UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Test Gear and Workshop Equipment

Notices

Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

Closed Thread
 
Thread Tools
Old 23rd Apr 2019, 3:17 pm   #1
linescan87
Heptode
 
linescan87's Avatar
 
Join Date: Mar 2014
Location: Meath, Ireland
Posts: 547
Default HP 6024A power supply FET.

Hi, can anyone recommend a replacement fet for this power supply? Its marked 5-486.

Thanks,
John Joe.
Attached Thumbnails
Click image for larger version

Name:	20190423_151240.jpg
Views:	218
Size:	85.8 KB
ID:	181718   Click image for larger version

Name:	20190423_151233.jpg
Views:	151
Size:	80.5 KB
ID:	181719  
linescan87 is offline  
Old 23rd Apr 2019, 3:37 pm   #2
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
Default Re: HP 6024A power supply FET.

The full HP part number will be 1855-0486.

There are listings of HP part numbers versus manufacturer's numbers floating around the web.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is offline  
Old 23rd Apr 2019, 4:19 pm   #3
MrBungle
Dekatron
 
MrBungle's Avatar
 
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
Default Re: HP 6024A power supply FET.

This part doesn't appear in any of the references I have.
MrBungle is offline  
Old 23rd Apr 2019, 4:57 pm   #4
linescan87
Heptode
 
linescan87's Avatar
 
Join Date: Mar 2014
Location: Meath, Ireland
Posts: 547
Default Re: HP 6024A power supply FET.

Hi lads, thanks for the replies. I was at this last year and drew a blank on a replacement. Have just rediscovered it while doing some much needed spring cleaning. Wondering should I hold onto it or chuck. Would be a shame to throw it out though cause it would certainly come in handy.

John Joe.
linescan87 is offline  
Old 23rd Apr 2019, 5:10 pm   #5
MrBungle
Dekatron
 
MrBungle's Avatar
 
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
Default Re: HP 6024A power supply FET.

There are a few direct replacement numbered parts on eBay. May be worth a punt.

Then there’s the possibility of playing guess the IRF part which mostly involves picking something about right and sticking your fingers in your ears. I had to do that in a tek scope preregulator that exploded. It exploded twice again before I got the right part
MrBungle is offline  
Old 23rd Apr 2019, 7:13 pm   #6
Marconi_MPT4
Heptode
 
Marconi_MPT4's Avatar
 
Join Date: Mar 2011
Location: Dorset, UK.
Posts: 519
Default Re: HP 6024A power supply FET.

In the HP 6024A manual, on page 5-21 it appears that if Q1 or Q2 blow up there is a very prescriptive flow-chart of parts to be replaced including offending FET's It is possible both FET's are matched as HP supplied them in a service kit.

Usually in this type of circuit the Gate-Source threshold voltage should be close. I guess at the very least replace Q1 and Q2 with similar type then power up and gradually increase the mains supply with a variac while monitoring circuit.

Rich
__________________
To an optimist a glass is half full; a pessimist half empty; an engineer twice as big as need be!
Marconi_MPT4 is offline  
Old 23rd Apr 2019, 8:56 pm   #7
linescan87
Heptode
 
linescan87's Avatar
 
Join Date: Mar 2014
Location: Meath, Ireland
Posts: 547
Default Re: HP 6024A power supply FET.

Mr. Bungle, I like the idea of guess the IRF number (sounds like my kind of work, haha!) I'll check out Ebay and see what comes up.

Rich, yes sounds like a good idea to use a variac. Thanks.

Cheers,
John Joe.
linescan87 is offline  
Old 24th Apr 2019, 4:31 pm   #8
Marconi_MPT4
Heptode
 
Marconi_MPT4's Avatar
 
Join Date: Mar 2011
Location: Dorset, UK.
Posts: 519
Default Re: HP 6024A power supply FET.

Looking through 1982 International Rectifier Hexfet Databook, there are a few 3A TO3 devices highlighted that could be possible. Some are still available manufactured by Infineon but have suffered from die-shrink curse(TO-204).. not cheap.

I guess with the considerable advances in technology it is almost certain current TO-220 package type could be used.

Rich
Attached Thumbnails
Click image for larger version

Name:	IR TO3 MOSFET.jpg
Views:	117
Size:	55.5 KB
ID:	181785  
__________________
To an optimist a glass is half full; a pessimist half empty; an engineer twice as big as need be!
Marconi_MPT4 is offline  
Old 24th Apr 2019, 7:05 pm   #9
MrBungle
Dekatron
 
MrBungle's Avatar
 
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
Default Re: HP 6024A power supply FET.

Good find. Don't agree with TO220 though. Not enough for this supply.

Spent a few minutes looking at this. Looking at the specifications and schematics I would replace A4Q1, 2, 3 and 4 (assuming all are populated?). These were apparently fitted with 1855-0473 originally. Someone has reported success with IRF450 as a replacement for that part [1] and it looks about right on spec sheet as it's primary side switching.

Now the pain with this is the IRF450 is really expensive or from hooky suppliers only now. After reading further, old FETs never die. IRF450 is now sold as an IRFP450 in TO-247 package! So options are spend £££ or bodge IRFP450's in. The latter are £2.47 a go from Farnell so I'd probably go there.

Disclaimer: EXPECT FIREWORKS.

Edit: also expect that it may have blown whatever drives the gate if the drain flashed over to gate as well. Last time I had a preregulator go on me, it took the following bits out in one go:

Click image for larger version

Name:	IMG_3486.jpg
Views:	112
Size:	35.5 KB
ID:	181788

[1] http://www.simonsdialogs.com/2014/09...supply-repair/
MrBungle is offline  
Old 25th Apr 2019, 11:32 am   #10
linescan87
Heptode
 
linescan87's Avatar
 
Join Date: Mar 2014
Location: Meath, Ireland
Posts: 547
Default Re: HP 6024A power supply FET.

Hi again Lads, lots to think about now. Mr.Bungle, IRFP450 sounds like the way to go.

Thanks again,
John Joe.
linescan87 is offline  
Old 25th Apr 2019, 12:40 pm   #11
Argus25
No Longer a Member
 
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Re: HP 6024A power supply FET.

Do you really need 500V rated ones ? If so these mil spec ones are pretty good. I have bought parts from this crowd and not received any fake items, they are certainly cheap enough:

https://www.ebay.co.uk/itm/1pcs-2N67...oAAOSwstxVXGDG

If 400V rating will do, go for these lovely ones from Harris:

https://www.ebay.co.uk/itm/2N6760-HA...cAAOSwx6pYq4y1

I have used a lot of Harris TO-3 fets , always wonderful

These ones also look genuine:

https://www.ebay.co.uk/itm/JANTX-2N6...EAAOSwl9BWLDGA
Argus25 is offline  
Old 25th Apr 2019, 2:28 pm   #12
MrBungle
Dekatron
 
MrBungle's Avatar
 
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
Default Re: HP 6024A power supply FET.

I’d assume that 500V would be required. 400V is too close to half wave rectified mains for my liking. Imagine a 250V supply (average here!) and that only gives you 50V for a transient.
MrBungle is offline  
Old 27th Apr 2019, 11:56 am   #13
linescan87
Heptode
 
linescan87's Avatar
 
Join Date: Mar 2014
Location: Meath, Ireland
Posts: 547
Default Re: HP 6024A power supply FET.

Hi lads, I've gone ahead and ordered the cheap fet's Argus suggested. We'll see how I get on, they should be here in a few weeks.

Thanks again for all your input,
John Joe.
linescan87 is offline  
Old 27th Apr 2019, 1:24 pm   #14
MrBungle
Dekatron
 
MrBungle's Avatar
 
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
Default Re: HP 6024A power supply FET.

Fingers crossed for you. Don’t forget safety glasses!
MrBungle is offline  
Old 27th Apr 2019, 3:14 pm   #15
linescan87
Heptode
 
linescan87's Avatar
 
Join Date: Mar 2014
Location: Meath, Ireland
Posts: 547
Default Re: HP 6024A power supply FET.

If they don't work I'll probably buy a load of IRFP450 and keep trying until the explosions stop....
linescan87 is offline  
Old 4th Jun 2019, 6:05 pm   #16
linescan87
Heptode
 
linescan87's Avatar
 
Join Date: Mar 2014
Location: Meath, Ireland
Posts: 547
Default Re: HP 6024A power supply FET.

Hi Lads,

Back to this. The Fets Argus suggested arrived last Thursday. As it's a rotten day here I decided to have a go at this. Fets fitted and the two 47r resistors replaced it's working away.

Thanks for all your input,
John Joe.
Attached Thumbnails
Click image for larger version

Name:	15596678578531006842630678032735.jpg
Views:	144
Size:	92.7 KB
ID:	184435   Click image for larger version

Name:	15596678782483378299137497932185.jpg
Views:	154
Size:	52.5 KB
ID:	184436  
linescan87 is offline  
Old 4th Jun 2019, 8:06 pm   #17
MrBungle
Dekatron
 
MrBungle's Avatar
 
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
Default Re: HP 6024A power supply FET.

Excellent. Nice job!
MrBungle is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 12:13 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.