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Electronics => Repair => Topic started by: trueblue2k2 on April 20, 2021, 05:10:17 am

Title: Hung Chang 5504 aka Beckman Philips Protek Tenma Oscilloscope
Post by: trueblue2k2 on April 20, 2021, 05:10:17 am

Hung Chang (Korea) series of mid-1980s oscilloscopes was made in 20, 40, 60, and 100 Mhz models, selling under Hung Chang, Protek, Beckman, Philips, Tenma, or other names. The 40Mhz Hung Chang 5504 sequence may be: (5) inch screen size, (5) 198[5] year, and (04) Mhz X10 rating. It has an off-white faceplate re-branded Beckman Industries 9104 or Protek 5504; or else a black faceplate as Philips PM-3209 or Tenma 72-740. "Instruction Manual" included by Hung Chang includes schematics, parts, and calibration adjustment control info. Link for Hung Chang 5504 manual:
http://www.i1epj.ham-radio-op.net/Laboratorio/file/HC5504%20Manual.pdf (http://www.i1epj.ham-radio-op.net/Laboratorio/file/HC5504%20Manual.pdf)

Title: Re: Hung Chang 5504 aka Beckman Philips Protek Tenma Oscilloscope
Post by: ssschuh on May 27, 2021, 01:42:57 pm

The link seems broken.
This one works.
http://www.i1epj.ham-radio-op.net/Laboratorio/files/HC5504%20Manual-LoRes.pdf (http://www.i1epj.ham-radio-op.net/Laboratorio/files/HC5504%20Manual-LoRes.pdf)

Thanks for sharing, I'm looking for the 5804 diagrams.
But looking at the horizontal and vertical boards on the 5504 manual (and also the 5602 that I had), they are the same as the 5804.
Unfortunately, my unit has a CPU board also, controlled via little buttons and leds on the front pannel, instead of physical the switches controlling vertical/horizontal/sweep mode. These controls are locked on ch1, so I need that circuit diagram too in order to fully repair it.
It has also other problems, like no sweep at all, even with external source, so I guess I have to diagnose the z-axis circuit.
And sometimes the dot faints, even though read out info shows always fine, so I suppose it's some z-axis input circuit issue.

Title: Re: Hung Chang 5504 aka Beckman Philips Protek Tenma Oscilloscope
Post by: linux-dude on May 30, 2022, 06:51:11 pm

I'm also looking for schema for 5804. Did you ever find it?

Sorry for resurrecting a dead thread.

Title: Re: Hung Chang 5504 aka Beckman Philips Protek Tenma Oscilloscope
Post by: ssschuh on April 14, 2023, 01:27:36 pm

I don't think the thread is dead, at least I'm still looking for info on HC5804.

I could find some rebranded specific models, but couldn't find any circuit or manual for them either.
The models are Tenma 72-925 and Protek P-2840.
I still couldn't find the rebranded models from Philips and Beckman.