Another Heathkit IP20 power supply repair

[Darko]

Hello to all, this is my first post on this forum, and I joined in hopes of repairing my vintage ip20 heathkit power supply. It seems that I need to replace a smoking capacitor 500 uF 50V and try to understand the amp adjustment, it seems the meter is not responding to any of the adjustments prescribed in the manual. I'm new to electronics so a bit of a learning curve, but I do recognize most of the components in the regulator, just not sure how it all works together. Will fiddle some more when I get the new caps soldered in.

 

[KrisBlueNZ]

Hi Darko and welcome to Electronics Point

This is a new project so it should go in a new thread, not in mrmodify's thread. I will move these two posts to a new thread. Please look in the Electronics Repair forum for the new thread and 'subscribe' to it by clicking Watch Thread. I will respond to your questions later.

 

[KrisBlueNZ]

Have you downloaded all of the information linked in the other IP-20 repair thread? There's an assembly manual and a separate schematic file.

What's the circuit reference of the capacitor that's smoking?

 

[Darko]

25-121 500uF 50V. Yes I did get the .pdf file original assembly instructions. I am just new to electronics but I can solder and do basic measurements, have to start somewhere and I hate to dump something that has traveled 50 years in time if it can be fixed.

 

[mrmodify]

Welcome Darko,
You have come to the right place. Hopefully I can help some. If not there are alot of people here that have the knowledge to help you. Thia is a great site!

 

[Darko]

Thank You all, and I am excited to have joined. I replaced the capacitor with a 470 uF 100V. It seems to work fine with the exception of some of the voltages not reaching the maximum voltage ie: 10 Volts reads 9.85 with fine adjust at max. But if I switch to 15V I can turn back the fine adjust and achieve 10.00V with barely any deviation. This unit has been sitting on a shelf for at least 35 years unused so it is great to see it up and running. I am a real noob when it comes to electronics, but have a great desire to understand how things work from the ground up. I have some understanding of basic principles, in electricity, but not so much as to fully understand a semi complex circuit. Picked up this electronics kit from a yard sale and hope to finish the course Macmillan Intek (1985).

 

[mrmodify]

Morning Darko, have you done the alignment procedures for the IP20? If not do that and that should correct the low voltage. I am currently working on a IP20 and have another one to do when I finish the first one.