Heathkit IP-28

[Brice]

Hi guys,

Anyone has a manual for a Heathkit IP28 supply?

I have one I wanted to rebuild, changed all resistors, caps and transistors but no luck.

It barely generates 15VDC on the 30V setting and collapse at any load.
Seems something is wrong.
I haven't touched transistors for 20 years and I had to refresh my memory as I am more of a tube guy.

Thanks

 

[llwhtt]

I think I had a early version of that PS, mine was full of leaky germanium transistors that cost more, if you can find them, than the unit was worth. Never got mine running but sounds like the same problem.

 

[Brice]

Thanks for your reply.
I guess this one will go also to recycling. Not worth the effort.
Thanks.
Brice.

 

[satellite65]

I believe that is the model that I have.
If so, I should still have the manual.
I'll try to remember to look for it tonight.

 

[llwhtt]

Mine had 2 TO-3 Germanium transistors in parallel used as the pass elements, they were about about $30 each last time I looked. If yours is silicon it should be worth repairing if you do it yourself.

 

[Brice]

Thanks guys.

Yes they are silicium transistors. That's what I had in mind: to repair it.

I got the general idea of the schematic but one thing escapes me: the reference voltage at the bottom of the voltage control is floating, meaning the negative is not at the negative of the PS.

Maybe the manual explains how this circuits works in details but for Q5 to conduct it need a base voltage > then ground to get the base current to flow to make this transistor pass. Unless I am getting senile

 

[llwhtt]

The manual will give you in full detail how it works and how to troubleshoot it if it doesn't. I can't read that schematic, where did you find so I can get a better look?

NEVER MIND, I found it.

 

[satellite65]

 

[satellite65]

 

[Brice]

THANKS !
This is exactly what I was looking for. This is great.
Thanks again.
Brice.

 

[satellite65]

THANKS !
This is exactly what I was looking for. This is great.
Thanks again.
Brice.

Any luck?

 

[Brice]

Nope. I changed the last transistor, with little hope to get it working and same: low voltage fluctuating.

After spending $25 in parts only and time lost, I cut my losses and bought a super nice linear one on Amazon for $30 free shipping...
That one went for recycling.

But thanks for your help regardless.

 

[keilau]

Hi guys,

Anyone has a manual for a Heathkit IP28 supply?

I have one I wanted to rebuild, changed all resistors, caps and transistors but no luck.

It barely generates 15VDC on the 30V setting and collapse at any load.
Seems something is wrong.
I haven't touched transistors for 20 years and I had to refresh my memory as I am more of a tube guy.

Thanks

Check this Ebay auction.
https://www.ebay.com/itm/HEATHKIT-A...716658?hash=item5b40889472:g:GZgAAOSwvTpaB1Tr

 

[valiss]

i hve found the solution to low voltage 15 volts problem,its the current control pot,it opens up,burns out,just bridge across the pot terminals and u will see the voltage go back to 30 volts
this is what fixed mine.