foreplay III problem help request

khingila · 3960

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Offline khingila

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on: April 11, 2011, 03:55:40 AM
i'm trying to get ready to go to work, and suddenly realise i've got a dead channel on the stereo; i've isolated it down to my extended foreplay III, which has been in problem-free use for several months. the leds on the b-side of one channel's pc board are not lit up, and i wonder if anyone can give me some suggestions for starting to troubleshoot the issue. thanks,

khingila

Offline Doc B.

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Reply #1 on: April 11, 2011, 05:21:06 AM
Give us voltage and resistance readings, per the manual.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline khingila

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Reply #2 on: April 11, 2011, 07:22:45 AM
thanks; i'll do so when i'm back home this evening.

khingila

Offline khingila

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Reply #3 on: April 11, 2011, 03:01:23 PM
all resistance readings are as per the manual; ditto voltages, with the exception of #31, where i'm reading 1.5 volts. not too surprisingly, 31 connects to the uncooperative B side of the C4S board. is solder joint reheating in order, or does this info suggest some other avenue of pursuit?

khingila

Offline Paul Joppa

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Reply #4 on: April 11, 2011, 04:22:07 PM
OK, you have a PC board so it must be an Extended Foreplay, right?  :^) 

That point should be connected to the "B" side terminal pf the PC board labeled "O". It should also be connected to the tube socket pin 8. It could be those connections are no good; less likely a bad tube, and also less likely a damaged transistor (MJE340) on the board.

Paul Joppa

Offline khingila

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Reply #5 on: April 11, 2011, 05:20:23 PM
swapping tubes lights up everything; that suggests to me that maybe my pin 8 solder joint is tenuous, and that jostling it has (temporarily) restored continuity...does that make sense?

khingila

Offline Paul Joppa

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Reply #6 on: April 11, 2011, 05:27:25 PM
Could be. Could also be a bad socket connection - a search will turn up many posts on cleaning and tightening socket connections, and on cleaning tube pins. Anyhow, glad to hear it's working again!

Paul Joppa

Offline khingila

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Reply #7 on: April 11, 2011, 05:43:19 PM
thank you, sir.

khingila

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