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

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Old 14th May 2022, 2:44 pm   #21
Bufo Bill
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Default Re: Hp 1825a

Think I have the rotating switch back together.
The A3 board switches I bought have been really tricky to fit, if you aren't careful the foil contacts on the board can lift when you lift the soldering iron after making a join. Either I'm really bad at this or the glue is a bit worse for wear after 50 years!
Bill.
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Old 15th May 2022, 10:32 pm   #22
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Default Re: Hp 1825a

Hopefully you got those contacts back in the right place, my 1825A is with the 181A in storage, I don't have space to keep everything in the same place, the 180A & the 182T are here.

David
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Old 16th May 2022, 6:09 pm   #23
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Default Re: Hp 1825a

I just hope I've found all the contacts! The ****** thing bounced on the bench and skittered on the floor.
Just some times, being such a clumsy s*d really gets my goat.
Cheers from Bill.
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Old 15th Jun 2022, 9:18 pm   #24
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Default Re: HP 1825A. Time base and delay generator.

Finally got my manual and went through the display switching contacts point by point. There are several bad traces. I intend to create little jumpers like I have seen online to repair the breaks. I'm not sure if the breaks were from rough Storage before my ownership (it was a bit rough-looking) or if I overworked the board when replacing the switches.
Does anyone have any tips for keeping boards in order when they need lots of soldering work doing?
Unfortunately there has been a disaster with the 182T. I would like the benefit of your advice, so feel free to split the thread if you feed its appropriate, Mods.
It started with no signal trace from the calibration voltages, and checking the test points the -100V and 15V rail fuses had both blown. This looks bad to me. I am wondering if anyone has suggestions for diagnosis before I start testing circuit components back from the fuses? I don't want to switch it back on without knowing what happened.
Cheers from Bill.
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Old 16th Jun 2022, 6:08 pm   #25
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Default Re: HP 1825A. Time base and delay generator.

The 182T PSU fault, my standard procedure with these (and the others in the 18x series) is to remove the plug-ins, remove fuse for the HV section, replace fuses and use a lamp limiter for fault finding & repair.
I have also removed a board from a 180A and repaired it using current limited bench supplies.
Please advise which variant of the PSU you have.

David
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Old 16th Jun 2022, 7:39 pm   #26
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Default Re: HP 1825A. Time base and delay generator.

David, thanks for your reply. I hope all is well with you.
I am unsure how to ID the variant of the PSU. Is it determined via serial number or would a photo help?
Many thanks from Bill.
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Old 16th Jun 2022, 9:40 pm   #27
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Default Re: HP 1825A. Time base and delay generator.

I'm well ATM thanks, looking through my pictures of the joblot of scopes I got from PP auctions, the later PSU regulator board has the fuses on the board, older design had them seperate.
Faults I've had so far are; the small plastic transistors O/C or blown apart, shorted PSU rectifier diodes and drifted resistors in the voltage adjustment divider chain.
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And yes I have managed to get a trace on all of them, even those marked "tube U/S", not looked at the scope modules that came with them yet, the SA modules are in very poor condition, only one has the attenuator & mixer present.
The 182T had an open focus pot, I replaced it with some fixed resistors till I can find a replacement, tube did have limited brightness, an adjustment of the intensity limit (following the manual) has improved it a bit.
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David

Last edited by factory; 16th Jun 2022 at 9:45 pm.
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Old 16th Jun 2022, 10:24 pm   #28
Bufo Bill
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Default Re: HP 1825A. Time base and delay generator.

David, you are a treasure, the PSU has the fuses on the board as with your picture.
I would be more than willing to offer you a replacement pot if you like. Might need a bit of cleaning up though. Drop me a PM.
Cheers from Bill.
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Old 4th Oct 2022, 8:36 pm   #29
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Default Re: HP 1825A. Time base and delay generator.

Hi, we're nearly there I think! The Delayed and Mixed functions are working well, there were several wires with breaks that were difficult to diagnose as the faults were intermittent. The push switches have cleaned themselves up with regular use (I gave them all a bit of a workout every time I sat at the work bench for the summer).
My only trouble now is that today the Main Trigger control seems to have no effect. Haven't had the time to investigate this evening, I will let you know how my investigation goes.
Cheers from Bill.
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Old 5th Oct 2022, 3:14 pm   #30
Bufo Bill
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Default Re: HP 1825A. Time base and delay generator.

This morning I dissected the Main Trigger Level pot, cleaned it and reinstalled it. Alas it is an ex-pot, to get all John Cleese about it.
Fortunately, a summer of compulsive buying has given me a carcass or two to plunder, and now all seems well.
This is the part where I say "Finally, it's done!" And five minutes later something else expires. But that's nine tenths of the hobby for me.
Cheers from Bill.
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