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Old Fluke Multimeters

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Dave Wise:
That's tricky, because you also have to guarantee that your ending (idle) state doesn't pull current through R4 and run down the battery.  If you remove R4, your part must drive LS1 to B+ (9V) but the SOT-23 parts are all 5.5V max.  I'm almost certain I can write a simple program for e.g. PIC10F320 which is available at Mouser for less than a dollar.

I drove LS1 with a pulse generator and found that my ears hear it best in a broad range from around 800Hz to 1200Hz.  The 8024B is still a lot louder.  Here's the outline of the program.  It should work as long as TONE-prime's period is longer than TONE's.  See any problems with it?

Set system clock to LFINTOSC 31kHz.
Clock Numerically Controlled Oscillator from LFINTOSC .
Set up NCO in Pulse Mode.  Inc = 37444 (1107 Hz), width = 16 (516us).
GIE = 0.  (Disable global interrupts - sources still wake us from sleep.)
while(1) {
 preload NCO accumulator to overflow on first increment;  (So TONE-prime starts ASAP.)
 clear TONE wake flag; enable TONE wake;
 sleep;
 enable NCO; disable TONE wake; clear NCO wake flag; enable NCO wake;
 while(1) {
  clear NCO and TONE wake flags;
  sleep;
  if (N1OUT == 0 and no TONE wake flag) {
   disable NCO; break;
  }
 }
}

blue_lateral:
What is the current wisdom on a replacement for c36 in the 8060a?

A while ago I tried to order all the caps on drtaylor's list. I was able (eventually) to get all those eventually except the Nichicon UTT 22uf aluminum electrolytics, which are discontinued. It seems the whole UTT series is discontinued, as is everything else I could find with a short enough length in 5mm diameter. I looked around and found a polymer cap from Kyocera, RPF0509220M035K. It wasn't in stock, apparently not in production yet. It was available for preorder at Mouser and DIgikey, so back in July 2023 I preordered some from Mouser, supposedly to ship in the first week of January 2024. The date has been pushed back several times, most recently to April 2, and I haven't got another delay notice from Mouser today so maybe they will ship tomorrow. There are also Kemet A759 polymers that rsjsouza suggested might work back on page 35. After the second or third time the ship date on the Kyoceras got pushed back I ordered some of the Kemets and I have those in my hand. They are taller than the original aluminum electrolytics by a lot, but it looks like they would fit. They do get really close to the processor circuit board above, and there is a bare via. It's a few thousandths clearance, and probably plenty, but I imagine I will try to insulate the tops anyway if I use them. One difference is the Kyoceras have a much worse leakage spec than the Kemets, but I don't believe it is an apples to apples comparison. I guess I will do some leakage testing at 9 or 10 volts when the Kyoceras get here and see how much worse (or better) for leakage the Kyoceras should be in an 8060a.

Any other currently available options?

Dave Wise:
Here are my capacitor notes in case I recap my 8060A.  (There's no trace of leakage today and all the caps are name-brand and measure good.)
After comparing leakage, I rejected polymer.  I found long-life Aluminum electrolytics for all circuit numbers.  The original C19 is a low leakage type and the best we can do there is only 1000 hours, using Nichicon type UKL.  Tantalum is low leakage but I exclude it because I don't know the polarity of the applied voltage.

All my caps have Chemi-Con logo, all 85C but no series marking except
C19 47/16 is LL series, low leakage, with LLA as modern replacement.
Others are probably SR/SRC/SRJ, with SRA as modern replacement.
SRA and LLA are 85C 1000h.

Original Dimensions
C1,C23,C24,C32,C34: 100uF 6.3V 2.5mmLS/6.3mmDIA/8mmHT
C12,C21,C28 10uF 16V 1.5/4/8
C36 22uF 16V 2.5/5/8
C19 47uF 16V 2.5/6.3/8

Charge pump cap C21 10/16 can be 6mm OD
All caps can be 11mm tall
RMS cap can be 18mm tall
Polymer leaks 10x more than regular - REJECT

DigiKey except as noted

C1,C23,C24,C32,C34: 100uF >=6.3V 2-2.5 <=6.3 <=11.2
Chemi-Con ELE-160ELL101MF11D 10/16 10K 2.5/6.3/11 at Mouser
Kyocera AVX REF0609101M010K 10V 3K 2.5/6.3/11
Chinsan ER1C101MP26307RU 16V 3K 2.5/6.3/8
C12: 10uF >=16V 1.5-2 <=4 <=11
Panasonic EEA-FC1E100 10/25 1K 1.5/4/7
Chemi-Con ELXY250ELL100MD07D 10/25 1K? 1.5/4/8 at Mouser
Rubycon 35ML10MEFC4X7 10/35 5K 1.5/4/7 at Mouser
C21: 10uF >=16V 1.5-2 <=6 <=11
Lumimax AEC10M50V0511 10/50 2K 2/5/11
Nichicon UPW1C100MDD 10/16 2K 2/5/11 at Arrow
Chemi-Con ELE-500ELL100ME11D 10/50 10K 2/5/11 at Mouser
C36: 22uF >=16V 2-3 <=5 <=11
Panasonic EEA-GA1C220H 22/16 1K 2.5/5/7
Chemi-Con ELE-500ELL220ME11D 22/50 10K 2/5/11 at Mouser
C19: 47uF >=16V LOW LEAKAGE 2-3 <=6.3 <=18
Chemi-Con ELE-350ELL470MF11D 47/35 .01CV/3uA 10K 2.5/6.3/11 at Mouser
Nichicon UKL1E470KEDANA 47/25 .002CV/.2uA 1K 2.6/6.3/11 at Mouser
Rubycon 35YXM47MEFR6.3X11 47/35 10K 2.5/6.3/12.5
CERAMIC: Murata RDEC71E476MWK1H03B 47/25 X7S IR=10Meg 5/5.5/4/7.5 $2.50 at Mouser

HTH,
Dave Wise

helius:
The 8060A's designer certainly schooled me about the desirability of solid polymer electrolyte caps in that instrument. You should at least read his advice and understand it, although you're free to select whichever components you prefer.

blue_lateral:
I do appreciate the extra options Dave Wise listed. I would prefer to use polymer however to prevent electrolyte spillage if it is practical to do so. I have several of these multimeters, and some will not be repairable. I have identified two bad MACs, and one of them is in an 8062a that was working fine when I put it away about 5 years ago. There is board damage too. I imagine that was preventable. The amount of board damage from corrosion varies, but so far only one unit was free of it. 

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