Hi All,

I'm going through my compressors g atm and have the following
question.

The little Bambi 75/150 silent jobby won't re-start once up to
pressure. It looks like it tries but I think the control unit backs it
off if it doesn't.

From memory I *think* it's better if not on a long lead but I'm sure
that shouldn't matter as it's only a small wattage compressor.

Now I'm not sure what's *supposed* to happen on *this* compressor
(it's been a while since I last used it) but when it's reached
pressure it shuts off ok but with no "pschtt" like the other two do
AND when it does shut off the air leaks back very slowly and I think
it sounds like it's coming back into the compressor pump (it's all
sealed so I can't be sure).

So, if it's supposed to have a pump pressure release valve (and I'm
wondering if it is as that would stop it being 'silent') I wonder if
it's stuck / leaking and if so, is it something that could be cleaned
/ serviced (by me) do you know please?

It's similar to this:

http://www.bambi-air.co.uk/about-us.html

All the best ..

T i m

T i m formulated the question :
Hi All,

I'm going through my compressors g atm and have the following
question.

The little Bambi 75/150 silent jobby won't re-start once up to
pressure. It looks like it tries but I think the control unit backs it
off if it doesn't.

From memory I *think* it's better if not on a long lead but I'm sure
that shouldn't matter as it's only a small wattage compressor.

Now I'm not sure what's *supposed* to happen on *this* compressor
(it's been a while since I last used it) but when it's reached
pressure it shuts off ok but with no "pschtt" like the other two do
AND when it does shut off the air leaks back very slowly and I think
it sounds like it's coming back into the compressor pump (it's all
sealed so I can't be sure).

So, if it's supposed to have a pump pressure release valve (and I'm
wondering if it is as that would stop it being 'silent') I wonder if
it's stuck / leaking and if so, is it something that could be cleaned
/ serviced (by me) do you know please?

Certain compressors are fitted with a valve which both stops the
compressor once it is up to pressure and allow it to start against no
compressed air load, until it is up to speed.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

In article ,
T i m writes:
Hi All,

I'm going through my compressors g atm and have the following
question.

The little Bambi 75/150 silent jobby won't re-start once up to
pressure. It looks like it tries but I think the control unit backs it
off if it doesn't.

Could be trying to start with compressor outlet already presurised
when not designed to do so, or could be that the start or run
capacitor for the motor has died, which will result in reduced
starting torque (or none at all if it completely dies).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Mon, 18 Aug 2008 23:30:51 +0100, Harry Bloomfield
wrote:


Now I'm not sure what's *supposed* to happen on *this* compressor
(it's been a while since I last used it) but when it's reached
pressure it shuts off ok but with no "pschtt" like the other two do
AND when it does shut off the air leaks back very slowly and I think
it sounds like it's coming back into the compressor pump (it's all
sealed so I can't be sure).

So, if it's supposed to have a pump pressure release valve (and I'm
wondering if it is as that would stop it being 'silent') I wonder if
it's stuck / leaking and if so, is it something that could be cleaned
/ serviced (by me) do you know please?

Certain compressors are fitted with a valve which both stops the
compressor once it is up to pressure and allow it to start against no
compressed air load, until it is up to speed.

Indeed and I think what I was eluding to above Harry but because I got
this second hand a long time ago, haven't used it much in the meantime
and don't have a manual for it I'm not sure what it's supposed to do
(I know what my other two compressors are supposed to do and they both
do it) ;-)

The reason I'm not sure if this Bambi jobby is designed the same is
because it's a quiet as a fridge in operation (they are used
extensively in dentists etc) and a nice loud "PSHHHST" every time it
reaches pressure might defeat the 'silent' badge a bit?

I might give them a call and see what they say before I look at it
closer myself.

All the best ..

T i m

On 19 Aug 2008 08:29:01 GMT, (Andrew
Gabriel) wrote:

In article ,
T i m writes:
Hi All,

I'm going through my compressors g atm and have the following
question.

The little Bambi 75/150 silent jobby won't re-start once up to
pressure. It looks like it tries but I think the control unit backs it
off if it doesn't.

Could be trying to start with compressor outlet already presurised
when not designed to do so,

That was one of my thoughts Andrew, reinforced by what I *think* is it
leaking (de-pressurizing) back through the pump (I'm pretty sure it's
not leaking elsewhere).

or could be that the start or run
capacitor for the motor has died, which will result in reduced
starting torque (or none at all if it completely dies).

Ah, now there's a thing. I've got a funny feeling I've already
replaced that but it was a long time ago. The compressor hasn't been
used much since then so I wonder if these caps 'dry out' or need
forming (or is that only for DC use?) etc?

The last time I worked on a problem with this little compressor I
believe it would start if plugged directly into the wall socket but
not of on an extension lead (and how I tried it last)[1]. As it's not
raining now I'll drag it out and try it both ways again and see what
happens.

All the best ..

T i m

[1] Only about 5m and very thick cable. I use it on my ARC / MIG
welders.

T i m wrote:
On 19 Aug 2008 08:29:01 GMT, (Andrew
Gabriel) wrote:

In article ,
T i m writes:
Hi All,

I'm going through my compressors g atm and have the following
question.

The little Bambi 75/150 silent jobby won't re-start once up to
pressure. It looks like it tries but I think the control unit backs it
off if it doesn't.
Could be trying to start with compressor outlet already presurised
when not designed to do so,

That was one of my thoughts Andrew, reinforced by what I *think* is it
leaking (de-pressurizing) back through the pump (I'm pretty sure it's
not leaking elsewhere).

or could be that the start or run
capacitor for the motor has died, which will result in reduced
starting torque (or none at all if it completely dies).

Ah, now there's a thing. I've got a funny feeling I've already
replaced that but it was a long time ago. The compressor hasn't been
used much since then so I wonder if these caps 'dry out' or need
forming (or is that only for DC use?) etc?

The last time I worked on a problem with this little compressor I
believe it would start if plugged directly into the wall socket but
not of on an extension lead (and how I tried it last)[1]. As it's not
raining now I'll drag it out and try it both ways again and see what
happens.

All the best ..

T i m

[1] Only about 5m and very thick cable. I use it on my ARC / MIG
welders.


Fridge type sealed compressors don't use capacitors to start in my
experience. Instead a current controlled relay in series with the run
winding, sense the stalled current and switch in the starter winding in
parallel with the run winding until the current drops and the motor is
running. The whole arrangement is protected with an auto resetting
thermal cutout in the event of motor failure ans possibly in this case,
starting into a high pressure load.
In normal automatic operation in a fridge or freezer, the compressor is
never required to re-start until the pressure has dropped.

Bob

On Tue, 19 Aug 2008 17:40:46 +0100, Bob Minchin
wrote:



The little Bambi 75/150 silent jobby won't re-start once up to
pressure. It looks like it tries but I think the control unit backs it
off if it doesn't.



Fridge type sealed compressors don't use capacitors to start in my
experience. Instead a current controlled relay in series with the run
winding, sense the stalled current and switch in the starter winding in
parallel with the run winding until the current drops and the motor is
running. The whole arrangement is protected with an auto resetting
thermal cutout in the event of motor failure ans possibly in this case,
starting into a high pressure load.
In normal automatic operation in a fridge or freezer, the compressor is
never required to re-start until the pressure has dropped.

Hi Bob and thanks for that (interesting).

I'm not sure if this is that type of compressor. I spoke to their T/S
today and he kindly sent me a manual with exploded and wiring diagram.

This one (if different from a fridge) is a little piston compressor
with some of it's moving bits in a bath of oil?

He suggested it (as I thought) it didn't have a 'dump valve' (the
thing that normally goes 'pchsst' when it reaches pressure) but the
pipe from the pump and non_return_valve would normally drop to
atmospheric pressure between stop-start phases, giving the pump a
chance to spin up a bit (pressurizing the air in the pipe from pump to
reservoir) when starting at pressure.

He also suggested therefore the issue might be the non_return_valve,
leaking slightly and this is not untypical.

I removed it and stripped it down earlier and although there was a bit
of gunge in there it wasn't 'terrible' (mind you, it only needs a spec
of stuff in the seat I guess).

I'll pop down the workshop later, put it back together and see what
happens fingers crossed.

All the best ..

T i m

On Tue, 19 Aug 2008 19:49:15 +0100, T i m wrote:



He also suggested therefore the issue might be the non_return_valve,
leaking slightly and this is not untypical.

I removed it and stripped it down earlier and although there was a bit
of gunge in there it wasn't 'terrible' (mind you, it only needs a spec
of stuff in the seat I guess).

I'll pop down the workshop later, put it back together and see what
happens fingers crossed.

No force with me tonight it seems. :-(

In spite of the valve being visually clean it still leaks when on the
compressor and even when I blow through it?

I know it might need a bit of back pressure to really close the valve
but the actual valve part is a rounded rubber cone sprung loaded onto
a conical seat so you would have thought it would sealed pretty
easily.

Apparently they are only 15 quid so it wouldn't be a show stopper if I
had to replace it (apparently we have a Bambi dealer pretty local so
I'll find out tomorrow). I need some fresh oil and an intake filter in
any case so ...

All the best,


T i m