$20 hp 34401A repair log

[squadchannel]

In mid-March, I found something interesting. "HEWLETT-PACKARD, unknown model."
I knew right away it was a 34401A.
It didn't even have a front bezel, and it was all cracked and dented.
The getter is still intact, so the VFD seems to be okay.


It's a gamble. This is my first 6-1/2!
I won the bid. 3,400 yen ($21).



It arrived. Just as I expected, it's all banged up.
On the top panel, it says "Mitsubishi Electric Corporation Communications Equipment Works". Looks like Mitsubishi tossed it out.



I'm a worried, but I'll try turning it on for now.



Bip. It powers on. Huh? It's starting to take measurements right away without any errors.
Still a bit confused by the differences in operation compared to the 3478A, I ran the self-test.



PASS!? What about the error log?



It's a bit of a letdown. It's in such bad condition, so I was sure it must have been discarded for a reason. It seems it was just thrown away.

First. I'm going to take it apart completely.



The VFD was barely hanging on. If it had been hit in the wrong spot, it would have definitely been toast.



The parts that need replacing are the front bezel, the keypad, the (non-existent) VFD window, and the rear bezel.
Somehow, all the capacitors and tantalum capacitors were still working. But I'm replacing them anyway. It's been 30 years, after all.

[squadchannel]

The problem is how to get the entire front assembly. It's very expensive on eBay.
So I turned my focus to Taobao. It looks like a few sellers have the parts.
I contacted one of them.

"Do you have the 34401A front bezel, VFD window, keypad, and rear bezel?"
"Yes, I have them."
"I want the HP ones."
"I had to dig deep in the back of my warehouse to finally find them. Is this okay?"



The condition is perfect. The silk screen on the VFD window often wear off, but this one is perfectly intact.
This is rare and expensive. I'm prepared for that.

"How much for the whole set?"
"160 yuan is fine."

160 yuan, 3800 yen, $23. Wait, what? Is it really that cheap? It's the whole set, right?
I'll take it right away!

A few days later, despite a few issues along the way, it arrived safely.



It's perfect. Not a single scratch on the VFD window. The bezel is a bit yellowed, but a quick polish will fix that.
The rear bezel is a fake. But I don't really care. (I'll explain the difference later.)
I polished it until it was sparkling clean. I put a protective film on the VFD window. I hate glare.

[squadchannel]

I did a bunch of things before it arrived.
Repaired the dented case. Fixed it with a hammer and a piece of wood. There are a lot of scratches, but strangely enough, the HP casing doesn't really bother me.




I also replaced the capacitors.




I took all the connectors off and polished them. The D-Sub 9 was broken, so I replaced it.



The plastic on the rear banana plug is cracked. It's not a big deal, though. I'll try replacing it.
I ordered to JLC, dyed them, and swapped them out. The color's a bit different, but it doesn't bother me. It's a jack on the back that I'll never use anyway.



I also took the switch apart, applied some grease, and called it done.




I fix for the relay sparking issue I'd seen in here before. I stacked three Kaputon tape.



now it's finished.



parts list:

designator	capacity	voltage	size	replace to
C512	47	10	7343	TCJY476M016R0045E
C312	22	20	7343	TCJY226M025R0070E
C311	22	20	7343	TCJY226M025R0070E
C559	22	20	7343	TCJY226M025R0070E
C323	22	20	7343	TCJY226M025R0070E
C322	22	20	7343	TCJY226M025R0070E
C411	4.7	10	3528	TCJB475M025R0150E
C554	1	35	3528	TCJB105M063R0300E
C557	22	20	7343	TCJY226M025R0070E
C552	1	35	3528	TCJB105M063R0300E
C706	47	10	7343	TCJY476M016R0045E
C753	1	35	3528	TCJB105M063R0300E
C551	1000	50	16x25	UHW1H102MHD6
C553	1000	50	16x25	UHW1H102MHD6
C556	2200	25	16x25	UHW1E222MHD6
C752	4700	25	18x35	UHW1E472MHD
C602	1	35	3528	TCJB105M063R0300E
C603	1	35	3528	TCJB105M063R0300E
C604	1	35	3528	TCJB105M063R0300E
J704				5788793-1

[squadchannel]

Measuring 10V and the difference in the bezel.





You get it, right? "O" and "0"

[squadchannel]

To-Do List:
Firmware Update (03-01-01 -> 06-05-01)

The VFD is definitely worn out, but it still works. I won't switch to LEDs.


And now for the next project... 53181A...

[BillyO]

Very nice!

What's the total cost so far?

[squadchannel]

34401A $20 + $10 shipping

Front panel unit $23 + $6 shipping (I just checked, and I bought it for 160 yuan $23.)

caps and connector $40

Total $99

It wasn't exactly cheap? well, at least I got to enjoy the fun of fixing it.

[BillyO]

For a 34401A, that's very cheap.  Awesome in fact.