On The Bench This Morning: $180 Crock-Pot from All-Clad So, after a little grocery shopping yesterday, I put this back on the bench this morning. Yesterday's testing with a 60W bulb as substitute load showed exactly what I feared; the unit would program normally, but as soon as the relay closed, it would flash for 1/2 a second and go out, then you'd have to power cycle the unit to get any further response.
Power supply is very crude; R1-C2 feed D2-D3, which output is applied across R6 & "GND" such that R1/C2/R6 form a voltage divider with current limited dependent on value of C2. Z1/Z2 (12V/1W) in series across this clamp voltage to 24V, produced across EC1 to power the rest of the PCB and the front panel with uPC.
The PCB had burned-up Silastic over C2 and the 5 diodes in the center area; you can still see some residue on the 2.2uF film capacitor in the parts pile. Testing of the crispies indicated that C2 was only about 1.2uF, and D3 had approx .1V higher VF and much higher junction capacitance than the other two 1N4007s; in retrospect this may have been due to tweezer probing with one leg lifted as I was unable to replicate by testing components in the slots afterwards.
All electrolytics tested good compared against new of same value, so suspecting Z1/Z2/D3 might have leakage or breakdown at operating voltages, I decided to go scatter-gun approach and replace everything that had burned up Silastic as reassembly of the PCB into unit for testing is very close quarters work with good chance of damaging wires if done repeatedly. Total cost: $4.50 from
Sayal Electronics. As you can see, I had to stack two 1uF to get 2 uF, 1uF was the biggest they had aside from ceiling fan run capacitors which were both way huge and stupid expensive at $12-15.
But, it worked. Testing with 60W blub showed unit powered up and output stayed live once engaged; testing after reassembly showed that you do get more for that $180 pricetag than just gorgeous polished SS. Unlike your typical crockpot whose temp is a function of wattage applied vs thermal mass of the ceramic vessel & contents, this one is actually closed-loop with thermal sensor in direct contact with the vessel and it heats up FAST... like hot inside the aluminum tub in 15-20 seconds... due to a 320W element. This gets food contents up to temp quickly, which is much safer in general.
Winner winner, pot roast dinner! And just about in time!!! Keeping it TEA-related:
As you can see, the ESR202 served quite well this time out; even in comparison to my DE-5000. It has a number of interesting extra features as well; see
a teardown & manual here on eevBlog:mnem