Rowe r85 main pwr supp problem

I have a R85 with a main power supply board with a burnt out resistor. The board is a 6-08873-01 and the burnt resistor is at location R500 on the board. The centre two colour bands are burnt beyond recognition but the ones at each end appear to be gold at one end and tan at the other. I cant locate a copy of the schematic for the board anywhere to identify what should be there.

It has also been suggested that the board being some 30 years old probably needs its capacitors replaced. It has 3 50v 2.2uf at positions C502, C503 and C504. Additionally a large cap 50v 3300uf at position C500 and a 50v 1500uf at position C501. I was wondering if any of these may be the culprits or as they are cheap enough if I should just replace them all anyway.

Cheers and to the very helpful guys that responded to my previous post it seems that the power supply was creating the problem as tapping the power supply stopped the problem, for a while.

Cheers,
JB

On Dec 11, 10:49*am, jukebox252
wrote:
I have a R85 with a main power supply board with a burnt out resistor.
The board is a 6-08873-01 and the burnt resistor is at location R500 on
the board. The centre two colour bands are burnt beyond recognition but
the ones at each end appear to be gold at one end and tan at the other.
I cant locate a copy of the schematic for the board anywhere to identify
what should be there.


Have looked at the schematic for this:


R 500 is 1/4w 47 ohm
If this is burnt, the most likely cause is a shorted zener diode
CR501. Replace with a 7.5v zener.
It is also possible but not likely that Q503 (on heatsink on top of
case) has shorted.

The 3 small transistors are MPSA06 and I would also replace these, as
some transistors like this are known to
"leak" with age.

If any of these components are dodgy, and fail, this could (at worst)
result in full rail voltage going to the boards
this could cause at least overheating, and possibly damage.

You should consider just changing all, then you know it will be good
for
many years more.


It has also been suggested that the board being some 30 years old
probably needs its capacitors replaced. It has 3 50v 2.2uf at positions
C502, C503 and C504. Additionally a large cap 50v 3300uf at position
C500 and a 50v 1500uf at position C501. I was wondering if any of these
may be the culprits or as they are cheap enough if I should just replace
them all anyway.


I have not had any of these fail on me - but just the same, these
machines are about 30 years old, old capacitors
are notorious for going leaky, or even developing a resistance across
them and new capacitors would be an excellent idea.
They wont be too expensive, few bucks and a few minutes to install.

Since you have to replace other parts, this isnt going to add much
trouble or cost to the exercise.


Cheers and to the very helpful guys that responded to my previous post
it seems that the power supply was creating the problem as tapping the
power supply stopped the problem, for a while.


Tapping means dry joints. Resolder ALL solder joints on the board, be
generous with the solder also.
Don't use that lead free rubbish.

The 3 pin plugs going to the transistors on the heatsink may also have
dodgy pins (in the plug part).
Same for the connector on the side that takes the power out to the
machine.

While Rowe made the best jukes on the market (IMHO), and this
particular series were among the best of their 45 models,

they were not always great with soldering and other minor things



Cheers,
JB

--
jukebox252

Kreed, what more can I say but thankyou.

I followed all your advice and replaced all the components you listed and now have a jukebox working like a Swiss watch. We have had it running all day without missing a beat.

In a previous post I made earlier this year you asked if I had a copy of the fold out schematics, no I dont, the manual I have is the general one with set-up and parts. I dont have any information to the depth that you obviously do.

I would love to get my hands on a copy though if they bacame available.

Many thanks again for all of your advice in getting our R85 running again.

JB