Hp 204c

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hey all, I got this HP 204C for free the other day. I've learned my lesson on powering up old test equip so I'm not going to even try before replacing all the 'lytics. While I'm doing that are there any other parts I should consider replacing?
The parts list mentions "Al Elec" caps and "Ta Elec" caps, what is the differance?
Also, should I go ahead and replace the ceramics, and these odd Titanium Dioxide capacitors in here? Thanks!
 
When Tantalums "go", they go catastrophically.

With respect to the non-electrolytic caps -- you would only replace these at your peril -- HP, Fluke, Krohn-Hite, Boonton used very high quality film (polystyrene, polycarbonate) caps from TRW and GE.

It would be cheaper to get a variac and power it up slowly -- although powering a Hewlett Packard 204C isn't like powering up a prewar Hallicrafters SX-28.
 
Hi jackinnj, I may just do the aluminum elecs, there are only a half dozen in there, and wait and see about the tantalums. All the electrolytics are sprague.
The output capacitor is a 300uF 10v electrolytic. Could this be something better?
Now, my biggest concern. This one has the Option 02, rechargable ni-cads. These appear to make a voltage divider and do some free filtering for the bipolar supply maybe? Are they needed for operation? The only reason I ask is the standard version uses a discrete regulator for -/+, this version does not.
Thanks!
 
I'd suggest checking all tantalum capacitors for any short-circuits, as that's the normal failure mode for old devices. May be a better decision to replace them before powering up. Aluminum electrolytics tend to just gas or dry up, failure mode is usually lowered capacitance or totally open - usually not disastrous.

4700uF isn't big compared to what a set of nicd batteries can do... :)

Cheers
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.