What did you last repair?

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#3,542
What does that mean? The batteries that last 4 or 5 years are the cheapest crap they sell at Wal-mart. The AGM I speak of was the second highest quality I could get locally.
So I fail to see how it has anything to do with driving a BMW. The same thing could be said if I drove a POS Jeep. Cheap batteries don't last as long as good ones.
Case in point:
OPTIMA YELLOWTOP® 9040-148 Group Size 48 - 444.99$CAD - the best one Canadian Tire sells: https://www.canadiantire.ca/en/pdp/...ose-agm-battery-800-cca-0100023p.html?loc=plp
MOTOMASTER ELIMINATOR AGM Group Size 48 (H6/L3) - 266.99$CAD - The second best one Canadian Tire sells: https://www.canadiantire.ca/en/pdp/...8-h6-l3-battery-760-cca-0104820p.html?loc=plp
Certified Group Size 48 (H6/L3) - 148.99$CAD - The cheapest one Canadian Tire sells (junk that lasts 4 or 5 years): https://www.canadiantire.ca/en/pdp/...8-h6-l3-battery-615-cca-0104803p.html?loc=plp
 
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#3,544
Last night, I put my old (2005) Gateway LCD computer monitor on the bench.
Upon boot-up, the power LED would flicker a few times (orange for standby, blue for ON)
Once the PC was booted, things were fine..... but I knew CAPS were starting to go.
It's got many many hours of use over the decades.

Pain in the rear to open the case up - those nasty "clips" ya know.
The SMPS PS caps were showing age, the main DC filter, C905, a 100uF450V was reading 88uF.
But why out such a large/high volt cap in there, when the monitor is designed for ONLY a 120V outlet.
I replaced it with what I had on hand, a 100uF/400V cap, along with all the secondary filter caps.
At that point, that cap will ONLY see about 165 volts DC anyway, a 250V cap should suffice.
See schematic.....

gateway PS.jpg
 
#3,545
Windshield washer fluid not getting job done at all. A little googling showed that for my model SUV, plastic fittings under the cowl were most likely the culprit. Looked and sure enough a plastic coupling was the problem. Broken ends would not pull out of the lines. Obvious that would either need to patch it, or risk it becoming much larger job with much more parts to replace. So, two thicknesses of heat shrink tubing joined the ends back together. Insert joke about how different trades repair everything as if the problem was in their wheelhouse.
 
#3,549
Dont they have REsistors in series with the output transistors that give you a window to see the current with a DMM? If the resistor is 0.15 Ohms, which is reasonable for such service, a 14 mV drop would be I=V/R or 0.014/0.15 = ~93mA. Since I have no idea what the power supply voltage is and / or what the voltage is across the output devices, I'll guess 35V. P=I*V, or 35*0.093 = ~3.25W for an output device at idle. Those heat sinks appear as though they could take it, so, there's some class A going on in the design.

Someone else would have to calculate when the amp switches from A to B, in terms of output power level, given that bias current.
 
#3,550
https://www.hifiengine.com/manual_library/marantz/16.shtml

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiTtM63yIf9AhUKXGwGHdeCCdAQFnoECBgQAQ&url=http://instrumentresources.com/notes_16_16b_amps_marantz.htm&usg=AOvVaw1E8z1gLJa0-fMcF0F1_K7R

80W / ch /8ohms.

That is Marantz 16, 1969-73.
The 16B was apparently 100W / ch / 8 ohms, 1970-72...total sold for both was between 4 and 5,000, so slightly rare.
A classic from the time when it was a good unit, not a brand from a trading company.
 
#3,551
jjasniew said:
Dont they have REsistors in series with the output transistors that give you a window to see the current with a DMM? If the resistor is 0.15 Ohms, which is reasonable for such service, a 14 mV drop would be I=V/R or 0.014/0.15 = ~93mA. Since I have no idea what the power supply voltage is and / or what the voltage is across the output devices, I'll guess 35V. P=I*V, or 35*0.093 = ~3.25W for an output device at idle. Those heat sinks appear as though they could take it, so, there's some class A going on in the design.

Someone else would have to calculate when the amp switches from A to B, in terms of output power level, given that bias current.
Click to expand...
If you're going to get technical, the plus/minus B+ voltages are 51 volts.
The outputs are two parallel pairs of PNP/NPN per channel, and since it's the "B" model, it's rated for 100W/channel.
 
#3,554
wiseoldtech said:
If you're going to get technical, the plus/minus B+ voltages are 51 volts.
The outputs are two parallel pairs of PNP/NPN per channel, and since it's the "B" model, it's rated for 100W/channel.
Click to expand...
So it’s 5 watts per output transistor. Eight of them makes 40 watts - perfectly acceptable. If an amplifier that is supposed to be 100W/ch has trouble with 40 watts of heat it will have trouble playing music - any music - that’s above background levels. And a lot of garbage grade receivers made today have trouble with 40 watts of heat, couldn’t be biased that high, and blow up on the first party. The heat sinks on that beast look like they’re good for twice that much before you’d burn your hand on it.

There is likely 20 or more watts of other heat scattered around inside (VAS’s, voltage regs, lights, trafo core losses). With 60 watts of power draw, you probably would measure 100 VA or more off the wall socket. Power factor at light load is even worse than full load because of reduced conduction angle. So not out of line with observations at all.
 
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#3,555
@wg_ski
The heatsinks are actually the side casing of each of those monoblocks, and the front/rear sides just add to the overall heat dissapation.
Being 4mm thick anodized aluminum all around, it adds to the weight of the huge power transformer inside.
And trust me, it's a bear to work on!
Luckily, the monoblocks are bolted together and can be seperated to work on each one.
The eight output transistors are each rated for 15 amps c-e.

I just did some final testing, and it puts out an excellent sine or square wave on the o'scope.
In normal usage or idling, the heatsinks only get mildly warm.

My neighbor, a tad picky as he is, should be quite satisfied with this amp.
I assume that he'll use it to power a pair of his monster speakers, the Bowers & Wilkins Matrix 800's.
A pair shown below. Original MSRP $15,000/pair

B&W Matrix800.jpg
 
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#3,557
I also got a "battery case" for my phone but it made it too thick for my clamping phone holder in the car. It weighs almost a kilogram now, too. What did I do? I got a magnetic mount with suction and some N52 bar magnets (to make it useful - the internal magnets would hold a phone but not a brick like this)... The phone just snaps in place now and wouldn't fall if I ran a curb!

Amazing the strength of the bonding of the double sided tape strips they included 🙂
 
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