Amplifier lamp replacement

On 30 Nov, 03:03, John Fields <jfie...@austininstruments.com> wrote:
On Fri, 28 Nov 2008 19:44:34 -0800 (PST), "Dave.H"



the19...@googlemail.com> wrote:
On 27 Nov, 12:50, "Dave.H" <the19...@googlemail.com> wrote:
I have an old stereo amplifier in whch some of the indicator lamps
have blown. Unfortunately two of these are enclosed in the VU meters,
I'm wondering if it's possible to open up the meters and replace them,
if not, hot glue some replacements to the exterior.

Picture:http://picasaweb.google.com.au/the1930s/Misc#5273147456088310786

TIA

Dave
Australia

Another question I have about this amp. There are four (output)
transistor mounted on a large heatsink at the rear of the chassis, two
of these have two core wires glued on to them. These wires are
soldered in holes on the PC board that have the diode ( >| ) symbol.
What are the purpose of these wires?
I have the schematic that is glued to the bottom of the unit, I can
remove the bottom and scan it if it helps.

---
I'd guess that what's glued onto the transistors are diodes and that
they're being used as temperature sensors.

JF  
Click to expand...
I think you're right. I took another, closer look under the hood of
the amp, they are not wires like I thought, but leads of a component
covered in clear insulation. And since that component is green, with a
black band, I take it to be a diode. The reason I didn't see the diode
before, was because it's covered in glue, which has dried out on one
transistor and the diode is hanging in midair. Should I just superglue
it back on, or is there a special type of glue for this?

Dave
Australia
 
On 30 Nov, 11:41, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
Dave.H wrote:
On 30 Nov, 03:03, John Fields <jfie...@austininstruments.com> wrote:

On Fri, 28 Nov 2008 19:44:34 -0800 (PST), "Dave.H"

the19...@googlemail.com> wrote:

On 27 Nov, 12:50, "Dave.H" <the19...@googlemail.com> wrote:

I have an old stereo amplifier in whch some of the indicator lamps
have blown. Unfortunately two of these are enclosed in the VU meters,
I'm wondering if it's possible to open up the meters and replace them,
if not, hot glue some replacements to the exterior.

Picture:http://picasaweb.google.com.au/the1930s/Misc#5273147456088310786

TIA

Dave
Australia

Another question I have about this amp. There are four (output)
transistor mounted on a large heatsink at the rear of the chassis, two
of these have two core wires glued on to them. These wires are
soldered in holes on the PC board that have the diode ( >| ) symbol.
What are the purpose of these wires?
I have the schematic that is glued to the bottom of the unit, I can
remove the bottom and scan it if it helps.

---
I'd guess that what's glued onto the transistors are diodes and that
they're being used as temperature sensors.

JF  

I think you're right. I took another, closer look under the hood of
the amp, they are not wires like I thought, but leads of a component
covered in clear insulation. And since that component is green, with a
black band, I take it to be a diode. The reason I didn't see the diode
before, was because it's covered in glue, which has dried out on one
transistor and the diode is hanging in midair. Should I just superglue
it back on, or is there a special type of glue for this?

Dave
Australia

Actually, I think they are normally hot glued on.

http://webpages.charter.net/jamie_5"
Click to expand...
The original glue is light brown stuff, I wasn't able to melt it with
a soldering iron. But I'll try hot glue.

Dave
Australia
 
Jamie wrote:

Actually, I think they are normally hot glued on.
Click to expand...
That's what I'd be tempted to use too. Make sure the surfaces are grease free
before doing this. Use Isopropyl Alcohol (isopropanol) ideally. Useful stuff.
The local pharmacist was out of 500ml bottles last time I wnt there, so I bought
a full 2 litres of the stuff !

Graham
 
Sjouke Burry wrote:

Eeyore wrote:
"Dave.H" wrote:

Another question I have about this amp. There are four (output)
transistor mounted on a large heatsink at the rear of the chassis, two
of these have two core wires glued on to them.

Glued ? Do they solder to anything ?

These wires are
soldered in holes on the PC board that have the diode ( >| ) symbol.
What are the purpose of these wires?

Bizarre.

Temperature sensor,to stop over heating.
Click to expand...
In the light of further info, certainly. I wouldn't personally mount them
like that though.

Graham
 
On Sat, 29 Nov 2008 16:01:30 -0800 (PST), "Dave.H"
<the1930s@googlemail.com> wrote:

On 30 Nov, 03:03, John Fields <jfie...@austininstruments.com> wrote:
On Fri, 28 Nov 2008 19:44:34 -0800 (PST), "Dave.H"



the19...@googlemail.com> wrote:
On 27 Nov, 12:50, "Dave.H" <the19...@googlemail.com> wrote:
I have an old stereo amplifier in whch some of the indicator lamps
have blown. Unfortunately two of these are enclosed in the VU meters,
I'm wondering if it's possible to open up the meters and replace them,
if not, hot glue some replacements to the exterior.

Picture:http://picasaweb.google.com.au/the1930s/Misc#5273147456088310786

TIA

Dave
Australia

Another question I have about this amp. There are four (output)
transistor mounted on a large heatsink at the rear of the chassis, two
of these have two core wires glued on to them. These wires are
soldered in holes on the PC board that have the diode ( >| ) symbol.
What are the purpose of these wires?
I have the schematic that is glued to the bottom of the unit, I can
remove the bottom and scan it if it helps.

---
I'd guess that what's glued onto the transistors are diodes and that
they're being used as temperature sensors.

JF  

I think you're right. I took another, closer look under the hood of
the amp, they are not wires like I thought, but leads of a component
covered in clear insulation. And since that component is green, with a
black band, I take it to be a diode. The reason I didn't see the diode
before, was because it's covered in glue, which has dried out on one
transistor and the diode is hanging in midair. Should I just superglue
it back on, or is there a special type of glue for this?
Click to expand...
---
I think most cyanoacrylates have an upper temp limit of about 85C, while
epoxies go up to about 100C, so what I'd do would be to clean up the
diodes and bond them to the housing with epoxy. While it's curing I'd
make sure the diodes stayed in contact with the housing by holding them
down with a little tape.

JF
 
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