Pioneer DVD Recorder/VCR Combo Issues - Videokarma.org TV - Video

vortalexfan · #1 09-29-2020, 01:05 PM

Greetings Everyone, the other day I picked up from the local computer repair shop that also doubles as an electronics recycling center, a 2004 Pioneer DVD Recorder/VHS Recorder Combo unit Model No. DVR-RT500 that attempts to power up but then shuts down after the initial power-up attempt, and I mean everything shuts down including the front panel display.

I was told that its a power supply issue by the shop computer shop manager.

When I got it home and took it apart and plugged it in, this large inductor (marked L501_1 on the schematic/service manual) makes a high pitched whining noise which I think that it is either shorted or just failed, and I know that was a very common issue with the Switch Mode Power Supplies in the Panasonic VCRs from the 1990s.

The Problem is that the service manual for this Combo unit doesn't list that part in the parts list and it doesn't say what the purpose is of that part in the service manual.

What I would like to know is, what the purpose is of that part, and whether or not that part could be easily sourced through a parts supplier like DigiKey or Mouser, and what the specs are of that part.

A Screenshot of the section of the service manual that shows that part in the power supply circuit is posted below.

Thanks for your help.

Ed in Tx · #2 09-29-2020, 04:20 PM

The purpose of that is AC line noise filtering either coming in or going out from the SMPS. It is simply in series with the AC coming in. That's not going to be the problem. Most likely one or more electrolytic capacitors on the secondary output side of the PS.

vortalexfan · #3 09-29-2020, 04:40 PM

Quote:

Originally Posted by Ed in Tx

The purpose of that is AC line noise filtering either coming in or going out from the SMPS. It is simply in series with the AC coming in. That's not going to be the problem. Most likely one or more electrolytic capacitors on the secondary output side of the PS.

OK, That's what I was thinking originally as well, but there don't seem to be any capacitors that appear to be bulging or anything that I can see of, but then again I guess an electrolytic doesn't always have to fail by venting...

How can I test if an electrolytic has failed or not? I'm asking because my ESR tester isn't working anymore for some reason (it reads "no or unknown part" everytime I attach an electrolytic capacitor to it, even known good ones).

Any particular values of capacitors that I should look out for that are known to be trouble prone in these things?

Ed in Tx · #4 09-29-2020, 05:17 PM

Yep they don't always look bad, which is why you need an ESR meter to test them in-circuit. Makes troubleshooting bad caps quick and easy.

vortalexfan · #5 09-29-2020, 05:36 PM

Quote:

Originally Posted by Ed in Tx

Yep they don't always look bad, which is why you need an ESR meter to test them in-circuit. Makes troubleshooting bad caps quick and easy.

Well I do have an ESR meter but like I said its malfunctioning for some reason. It refuses to recognize that a capacitor is attached and thus won't perform an ESR test.

vortalexfan · #6 09-30-2020, 01:58 PM

I got my ESR Meter Fixed, apparently I was hooking up my test leads wrong.

Anyways, I got the power supply fixed so that the Combo unit will power up now, but for some reason its only partially working as the unit powers up through the self diagnostics phase and then shows the dim clock display like its supposed to, but then the unit powers on and proceeds to show the brightened clock and channel readout and then shows both the VCR and DVD mode lights lit up and then goes into DVD Mode where its then "Frozen" in that mode with unresponsive front panel buttons, including the power button.

Do you know what that's all about?

There is a black ribbon cable that went from the power supply board to the main board on the VCR part that when I first opened up this unit it was disconnected and I reconnected it but I'm not sure if I reconnected it correctly or not (there is one wired on the ribbon cable that's white colored which i'm assuming is "Pin 1" and I installed it with the white wire connected so that it was on the left side of the cable plugin but maybe it was supposd to be facing the right side?

thanks for your help.

Ed in Tx · #7 10-01-2020, 03:16 PM

Couldn't even guess. Might be a problem induced when that ribbon cable wasn't connected or properly done before power on. Or could be some reset issue VCR or DVD section.. no telling. Maybe someone else has an idea. Good luck.

vortalexfan · #8 10-01-2020, 04:08 PM

Quote:

Originally Posted by Ed in Tx

Couldn't even guess. Might be a problem induced when that ribbon cable wasn't connected or properly done before power on. Or could be some reset issue VCR or DVD section.. no telling. Maybe someone else has an idea. Good luck.

Well I figured it out, it had more bad caps in it power supply than just the ones I replaced. So I'm just going to be recapping the whole power supply. There were some caps that had an ESR reading as high as 36 ohms.

vortalexfan · #9 10-06-2020, 09:35 PM

Well I completely Recapped the power supply for this combo unit and the thing is doing the same thing where none of the buttons on the front panel are being responsive, the unit will power itself on but then it won't let you power it off with the power switch. or let you change modes (its acting like its stuck in DVD mode) and you can't open the DVD player (even though its in DVD mode).

Any ideas as to what could be going on with this thing?