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kevin gilmore

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  • 4 weeks later...

Need some advice on mounting the 8N80C onto the heatsink. The version of 8N80C I've got has a plastic tab at the back, unlike the usual TO-220 package with a metal tab. I wonder whether I still need to use a plastic washer on the tab before I put the screw through. The problem is the hole on the tab is too small for the regular TO-220 plastic washer and I dont want to enlarge the hole with a drill bit. Please advice.

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11 hours ago, matthew-levi said:

Need some advice on mounting the 8N80C onto the heatsink. The version of 8N80C I've got has a plastic tab at the back, unlike the usual TO-220 package with a metal tab. I wonder whether I still need to use a plastic washer on the tab before I put the screw through. The problem is the hole on the tab is too small for the regular TO-220 plastic washer and I dont want to enlarge the hole with a drill bit. Please advice.

Isolated semis you normally just mount with a bit of thermal compound between the package and the heatsink and a metal screw. That's the benefit of the full-isolated package - faster mounting (the downside is poorer thermal performance compared to a regular TO-220).

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  • 3 weeks later...
16 hours ago, matthew-levi said:

Can anyone tell me how I can delete the photos in my media storage on this forum. It seems that I only have 500mb of storage, and my previous photos has taken up most of the space. How can I delete my previous photos to make space for new photos I want to post.

As far as I know there is no way for users to do this, only Admin's have rights to manage attachments.  I'll look into it a bit further but honestly, just get yourself some photo hosting space for cheap and don't pile stuff onto Todd's server. Something like https://pbase.com/pricing.html will run you $23 a year for 3000MB of storage.

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  • 2 weeks later...

I am almost ready to test. The power supply seems to be working ok. With no load, the HT voltages are 368V and -370V. The low voltages are 15.07V and -15.09V. The terminal blocks will only be used for power to the boards, signal leads will be soldered directly to the input and output pins.

I want to proceed to testing the amp boards without the servos. On the earlier posts in this forum, ppl mentioned about a jumper to connect the servo. But I dont see any jumper on this board. Can I just not install the op amp to disable the servo. I have put sockets for the op amps.

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Just a couple of comments:

  1. The sockets you used for the opamps are shit. Machined pin sockets such as Mill-Max 110-93-308-41-001000 are greatly preferred for reliability.
  2. The terminal blocks look suspect. Normally, Phoenix Contact terminal blocks are used. Did you check the voltage ratings on the ones you used, compared to what you are running through them?
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The terminal blocks on the boards are all from Mousser and they are Pheonix brand. I will check on the op amp sockets and see if I can order the ones you suggested.

To all, I would still like to get an advice on no putting on the op amps to do testing. I actually could not see the op amp on the schematics that I found. Is the op amp optional in the operational of the amp assuming I can balance the DC offsets through the trimmer pots.

 

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Just want to report that the amp seems to be working, at least I can adjust the off-set and balance the O+/O-.

I will let it run ahwile and remeasure/re-balance. The next is put together the case work and also connect the headphone connector and some music. I will report further once everything is up and running. 

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