Old style power cable needed - Page 1
Forum section: electronics / repair

author: jeffjmr
author_rank: Regular Contributor
timestamp: September 24, 2021, 08:34:48 pm
content: I need to replace my power cable on my Heath TT-1.It is an IEC 30620 C1. I can find notebook power supply cables that are functional equivalents but they are all too short. There do not appear to be any C1 connectors available anywhere to assemble one either.Any ideas?Thanks,Jeff

author: PaulAm
author_rank: Frequent Contributor
timestamp: September 24, 2021, 11:53:02 pm
content: If you go to the hp -agilent-keysignt-equipment group and search for the topic "Current source for old oval HP power cords", one member has submitted an stl file to pring a compatible housing using some standard crimp pins.Actually, you don't even have to do that, it's on thingiverse:https://www.thingiverse.com/thing:4862134

author: mr.fabe
author_rank: Regular Contributor
timestamp: September 25, 2021, 01:52:47 am
content: How about this one with the ground pin?https://www.ebay.com/itm/174952307919?epid=19031315127&hash=item28bbf85ccf:g:8RsAAOSwf4hggfYRIf not, you may want to follow what others have done with their TT-1's and modify the IEC connector to C8 type or the C14 type.

author: andy3055
author_rank: Super Contributor
timestamp: September 25, 2021, 04:23:07 am
content: Can you post a picture of the receptacle? If my guess is correct, you may be able to use a C7 instead of C1.Most probably this one:https://www.ebay.com/itm/324737207087?hash=item4b9bd88b2f:g:c1IAAOSw~ZRhB-GF

author: jeffjmr
author_rank: Regular Contributor
timestamp: September 26, 2021, 02:52:05 am
content: Quote from: andy3055 on September 25, 2021, 04:23:07 amBingo!I had already confirmed I could use a C7, but had not found one longer than 18”. That 3 footer will work perfectly.Just have to decide now the pros and cons to converting to C14, specifically how grounding the chassis of the TT-1 might affect safety or performance.Thanks!Jeff

author: andy3055
author_rank: Super Contributor
timestamp: September 26, 2021, 04:12:10 am
content: C1 is a 2 conductor cable with no ground. so what is the deal with the grounding you have mentioned?

author: jeffjmr
author_rank: Regular Contributor
timestamp: September 27, 2021, 02:31:08 am
content: Quote from: andy3055 on September 26, 2021, 04:12:10 amNo issue if I stick with C1 but some TT-1 owners convert to C14. I am assuming they hookup the ground lead but I guess maybe they just use the live and neutral and use the C14 for polarity. I would like to find out and know what affect hooking up the ground lead to the chassis might have.Jeff

author: BrokenYugo
author_rank: Super Contributor
timestamp: September 27, 2021, 04:47:50 am
content: I can't see how grounding it would do anything but improve safety, any Y cap leakage would be shunted to earth, but that shouldn't be any issue.

author: jeffjmr
author_rank: Regular Contributor
timestamp: September 28, 2021, 12:10:36 am
content: I’m in the US, so connecting the ground to the chassis will introduce the neutral to the chassis resulting in mains power potential between the live and chassis. As built the chassis is insulated from the neutral line.If my analysis is faulty someone please correct me.Jeff

author: jpwolfe31
author_rank: Contributor
timestamp: September 30, 2021, 04:31:01 am
content: If the instrument fails and the mains shorts to the enclosure, and the enclosure is grounded (or neutral) the fuse will blow or the breaker will trip. If the same happens without ground, the mains voltage is on the enclosure and if you touch it, you may be the path to ground.

author: mansaxel
author_rank: Super Contributor
timestamp: September 30, 2021, 09:03:03 pm
content: Defeating a ground for an appliance is a very serious problem. The device has been designed with things like isolation distances and insulating layers based on the assumption that exposed conductive chassis will be grounded.An ungrounded appliance will have another design, with more insulation and no exposed metalwork.That horrible NEMA connector is best replaced by a "Mickey Mouse" connector, the IEC C5/C6 combination:It fits reasonably well, with small modifications, in the NEMA cutout.

author: tooki
author_rank: Super Contributor
timestamp: September 30, 2021, 09:12:38 pm
content: Quote from: mansaxel on September 30, 2021, 09:03:03 pmOh, sweet summer child.You forget that not everything was build recently, with modern safety standards.The device in question is an old device originally built without a ground (so no ground to defeat). It’s also a metal chassis. It used to be very common to have exposed metalwork, or even live chassis.The question being asked is whether adding a ground to this device introduces anynewhazards.P.S. It’s a common misconception that exposed metalwork requires grounding, even in modern devices. It does not. You can go to any electronics store and buy things like DVD players, stereos, TVs and toasters that have metal housings and are mains powered without a grounded cord.

author: mansaxel
author_rank: Super Contributor
timestamp: September 30, 2021, 09:16:12 pm
content: Quote from: tooki on September 30, 2021, 09:12:38 pmOK. Understood. I got the original question wrong. No, adding a ground should not be a problem.The devices with exposed metal chassis but 2-pole mains will be double insulated which probably is not the case with the old device.

author: CaptDon
author_rank: Super Contributor
timestamp: October 01, 2021, 02:33:21 am
content: Some of the older electric typewriters used those cords. Look around second hand stores!!One local store here has a bin with nothing but used power cords left over from dead donatedappliances. I still see the cords you are looking for from time to time. It is a bit late in the yearfor the amateur radio hamfests, but you may find cords there also!!

author: factory
author_rank: Super Contributor
timestamp: October 02, 2021, 02:20:29 pm
content: Quote from: jeffjmr on September 26, 2021, 02:52:05 amCan't understand why you didn't post a picture of the two pin connector in question and add some measurements of the pin spacing/diameter etc.Note: modern IEC C1 & C7 connectors do not have the same pin spacing.David