This is why you DONT plug in stuff you got before having a look inside first

[HairyWombat]

I have seen this said by many before, take it apart before plugging it in.
Up to now I have not seen anything of concern, I have been very lucky

Bought a lot of Fluke bench meters and one is a Fluke 8010A, thought I would share what I found.
Looks harmless enough on the outside.


Back looks fine, HV insulation plate is missing.


Covers off, hmm what's that!!





Looks to be some dodgy TRIAC chopper to drop 240VAC to this 120VAC ONLY 8010A
The HV insulation plate was cut up and a piece jammed under the TRIAC, so that's where it went.

What a horrible thing to do to any equipment let alone a bench meter.
There are so many better solutions than this horrible mess.

From what I can tell it appears to be this.


So yeah look first and don't just assume it will be ok and some idiot has not been inside and screwed things up.
Disregarding a the dried caps killing components scenario, which I never thought of before, this is a damn good reason to check first.
After this I will always pop the cover and have a good looky first.

I did plug this in first and the meter fired up, I so wish I hadnt and never will again.

[SteveThackery]

Wow! 😳

[madires]

Poor little Fluke! I fully agree, it's a good idea to open used devices first to check for surprises. And also cheap Chinese stuff.

[amyk]

"If it looks stupid but it works, it's not stupid"?

[HairyWombat]

"If it looks stupid but it works, it's not stupid"?

Yeah normally I might agree but I'm quite sure that does not apply here with 240VAC
It's a very stupid idea, apart from the fact the transformer will probably blow the noise on the main rail would be hideous and probably take out the regulator.
Don't think I would be trusting any readings from that meter like that.

To be honest it wasn't even worth trying to convert, it has a fixed crystal frequency set for 60Hz for noise suppression.
Pretty much only good in the US, for parts anywhere else.

[andrewtaylor]

Looks to be some dodgy TRIAC chopper to drop 240VAC to this 120VAC ONLY 8010A
The HV insulation plate was cut up and a piece jammed under the TRIAC, so that's where it went.

What a horrible thing to do to any equipment let alone a bench meter.
There are so many better solutions than this horrible mess.

I suppose you will give this fluke a new tranny with a correst 240V primaray winding 

[Wazza]

Hi all,

For the Fluke 8010, to convert it from 110Vac to 240Vac the transformer and a crystal (for 50Hz operation) need to be changed. These are getting rarer these
days due to age of the 8000 series.

The missing shield is more of a concern, for safety's sake I'd only be using the meter as a parts mule.

Regards,

Waz

[HairyWombat]

I suppose you will give this fluke a new tranny with a correst 240V primaray winding 

Nah I agree with Wazza, even though its clean there is no point, she's a parts mule.
There was an 8010M in the lot with switchable voltage which is fine.

[amyk]

"If it looks stupid but it works, it's not stupid"?

Yeah normally I might agree but I'm quite sure that does not apply here with 240VAC
It's a very stupid idea, apart from the fact the transformer will probably blow the noise on the main rail would be hideous and probably take out the regulator.
Don't think I would be trusting any readings from that meter like that.

To be honest it wasn't even worth trying to convert, it has a fixed crystal frequency set for 60Hz for noise suppression.
Pretty much only good in the US, for parts anywhere else.

The last owner was probably using it like that; the glue having turned yellow-brownish indicates it has been installed for quite some time. The URL on the PCB leads to a site that went offline in 2007 but was active in 2005.

[inse]

The TRIAC circuit will surely cause some nasty switching noise you probably would avoid in a measurement device.
If there is no chance to reconfigure the transformer for 240V and no original part available, you could still place a standard print transformer inside.
And if it was dead bug style or you need two of them, there was enough space.

[HairyWombat]

The last owner was probably using it like that; the glue having turned yellow-brownish indicates it has been installed for quite some time. The URL on the PCB leads to a site that went offline in 2007 but was active in 2005.

The glue was some sort of builders epoxy, mixed badly. They probably got sued for killing someone.

The TRIAC circuit will surely cause some nasty switching noise you probably would avoid in a measurement device.
If there is no chance to reconfigure the transformer for 240V and no original part available, you could still place a standard print transformer inside.
And if it was dead bug style or you need two of them, there was enough space.

Then you have the 60Hz crystal issue, and 3.5 digit bench meters are no longer useful.
Couldn't sell it so no it's for parts unless someone here really wants it, which I highly doubt.
In fact the LCD may go into a sun damaged 8020A I got for 20bucks that would deserve it better then I will have a go at re-filming the old 8020A LCD.

[NiHaoMike]

How about a series capacitor instead of the triac and then add a zener across the DC output?

[TerraHertz]

For what it's worth, the 8010A Option 01 units (internal rechargable  battery)  ARE switchable for 110 or 220V mains, and also have two crystals (selectable) to work with 50 or 60 Hz.

[HairyWombat]

How about a series capacitor instead of the triac and then add a zener across the DC output?

It would work, not sure how long the cap would last and it's better than the TRIAC.
I don't think I like the idea for a transformer, maybe for a fan.

For what it's worth, the 8010A Option 01 units (internal rechargable  battery)  ARE switchable for 110 or 220V mains, and also have two crystals (selectable) to work with 50 or 60 Hz.

That's true and it comes with a lot more parts fitted including a tiny toroid boost circuit to produce the +- rails from the battery, would be an easy conversion if it was only 120V then.
Seems strange that the Option-01 Battery units were voltage/frequency switchable but the normal version wasn't 110V 60Hz or 240V 50Hz only.

There was an 8010M in the lot also (no dodgy with that one) it seems to come with the Option-01 battery bits by default and is switchable.
Unlike the 8050A the 8010M seems fine without the battery fitted I don't think it was ever installed but has the housing and all bits, ex RAAF.
The 8010M works fine, needs caps, so even more reason to sacrifice the 8010A

The third unit in the lot was an 8050A with battery option, removed leaky battery and cleaned it up.
This is a nice clean unit and will restore well with an LM317 Mod and caps (gotta post my non-destructive mod method when I get a chance).

[Uunoctium]

I recently bought a 3437A System Voltmeter at a bargain price.

The very first step was to remove the covers and look for the Rifa firecrackers. None!

After switching it on, all the buttons lit up and all the segments on both displays came on, but there was no response to any of the knobs.

Turning it on was a mistake, though. It’s unclear how long the previous owner had been running the device in this state – so, effectively, I had bought the damage along with it.

What bothered me was that HP had, without exception, mounted all ICs in the same orientation relative to pin 1 – but apparently not the main processor (a custom part, the white-ceramic version).

So I took screenshots from a few YouTube repair videos, and it became clear: the processor had been fitted the wrong way round in its socket. 
Normally, that’s an instant kill!

Once fitted correctly, not much changed, apart from a single “E” appearing on the display.
I then continued searching for the actual fault – and found and repaired it. The two Sprague 220 µF capacitors supplying the –6 V (and –3 V for the processor) were completely dried out. I measured just 160 nF + 50 pF.

The display was then very nervous, but all the knobs were working. However, the displayed voltage was approximately 1.5 times too high.
Cleaning the very dirty acquisition board and replacing all the electrolytics in it finally resulted in a stable zero reading, and the displayed voltages are now close to a 289.

It’s not really worth talking about a routine repair, but all kudos to HP!

I never thought a processor powered backwards would survive – but it did!


(image shows processor mounted in right orientation!)

[HairyWombat]

Got another one.
Picked up a 33120A from the bay of E for US$285 delivered with GST
He sent me pics of it hooked up to a scope even.

Got it today and something was rattling around inside, it was the main board.

What the.... it was under that much tension it was bent like a banana.



Whoever put it back together last really did not care, transformer screws were loose too.
There seems to be nothing wrong with it so not even sure why it was pulled apart, they didn't even recap it.
Sat the board on some blocks of foam and sat a fluke 87-3 with holster on top for a few hours, seemed to mostly pull flat again.
Not sure about long term stress damage to the PCB but it cant be a good thing to do to 4 layer boards.
Everything seems dated 2000/2001 so she needs caps and those 22mm 15000uF caps are getting harder to get.

So again, having a looky inside first before going near it with power is such a good motto.
Don't forget to check the mains voltage on imported gear while you are at it, got excited once and bang went the fuse on a 34401A, silly boy 

Also had a vendor think that another 34401A I got from Japan is only 110VAC, I wasn't going to tell him any different for AUD$400 delivered.

[Obin]

well, flex pcb's are getting more common these days

[Gyro]

That plastic bump stop in the middle of the PCB was clearly put on the wrong side! 
 
Those electrolytics look a very strange colour.


Edit: ...but seriously, the majority of passives seem to be oriented at 90' to the flex which has probably saved them from cracking. Hopefully there was enough lead flex on the ICs to save them from package damage. Time will tell.       

[HairyWombat]

That plastic bump stop in the middle of the PCB was clearly put on the wrong side! 
 
Those electrolytics look a very strange colour.

You mean the Kapton tape stickers they stick on top, yeah seems to be an Agilent thing.
Gemini reckons it was for early auto place machines to get suction, makes sense but I never trust anything AI says.

[Gyro]

Ah, Kapton, that makes sense.