Wherw are the contacts on HP4 toner cart?

My HP4 prints black pages, one possibility is bad electrical contacts
to the toner cart.

Can anyone point to a clear diagram of where these are, on the printer
&/or the cart? (I can work out one from the other.)

I have the HP4 service manual, can't find it there but if you have a
page number please advise.

Alan wrote:
My HP4 prints black pages, one possibility is bad electrical contacts
to the toner cart.

Can anyone point to a clear diagram of where these are, on the printer
&/or the cart? (I can work out one from the other.)

I have the HP4 service manual, can't find it there but if you have a
page number please advise.

Page 7-26, Figure 7-5 and Table 7-8 in my manual gives all this information. If
cleaning the contacts on the cartridge and in the printer does not fix the
problem then the problem is likely to be as follows.
1. Toner Cartridge (not likely but easy to change to eliminate).
2. High Voltage Power Supply.
3. DC Controller
4. Formatter
In that order.
Good luck
Tony