PL700II blues

The Rebel

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#41
Would this be something to invest in, or do I want something newer? I'm looking at similar scopes. Not well versed on what I should look to buy for this hobby.
 

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#43
The Tek scope is plenty adequate for repairs. A popular 4 channel digital scope is a Rigol ds1054z at only $350. It's a 50mhz scope that can be cracked to 100mhz. The thing I don't like about it i the trace is not as fine as the analog scopes such as the Tektronix. Ed Blackwood commented on this earlier in a post on scopes here.

If you have a scope then you need a signal generator. I have a an HP 204 which covers 1 HZ to more than 100KHZ at reasonably low distortion. It's an oscillator not a function generator. An alternative that I've used in a pinch is an app on a phone and they're free. Another low cost option for a scope is a USB type. USB scopes
 

The Rebel

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#45
The Tek scope is plenty adequate for repairs. A popular 4 channel digital scope is a Rigol ds1054z at only $350. It's a 50mhz scope that can be cracked to 100mhz. The thing I don't like about it i the trace is not as fine as the analog scopes such as the Tektronix. Ed Blackwood commented on this earlier in a post on scopes here.

If you have a scope then you need a signal generator. I have a an HP 204 which covers 1 HZ to more than 100KHZ at reasonably low distortion. It's an oscillator not a function generator. An alternative that I've used in a pinch is an app on a phone and they're free. Another low cost option for a scope is a USB type. USB scopes
That's great info! Thanks. I have much homework to do. Old hard head doesn't soak it up that easy any more.
The Tektronix I posted a pic of looks to go for under $150 shipped. Should I wait and get something different?
 

62vauxhall

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#48
It’s compact, I like that. And brand new! I’ve yet to take the plunge. Been hesitant. Concern for age related issues in my price range.

I don’t know anything about them either but got the impression somewhere that inexpensive new Chi-scopes were not worth owning. But if this one comes endorsed by Perry, it could be the one I should have.
 
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#49
Here is the link to the scope forum. scopes

It doesn't surprise me that the scope Perry listed is similar to Rigol I've got. the only difference being 2 channel vs 4. There are multiple vendors. I went with Saelig instruments as they've been around a while.
 

WOPL Sniffer

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#50
It’s compact, I like that. And brand new! I’ve yet to take the plunge. Been hesitant. Concern for age related issues in my price range.

I don’t know anything about them either but got the impression somewhere that inexpensive new Chi-scopes were not worth owning. But if this one comes endorsed by Perry, it could be the one I should have.

I could endorse a 50 year old Tektronix 475 I used in the Navy but they are too old for me. could last 6 minutes, could last 6 months..... (where did I hear that before :D)? I have limited room and being portable, you can charge it up and move around with it..... Doesn't weigh a ton and it's new. For looking at the amps and stuff, or tracing a 2Khz signal through the preamp, it works tits.... Could I fix the space shuttle with it?? Probably not but then again..... I couldn't fix the space shuttle with any scope....
 

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#51
I could endorse a 50 year old Tektronix 475 I used in the Navy but they are too old for me. could last 6 minutes, could last 6 months..... (where did I hear that before :D)? I have limited room and being portable, you can charge it up and move around with it..... Doesn't weigh a ton and it's new. For looking at the amps and stuff, or tracing a 2Khz signal through the preamp, it works tits.... Could I fix the space shuttle with it?? Probably not but then again..... I couldn't fix the space shuttle with any scope....
Now you are being modest Perry...
 

Gepetto

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#54
That's great info! Thanks. I have much homework to do. Old hard head doesn't soak it up that easy any more.
The Tektronix I posted a pic of looks to go for under $150 shipped. Should I wait and get something different?
Kevin, trying to get this thread back on your original topic. (the horror!!! :))

While a scope is a useful tool to have in your toolkit, it is not essential to you fixing your current left channel problem as your recent right channel experience has proven. Still many things to be run down.

I'll start:
Have you checked each connection into the Phoenix connector to ensure you are grabbing wire and not the insulation on the wire?
Have you bypassed the relay on the DCP on the left channel?
Have you ensured that the +/-15V is getting to the left channel by looking at the output side of R40L and R41L?
Have you ensured that none of the resistors R35L, R37L, R36L, R39L and also that D13L is OK? Remember what that misplaced ground did to the other channel.
 

The Rebel

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#55
Kevin, trying to get this thread back on your original topic. (the horror!!! :))

While a scope is a useful tool to have in your toolkit, it is not essential to you fixing your current left channel problem as your recent right channel experience has proven. Still many things to be run down.

I'll start:
Have you checked each connection into the Phoenix connector to ensure you are grabbing wire and not the insulation on the wire?
Have you bypassed the relay on the DCP on the left channel?
Have you ensured that the +/-15V is getting to the left channel by looking at the output side of R40L and R41L?
Have you ensured that none of the resistors R35L, R37L, R36L, R39L and also that D13L is OK? Remember what that misplaced ground did to the other channel.
Yessir, just got this back to the bench. I work on a lot of speakers, had to take a break from this amp for a minute.
Everything you mentioned checks out good. Except I do not know how to bypass the relay for the DCP, so I haven't checked that .
I did, however, send the top of Q1 into orbit the last thing I did. POP!! Sounded like a firecracker going off. :rolleyes:
Last thing I was checking was R41L, probe must have slipped.. BAM! then relay click(I believe) :oops::( What a dumbass. Just hope I didn't flub anything else in the process.
I need what Northwinds is having in his avatar. lol o_O
 
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