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7704A heatsink 54C/130F too hot?


John Brown
 

A free 7704A showed up here and seems to work 'OK'. I noticed the heatsink was REALLY hot to touch. The measured temperature is 130F / 54C. Is this in the normal range? (Yes this is a cross-post from the other group.)

Voltages check normal. I'm reading all the past posts and getting ready to address the trace dimming after about 5 minutes (still usable) and uneven trace (dim left to bright right), especially at faster sweep rates.

W0MPM John


Chuck Harris
 

Does the fan work?

-Chuck Harris

John Brown via groups.io wrote:

A free 7704A showed up here and seems to work 'OK'. I noticed the heatsink was REALLY hot to touch. The measured temperature is 130F / 54C. Is this in the normal range? (Yes this is a cross-post from the other group.)

Voltages check normal. I'm reading all the past posts and getting ready to address the trace dimming after about 5 minutes (still usable) and uneven trace (dim left to bright right), especially at faster sweep rates.

W0MPM John






John Brown
 

Don't see a fan on the 7704a. Searching in the manual can't find any reference or illustration showing a fan. And the temperature is even behind each of the pass transistors so it does not appear any one element is generating a bunch more heat than the others.

Maybe this is normal? But as Maui said 'Hot hot hot'. (You have to be conversant with Disney princesses to understand. My assistant is 4 1/2.)

--
W0MPM John


Colin Herbert
 

I don't think that the 7704 or 7704A have a fan. They both have SMPS power-supplies, don't they? Take a look at the back of either and you can see a sizeable heat-sink with several fins, but no vent-hole, with or without a filter, that might indicate the presence of a fan. TekWiki is your friend.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of John Brown via groups.io
Sent: 03 November 2020 17:04
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7704A heatsink 54C/130F too hot?

Don't see a fan on the 7704a. Searching in the manual can't find any reference or illustration showing a fan. And the temperature is even behind each of the pass transistors so it does not appear any one element is generating a bunch more heat than the others.

Maybe this is normal? But as Maui said 'Hot hot hot'. (You have to be conversant with Disney princesses to understand. My assistant is 4 1/2.)

--
W0MPM John


Chuck Harris
 

Looking through the manual, I see that the 7704A, like the 7904,
has no fan. The 7904A, on the other hand has a fan, hence my
question about fans...

Power transistors and rectifiers laugh at 130F heat. Many are
rated for operation up to 200C.

The real concern for the engineers is will someone, or something,
get burned by this exposed heat sink? And, the answer is no, as
long as the temperature stays below about 180F (80C), you would
touch it, and move away long before getting burned.

-Chuck Harris

Chuck Harris wrote:

Does the fan work?

-Chuck Harris

John Brown via groups.io wrote:
A free 7704A showed up here and seems to work 'OK'. I noticed the heatsink was REALLY hot to touch. The measured temperature is 130F / 54C. Is this in the normal range? (Yes this is a cross-post from the other group.)

Voltages check normal. I'm reading all the past posts and getting ready to address the trace dimming after about 5 minutes (still usable) and uneven trace (dim left to bright right), especially at faster sweep rates.

W0MPM John










Dave Seiter
 

Some 7704As have fans (I assume the newest ones), I have one.
-Dave

On Tuesday, November 3, 2020, 09:26:33 AM PST, Colin Herbert via groups.io <colingherbert=blueyonder.co.uk@groups.io> wrote:

I don't think that the 7704 or 7704A have a fan. They both have SMPS power-supplies, don't they? Take a look at the back of either and you can see a sizeable heat-sink with several fins, but no vent-hole, with or without a filter, that might indicate the presence of a fan. TekWiki is your friend.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of John Brown via groups.io
Sent: 03 November 2020 17:04
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7704A heatsink 54C/130F too hot?

Don't see a fan on the 7704a. Searching in the manual can't find any reference or illustration showing a fan. And the temperature is even behind each of the pass transistors so it does not appear any one element is generating a bunch more heat than the others.

Maybe this is normal? But as Maui said 'Hot hot hot'. (You have to be conversant with Disney princesses to understand. My assistant is 4 1/2.)

--
W0MPM John