30 Jul
2014
30 Jul
'14
5:30 p.m.
I've got an HP 85a that didn't fare well in it's recent travels to me. The
flyback transformer broke away from the video board breaking 4 of the 6/7
leads (this was apparently an early flyback, it had a U shaped threaded rod
secured with nuts & washers on the backside of the video board that broke
at the outside bend). The unit did boot and run before it's trip so its
worth repairing. I've not been able to source the transformer (or the
video board) at anything below just buying a complete machine again.
Anyone got a lead on one or know of a transformer that could be substituted?
Tom
31 Jul
31 Jul
2:51 p.m.
I've got an HP 85a that didn't fare well in it's recent travels to me. The
flyback transformer broke away from the video board breaking 4 of the 6/7
leads (this was apparently an early flyback, it had a U shaped threaded rod
secured with nuts & washers on the backside of the video board that broke
at the outside bend). The unit did boot and run before it's trip so its
worth repairing. I've not been able to source the transformer (or the
video board) at anything below just buying a complete machine again.
Anyone got a lead on one or know of a transformer that could be substituted?
Ouch!. I asusme the wires are broken off close to the potting compound so
there is no way or sodlerign to the ends of the windings...
AFAIK HP never supplied the transformer as a sperate part. All reparis o
nthe HP85 were done by IC and board swapping (only socketed IC's got
replaced speawtely). SO, unless some 3rd party made an equivalent
transformer, the chances of finding the bare transformer as slim
There was a chap who appeared to be breaking up HP85s and silling the
bits on Ebay. I thimk he had the monitor unit, including the video PCB,
at one point. His prices were high to say the least, but...
-tony
4:45 p.m.
I removed the flyback with just that plan in mind. Got it successfully
removed and still had 2 of the 6 leads still in place, but then realized
that there were 5 broke transformer leads and 4 pins to solder them to with
the extra lead splitting the difference between two pins. Well, I picked
one and so far, I've managed to get the monitor to come back to life with a
nice scan but the computer refuses to boot. Will need to see if the problem
is still the video board or other. Hoping I haven't sent 800v down a 5v
line.
I've seen the ebay piece your talking about and I agree, if that the going
rate, this one might get to be a parts unit and I'll keep looking for
another.
1 Aug
1 Aug
1:54 p.m.
I removed the flyback with just that plan in mind. Got it successfully
removed and still had 2 of the 6 leads still in place, but then realized
that there were 5 broke transformer leads and 4 pins to solder them to with
the extra lead splitting the difference between two pins. Well, I picked
one and so far, I've managed to get the monitor to come back to life with a
The officil HP85 service manual (I am pretty sure it's o nthe Australian
Museum site) is called the 'Assembly Level Service Manual' which sounds
liek a boardswapper guide. It is,, but the full scheamtics are in the
back. Fig 10-6 shows the video circuitry. The pin where 2 wires go seems
to be pin 5, the one conencted to a 12V rail. This should be fairly easy
to identify.
nice scan but the computer refuses to boot. Will need
to see if the problem
is still the video board or other. Hoping I haven't sent 800v down a 5v
line.
I doubt it. I don;t think any other part of the computer runs off the
flyback circuit.
Many HP85 probleems are due to bad contacts on the ribbon cables. It's
worth checking all of them.. Then check the PSU rails, You might read
section 2-26 in the service manual too.
I've seen the ebay piece your talking about and I
agree, if that the going
rate, this one might get to be a parts unit and I'll keep looking for
another.
YEs. I thought about buying an HP85 keybaord to use with my 9915. It's
the same keyboard matrix, all I'd have to do would eb to wire up the
cable and case it. But not at that price...
-tony
5:12 p.m.
Yea, got the service manual and printed out the CRT schematic and board
layout to help trace, I missed the pin 5 double up...will need to double
check that. Yes I've been fighting those ribbon cables, in fact, I was
mulling this over today, I need to check continuity on those just to make
sure that I'd got it back together correctly, they ain't fun at all. Will
check the PSU rails. I know the machine was running before it shipped, the
fella I bought it from sent a video of it working, then promptly wadded it
up in two layers of bubble wrap and brown paper and shipped it US mangle
service.
Anyway, I've not given the machine up for lost yet, will keep poking at it
till one of us gives up.
Thanks,
Tom
On Fri, Aug 1, 2014 at 3:54 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
I removed the flyback with just that plan in mind. Got it successfully
removed and still had 2 of the 6 leads still in place, but then realized
that there were 5 broke transformer leads and 4 pins to solder them to
with
the extra lead splitting the difference between
two pins. Well, I
picked
one and so far, I've managed to get the
monitor to come back to life
with a
The officil HP85 service manual (I am pretty sure it's o nthe Australian
Museum site) is called the 'Assembly Level Service Manual' which sounds
liek a boardswapper guide. It is,, but the full scheamtics are in the
back. Fig 10-6 shows the video circuitry. The pin where 2 wires go seems
to be pin 5, the one conencted to a 12V rail. This should be fairly easy
to identify.
nice scan but the computer refuses to boot. Will
need to see if the
problem
is still the video board or other. Hoping I
haven't sent 800v down a 5v
line.
I doubt it. I don;t think any other part of the computer runs off the
flyback circuit.
Many HP85 probleems are due to bad contacts on the ribbon cables. It's
worth checking all of them.. Then check the PSU rails, You might read
section 2-26 in the service manual too.
I've seen the ebay piece your talking about
and I agree, if that the
going
rate, this one might get to be a parts unit and
I'll keep looking for
another.
YEs. I thought about buying an HP85 keybaord to use with my 9915. It's
the same keyboard matrix, all I'd have to do would eb to wire up the
cable and case it. But not at that price...
-tony
31 Jul
31 Jul
6:18 p.m.
New subject: Apple IIGS Flybacks. Was: HP 85 Flyback Transformer
BTW...
I'm still looking for a pair of flybacks for the Apple IIGS RGB monitors
:) Also, a spare power supply case for it (mine has NO power supply)
:o)
Thanks!
---
Enviado do meu Motorola PT550
Meu site: http://www.tabalabs.com.br
----- Original Message -----
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
To: <cctalk at classiccmp.org>
Sent: Thursday, July 31, 2014 6:51 PM
Subject: Re: HP 85 Flyback Transformer
I've got an HP 85a that didn't fare well in it's recent travels to me.
The
flyback transformer broke away from the video board breaking 4 of the 6/7
leads (this was apparently an early flyback, it had a U shaped threaded
rod
secured with nuts & washers on the backside of the video board that broke
at the outside bend). The unit did boot and run before it's trip so its
worth repairing. I've not been able to source the transformer (or the
video board) at anything below just buying a complete machine again.
Anyone got a lead on one or know of a transformer that could be
substituted?
Ouch!. I asusme the wires are broken off close to the potting compound so
there is no way or sodlerign to the ends of the windings...
AFAIK HP never supplied the transformer as a sperate part. All reparis o
nthe HP85 were done by IC and board swapping (only socketed IC's got
replaced speawtely). SO, unless some 3rd party made an equivalent
transformer, the chances of finding the bare transformer as slim
There was a chap who appeared to be breaking up HP85s and silling the
bits on Ebay. I thimk he had the monitor unit, including the video PCB,
at one point. His prices were high to say the least, but...
-tony 
1 Aug
1 Aug
10:42 a.m.
On 07/30/2014 5:30 PM, pdaguytom . wrote:
I've got an HP 85a that didn't fare well in
it's recent travels to me. The
flyback transformer broke away from the video board breaking 4 of the 6/7
leads (this was apparently an early flyback, it had a U shaped threaded rod
secured with nuts & washers on the backside of the video board that broke
at the outside bend). The unit did boot and run before it's trip so its
worth repairing. I've not been able to source the transformer (or the
video board) at anything below just buying a complete machine again.
Anyone got a lead on one or know of a transformer that could be substituted?
Tom
The flyback can probably be substituted if you can figure out the
frequency and output voltages and match to a similar one. Is the HV
diode separate or integrated into the flyback body? Is the insulation
wax or some other compound?
Depending on the era it is possible that HP used off-the-shelf flyback
for their monitor so if there are manufacturers markings on the flyback
that may give a guide.
There is a TV/Radio parts shop in our area that has(had?) a cross
reference for flybacks and they may be able to help -
http://mainelectronics.com/orderform.html (contact info at bottom of
this page).
I have a collection of NOS Motorola 1970s B&W monitor parts that were
used in arcade games, including a variety of flybacks. However I have no
idea if these are potentially of any use to you...
I've had some success soldering on tiny wires to flybacks where there
was just a smidgen of wire sticking out. A steady hand and a hot tip (to
melt off the varnish) can work wonders. The added wire needs to have
flex available after added so it isn't going to stress the joint if the
flyback body shifts at all.
Good hunting!
John :-#)#
--
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
www.flippers.com
"Old pinballers never die, they just flip out"
5:28 p.m.
John,
I've dug through the service manual and it offers the part number, and
voltages, will need to check if the freq. is shown. From what I can tell
from the schematic, the flyback is generating 8KV for
the CRT, 800v for
intensity through a pot on the back of the machine, 12v, and 48v.
There
are at least 2 flavors that HP sourced, I thought I had a replacement found
(it was already sold) with the same part number but looked like a newer
style, totally enclosed, where the one that came with my unit is an open
frame/coil (suitable sealed of course). I did successfully solder back the
broken leads, just had an extra lead that I wasn't sure which where it'd
come from. I think Tony may have pointed me in the right direction on
this, will need to go back and check my work. I trained in the early
eighties as a radio/tv tech then went on to flight instruct and do fire
protection design and sales for the next 25 years, just a little rusty
still. I'll check those folks out and see if they may have a cross
reference to this flyback.
Tom
On Fri, Aug 1, 2014 at 12:42 PM, John Robertson <pinball at telus.net> wrote:
On 07/30/2014 5:30 PM, pdaguytom . wrote:
I've got an HP 85a that didn't fare well
in it's recent travels to me.
The
flyback transformer broke away from the video board breaking 4 of the 6/7
leads (this was apparently an early flyback, it had a U shaped threaded
rod
secured with nuts & washers on the backside of the video board that broke
at the outside bend). The unit did boot and run before it's trip so its
worth repairing. I've not been able to source the transformer (or the
video board) at anything below just buying a complete machine again.
Anyone got a lead on one or know of a transformer that could be
substituted?
Tom
The flyback can probably be substituted if you can figure out the
frequency and
output voltages and match to a similar one. Is the HV diode
separate or integrated into the flyback body? Is the insulation wax or some
other compound?
Depending on the era it is possible that HP used off-the-shelf flyback for
their monitor so if there are manufacturers markings on the flyback that
may give a guide.
There is a TV/Radio parts shop in our area that has(had?) a cross
reference for flybacks and they may be able to help -
http://mainelectronics.com/orderform.html (contact info at bottom of this
page).
I have a collection of NOS Motorola 1970s B&W monitor parts that were used
in arcade games, including a variety of flybacks. However I have no idea if
these are potentially of any use to you...
I've had some success soldering on tiny wires to flybacks where there was
just a smidgen of wire sticking out. A steady hand and a hot tip (to melt
off the varnish) can work wonders. The added wire needs to have flex
available after added so it isn't going to stress the joint if the flyback
body shifts at all.
Good hunting!
John :-#)#
--
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
www.flippers.com
"Old pinballers never die, they just flip out"
3564
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7 comments
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participants (4)
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alexandre.tabajara＠gmail.com -
ard＠p850ug1.demon.co.uk -
pdaguytom＠gmail.com -
pinball＠telus.net