Beseler Dichro 45 Computer

[Bill Peters]

Hi,

I just acquired a Beseler Dichro 45 Color Computer enlarger head. I seek
your help on two issues:

1) The lamp doesn't light. The fan and electronic displays seem fine.
The bulb is good.

I just have the head - none of the cables that plug into the sockets in
the bottom. Is a timer cable to the six pin connector on the bottom
needed to light the lamp?

Other advice?

2) Any advice on using the head would be welcome. What do the "status"
and "density" switch settings on the front do?

Thanks!
Bill Peters

[Ken]

Bill Peters wrote:
>
> I just have the head - none of the cables that plug into the sockets in
> the bottom. Is a timer cable to the six pin connector on the bottom
> needed to light the lamp?

Yep. Either that or the D.A.T.A. control module that plugs into the
larger plug. On mine I found that the control module needed to be
plugged in. Otherwise the timer control, when used on the six pin,
was somewhat erratic. I was using the Jobo Color Star 2000.
It may not be a problem with another timer.

What's happening is that an un-terminated input lead is acting like
an antenna and causing false triggering of the lamp control circuitry.
IIRC, there is a simple fix for this. A competent electronic tech should
be able to figure it out. I don't have access to mine at the present but
if I remember correctly, the six pin connector housing
has only two pins in it and these go to the timer.

> Other advice?

Yeah, there was a light leak from around the lever that flips the
filters out of the way for focusing. It would leak light onto the
print. Took me a while to figure out where it was coming from.

> 2) Any advice on using the head would be welcome. What do the "status"

The "status" is part of the self-check on power up. All the
numeric display lights should be lit. It basically lets you know
that it's working.

> and "density" switch settings on the front do?

It's been 5 years... but as I recall, not much.
It should be obvious what the correct position is once
you get the lamp to light up. The CYM display should
change to indicate the filter settings.

HTH,
--
 Ken

[Bill Peters]

Ken,

Thanks for the very helpful response. With the help of a friend who is
an electronics wizard I located the two active pins on the six pin
connector. These lead to a four pin isolator (of unknown type) on the
circuit board. There is a logic level voltage (4V) on the output pins of
the isolator. Shorting the output pins of the isolator with a 3300 ohm
resistor lights the lamp. Problem solved!

My friend suggests replacing all the 20 to 30 year old electrolytic
capacitors with new ones. When these fail they can take out transistors
or logic and potentially leave the circuits unfixable.

I appreciate your advice about the filter lever light leak. Since I now
have the head in pieces all over my bench I will take care to solve this
as I put it back together.

Cheers,
Bill Peters

[Bill Peters]

Ken,

Thanks for the very helpful response. With the help of a friend who is
an electronics wizard I located the two active pins on the six pin
connector. These lead to a four pin isolator (of unknown type) on the
circuit board. There is a logic level voltage (4V) on the output pins of
the isolator. Shorting the output pins of the isolator with a 3300 ohm
resistor lights the lamp. Problem solved!

My friend suggests replacing all the 20 to 30 year old electrolytic
capacitors with new ones. When these fail they can take out transistors
or logic and potentially leave the circuits unfixable.

I appreciate your advice about the filter lever light leak. Since I now
have the head in pieces all over my bench I will take care to solve this
as I put it back together.

Cheers,
Bill Peters

[Bill Peters]

Ken,

Thanks for the very helpful response. With the help of a friend who is
an electronics wizard I located the two active pins on the six pin
connector. These lead to a four pin isolator (of unknown type) on the
circuit board. There is a logic level voltage (4V) on the output pins of
the isolator. Shorting the output pins of the isolator with a 3300 ohm
resistor lights the lamp. Problem solved!

My friend suggests replacing all the 20 to 30 year old electrolytic
capacitors with new ones. When these fail they can take out transistors
or logic and potentially leave the circuits unfixable.

I appreciate your advice about the filter lever light leak. Since I now
have the head in pieces all over my bench I will take care to solve this
as I put it back together.

Cheers,
Bill Peters

[Ken]

Bill Peters wrote:
>
> With the help of a friend who is
> an electronics wizard I located the two active pins on the six pin
> connector. These lead to a four pin isolator (of unknown type) on the
> circuit board. There is a logic level voltage (4V) on the output pins of
> the isolator. Shorting the output pins of the isolator with a 3300 ohm
> resistor lights the lamp. Problem solved!

Bill,

FWIW, My color head came with a cord with the six pin connector on
one end and a standard 120 VAC male plug on the other. I plugged
that into the outlet of a Jobo Colorstar 2000 analyzer/timer.
The Jobo, like most timers, applies 120 VAC to the two wires going
to the six pin connector. Most likely the four pin isolator is a
relay, either electromechanical or solid state. The 4V logic level
on the output would explain the sensitivity to false triggering on
my head when the D.A.T.A. module wasn't plugged in. I'm sure
the D.A.T.A. module was using logic to control the head.
If false triggering is a problem, I suspect tying the offending
input lead, on the large connector, high or low will solve the
problem. I wrote Beseler's tech dept. about this yesterday.
I let you know if I get an answer.

> My friend suggests replacing all the 20 to 30 year old electrolytic
> capacitors with new ones. When these fail they can take out transistors
> or logic and potentially leave the circuits unfixable.

Good thinking!! While your in there, check the CPU socket.
If it's the tin plated type I'd replace it with a gold plated
one. I've had a lot of problems with cheap IC sockets on various
equipment I've worked on over the years. Especially when they get
old.

--
 Ken

[Bill Peters]

Ken,

Thanks for all of your very helpful suggestions. I now have the head
working and it seems to behave correctly in every respect. At first I
thought there might be a problem when the yellow read out said "d 45" in
the status mode. It took me a couple of minutes to arrive at the ah ha
that this was short hand for "Dicho 45" and an indication that all was
well. Duh!

I replaced all the electrolytic capacitors and installed a small 12V
relay rather than using the original opto-isolator to control the lamp.

I still need to learn how to properly adjust the head using the trim
pots on the bottom. It looks like these just zero the three colors but
I'd like your advice (or that of someone who has a manual) to know for
sure.

My apologies to you and the newsgroup for the multiple posts of my last
messages - an ISP problem.

Thanks again,
Bill

[c._downs]

On Wed, 23 Aug 2000 02:55:48 GMT, Bill Peters <bill....@home.com>
wrote:

Bill please contact me by Email and we will work out something on the
manual!
C. Downs
natur...@mindspring.com