Heathkit IG 1275 Repair and Checkin
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- Опубликовано: 10 фев 2025
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In this video we take a look at a Heathkit IG 1275 that has decided to not act quite right on its owner. This was a rush repair as I only had a limited time window to get it back to it owner before a trip out of town back to their lab. So speed trouble shooting and off to the races let see how fast we can get it fixed!
** Repair exposes the Tech to mains electric and should only be done by trained personnel. Errors can be fatal. **
Hi Zen, I acquired one of these veeeery cheap ... no transformer, blown fuse, and burnt front-end components. I rebuilt the power supply using a scavenged transformer from an old Pioneer stereo, replaced all electrolytics and several shorted Ta caps, and a couple of dead chips. Calibration was okay, except the frequency max was a bit low. More work than was warranted, but a great learning exercise ... and fine for what I use it for. Cheers from DownUnder, Ian
Great to hear it is up and running. That one really sounds like a mess *looks at some Wavetek stuff in the corner* yep know that feeling. I was surprised with some of the dial tracking on this unit but then again I am used to HP gear setting the dial to 1Khz the frequency counter was reading 1.59.
The caps weren't self-discharging; you could see they were discharging through the sourcemeter at a rate of 10mA. You might want to be careful with that, higher currents and a battery might be quite unintentionally interesting.
I will double check but the SMU when the output is off has 4 modes. High Z, Normal, Guard, Zero. It was set to zero which I thought was open circuit. IE no drive or load but the meter portion was hooked up. I will have to check the documentation now for exactly what this setting is doing.
Referring to the trained professional banner at the start, speaking as a trained professional, are you not supposed to analyse the problem before replacing stuff lest one end up with 2 problems?
I would have checked the voltage/ripple on the power rails before replacing the filter caps. If ok, I would have moved on to troubleshooting and then come back to change the filters last. Just the sequence I would have taken.
I cant remember If i did check the power rails or started with an ohm meter on the caps and found a bad one. Once I found one bad cap all of them went for longevity sake. This unit lives about 6 hours away from the lab so getting it back in for repair is difficult at best.
Zenwizard, what is your favorite solder and diameter?
Something “Good brand” in no specific order
Kester
Mg Chemicals
Multi Core
Diameter for THT - 0.31” 0.8mm
Diameter for SMD - 0.38mm
Alloy 63/37
Customer should be happy, but I assume you didn't let it go with the 6v3 caps in it !