posted

Update - This project is on hold until I have the mula to buy more sand.

I hate when stuff is lost.

I was going to take some in-progress pics after I found my "lost" camera.

Turns out my daughter borrowed the cam and lost the USB adapter cable.

Got the camera back but haven't been able to upload nuttin.

Recently I lost a bag of pricey $$$ sand I had bought from BDent for the KGBH.

No money in the budget to replace it at this time.

Prolly wont be until the end of Feb until I can scrape the funds together to replenish.

Hoping that I will be able to find the lost parts in the meantime.

Meanwhile, there's a few other DIY projects that i'm pursuing.

Currently building a 1974 vintage Mark-8 "minicompter".

There's also a 1971 Kenbak-1 in the works too. This design pre-dated microprocessor chips.

Still need to find a pcb or some gerbers for the Kenbak.

Failing that, perfboard with wirewrap is an option.

  • 4 months later...
Posted

The necromancy continues...

 

After four months of searching in vain, I found my bag of lost BH sand.

It was shoved into a shopping bag of Home Depot door parts that was bought around the same time.

My daughter was cleaning the living room and rearranged all my stuff, and put it elsewhere.

Got lucky for waiting and saved ~$170. (repurchase cost)

 

Time to get this project back on track.

Almost done stuffing the boards, will post pics in a day or two.

Posted (edited)

Really look forward to see your build.

Did you have a hard time finding any of the sands? I assume some of them are EOL?

 

Wasn't hard to find when I bought them almost a year ago.

Yes, they are all EOL, I sourced them through B&D.

One of the transistors is no longer available at B&D, the only source is through a Chinese distributor on ebay.

Didn't want to go that route with all the fakes being sold these days.

Edited by livewire

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