smoking hp85


When I powered up my hp85 this weekend, the following happened:

1. The tape light came on
2. A burning smell eminated from the back

So I took the cover off and tried again. There are a couple of transformers near the CRT. One of them was smoking.

Any advice?




Have you tried laying an HP-10BII across it?

Sorry. Couldn't resist.


:) I don't have a 10iib but if i did...

On a more serious note, I discovered that a capacitor downstream of the transformer had gone bad (it reads shorted).

Hopefully the transformer is still good (even though it was smoking, it still reads good) and replacing the capacitor will get it working.



Nice find. There are many here who know more about electronics than I.... but I agree. If the voltages look right, the transformer should be OK. I wouldn't power it up and then go out to dinner, though...



I replaced the bad capapcitor and re-installed the transformer. I accidentally put the transformer in backwards. Belive it or not, it only blew the main fuse.

After properly re-installing the (still good) transformer, my hp85 is up and running again!! :^)

Now onto replacing the little gummy wheel so I can get the cassette drive working too.


Possibly Related Threads...
Thread Author Replies Views Last Post
  HP85 tape reader; end of tape detection inaki 9 2,596 04-25-2013, 02:25 PM
Last Post: Paul Berger (Canada)
  HP85 Programmable ROM cardtridge 82929A-service ROM not working- inaki 2 1,501 04-25-2013, 08:08 AM
Last Post: inaki
  HP85 Waveform Analysis inaki 1 891 04-23-2013, 01:20 PM
Last Post: Paul Berger (Canada)
  Authentic HP85 color? inaki 3 1,173 03-11-2013, 10:27 PM
Last Post: Calum Tait
  Hp85 PRM-85 board Roe Peterson 2 1,056 12-08-2012, 12:00 PM
Last Post: Roe Peterson
  Calculator from a smoking environment: What is to be done? Peter Murphy (Livermore) 18 3,474 12-27-2011, 05:39 PM
Last Post: robert rozee
  Some news (HP85 now A and B) Olivier De Smet 3 1,165 05-28-2010, 06:39 AM
Last Post: Johnny Bjoern Rasmussen
  How to list an HP85 ? Adrian Godwin 3 1,099 02-12-2008, 06:35 PM
Last Post: Adrian Godwin
  HP85: NOS HP98200A sealed tapes... still useful? Jose V Gavila (Spain) 5 1,551 01-21-2008, 11:38 AM
Last Post: Jose V Gavila (Spain)
  HELP! Wanted, a missing part of an HP85... Gabriele Zaverio 0 517 11-11-2007, 07:20 AM
Last Post: Gabriele Zaverio

Forum Jump: